diff --git a/.gitattributes b/.gitattributes
index 38bba729fc191..d226cebf5d81d 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -27,4 +27,5 @@
 # These should also not be modified by git.
 tests/basics/string_cr_conversion.py -text
 tests/basics/string_crlf_conversion.py -text
+tests/micropython/test_normalize_newlines.py.exp -text
 # CIRCUITPY-CHANGE: remove non-CircuitPython tests
diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 4db04e1d0eddb..c39faf99f00d2 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -9,7 +9,7 @@
 
 repos:
   - repo: https://github.com/pre-commit/pre-commit-hooks
-    rev: v5.0.0
+    rev: v6.0.0
     hooks:
       - id: check-yaml
       - id: end-of-file-fixer
@@ -55,7 +55,7 @@ repos:
         language: python
   - repo: https://github.com/astral-sh/ruff-pre-commit
     # Ruff version.
-    rev: v0.9.4
+    rev: v0.15.7
     hooks:
       # Run the linter.
       - id: ruff
@@ -63,6 +63,6 @@ repos:
       # Run the formatter.
       - id: ruff-format
   - repo: https://github.com/tox-dev/pyproject-fmt
-    rev: "v2.5.0"
+    rev: "v2.21.0"
     hooks:
       - id: pyproject-fmt
diff --git a/LICENSE_MicroPython b/LICENSE_MicroPython
index 469ae1927396d..1fad9b4134e01 100644
--- a/LICENSE_MicroPython
+++ b/LICENSE_MicroPython
@@ -1,6 +1,6 @@
 The MIT License (MIT)
 
-Copyright (c) 2013-2024 Damien P. George
+Copyright (c) 2013-2025 Damien P. George
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
diff --git a/Makefile b/Makefile
index c2aebc61f1c0b..175a1b6a3025f 100644
--- a/Makefile
+++ b/Makefile
@@ -375,5 +375,6 @@ coverage-fresh:
 	make -j -C ports/unix VARIANT=coverage
 
 .PHONY: run-tests
+# If TESTS="abc.py def.py" is specified as an arg, run only those tests. Otherwise, run all tests.
 run-tests:
-	cd tests; MICROPY_MICROPYTHON=../ports/unix/build-coverage/micropython ./run-tests.py
+	cd tests; MICROPY_MICROPYTHON=../ports/unix/build-coverage/micropython ./run-tests.py $(TESTS)
diff --git a/docs/library/collections.rst b/docs/library/collections.rst
index b006a97dcaf22..c3ec763d20e1b 100644
--- a/docs/library/collections.rst
+++ b/docs/library/collections.rst
@@ -109,3 +109,19 @@ Classes
         a 2
         w 5
         b 3
+
+    .. method:: OrderedDict.popitem()
+
+        Remove and return a (key, value) pair from the dictionary.
+        Pairs are returned in LIFO order.
+
+        .. admonition:: Difference to CPython
+            :class: attention
+
+            ``OrderedDict.popitem()`` does not support the ``last=False`` argument and
+            will always remove and return the last item if present.
+
+            A workaround for this is to use ``pop(<first_key>)`` to remove the first item::
+
+                first_key = next(iter(d))
+                d.pop(first_key)
diff --git a/docs/library/platform.rst b/docs/library/platform.rst
index c091477d84cb1..c19ef0f5df524 100644
--- a/docs/library/platform.rst
+++ b/docs/library/platform.rst
@@ -36,3 +36,11 @@ Functions
    Returns a tuple of strings *(lib, version)*, where *lib* is the name of the
    libc that MicroPython is linked to, and *version* the corresponding version
    of this libc.
+
+.. function:: processor()
+
+   Returns a string with a detailed name of the processor, if one is available.
+   If no name for the processor is known, it will return an empty string
+   instead.
+
+   This is currently available only on RISC-V targets (both 32 and 64 bits).
diff --git a/docs/library/re.rst b/docs/library/re.rst
index 19b15d2d2c299..b8aeefd90cfa4 100644
--- a/docs/library/re.rst
+++ b/docs/library/re.rst
@@ -154,8 +154,8 @@ Regex objects
 Compiled regular expression. Instances of this class are created using
 `re.compile()`.
 
-.. method:: regex.match(string)
-            regex.search(string)
+.. method:: regex.match(string, [pos, [endpos]])
+            regex.search(string, [pos, [endpos]])
             regex.sub(replace, string, count=0, flags=0, /)
 
    Similar to the module-level functions :meth:`match`, :meth:`search`
@@ -163,6 +163,16 @@ Compiled regular expression. Instances of this class are created using
    Using methods is (much) more efficient if the same regex is applied to
    multiple strings.
 
+   The optional second parameter *pos* gives an index in the string where the
+   search is to start; it defaults to ``0``. This is not completely equivalent
+   to slicing the string; the ``'^'`` pattern character matches at the real
+   beginning of the string and at positions just after a newline, but not
+   necessarily at the index where the search is to start.
+
+   The optional parameter *endpos* limits how far the string will be searched;
+   it will be as if the string is *endpos* characters long, so only the
+   characters from *pos* to ``endpos - 1`` will be searched for a match.
+
 .. method:: regex.split(string, max_split=-1, /)
 
    Split a *string* using regex. If *max_split* is given, it specifies
diff --git a/docs/library/sys.rst b/docs/library/sys.rst
index 8def36a2b07a2..c9c687df35936 100644
--- a/docs/library/sys.rst
+++ b/docs/library/sys.rst
@@ -12,17 +12,9 @@ Functions
 .. function:: exit(retval=0, /)
 
    Terminate current program with a given exit code. Underlyingly, this
-   function raise as `SystemExit` exception. If an argument is given, its
+   function raises a `SystemExit` exception. If an argument is given, its
    value given as an argument to `SystemExit`.
 
-.. function:: print_exception(exc, file=sys.stdout, /)
-
-   This function is deprecated and will be removed starting in
-   CircuitPython 10.x, `traceback.print_exception()` should be used instead.
-
-   Print exception with a traceback to a file-like object *file* (or
-   `sys.stdout` by default).
-
    .. admonition:: Difference to CPython
       :class: attention
 
@@ -52,6 +44,8 @@ Constants
    * *version* - tuple (major, minor, micro), e.g. (1, 7, 0)
    * *_machine* - string describing the underlying machine
    * *_mpy* - supported mpy file-format version (optional attribute)
+   * *_build* - string that can help identify the configuration that
+     MicroPython was built with
 
    This object is the recommended way to distinguish CircuitPython from other
    Python implementations (note that it still may not exist in the very
@@ -116,15 +110,15 @@ Constants
 
 .. data:: stderr
 
-   Standard error ``stream``.
+   Standard error `stream`.
 
 .. data:: stdin
 
-   Standard input ``stream``.
+   Standard input `stream`.
 
 .. data:: stdout
 
-   Standard output ``stream``.
+   Standard output `stream`.
 
 .. data:: version
 
diff --git a/docs/reference/glossary.rst b/docs/reference/glossary.rst
index 9e9330de4ccfe..391dc307d2343 100644
--- a/docs/reference/glossary.rst
+++ b/docs/reference/glossary.rst
@@ -186,6 +186,13 @@ Glossary
         Most MicroPython boards make a REPL available over a UART, and this is
         typically accessible on a host PC via USB.
 
+    small integer
+        MicroPython optimises the internal representation of integers such that
+        "small" values do not take up space on the heap, and calculations with
+        them do not require heap allocation. On most 32-bit ports, this
+        corresponds to values in the interval ``-2**30 <= x < 2**30``, but this
+        should be considered an implementation detail and not relied upon.
+
     stream
         Also known as a "file-like object". A Python object which provides
         sequential read-write access to the underlying data. A stream object
diff --git a/extmod/extmod.mk b/extmod/extmod.mk
index daa6f267342ae..5b2772e4e2a99 100644
--- a/extmod/extmod.mk
+++ b/extmod/extmod.mk
@@ -162,7 +162,7 @@ endif
 
 ifeq ($(MICROPY_VFS_LFS2),1)
 CFLAGS_EXTMOD += -DMICROPY_VFS_LFS2=1
-CFLAGS_THIRDPARTY += -DLFS2_NO_MALLOC -DLFS2_NO_DEBUG -DLFS2_NO_WARN -DLFS2_NO_ERROR -DLFS2_NO_ASSERT
+CFLAGS_THIRDPARTY += -DLFS2_NO_MALLOC -DLFS2_NO_DEBUG -DLFS2_NO_WARN -DLFS2_NO_ERROR -DLFS2_NO_ASSERT -DLFS2_DEFINES=extmod/littlefs-include/lfs2_defines.h
 SRC_THIRDPARTY_C += $(addprefix $(LITTLEFS_DIR)/,\
 	lfs2.c \
 	lfs2_util.c \
@@ -461,7 +461,7 @@ ESP_HOSTED_SRC_C = $(addprefix $(ESP_HOSTED_DIR)/,\
 	)
 
 ifeq ($(MICROPY_PY_BLUETOOTH),1)
-ESP_HOSTED_SRC_C += $(ESP_HOSTED_DIR)/esp_hosted_bthci.c
+ESP_HOSTED_SRC_C += $(ESP_HOSTED_DIR)/esp_hosted_bthci_uart.c
 endif
 
 # Include the protobuf-c support functions
diff --git a/extmod/lwip-include/arch/cc.h b/extmod/lwip-include/arch/cc.h
deleted file mode 100644
index 400dc6ec75de1..0000000000000
--- a/extmod/lwip-include/arch/cc.h
+++ /dev/null
@@ -1,41 +0,0 @@
-#ifndef MICROPY_INCLUDED_EXTMOD_LWIP_INCLUDE_ARCH_CC_H
-#define MICROPY_INCLUDED_EXTMOD_LWIP_INCLUDE_ARCH_CC_H
-
-#include <stdint.h>
-
-// Generate lwip's internal types from stdint
-
-typedef uint8_t u8_t;
-typedef int8_t s8_t;
-typedef uint16_t u16_t;
-typedef int16_t s16_t;
-typedef uint32_t u32_t;
-typedef int32_t s32_t;
-
-typedef u32_t mem_ptr_t;
-
-#define U16_F "hu"
-#define S16_F "hd"
-#define X16_F "hx"
-#define U32_F "u"
-#define S32_F "d"
-#define X32_F "x"
-
-#define X8_F  "02x"
-#define SZT_F "u"
-
-#define BYTE_ORDER LITTLE_ENDIAN
-
-#define LWIP_CHKSUM_ALGORITHM 2
-
-#include <assert.h>
-#define LWIP_PLATFORM_DIAG(x)
-#define LWIP_PLATFORM_ASSERT(x)  { assert(1); }
-
-//#define PACK_STRUCT_FIELD(x) x __attribute__((packed))
-#define PACK_STRUCT_FIELD(x) x
-#define PACK_STRUCT_STRUCT __attribute__((packed))
-#define PACK_STRUCT_BEGIN
-#define PACK_STRUCT_END
-
-#endif // MICROPY_INCLUDED_EXTMOD_LWIP_INCLUDE_ARCH_CC_H
diff --git a/extmod/lwip-include/arch/perf.h b/extmod/lwip-include/arch/perf.h
deleted file mode 100644
index d310fc339f162..0000000000000
--- a/extmod/lwip-include/arch/perf.h
+++ /dev/null
@@ -1,7 +0,0 @@
-#ifndef MICROPY_INCLUDED_EXTMOD_LWIP_INCLUDE_ARCH_PERF_H
-#define MICROPY_INCLUDED_EXTMOD_LWIP_INCLUDE_ARCH_PERF_H
-
-#define PERF_START    /* null definition */
-#define PERF_STOP(x)  /* null definition */
-
-#endif // MICROPY_INCLUDED_EXTMOD_LWIP_INCLUDE_ARCH_PERF_H
diff --git a/extmod/lwip-include/lwipopts.h b/extmod/lwip-include/lwipopts.h
deleted file mode 100644
index 584decfe85f83..0000000000000
--- a/extmod/lwip-include/lwipopts.h
+++ /dev/null
@@ -1,36 +0,0 @@
-#ifndef MICROPY_INCLUDED_EXTMOD_LWIP_INCLUDE_LWIPOPTS_H
-#define MICROPY_INCLUDED_EXTMOD_LWIP_INCLUDE_LWIPOPTS_H
-
-#include <py/mpconfig.h>
-#include <py/misc.h>
-#include <py/mphal.h>
-
-// We're running without an OS for this port. We don't provide any services except light protection.
-#define NO_SYS 1
-
-#define SYS_LIGHTWEIGHT_PROT 1
-#include <stdint.h>
-typedef uint32_t sys_prot_t;
-
-#define TCP_LISTEN_BACKLOG 1
-
-// We'll put these into a proper ifdef once somebody implements an ethernet driver
-#define LWIP_ARP 0
-#define LWIP_ETHERNET 0
-
-#define LWIP_DNS 1
-
-#define LWIP_NETCONN 0
-#define LWIP_SOCKET 0
-
-// CIRCUITPY-CHANGE: #if instead of #ifdef
-#if MICROPY_PY_LWIP_SLIP
-#define LWIP_HAVE_SLIPIF 1
-#endif
-
-// For now, we can simply define this as a macro for the timer code. But this function isn't
-// universal and other ports will need to do something else. It may be necessary to move
-// things like this into a port-provided header file.
-#define sys_now mp_hal_ticks_ms
-
-#endif // MICROPY_INCLUDED_EXTMOD_LWIP_INCLUDE_LWIPOPTS_H
diff --git a/extmod/lwip-include/lwipopts_common.h b/extmod/lwip-include/lwipopts_common.h
deleted file mode 100644
index 3e4230909499e..0000000000000
--- a/extmod/lwip-include/lwipopts_common.h
+++ /dev/null
@@ -1,111 +0,0 @@
-/*
- * This file is part of the MicroPython project, http://micropython.org/
- *
- * The MIT License (MIT)
- *
- * Copyright (c) 2025 Damien P. George
- *
- * Permission is hereby granted, free of charge, to any person obtaining a copy
- * of this software and associated documentation files (the "Software"), to deal
- * in the Software without restriction, including without limitation the rights
- * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
- * copies of the Software, and to permit persons to whom the Software is
- * furnished to do so, subject to the following conditions:
- *
- * The above copyright notice and this permission notice shall be included in
- * all copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
- * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
- * THE SOFTWARE.
- */
-#ifndef MICROPY_INCLUDED_LWIPOPTS_COMMON_H
-#define MICROPY_INCLUDED_LWIPOPTS_COMMON_H
-
-#include "py/mpconfig.h"
-
-// This sys-arch protection is not needed.
-// Ports either protect lwIP code with flags, or run it at PendSV priority.
-#define SYS_ARCH_DECL_PROTECT(lev) do { } while (0)
-#define SYS_ARCH_PROTECT(lev) do { } while (0)
-#define SYS_ARCH_UNPROTECT(lev) do { } while (0)
-
-#define NO_SYS                          1
-#define SYS_LIGHTWEIGHT_PROT            1
-#define MEM_ALIGNMENT                   4
-
-#define LWIP_CHKSUM_ALGORITHM           3
-#define LWIP_CHECKSUM_CTRL_PER_NETIF    1
-
-#define LWIP_ARP                        1
-#define LWIP_ETHERNET                   1
-#define LWIP_RAW                        1
-#define LWIP_NETCONN                    0
-#define LWIP_SOCKET                     0
-#define LWIP_STATS                      0
-#define LWIP_NETIF_HOSTNAME             1
-
-#define LWIP_DHCP                       1
-#define LWIP_DHCP_CHECK_LINK_UP         1
-#define LWIP_DHCP_DOES_ACD_CHECK        0 // to speed DHCP up
-#define LWIP_DNS                        1
-#define LWIP_DNS_SUPPORT_MDNS_QUERIES   1
-#define LWIP_MDNS_RESPONDER             1
-#define LWIP_IGMP                       1
-
-#if MICROPY_PY_LWIP_PPP
-#define PPP_SUPPORT                     1
-#define PAP_SUPPORT                     1
-#define CHAP_SUPPORT                    1
-#endif
-
-#define LWIP_NUM_NETIF_CLIENT_DATA      LWIP_MDNS_RESPONDER
-#define MEMP_NUM_UDP_PCB                (4 + LWIP_MDNS_RESPONDER)
-
-// The mDNS responder requires 5 timers per IP version plus 2 others. Not having enough silently breaks it.
-#define MEMP_NUM_SYS_TIMEOUT            (LWIP_NUM_SYS_TIMEOUT_INTERNAL + (LWIP_MDNS_RESPONDER * (2 + (5 * (LWIP_IPV4 + LWIP_IPV6)))))
-
-#define SO_REUSE                        1
-#define TCP_LISTEN_BACKLOG              1
-
-// TCP memory settings.
-// Default lwIP settings takes 15800 bytes; TCP d/l: 380k/s local, 7.2k/s remote; TCP u/l is very slow.
-#ifndef MEM_SIZE
-
-#if 0
-// lwIP takes 19159 bytes; TCP d/l and u/l are around 320k/s on local network.
-#define MEM_SIZE (5000)
-#define TCP_WND (4 * TCP_MSS)
-#define TCP_SND_BUF (4 * TCP_MSS)
-#endif
-
-#if 1
-// lwIP takes 26700 bytes; TCP dl/ul are around 750/600 k/s on local network.
-#define MEM_SIZE (8000)
-#define TCP_MSS (800)
-#define TCP_WND (8 * TCP_MSS)
-#define TCP_SND_BUF (8 * TCP_MSS)
-#define MEMP_NUM_TCP_SEG (32)
-#endif
-
-#if 0
-// lwIP takes 45600 bytes; TCP dl/ul are around 1200/1000 k/s on local network.
-#define MEM_SIZE (16000)
-#define TCP_MSS (1460)
-#define TCP_WND (8 * TCP_MSS)
-#define TCP_SND_BUF (8 * TCP_MSS)
-#define MEMP_NUM_TCP_SEG (32)
-#endif
-
-#endif // MEM_SIZE
-
-// Needed for PPP.
-#define sys_jiffies sys_now
-
-typedef uint32_t sys_prot_t;
-
-#endif // MICROPY_INCLUDED_LWIPOPTS_COMMON_H
diff --git a/extmod/modjson.c b/extmod/modjson.c
index 67da36f0ccf71..77f4a336aa821 100644
--- a/extmod/modjson.c
+++ b/extmod/modjson.c
@@ -227,7 +227,8 @@ static mp_obj_t _mod_json_load(mp_obj_t stream_obj, bool return_first_json) {
     for (;;) {
     cont:
         if (S_END(s)) {
-            break;
+            // Input finished abruptly in the middle of a composite entity.
+            goto fail;
         }
         mp_obj_t next = MP_OBJ_NULL;
         bool enter = false;
diff --git a/extmod/modplatform.c b/extmod/modplatform.c
index c6d4d31b97ec1..e1f5476c3b3aa 100644
--- a/extmod/modplatform.c
+++ b/extmod/modplatform.c
@@ -61,11 +61,49 @@ static mp_obj_t platform_libc_ver(size_t n_args, const mp_obj_t *pos_args, mp_ma
 }
 static MP_DEFINE_CONST_FUN_OBJ_KW(platform_libc_ver_obj, 0, platform_libc_ver);
 
+#ifdef __riscv
+static mp_obj_t platform_processor(void) {
+    #if (__riscv_xlen <= 64) && !defined(__linux__)
+    uintptr_t misa_csr = 0;
+
+    // Load the MISA CSR directly.
+    __asm volatile (
+        "csrr %0, misa \n"
+        : "+r" (misa_csr)
+        :
+        :
+        );
+
+    char processor_buffer[31] = { // "RV32"/"RV64" + up to 26 chars.
+        #if (__riscv_xlen < 64)
+        "RV32"
+        #else
+        "RV64"
+        #endif
+    };
+    mp_uint_t offset = 4;
+    for (mp_uint_t bit = 0; bit < 26; bit++) {
+        if (misa_csr & (1U << bit)) {
+            processor_buffer[offset++] = 'A' + bit;
+        }
+    }
+
+    return mp_obj_new_str(processor_buffer, offset);
+    #else
+    return MP_OBJ_NEW_QSTR(MP_QSTR_);
+    #endif
+}
+static MP_DEFINE_CONST_FUN_OBJ_0(platform_processor_obj, platform_processor);
+#endif
+
 static const mp_rom_map_elem_t modplatform_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_platform) },
     { MP_ROM_QSTR(MP_QSTR_platform), MP_ROM_PTR(&platform_platform_obj) },
     { MP_ROM_QSTR(MP_QSTR_python_compiler), MP_ROM_PTR(&platform_python_compiler_obj) },
     { MP_ROM_QSTR(MP_QSTR_libc_ver), MP_ROM_PTR(&platform_libc_ver_obj) },
+    #ifdef __riscv
+    { MP_ROM_QSTR(MP_QSTR_processor), MP_ROM_PTR(&platform_processor_obj) },
+    #endif
 };
 
 static MP_DEFINE_CONST_DICT(modplatform_globals, modplatform_globals_table);
diff --git a/extmod/modre.c b/extmod/modre.c
index ba2927eb4a8a6..36fff1d1dc668 100644
--- a/extmod/modre.c
+++ b/extmod/modre.c
@@ -196,10 +196,11 @@ static void re_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t
 
 // Note: this function can't be named re_exec because it may clash with system headers, eg on FreeBSD
 static mp_obj_t re_exec_helper(bool is_anchored, uint n_args, const mp_obj_t *args) {
-    (void)n_args;
     mp_obj_re_t *self;
+    bool was_compiled = false;
     if (mp_obj_is_type(args[0], (mp_obj_type_t *)&re_type)) {
         self = MP_OBJ_TO_PTR(args[0]);
+        was_compiled = true;
     } else {
         self = MP_OBJ_TO_PTR(mod_re_compile(1, args));
     }
@@ -207,37 +208,28 @@ static mp_obj_t re_exec_helper(bool is_anchored, uint n_args, const mp_obj_t *ar
     size_t len;
     subj.begin_line = subj.begin = mp_obj_str_get_data(args[1], &len);
     subj.end = subj.begin + len;
-    // CIRCUITPY-CHANGE
-    #if MICROPY_PY_RE_MATCH_SPAN_START_END && !(defined(MICROPY_ENABLE_DYNRUNTIME) && MICROPY_ENABLE_DYNRUNTIME)
-
-    if (n_args > 2) {
-        const mp_obj_type_t *self_type = mp_obj_get_type(args[1]);
-        mp_int_t str_len = MP_OBJ_SMALL_INT_VALUE(mp_obj_len(args[1]));
-        const byte *begin = (const byte *)subj.begin;
 
-        int pos = mp_obj_get_int(args[2]);
-        if (pos >= str_len) {
-            return mp_const_none;
-        }
-        if (pos < 0) {
-            pos = 0;
+    if (was_compiled && n_args > 2) {
+        // Arg #2 is starting-pos
+        mp_int_t startpos = mp_obj_get_int(args[2]);
+        if (startpos > (mp_int_t)len) {
+            startpos = len;
+        } else if (startpos < 0) {
+            startpos = 0;
         }
-        const byte *pos_ptr = str_index_to_ptr(self_type, begin, len, MP_OBJ_NEW_SMALL_INT(pos), true);
-
-        const byte *endpos_ptr = (const byte *)subj.end;
+        subj.begin += startpos;
         if (n_args > 3) {
-            int endpos = mp_obj_get_int(args[3]);
-            if (endpos <= pos) {
-                return mp_const_none;
+            // Arg #3 is ending-pos
+            mp_int_t endpos = mp_obj_get_int(args[3]);
+            if (endpos > (mp_int_t)len) {
+                endpos = len;
+            } else if (endpos < startpos) {
+                endpos = startpos;
             }
-            // Will cap to length
-            endpos_ptr = str_index_to_ptr(self_type, begin, len, args[3], true);
+            subj.end = subj.begin_line + endpos;
         }
-
-        subj.begin = (const char *)pos_ptr;
-        subj.end = (const char *)endpos_ptr;
     }
-    #endif
+
     int caps_num = (self->re.sub + 1) * 2;
     mp_obj_match_t *match = m_new_obj_var(mp_obj_match_t, caps, char *, caps_num);
     // cast is a workaround for a bug in msvc: it treats const char** as a const pointer instead of a pointer to pointer to const char
@@ -458,6 +450,9 @@ static mp_obj_t mod_re_compile(size_t n_args, const mp_obj_t *args) {
     const char *re_str = mp_obj_str_get_str(args[0]);
     int size = re1_5_sizecode(re_str);
     if (size == -1) {
+        #if MICROPY_ERROR_REPORTING >= MICROPY_ERROR_REPORTING_NORMAL
+        mp_raise_ValueError(MP_ERROR_TEXT("regex too complex"));
+        #endif
         goto error;
     }
     mp_obj_re_t *o = mp_obj_malloc_var(mp_obj_re_t, re.insts, char, size, (mp_obj_type_t *)&re_type);
@@ -470,6 +465,7 @@ static mp_obj_t mod_re_compile(size_t n_args, const mp_obj_t *args) {
     int error = re1_5_compilecode(&o->re, re_str);
     if (error != 0) {
     error:
+        // CIRCUITPY-CHANGE: capitalized
         mp_raise_ValueError(MP_ERROR_TEXT("Error in regex"));
     }
     #if MICROPY_PY_RE_DEBUG
diff --git a/extmod/modtime.c b/extmod/modtime.c
index deb4bb4c9ace7..ee898828a4ab1 100644
--- a/extmod/modtime.c
+++ b/extmod/modtime.c
@@ -53,26 +53,26 @@
 // - weekday is 0-6 for Mon-Sun
 // - yearday is 1-366
 static mp_obj_t time_localtime(size_t n_args, const mp_obj_t *args) {
+    timeutils_struct_time_t tm;
     if (n_args == 0 || args[0] == mp_const_none) {
         // Get current date and time.
-        return mp_time_localtime_get();
+        mp_time_localtime_get(&tm);
     } else {
         // Convert given seconds to tuple.
-        mp_int_t seconds = mp_obj_get_int(args[0]);
-        timeutils_struct_time_t tm;
+        mp_timestamp_t seconds = timeutils_obj_get_timestamp(args[0]);
         timeutils_seconds_since_epoch_to_struct_time(seconds, &tm);
-        mp_obj_t tuple[8] = {
-            tuple[0] = mp_obj_new_int(tm.tm_year),
-            tuple[1] = mp_obj_new_int(tm.tm_mon),
-            tuple[2] = mp_obj_new_int(tm.tm_mday),
-            tuple[3] = mp_obj_new_int(tm.tm_hour),
-            tuple[4] = mp_obj_new_int(tm.tm_min),
-            tuple[5] = mp_obj_new_int(tm.tm_sec),
-            tuple[6] = mp_obj_new_int(tm.tm_wday),
-            tuple[7] = mp_obj_new_int(tm.tm_yday),
-        };
-        return mp_obj_new_tuple(8, tuple);
     }
+    mp_obj_t tuple[8] = {
+        mp_obj_new_int(tm.tm_year),
+        mp_obj_new_int(tm.tm_mon),
+        mp_obj_new_int(tm.tm_mday),
+        mp_obj_new_int(tm.tm_hour),
+        mp_obj_new_int(tm.tm_min),
+        mp_obj_new_int(tm.tm_sec),
+        mp_obj_new_int(tm.tm_wday),
+        mp_obj_new_int(tm.tm_yday),
+    };
+    return mp_obj_new_tuple(8, tuple);
 }
 MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mp_time_localtime_obj, 0, 1, time_localtime);
 
@@ -90,7 +90,7 @@ static mp_obj_t time_mktime(mp_obj_t tuple) {
         mp_raise_TypeError(MP_ERROR_TEXT("mktime needs a tuple of length 8 or 9"));
     }
 
-    return mp_obj_new_int_from_uint(timeutils_mktime(mp_obj_get_int(elem[0]),
+    return timeutils_obj_from_timestamp(timeutils_mktime(mp_obj_get_int(elem[0]),
         mp_obj_get_int(elem[1]), mp_obj_get_int(elem[2]), mp_obj_get_int(elem[3]),
         mp_obj_get_int(elem[4]), mp_obj_get_int(elem[5])));
 }
diff --git a/extmod/vfs.c b/extmod/vfs.c
index 0cf93c3966c90..c4156990bcc38 100644
--- a/extmod/vfs.c
+++ b/extmod/vfs.c
@@ -101,7 +101,7 @@ mp_vfs_mount_t *mp_vfs_lookup_path(const char *path, const char **path_out) {
     return MP_STATE_VM(vfs_cur);
 }
 
-// Version of mp_vfs_lookup_path that takes and returns uPy string objects.
+// Version of mp_vfs_lookup_path that takes and returns MicroPython string objects.
 static mp_vfs_mount_t *lookup_path(mp_obj_t path_in, mp_obj_t *path_out) {
     const char *path = mp_obj_str_get_str(path_in);
     const char *p_out;
diff --git a/extmod/vfs_blockdev.c b/extmod/vfs_blockdev.c
index 0cd3cc6f0c631..74d1262364ef4 100644
--- a/extmod/vfs_blockdev.c
+++ b/extmod/vfs_blockdev.c
@@ -108,7 +108,7 @@ static int mp_vfs_blockdev_call_rw(mp_obj_t *args, size_t block_num, size_t bloc
         // and negative integer on errors. Check for positive integer
         // results as some callers (i.e. littlefs) will produce corrupt
         // results from these.
-        int i = MP_OBJ_SMALL_INT_VALUE(ret);
+        int i = mp_obj_get_int(ret);
         return i > 0 ? (-MP_EINVAL) : i;
     }
 }
diff --git a/extmod/vfs_fat.c b/extmod/vfs_fat.c
index 6267452cd32c7..95ed79eb18bd5 100644
--- a/extmod/vfs_fat.c
+++ b/extmod/vfs_fat.c
@@ -58,7 +58,7 @@
 
 // CIRCUITPY-CHANGE
 // Factoring this common call saves about 90 bytes.
-static NORETURN void mp_raise_OSError_fresult(FRESULT res) {
+static MP_NORETURN void mp_raise_OSError_fresult(FRESULT res) {
     mp_raise_OSError(fresult_to_errno_table[res]);
 }
 
diff --git a/extmod/vfs_lfsx.c b/extmod/vfs_lfsx.c
index 4b10ca3aa597c..bbdd21cfb9176 100644
--- a/extmod/vfs_lfsx.c
+++ b/extmod/vfs_lfsx.c
@@ -104,6 +104,12 @@ static void MP_VFS_LFSx(init_config)(MP_OBJ_VFS_LFSx * self, mp_obj_t bdev, size
     config->read_buffer = m_new(uint8_t, config->cache_size);
     config->prog_buffer = m_new(uint8_t, config->cache_size);
     config->lookahead_buffer = m_new(uint8_t, config->lookahead_size);
+    #ifdef LFS2_MULTIVERSION
+    // This can be set to override the on-disk lfs version.
+    // eg. for compat with lfs2 < v2.6 add the following to make:
+    // CFLAGS += '-DLFS2_MULTIVERSION=0x00020000'
+    config->disk_version = LFS2_MULTIVERSION;
+    #endif
     #endif
 }
 
@@ -300,7 +306,7 @@ static mp_obj_t MP_VFS_LFSx(chdir)(mp_obj_t self_in, mp_obj_t path_in) {
         struct LFSx_API (info) info;
         int ret = LFSx_API(stat)(&self->lfs, path, &info);
         if (ret < 0 || info.type != LFSx_MACRO(_TYPE_DIR)) {
-            mp_raise_OSError(-MP_ENOENT);
+            mp_raise_OSError(MP_ENOENT);
         }
     }
 
@@ -378,7 +384,7 @@ static mp_obj_t MP_VFS_LFSx(stat)(mp_obj_t self_in, mp_obj_t path_in) {
         mp_raise_OSError(-ret);
     }
 
-    mp_uint_t mtime = 0;
+    mp_timestamp_t mtime = 0;
     #if LFS_BUILD_VERSION == 2
     uint8_t mtime_buf[8];
     lfs2_ssize_t sz = lfs2_getattr(&self->lfs, path, LFS_ATTR_MTIME, &mtime_buf, sizeof(mtime_buf));
@@ -400,9 +406,9 @@ static mp_obj_t MP_VFS_LFSx(stat)(mp_obj_t self_in, mp_obj_t path_in) {
     t->items[4] = MP_OBJ_NEW_SMALL_INT(0); // st_uid
     t->items[5] = MP_OBJ_NEW_SMALL_INT(0); // st_gid
     t->items[6] = mp_obj_new_int_from_uint(info.size); // st_size
-    t->items[7] = mp_obj_new_int_from_uint(mtime); // st_atime
-    t->items[8] = mp_obj_new_int_from_uint(mtime); // st_mtime
-    t->items[9] = mp_obj_new_int_from_uint(mtime); // st_ctime
+    t->items[7] = timeutils_obj_from_timestamp(mtime); // st_atime
+    t->items[8] = timeutils_obj_from_timestamp(mtime); // st_mtime
+    t->items[9] = timeutils_obj_from_timestamp(mtime); // st_ctime
 
     return MP_OBJ_FROM_PTR(t);
 }
diff --git a/extmod/vfs_lfsx_file.c b/extmod/vfs_lfsx_file.c
index ab5cce50088b9..56daa53e06869 100644
--- a/extmod/vfs_lfsx_file.c
+++ b/extmod/vfs_lfsx_file.c
@@ -90,9 +90,9 @@ mp_obj_t MP_VFS_LFSx(file_open)(mp_obj_t self_in, mp_obj_t path_in, mp_obj_t mod
     }
 
     #if LFS_BUILD_VERSION == 1
-    MP_OBJ_VFS_LFSx_FILE *o = mp_obj_malloc_var_with_finaliser(MP_OBJ_VFS_LFSx_FILE, uint8_t, self->lfs.cfg->prog_size, type);
+    MP_OBJ_VFS_LFSx_FILE *o = mp_obj_malloc_var_with_finaliser(MP_OBJ_VFS_LFSx_FILE, file_buffer, uint8_t, self->lfs.cfg->prog_size, type);
     #else
-    MP_OBJ_VFS_LFSx_FILE *o = mp_obj_malloc_var_with_finaliser(MP_OBJ_VFS_LFSx_FILE, uint8_t, self->lfs.cfg->cache_size, type);
+    MP_OBJ_VFS_LFSx_FILE *o = mp_obj_malloc_var_with_finaliser(MP_OBJ_VFS_LFSx_FILE, file_buffer, uint8_t, self->lfs.cfg->cache_size, type);
     #endif
     o->vfs = self;
     #if !MICROPY_GC_CONSERVATIVE_CLEAR
diff --git a/extmod/vfs_posix.c b/extmod/vfs_posix.c
index bd9a6d84062cf..27f833e802f69 100644
--- a/extmod/vfs_posix.c
+++ b/extmod/vfs_posix.c
@@ -137,7 +137,7 @@ static mp_obj_t vfs_posix_make_new(const mp_obj_type_t *type, size_t n_args, siz
         vstr_add_char(&vfs->root, '/');
     }
     vfs->root_len = vfs->root.len;
-    vfs->readonly = false;
+    vfs->readonly = !MICROPY_VFS_POSIX_WRITABLE;
 
     return MP_OBJ_FROM_PTR(vfs);
 }
@@ -160,10 +160,21 @@ static mp_obj_t vfs_posix_umount(mp_obj_t self_in) {
 }
 static MP_DEFINE_CONST_FUN_OBJ_1(vfs_posix_umount_obj, vfs_posix_umount);
 
+static inline bool vfs_posix_is_readonly(mp_obj_vfs_posix_t *self) {
+    return !MICROPY_VFS_POSIX_WRITABLE || self->readonly;
+}
+
+static void vfs_posix_require_writable(mp_obj_t self_in) {
+    mp_obj_vfs_posix_t *self = MP_OBJ_TO_PTR(self_in);
+    if (vfs_posix_is_readonly(self)) {
+        mp_raise_OSError(MP_EROFS);
+    }
+}
+
 static mp_obj_t vfs_posix_open(mp_obj_t self_in, mp_obj_t path_in, mp_obj_t mode_in) {
     mp_obj_vfs_posix_t *self = MP_OBJ_TO_PTR(self_in);
     const char *mode = mp_obj_str_get_str(mode_in);
-    if (self->readonly
+    if (vfs_posix_is_readonly(self)
         && (strchr(mode, 'w') != NULL || strchr(mode, 'a') != NULL || strchr(mode, '+') != NULL)) {
         mp_raise_OSError(MP_EROFS);
     }
@@ -303,6 +314,7 @@ typedef struct _mp_obj_listdir_t {
 } mp_obj_listdir_t;
 
 static mp_obj_t vfs_posix_mkdir(mp_obj_t self_in, mp_obj_t path_in) {
+    vfs_posix_require_writable(self_in);
     mp_obj_vfs_posix_t *self = MP_OBJ_TO_PTR(self_in);
     const char *path = vfs_posix_get_path_str(self, path_in);
     MP_THREAD_GIL_EXIT();
@@ -320,11 +332,13 @@ static mp_obj_t vfs_posix_mkdir(mp_obj_t self_in, mp_obj_t path_in) {
 static MP_DEFINE_CONST_FUN_OBJ_2(vfs_posix_mkdir_obj, vfs_posix_mkdir);
 
 static mp_obj_t vfs_posix_remove(mp_obj_t self_in, mp_obj_t path_in) {
+    vfs_posix_require_writable(self_in);
     return vfs_posix_fun1_helper(self_in, path_in, unlink);
 }
 static MP_DEFINE_CONST_FUN_OBJ_2(vfs_posix_remove_obj, vfs_posix_remove);
 
 static mp_obj_t vfs_posix_rename(mp_obj_t self_in, mp_obj_t old_path_in, mp_obj_t new_path_in) {
+    vfs_posix_require_writable(self_in);
     mp_obj_vfs_posix_t *self = MP_OBJ_TO_PTR(self_in);
     const char *old_path = vfs_posix_get_path_str(self, old_path_in);
     const char *new_path = vfs_posix_get_path_str(self, new_path_in);
@@ -339,6 +353,7 @@ static mp_obj_t vfs_posix_rename(mp_obj_t self_in, mp_obj_t old_path_in, mp_obj_
 static MP_DEFINE_CONST_FUN_OBJ_3(vfs_posix_rename_obj, vfs_posix_rename);
 
 static mp_obj_t vfs_posix_rmdir(mp_obj_t self_in, mp_obj_t path_in) {
+    vfs_posix_require_writable(self_in);
     return vfs_posix_fun1_helper(self_in, path_in, rmdir);
 }
 static MP_DEFINE_CONST_FUN_OBJ_2(vfs_posix_rmdir_obj, vfs_posix_rmdir);
diff --git a/extmod/vfs_reader.c b/extmod/vfs_reader.c
index de5c4e03d3c13..6c36770295be6 100644
--- a/extmod/vfs_reader.c
+++ b/extmod/vfs_reader.c
@@ -83,7 +83,7 @@ void mp_reader_new_file(mp_reader_t *reader, qstr filename) {
     };
     mp_obj_t file = mp_vfs_open(MP_ARRAY_SIZE(args), &args[0], (mp_map_t *)&mp_const_empty_map);
 
-    const mp_stream_p_t *stream_p = mp_get_stream(file);
+    const mp_stream_p_t *stream_p = mp_get_stream_raise(file, MP_STREAM_OP_READ);
     int errcode = 0;
 
     #if MICROPY_VFS_ROM
diff --git a/frozen/Adafruit_CircuitPython_asyncio b/frozen/Adafruit_CircuitPython_asyncio
index e69ac03dccfd8..1f9fee3c5d99d 160000
--- a/frozen/Adafruit_CircuitPython_asyncio
+++ b/frozen/Adafruit_CircuitPython_asyncio
@@ -1 +1 @@
-Subproject commit e69ac03dccfd87ccaf3655dc751331ff922f525f
+Subproject commit 1f9fee3c5d99d60b069c4a366678b391c198d955
diff --git a/lib/berkeley-db-1.xx b/lib/berkeley-db-1.xx
index 85373b548f1fb..0f3bb6947c2f5 160000
--- a/lib/berkeley-db-1.xx
+++ b/lib/berkeley-db-1.xx
@@ -1 +1 @@
-Subproject commit 85373b548f1fb0119a463582570b44189dfb09ae
+Subproject commit 0f3bb6947c2f57233916dccd7bb425d7bf86e5a6
diff --git a/lib/libm_dbl/libm.h b/lib/libm_dbl/libm.h
index cbae6916625e2..fa49ad1cddda5 100644
--- a/lib/libm_dbl/libm.h
+++ b/lib/libm_dbl/libm.h
@@ -89,7 +89,9 @@ do {                                              \
   (d) = __u.f;                                    \
 } while (0)
 
+#if !defined(DBL_EPSILON)
 #define DBL_EPSILON 2.22044604925031308085e-16
+#endif
 
 int __rem_pio2(double, double*);
 int __rem_pio2_large(double*, double*, int, int, int);
diff --git a/lib/libm_dbl/rint.c b/lib/libm_dbl/rint.c
index fbba390e7d723..b85dec8f2465e 100644
--- a/lib/libm_dbl/rint.c
+++ b/lib/libm_dbl/rint.c
@@ -2,7 +2,7 @@
 #include <math.h>
 #include <stdint.h>
 
-#if FLT_EVAL_METHOD==0 || FLT_EVAL_METHOD==1
+#if FLT_EVAL_METHOD==0 || FLT_EVAL_METHOD==1 || FLT_EVAL_METHOD==16
 #define EPS DBL_EPSILON
 #elif FLT_EVAL_METHOD==2
 #define EPS LDBL_EPSILON
diff --git a/lib/littlefs/lfs2.c b/lib/littlefs/lfs2.c
index 613213669c8f7..8d18b7d110521 100644
--- a/lib/littlefs/lfs2.c
+++ b/lib/littlefs/lfs2.c
@@ -93,6 +93,7 @@ static int lfs2_bd_read(lfs2_t *lfs2,
             // bypass cache?
             diff = lfs2_aligndown(diff, lfs2->cfg->read_size);
             int err = lfs2->cfg->read(lfs2->cfg, block, off, data, diff);
+            LFS2_ASSERT(err <= 0);
             if (err) {
                 return err;
             }
@@ -282,6 +283,21 @@ static int lfs2_bd_erase(lfs2_t *lfs2, lfs2_block_t block) {
 
 
 /// Small type-level utilities ///
+
+// some operations on paths
+static inline lfs2_size_t lfs2_path_namelen(const char *path) {
+    return strcspn(path, "/");
+}
+
+static inline bool lfs2_path_islast(const char *path) {
+    lfs2_size_t namelen = lfs2_path_namelen(path);
+    return path[namelen + strspn(path + namelen, "/")] == '\0';
+}
+
+static inline bool lfs2_path_isdir(const char *path) {
+    return path[lfs2_path_namelen(path)] != '\0';
+}
+
 // operations on block pairs
 static inline void lfs2_pair_swap(lfs2_block_t pair[2]) {
     lfs2_block_t t = pair[0];
@@ -389,18 +405,15 @@ struct lfs2_diskoff {
 
 // operations on global state
 static inline void lfs2_gstate_xor(lfs2_gstate_t *a, const lfs2_gstate_t *b) {
-    for (int i = 0; i < 3; i++) {
-        ((uint32_t*)a)[i] ^= ((const uint32_t*)b)[i];
-    }
+    a->tag ^= b->tag;
+    a->pair[0] ^= b->pair[0];
+    a->pair[1] ^= b->pair[1];
 }
 
 static inline bool lfs2_gstate_iszero(const lfs2_gstate_t *a) {
-    for (int i = 0; i < 3; i++) {
-        if (((uint32_t*)a)[i] != 0) {
-            return false;
-        }
-    }
-    return true;
+    return a->tag == 0
+            && a->pair[0] == 0
+            && a->pair[1] == 0;
 }
 
 #ifndef LFS2_READONLY
@@ -550,9 +563,9 @@ static int lfs2_dir_compact(lfs2_t *lfs2,
         lfs2_mdir_t *source, uint16_t begin, uint16_t end);
 static lfs2_ssize_t lfs2_file_flushedwrite(lfs2_t *lfs2, lfs2_file_t *file,
         const void *buffer, lfs2_size_t size);
-static lfs2_ssize_t lfs2_file_rawwrite(lfs2_t *lfs2, lfs2_file_t *file,
+static lfs2_ssize_t lfs2_file_write_(lfs2_t *lfs2, lfs2_file_t *file,
         const void *buffer, lfs2_size_t size);
-static int lfs2_file_rawsync(lfs2_t *lfs2, lfs2_file_t *file);
+static int lfs2_file_sync_(lfs2_t *lfs2, lfs2_file_t *file);
 static int lfs2_file_outline(lfs2_t *lfs2, lfs2_file_t *file);
 static int lfs2_file_flush(lfs2_t *lfs2, lfs2_file_t *file);
 
@@ -574,65 +587,72 @@ static int lfs21_traverse(lfs2_t *lfs2,
         int (*cb)(void*, lfs2_block_t), void *data);
 #endif
 
-static int lfs2_dir_rawrewind(lfs2_t *lfs2, lfs2_dir_t *dir);
+static int lfs2_dir_rewind_(lfs2_t *lfs2, lfs2_dir_t *dir);
 
 static lfs2_ssize_t lfs2_file_flushedread(lfs2_t *lfs2, lfs2_file_t *file,
         void *buffer, lfs2_size_t size);
-static lfs2_ssize_t lfs2_file_rawread(lfs2_t *lfs2, lfs2_file_t *file,
+static lfs2_ssize_t lfs2_file_read_(lfs2_t *lfs2, lfs2_file_t *file,
         void *buffer, lfs2_size_t size);
-static int lfs2_file_rawclose(lfs2_t *lfs2, lfs2_file_t *file);
-static lfs2_soff_t lfs2_file_rawsize(lfs2_t *lfs2, lfs2_file_t *file);
+static int lfs2_file_close_(lfs2_t *lfs2, lfs2_file_t *file);
+static lfs2_soff_t lfs2_file_size_(lfs2_t *lfs2, lfs2_file_t *file);
 
-static lfs2_ssize_t lfs2_fs_rawsize(lfs2_t *lfs2);
-static int lfs2_fs_rawtraverse(lfs2_t *lfs2,
+static lfs2_ssize_t lfs2_fs_size_(lfs2_t *lfs2);
+static int lfs2_fs_traverse_(lfs2_t *lfs2,
         int (*cb)(void *data, lfs2_block_t block), void *data,
         bool includeorphans);
 
 static int lfs2_deinit(lfs2_t *lfs2);
-static int lfs2_rawunmount(lfs2_t *lfs2);
+static int lfs2_unmount_(lfs2_t *lfs2);
 
 
 /// Block allocator ///
+
+// allocations should call this when all allocated blocks are committed to
+// the filesystem
+//
+// after a checkpoint, the block allocator may realloc any untracked blocks
+static void lfs2_alloc_ckpoint(lfs2_t *lfs2) {
+    lfs2->lookahead.ckpoint = lfs2->block_count;
+}
+
+// drop the lookahead buffer, this is done during mounting and failed
+// traversals in order to avoid invalid lookahead state
+static void lfs2_alloc_drop(lfs2_t *lfs2) {
+    lfs2->lookahead.size = 0;
+    lfs2->lookahead.next = 0;
+    lfs2_alloc_ckpoint(lfs2);
+}
+
 #ifndef LFS2_READONLY
 static int lfs2_alloc_lookahead(void *p, lfs2_block_t block) {
     lfs2_t *lfs2 = (lfs2_t*)p;
-    lfs2_block_t off = ((block - lfs2->free.off)
+    lfs2_block_t off = ((block - lfs2->lookahead.start)
             + lfs2->block_count) % lfs2->block_count;
 
-    if (off < lfs2->free.size) {
-        lfs2->free.buffer[off / 32] |= 1U << (off % 32);
+    if (off < lfs2->lookahead.size) {
+        lfs2->lookahead.buffer[off / 8] |= 1U << (off % 8);
     }
 
     return 0;
 }
 #endif
 
-// indicate allocated blocks have been committed into the filesystem, this
-// is to prevent blocks from being garbage collected in the middle of a
-// commit operation
-static void lfs2_alloc_ack(lfs2_t *lfs2) {
-    lfs2->free.ack = lfs2->block_count;
-}
-
-// drop the lookahead buffer, this is done during mounting and failed
-// traversals in order to avoid invalid lookahead state
-static void lfs2_alloc_drop(lfs2_t *lfs2) {
-    lfs2->free.size = 0;
-    lfs2->free.i = 0;
-    lfs2_alloc_ack(lfs2);
-}
-
 #ifndef LFS2_READONLY
-static int lfs2_fs_rawgc(lfs2_t *lfs2) {
-    // Move free offset at the first unused block (lfs2->free.i)
-    // lfs2->free.i is equal lfs2->free.size when all blocks are used
-    lfs2->free.off = (lfs2->free.off + lfs2->free.i) % lfs2->block_count;
-    lfs2->free.size = lfs2_min(8*lfs2->cfg->lookahead_size, lfs2->free.ack);
-    lfs2->free.i = 0;
+static int lfs2_alloc_scan(lfs2_t *lfs2) {
+    // move lookahead buffer to the first unused block
+    //
+    // note we limit the lookahead buffer to at most the amount of blocks
+    // checkpointed, this prevents the math in lfs2_alloc from underflowing
+    lfs2->lookahead.start = (lfs2->lookahead.start + lfs2->lookahead.next)
+            % lfs2->block_count;
+    lfs2->lookahead.next = 0;
+    lfs2->lookahead.size = lfs2_min(
+            8*lfs2->cfg->lookahead_size,
+            lfs2->lookahead.ckpoint);
 
     // find mask of free blocks from tree
-    memset(lfs2->free.buffer, 0, lfs2->cfg->lookahead_size);
-    int err = lfs2_fs_rawtraverse(lfs2, lfs2_alloc_lookahead, lfs2, true);
+    memset(lfs2->lookahead.buffer, 0, lfs2->cfg->lookahead_size);
+    int err = lfs2_fs_traverse_(lfs2, lfs2_alloc_lookahead, lfs2, true);
     if (err) {
         lfs2_alloc_drop(lfs2);
         return err;
@@ -645,36 +665,49 @@ static int lfs2_fs_rawgc(lfs2_t *lfs2) {
 #ifndef LFS2_READONLY
 static int lfs2_alloc(lfs2_t *lfs2, lfs2_block_t *block) {
     while (true) {
-        while (lfs2->free.i != lfs2->free.size) {
-            lfs2_block_t off = lfs2->free.i;
-            lfs2->free.i += 1;
-            lfs2->free.ack -= 1;
-
-            if (!(lfs2->free.buffer[off / 32] & (1U << (off % 32)))) {
+        // scan our lookahead buffer for free blocks
+        while (lfs2->lookahead.next < lfs2->lookahead.size) {
+            if (!(lfs2->lookahead.buffer[lfs2->lookahead.next / 8]
+                    & (1U << (lfs2->lookahead.next % 8)))) {
                 // found a free block
-                *block = (lfs2->free.off + off) % lfs2->block_count;
-
-                // eagerly find next off so an alloc ack can
-                // discredit old lookahead blocks
-                while (lfs2->free.i != lfs2->free.size &&
-                        (lfs2->free.buffer[lfs2->free.i / 32]
-                            & (1U << (lfs2->free.i % 32)))) {
-                    lfs2->free.i += 1;
-                    lfs2->free.ack -= 1;
+                *block = (lfs2->lookahead.start + lfs2->lookahead.next)
+                        % lfs2->block_count;
+
+                // eagerly find next free block to maximize how many blocks
+                // lfs2_alloc_ckpoint makes available for scanning
+                while (true) {
+                    lfs2->lookahead.next += 1;
+                    lfs2->lookahead.ckpoint -= 1;
+
+                    if (lfs2->lookahead.next >= lfs2->lookahead.size
+                            || !(lfs2->lookahead.buffer[lfs2->lookahead.next / 8]
+                                & (1U << (lfs2->lookahead.next % 8)))) {
+                        return 0;
+                    }
                 }
-
-                return 0;
             }
+
+            lfs2->lookahead.next += 1;
+            lfs2->lookahead.ckpoint -= 1;
         }
 
-        // check if we have looked at all blocks since last ack
-        if (lfs2->free.ack == 0) {
-            LFS2_ERROR("No more free space %"PRIu32,
-                    lfs2->free.i + lfs2->free.off);
+        // In order to keep our block allocator from spinning forever when our
+        // filesystem is full, we mark points where there are no in-flight
+        // allocations with a checkpoint before starting a set of allocations.
+        //
+        // If we've looked at all blocks since the last checkpoint, we report
+        // the filesystem as out of storage.
+        //
+        if (lfs2->lookahead.ckpoint <= 0) {
+            LFS2_ERROR("No more free space 0x%"PRIx32,
+                    (lfs2->lookahead.start + lfs2->lookahead.next)
+                        % lfs2->block_count);
             return LFS2_ERR_NOSPC;
         }
 
-        int err = lfs2_fs_rawgc(lfs2);
+        // No blocks in our lookahead buffer, we need to scan the filesystem for
+        // unused blocks in the next lookahead window.
+        int err = lfs2_alloc_scan(lfs2);
         if(err) {
             return err;
         }
@@ -690,11 +723,14 @@ static lfs2_stag_t lfs2_dir_getslice(lfs2_t *lfs2, const lfs2_mdir_t *dir,
     lfs2_tag_t ntag = dir->etag;
     lfs2_stag_t gdiff = 0;
 
+    // synthetic moves
     if (lfs2_gstate_hasmovehere(&lfs2->gdisk, dir->pair) &&
-            lfs2_tag_id(gmask) != 0 &&
-            lfs2_tag_id(lfs2->gdisk.tag) <= lfs2_tag_id(gtag)) {
-        // synthetic moves
-        gdiff -= LFS2_MKTAG(0, 1, 0);
+            lfs2_tag_id(gmask) != 0) {
+        if (lfs2_tag_id(lfs2->gdisk.tag) == lfs2_tag_id(gtag)) {
+            return LFS2_ERR_NOENT;
+        } else if (lfs2_tag_id(lfs2->gdisk.tag) < lfs2_tag_id(gtag)) {
+            gdiff -= LFS2_MKTAG(0, 1, 0);
+        }
     }
 
     // iterate over dir block backwards (for faster lookups)
@@ -704,6 +740,7 @@ static lfs2_stag_t lfs2_dir_getslice(lfs2_t *lfs2, const lfs2_mdir_t *dir,
         int err = lfs2_bd_read(lfs2,
                 NULL, &lfs2->rcache, sizeof(ntag),
                 dir->pair[0], off, &ntag, sizeof(ntag));
+        LFS2_ASSERT(err <= 0);
         if (err) {
             return err;
         }
@@ -732,6 +769,7 @@ static lfs2_stag_t lfs2_dir_getslice(lfs2_t *lfs2, const lfs2_mdir_t *dir,
             err = lfs2_bd_read(lfs2,
                     NULL, &lfs2->rcache, diff,
                     dir->pair[0], off+sizeof(tag)+goff, gbuffer, diff);
+            LFS2_ASSERT(err <= 0);
             if (err) {
                 return err;
             }
@@ -793,9 +831,6 @@ static int lfs2_dir_getread(lfs2_t *lfs2, const lfs2_mdir_t *dir,
                 size -= diff;
                 continue;
             }
-
-            // rcache takes priority
-            diff = lfs2_min(diff, rcache->off-off);
         }
 
         // load to cache, first condition can no longer fail
@@ -1247,6 +1282,7 @@ static lfs2_stag_t lfs2_dir_fetchmatch(lfs2_t *lfs2,
                     if (err == LFS2_ERR_CORRUPT) {
                         break;
                     }
+                    return err;
                 }
 
                 lfs2_fcrc_fromle32(&fcrc);
@@ -1438,32 +1474,46 @@ static int lfs2_dir_find_match(void *data,
     return LFS2_CMP_EQ;
 }
 
+// lfs2_dir_find tries to set path and id even if file is not found
+//
+// returns:
+// - 0                  if file is found
+// - LFS2_ERR_NOENT      if file or parent is not found
+// - LFS2_ERR_NOTDIR     if parent is not a dir
 static lfs2_stag_t lfs2_dir_find(lfs2_t *lfs2, lfs2_mdir_t *dir,
         const char **path, uint16_t *id) {
     // we reduce path to a single name if we can find it
     const char *name = *path;
-    if (id) {
-        *id = 0x3ff;
-    }
 
     // default to root dir
     lfs2_stag_t tag = LFS2_MKTAG(LFS2_TYPE_DIR, 0x3ff, 0);
     dir->tail[0] = lfs2->root[0];
     dir->tail[1] = lfs2->root[1];
 
+    // empty paths are not allowed
+    if (*name == '\0') {
+        return LFS2_ERR_INVAL;
+    }
+
     while (true) {
 nextname:
-        // skip slashes
-        name += strspn(name, "/");
+        // skip slashes if we're a directory
+        if (lfs2_tag_type3(tag) == LFS2_TYPE_DIR) {
+            name += strspn(name, "/");
+        }
         lfs2_size_t namelen = strcspn(name, "/");
 
-        // skip '.' and root '..'
-        if ((namelen == 1 && memcmp(name, ".", 1) == 0) ||
-            (namelen == 2 && memcmp(name, "..", 2) == 0)) {
+        // skip '.'
+        if (namelen == 1 && memcmp(name, ".", 1) == 0) {
             name += namelen;
             goto nextname;
         }
 
+        // error on unmatched '..', trying to go above root?
+        if (namelen == 2 && memcmp(name, "..", 2) == 0) {
+            return LFS2_ERR_INVAL;
+        }
+
         // skip if matched by '..' in name
         const char *suffix = name + namelen;
         lfs2_size_t sufflen;
@@ -1475,7 +1525,9 @@ static lfs2_stag_t lfs2_dir_find(lfs2_t *lfs2, lfs2_mdir_t *dir,
                 break;
             }
 
-            if (sufflen == 2 && memcmp(suffix, "..", 2) == 0) {
+            if (sufflen == 1 && memcmp(suffix, ".", 1) == 0) {
+                // noop
+            } else if (sufflen == 2 && memcmp(suffix, "..", 2) == 0) {
                 depth -= 1;
                 if (depth == 0) {
                     name = suffix + sufflen;
@@ -1489,14 +1541,14 @@ static lfs2_stag_t lfs2_dir_find(lfs2_t *lfs2, lfs2_mdir_t *dir,
         }
 
         // found path
-        if (name[0] == '\0') {
+        if (*name == '\0') {
             return tag;
         }
 
         // update what we've found so far
         *path = name;
 
-        // only continue if we hit a directory
+        // only continue if we're a directory
         if (lfs2_tag_type3(tag) != LFS2_TYPE_DIR) {
             return LFS2_ERR_NOTDIR;
         }
@@ -1516,8 +1568,7 @@ static lfs2_stag_t lfs2_dir_find(lfs2_t *lfs2, lfs2_mdir_t *dir,
             tag = lfs2_dir_fetchmatch(lfs2, dir, dir->tail,
                     LFS2_MKTAG(0x780, 0, 0),
                     LFS2_MKTAG(LFS2_TYPE_NAME, 0, namelen),
-                     // are we last name?
-                    (strchr(name, '/') == NULL) ? id : NULL,
+                    id,
                     lfs2_dir_find_match, &(struct lfs2_dir_find_match){
                         lfs2, name, namelen});
             if (tag < 0) {
@@ -2105,13 +2156,14 @@ static int lfs2_dir_splittingcompact(lfs2_t *lfs2, lfs2_mdir_t *dir,
             // And we cap at half a block to avoid degenerate cases with
             // nearly-full metadata blocks.
             //
+            lfs2_size_t metadata_max = (lfs2->cfg->metadata_max)
+                    ? lfs2->cfg->metadata_max
+                    : lfs2->cfg->block_size;
             if (end - split < 0xff
                     && size <= lfs2_min(
-                        lfs2->cfg->block_size - 40,
+                        metadata_max - 40,
                         lfs2_alignup(
-                            (lfs2->cfg->metadata_max
-                                ? lfs2->cfg->metadata_max
-                                : lfs2->cfg->block_size)/2,
+                            metadata_max/2,
                             lfs2->cfg->prog_size))) {
                 break;
             }
@@ -2146,14 +2198,16 @@ static int lfs2_dir_splittingcompact(lfs2_t *lfs2, lfs2_mdir_t *dir,
             && lfs2_pair_cmp(dir->pair, (const lfs2_block_t[2]){0, 1}) == 0) {
         // oh no! we're writing too much to the superblock,
         // should we expand?
-        lfs2_ssize_t size = lfs2_fs_rawsize(lfs2);
+        lfs2_ssize_t size = lfs2_fs_size_(lfs2);
         if (size < 0) {
             return size;
         }
 
-        // do we have extra space? littlefs can't reclaim this space
-        // by itself, so expand cautiously
-        if ((lfs2_size_t)size < lfs2->block_count/2) {
+        // littlefs cannot reclaim expanded superblocks, so expand cautiously
+        //
+        // if our filesystem is more than ~88% full, don't expand, this is
+        // somewhat arbitrary
+        if (lfs2->block_count - size > lfs2->block_count/8) {
             LFS2_DEBUG("Expanding superblock at rev %"PRIu32, dir->rev);
             int err = lfs2_dir_split(lfs2, dir, attrs, attrcount,
                     source, begin, end);
@@ -2166,7 +2220,8 @@ static int lfs2_dir_splittingcompact(lfs2_t *lfs2, lfs2_mdir_t *dir,
                 // we can do, we'll error later if we've become frozen
                 LFS2_WARN("Unable to expand superblock");
             } else {
-                end = begin;
+                // duplicate the superblock entry into the new superblock
+                end = 1;
             }
         }
     }
@@ -2213,7 +2268,7 @@ static int lfs2_dir_relocatingcommit(lfs2_t *lfs2, lfs2_mdir_t *dir,
         }
     }
 
-    if (dir->erased) {
+    if (dir->erased && dir->count < 0xff) {
         // try to commit
         struct lfs2_commit commit = {
             .block = dir->pair[0],
@@ -2312,7 +2367,8 @@ fixmlist:;
             if (d->m.pair != pair) {
                 for (int i = 0; i < attrcount; i++) {
                     if (lfs2_tag_type3(attrs[i].tag) == LFS2_TYPE_DELETE &&
-                            d->id == lfs2_tag_id(attrs[i].tag)) {
+                            d->id == lfs2_tag_id(attrs[i].tag) &&
+                            d->type != LFS2_TYPE_DIR) {
                         d->m.pair[0] = LFS2_BLOCK_NULL;
                         d->m.pair[1] = LFS2_BLOCK_NULL;
                     } else if (lfs2_tag_type3(attrs[i].tag) == LFS2_TYPE_DELETE &&
@@ -2333,7 +2389,9 @@ fixmlist:;
 
             while (d->id >= d->m.count && d->m.split) {
                 // we split and id is on tail now
-                d->id -= d->m.count;
+                if (lfs2_pair_cmp(d->m.tail, lfs2->root) != 0) {
+                    d->id -= d->m.count;
+                }
                 int err = lfs2_dir_fetch(lfs2, &d->m, d->m.tail);
                 if (err) {
                     return err;
@@ -2499,7 +2557,7 @@ static int lfs2_dir_orphaningcommit(lfs2_t *lfs2, lfs2_mdir_t *dir,
         if (err != LFS2_ERR_NOENT) {
             if (lfs2_gstate_hasorphans(&lfs2->gstate)) {
                 // next step, clean up orphans
-                err = lfs2_fs_preporphans(lfs2, -hasparent);
+                err = lfs2_fs_preporphans(lfs2, -(int8_t)hasparent);
                 if (err) {
                     return err;
                 }
@@ -2564,7 +2622,7 @@ static int lfs2_dir_commit(lfs2_t *lfs2, lfs2_mdir_t *dir,
 
 /// Top level directory operations ///
 #ifndef LFS2_READONLY
-static int lfs2_rawmkdir(lfs2_t *lfs2, const char *path) {
+static int lfs2_mkdir_(lfs2_t *lfs2, const char *path) {
     // deorphan if we haven't yet, needed at most once after poweron
     int err = lfs2_fs_forceconsistency(lfs2);
     if (err) {
@@ -2575,18 +2633,18 @@ static int lfs2_rawmkdir(lfs2_t *lfs2, const char *path) {
     cwd.next = lfs2->mlist;
     uint16_t id;
     err = lfs2_dir_find(lfs2, &cwd.m, &path, &id);
-    if (!(err == LFS2_ERR_NOENT && id != 0x3ff)) {
+    if (!(err == LFS2_ERR_NOENT && lfs2_path_islast(path))) {
         return (err < 0) ? err : LFS2_ERR_EXIST;
     }
 
     // check that name fits
-    lfs2_size_t nlen = strlen(path);
+    lfs2_size_t nlen = lfs2_path_namelen(path);
     if (nlen > lfs2->name_max) {
         return LFS2_ERR_NAMETOOLONG;
     }
 
     // build up new directory
-    lfs2_alloc_ack(lfs2);
+    lfs2_alloc_ckpoint(lfs2);
     lfs2_mdir_t dir;
     err = lfs2_dir_alloc(lfs2, &dir);
     if (err) {
@@ -2660,7 +2718,7 @@ static int lfs2_rawmkdir(lfs2_t *lfs2, const char *path) {
 }
 #endif
 
-static int lfs2_dir_rawopen(lfs2_t *lfs2, lfs2_dir_t *dir, const char *path) {
+static int lfs2_dir_open_(lfs2_t *lfs2, lfs2_dir_t *dir, const char *path) {
     lfs2_stag_t tag = lfs2_dir_find(lfs2, &dir->m, &path, NULL);
     if (tag < 0) {
         return tag;
@@ -2704,14 +2762,14 @@ static int lfs2_dir_rawopen(lfs2_t *lfs2, lfs2_dir_t *dir, const char *path) {
     return 0;
 }
 
-static int lfs2_dir_rawclose(lfs2_t *lfs2, lfs2_dir_t *dir) {
+static int lfs2_dir_close_(lfs2_t *lfs2, lfs2_dir_t *dir) {
     // remove from list of mdirs
     lfs2_mlist_remove(lfs2, (struct lfs2_mlist *)dir);
 
     return 0;
 }
 
-static int lfs2_dir_rawread(lfs2_t *lfs2, lfs2_dir_t *dir, struct lfs2_info *info) {
+static int lfs2_dir_read_(lfs2_t *lfs2, lfs2_dir_t *dir, struct lfs2_info *info) {
     memset(info, 0, sizeof(*info));
 
     // special offset for '.' and '..'
@@ -2756,9 +2814,9 @@ static int lfs2_dir_rawread(lfs2_t *lfs2, lfs2_dir_t *dir, struct lfs2_info *inf
     return true;
 }
 
-static int lfs2_dir_rawseek(lfs2_t *lfs2, lfs2_dir_t *dir, lfs2_off_t off) {
+static int lfs2_dir_seek_(lfs2_t *lfs2, lfs2_dir_t *dir, lfs2_off_t off) {
     // simply walk from head dir
-    int err = lfs2_dir_rawrewind(lfs2, dir);
+    int err = lfs2_dir_rewind_(lfs2, dir);
     if (err) {
         return err;
     }
@@ -2793,12 +2851,12 @@ static int lfs2_dir_rawseek(lfs2_t *lfs2, lfs2_dir_t *dir, lfs2_off_t off) {
     return 0;
 }
 
-static lfs2_soff_t lfs2_dir_rawtell(lfs2_t *lfs2, lfs2_dir_t *dir) {
+static lfs2_soff_t lfs2_dir_tell_(lfs2_t *lfs2, lfs2_dir_t *dir) {
     (void)lfs2;
     return dir->pos;
 }
 
-static int lfs2_dir_rawrewind(lfs2_t *lfs2, lfs2_dir_t *dir) {
+static int lfs2_dir_rewind_(lfs2_t *lfs2, lfs2_dir_t *dir) {
     // reload the head dir
     int err = lfs2_dir_fetch(lfs2, &dir->m, dir->head);
     if (err) {
@@ -3004,7 +3062,7 @@ static int lfs2_ctz_traverse(lfs2_t *lfs2,
 
 
 /// Top level file operations ///
-static int lfs2_file_rawopencfg(lfs2_t *lfs2, lfs2_file_t *file,
+static int lfs2_file_opencfg_(lfs2_t *lfs2, lfs2_file_t *file,
         const char *path, int flags,
         const struct lfs2_file_config *cfg) {
 #ifndef LFS2_READONLY
@@ -3029,7 +3087,7 @@ static int lfs2_file_rawopencfg(lfs2_t *lfs2, lfs2_file_t *file,
 
     // allocate entry for file if it doesn't exist
     lfs2_stag_t tag = lfs2_dir_find(lfs2, &file->m, &path, &file->id);
-    if (tag < 0 && !(tag == LFS2_ERR_NOENT && file->id != 0x3ff)) {
+    if (tag < 0 && !(tag == LFS2_ERR_NOENT && lfs2_path_islast(path))) {
         err = tag;
         goto cleanup;
     }
@@ -3049,8 +3107,14 @@ static int lfs2_file_rawopencfg(lfs2_t *lfs2, lfs2_file_t *file,
             goto cleanup;
         }
 
+        // don't allow trailing slashes
+        if (lfs2_path_isdir(path)) {
+            err = LFS2_ERR_NOTDIR;
+            goto cleanup;
+        }
+
         // check that name fits
-        lfs2_size_t nlen = strlen(path);
+        lfs2_size_t nlen = lfs2_path_namelen(path);
         if (nlen > lfs2->name_max) {
             err = LFS2_ERR_NAMETOOLONG;
             goto cleanup;
@@ -3166,22 +3230,22 @@ static int lfs2_file_rawopencfg(lfs2_t *lfs2, lfs2_file_t *file,
 #ifndef LFS2_READONLY
     file->flags |= LFS2_F_ERRED;
 #endif
-    lfs2_file_rawclose(lfs2, file);
+    lfs2_file_close_(lfs2, file);
     return err;
 }
 
 #ifndef LFS2_NO_MALLOC
-static int lfs2_file_rawopen(lfs2_t *lfs2, lfs2_file_t *file,
+static int lfs2_file_open_(lfs2_t *lfs2, lfs2_file_t *file,
         const char *path, int flags) {
     static const struct lfs2_file_config defaults = {0};
-    int err = lfs2_file_rawopencfg(lfs2, file, path, flags, &defaults);
+    int err = lfs2_file_opencfg_(lfs2, file, path, flags, &defaults);
     return err;
 }
 #endif
 
-static int lfs2_file_rawclose(lfs2_t *lfs2, lfs2_file_t *file) {
+static int lfs2_file_close_(lfs2_t *lfs2, lfs2_file_t *file) {
 #ifndef LFS2_READONLY
-    int err = lfs2_file_rawsync(lfs2, file);
+    int err = lfs2_file_sync_(lfs2, file);
 #else
     int err = 0;
 #endif
@@ -3272,7 +3336,7 @@ static int lfs2_file_relocate(lfs2_t *lfs2, lfs2_file_t *file) {
 #ifndef LFS2_READONLY
 static int lfs2_file_outline(lfs2_t *lfs2, lfs2_file_t *file) {
     file->off = file->pos;
-    lfs2_alloc_ack(lfs2);
+    lfs2_alloc_ckpoint(lfs2);
     int err = lfs2_file_relocate(lfs2, file);
     if (err) {
         return err;
@@ -3364,7 +3428,7 @@ static int lfs2_file_flush(lfs2_t *lfs2, lfs2_file_t *file) {
 }
 
 #ifndef LFS2_READONLY
-static int lfs2_file_rawsync(lfs2_t *lfs2, lfs2_file_t *file) {
+static int lfs2_file_sync_(lfs2_t *lfs2, lfs2_file_t *file) {
     if (file->flags & LFS2_F_ERRED) {
         // it's not safe to do anything if our file errored
         return 0;
@@ -3379,6 +3443,15 @@ static int lfs2_file_rawsync(lfs2_t *lfs2, lfs2_file_t *file) {
 
     if ((file->flags & LFS2_F_DIRTY) &&
             !lfs2_pair_isnull(file->m.pair)) {
+        // before we commit metadata, we need sync the disk to make sure
+        // data writes don't complete after metadata writes
+        if (!(file->flags & LFS2_F_INLINE)) {
+            err = lfs2_bd_sync(lfs2, &lfs2->pcache, &lfs2->rcache, false);
+            if (err) {
+                return err;
+            }
+        }
+
         // update dir entry
         uint16_t type;
         const void *buffer;
@@ -3477,7 +3550,7 @@ static lfs2_ssize_t lfs2_file_flushedread(lfs2_t *lfs2, lfs2_file_t *file,
     return size;
 }
 
-static lfs2_ssize_t lfs2_file_rawread(lfs2_t *lfs2, lfs2_file_t *file,
+static lfs2_ssize_t lfs2_file_read_(lfs2_t *lfs2, lfs2_file_t *file,
         void *buffer, lfs2_size_t size) {
     LFS2_ASSERT((file->flags & LFS2_O_RDONLY) == LFS2_O_RDONLY);
 
@@ -3502,11 +3575,7 @@ static lfs2_ssize_t lfs2_file_flushedwrite(lfs2_t *lfs2, lfs2_file_t *file,
     lfs2_size_t nsize = size;
 
     if ((file->flags & LFS2_F_INLINE) &&
-            lfs2_max(file->pos+nsize, file->ctz.size) >
-            lfs2_min(0x3fe, lfs2_min(
-                lfs2->cfg->cache_size,
-                (lfs2->cfg->metadata_max ?
-                    lfs2->cfg->metadata_max : lfs2->cfg->block_size) / 8))) {
+            lfs2_max(file->pos+nsize, file->ctz.size) > lfs2->inline_max) {
         // inline file doesn't fit anymore
         int err = lfs2_file_outline(lfs2, file);
         if (err) {
@@ -3535,7 +3604,7 @@ static lfs2_ssize_t lfs2_file_flushedwrite(lfs2_t *lfs2, lfs2_file_t *file,
                 }
 
                 // extend file with new blocks
-                lfs2_alloc_ack(lfs2);
+                lfs2_alloc_ckpoint(lfs2);
                 int err = lfs2_ctz_extend(lfs2, &file->cache, &lfs2->rcache,
                         file->block, file->pos,
                         &file->block, &file->off);
@@ -3578,13 +3647,13 @@ static lfs2_ssize_t lfs2_file_flushedwrite(lfs2_t *lfs2, lfs2_file_t *file,
         data += diff;
         nsize -= diff;
 
-        lfs2_alloc_ack(lfs2);
+        lfs2_alloc_ckpoint(lfs2);
     }
 
     return size;
 }
 
-static lfs2_ssize_t lfs2_file_rawwrite(lfs2_t *lfs2, lfs2_file_t *file,
+static lfs2_ssize_t lfs2_file_write_(lfs2_t *lfs2, lfs2_file_t *file,
         const void *buffer, lfs2_size_t size) {
     LFS2_ASSERT((file->flags & LFS2_O_WRONLY) == LFS2_O_WRONLY);
 
@@ -3628,25 +3697,19 @@ static lfs2_ssize_t lfs2_file_rawwrite(lfs2_t *lfs2, lfs2_file_t *file,
 }
 #endif
 
-static lfs2_soff_t lfs2_file_rawseek(lfs2_t *lfs2, lfs2_file_t *file,
+static lfs2_soff_t lfs2_file_seek_(lfs2_t *lfs2, lfs2_file_t *file,
         lfs2_soff_t off, int whence) {
     // find new pos
+    //
+    // fortunately for us, littlefs is limited to 31-bit file sizes, so we
+    // don't have to worry too much about integer overflow
     lfs2_off_t npos = file->pos;
     if (whence == LFS2_SEEK_SET) {
         npos = off;
     } else if (whence == LFS2_SEEK_CUR) {
-        if ((lfs2_soff_t)file->pos + off < 0) {
-            return LFS2_ERR_INVAL;
-        } else {
-            npos = file->pos + off;
-        }
+        npos = file->pos + (lfs2_off_t)off;
     } else if (whence == LFS2_SEEK_END) {
-        lfs2_soff_t res = lfs2_file_rawsize(lfs2, file) + off;
-        if (res < 0) {
-            return LFS2_ERR_INVAL;
-        } else {
-            npos = res;
-        }
+        npos = (lfs2_off_t)lfs2_file_size_(lfs2, file) + (lfs2_off_t)off;
     }
 
     if (npos > lfs2->file_max) {
@@ -3661,13 +3724,8 @@ static lfs2_soff_t lfs2_file_rawseek(lfs2_t *lfs2, lfs2_file_t *file,
 
     // if we're only reading and our new offset is still in the file's cache
     // we can avoid flushing and needing to reread the data
-    if (
-#ifndef LFS2_READONLY
-        !(file->flags & LFS2_F_WRITING)
-#else
-        true
-#endif
-            ) {
+    if ((file->flags & LFS2_F_READING)
+            && file->off != lfs2->cfg->block_size) {
         int oindex = lfs2_ctz_index(lfs2, &(lfs2_off_t){file->pos});
         lfs2_off_t noff = npos;
         int nindex = lfs2_ctz_index(lfs2, &noff);
@@ -3692,7 +3750,7 @@ static lfs2_soff_t lfs2_file_rawseek(lfs2_t *lfs2, lfs2_file_t *file,
 }
 
 #ifndef LFS2_READONLY
-static int lfs2_file_rawtruncate(lfs2_t *lfs2, lfs2_file_t *file, lfs2_off_t size) {
+static int lfs2_file_truncate_(lfs2_t *lfs2, lfs2_file_t *file, lfs2_off_t size) {
     LFS2_ASSERT((file->flags & LFS2_O_WRONLY) == LFS2_O_WRONLY);
 
     if (size > LFS2_FILE_MAX) {
@@ -3700,15 +3758,12 @@ static int lfs2_file_rawtruncate(lfs2_t *lfs2, lfs2_file_t *file, lfs2_off_t siz
     }
 
     lfs2_off_t pos = file->pos;
-    lfs2_off_t oldsize = lfs2_file_rawsize(lfs2, file);
+    lfs2_off_t oldsize = lfs2_file_size_(lfs2, file);
     if (size < oldsize) {
         // revert to inline file?
-        if (size <= lfs2_min(0x3fe, lfs2_min(
-                lfs2->cfg->cache_size,
-                (lfs2->cfg->metadata_max ?
-                    lfs2->cfg->metadata_max : lfs2->cfg->block_size) / 8))) {
+        if (size <= lfs2->inline_max) {
             // flush+seek to head
-            lfs2_soff_t res = lfs2_file_rawseek(lfs2, file, 0, LFS2_SEEK_SET);
+            lfs2_soff_t res = lfs2_file_seek_(lfs2, file, 0, LFS2_SEEK_SET);
             if (res < 0) {
                 return (int)res;
             }
@@ -3753,14 +3808,14 @@ static int lfs2_file_rawtruncate(lfs2_t *lfs2, lfs2_file_t *file, lfs2_off_t siz
         }
     } else if (size > oldsize) {
         // flush+seek if not already at end
-        lfs2_soff_t res = lfs2_file_rawseek(lfs2, file, 0, LFS2_SEEK_END);
+        lfs2_soff_t res = lfs2_file_seek_(lfs2, file, 0, LFS2_SEEK_END);
         if (res < 0) {
             return (int)res;
         }
 
         // fill with zeros
         while (file->pos < size) {
-            res = lfs2_file_rawwrite(lfs2, file, &(uint8_t){0}, 1);
+            res = lfs2_file_write_(lfs2, file, &(uint8_t){0}, 1);
             if (res < 0) {
                 return (int)res;
             }
@@ -3768,7 +3823,7 @@ static int lfs2_file_rawtruncate(lfs2_t *lfs2, lfs2_file_t *file, lfs2_off_t siz
     }
 
     // restore pos
-    lfs2_soff_t res = lfs2_file_rawseek(lfs2, file, pos, LFS2_SEEK_SET);
+    lfs2_soff_t res = lfs2_file_seek_(lfs2, file, pos, LFS2_SEEK_SET);
     if (res < 0) {
       return (int)res;
     }
@@ -3777,13 +3832,13 @@ static int lfs2_file_rawtruncate(lfs2_t *lfs2, lfs2_file_t *file, lfs2_off_t siz
 }
 #endif
 
-static lfs2_soff_t lfs2_file_rawtell(lfs2_t *lfs2, lfs2_file_t *file) {
+static lfs2_soff_t lfs2_file_tell_(lfs2_t *lfs2, lfs2_file_t *file) {
     (void)lfs2;
     return file->pos;
 }
 
-static int lfs2_file_rawrewind(lfs2_t *lfs2, lfs2_file_t *file) {
-    lfs2_soff_t res = lfs2_file_rawseek(lfs2, file, 0, LFS2_SEEK_SET);
+static int lfs2_file_rewind_(lfs2_t *lfs2, lfs2_file_t *file) {
+    lfs2_soff_t res = lfs2_file_seek_(lfs2, file, 0, LFS2_SEEK_SET);
     if (res < 0) {
         return (int)res;
     }
@@ -3791,7 +3846,7 @@ static int lfs2_file_rawrewind(lfs2_t *lfs2, lfs2_file_t *file) {
     return 0;
 }
 
-static lfs2_soff_t lfs2_file_rawsize(lfs2_t *lfs2, lfs2_file_t *file) {
+static lfs2_soff_t lfs2_file_size_(lfs2_t *lfs2, lfs2_file_t *file) {
     (void)lfs2;
 
 #ifndef LFS2_READONLY
@@ -3805,18 +3860,24 @@ static lfs2_soff_t lfs2_file_rawsize(lfs2_t *lfs2, lfs2_file_t *file) {
 
 
 /// General fs operations ///
-static int lfs2_rawstat(lfs2_t *lfs2, const char *path, struct lfs2_info *info) {
+static int lfs2_stat_(lfs2_t *lfs2, const char *path, struct lfs2_info *info) {
     lfs2_mdir_t cwd;
     lfs2_stag_t tag = lfs2_dir_find(lfs2, &cwd, &path, NULL);
     if (tag < 0) {
         return (int)tag;
     }
 
+    // only allow trailing slashes on dirs
+    if (strchr(path, '/') != NULL
+            && lfs2_tag_type3(tag) != LFS2_TYPE_DIR) {
+        return LFS2_ERR_NOTDIR;
+    }
+
     return lfs2_dir_getinfo(lfs2, &cwd, lfs2_tag_id(tag), info);
 }
 
 #ifndef LFS2_READONLY
-static int lfs2_rawremove(lfs2_t *lfs2, const char *path) {
+static int lfs2_remove_(lfs2_t *lfs2, const char *path) {
     // deorphan if we haven't yet, needed at most once after poweron
     int err = lfs2_fs_forceconsistency(lfs2);
     if (err) {
@@ -3872,7 +3933,9 @@ static int lfs2_rawremove(lfs2_t *lfs2, const char *path) {
     }
 
     lfs2->mlist = dir.next;
-    if (lfs2_tag_type3(tag) == LFS2_TYPE_DIR) {
+    if (lfs2_gstate_hasorphans(&lfs2->gstate)) {
+        LFS2_ASSERT(lfs2_tag_type3(tag) == LFS2_TYPE_DIR);
+
         // fix orphan
         err = lfs2_fs_preporphans(lfs2, -1);
         if (err) {
@@ -3895,7 +3958,7 @@ static int lfs2_rawremove(lfs2_t *lfs2, const char *path) {
 #endif
 
 #ifndef LFS2_READONLY
-static int lfs2_rawrename(lfs2_t *lfs2, const char *oldpath, const char *newpath) {
+static int lfs2_rename_(lfs2_t *lfs2, const char *oldpath, const char *newpath) {
     // deorphan if we haven't yet, needed at most once after poweron
     int err = lfs2_fs_forceconsistency(lfs2);
     if (err) {
@@ -3914,7 +3977,7 @@ static int lfs2_rawrename(lfs2_t *lfs2, const char *oldpath, const char *newpath
     uint16_t newid;
     lfs2_stag_t prevtag = lfs2_dir_find(lfs2, &newcwd, &newpath, &newid);
     if ((prevtag < 0 || lfs2_tag_id(prevtag) == 0x3ff) &&
-            !(prevtag == LFS2_ERR_NOENT && newid != 0x3ff)) {
+            !(prevtag == LFS2_ERR_NOENT && lfs2_path_islast(newpath))) {
         return (prevtag < 0) ? (int)prevtag : LFS2_ERR_INVAL;
     }
 
@@ -3925,8 +3988,14 @@ static int lfs2_rawrename(lfs2_t *lfs2, const char *oldpath, const char *newpath
     struct lfs2_mlist prevdir;
     prevdir.next = lfs2->mlist;
     if (prevtag == LFS2_ERR_NOENT) {
+        // if we're a file, don't allow trailing slashes
+        if (lfs2_path_isdir(newpath)
+                && lfs2_tag_type3(oldtag) != LFS2_TYPE_DIR) {
+            return LFS2_ERR_NOTDIR;
+        }
+
         // check that name fits
-        lfs2_size_t nlen = strlen(newpath);
+        lfs2_size_t nlen = lfs2_path_namelen(newpath);
         if (nlen > lfs2->name_max) {
             return LFS2_ERR_NAMETOOLONG;
         }
@@ -3938,7 +4007,9 @@ static int lfs2_rawrename(lfs2_t *lfs2, const char *oldpath, const char *newpath
             newoldid += 1;
         }
     } else if (lfs2_tag_type3(prevtag) != lfs2_tag_type3(oldtag)) {
-        return LFS2_ERR_ISDIR;
+        return (lfs2_tag_type3(prevtag) == LFS2_TYPE_DIR)
+                ? LFS2_ERR_ISDIR
+                : LFS2_ERR_NOTDIR;
     } else if (samepair && newid == newoldid) {
         // we're renaming to ourselves??
         return 0;
@@ -3984,7 +4055,8 @@ static int lfs2_rawrename(lfs2_t *lfs2, const char *oldpath, const char *newpath
             {LFS2_MKTAG_IF(prevtag != LFS2_ERR_NOENT,
                 LFS2_TYPE_DELETE, newid, 0), NULL},
             {LFS2_MKTAG(LFS2_TYPE_CREATE, newid, 0), NULL},
-            {LFS2_MKTAG(lfs2_tag_type3(oldtag), newid, strlen(newpath)), newpath},
+            {LFS2_MKTAG(lfs2_tag_type3(oldtag),
+                newid, lfs2_path_namelen(newpath)), newpath},
             {LFS2_MKTAG(LFS2_FROM_MOVE, newid, lfs2_tag_id(oldtag)), &oldcwd},
             {LFS2_MKTAG_IF(samepair,
                 LFS2_TYPE_DELETE, newoldid, 0), NULL}));
@@ -4007,8 +4079,10 @@ static int lfs2_rawrename(lfs2_t *lfs2, const char *oldpath, const char *newpath
     }
 
     lfs2->mlist = prevdir.next;
-    if (prevtag != LFS2_ERR_NOENT
-            && lfs2_tag_type3(prevtag) == LFS2_TYPE_DIR) {
+    if (lfs2_gstate_hasorphans(&lfs2->gstate)) {
+        LFS2_ASSERT(prevtag != LFS2_ERR_NOENT
+                && lfs2_tag_type3(prevtag) == LFS2_TYPE_DIR);
+
         // fix orphan
         err = lfs2_fs_preporphans(lfs2, -1);
         if (err) {
@@ -4030,7 +4104,7 @@ static int lfs2_rawrename(lfs2_t *lfs2, const char *oldpath, const char *newpath
 }
 #endif
 
-static lfs2_ssize_t lfs2_rawgetattr(lfs2_t *lfs2, const char *path,
+static lfs2_ssize_t lfs2_getattr_(lfs2_t *lfs2, const char *path,
         uint8_t type, void *buffer, lfs2_size_t size) {
     lfs2_mdir_t cwd;
     lfs2_stag_t tag = lfs2_dir_find(lfs2, &cwd, &path, NULL);
@@ -4088,7 +4162,7 @@ static int lfs2_commitattr(lfs2_t *lfs2, const char *path,
 #endif
 
 #ifndef LFS2_READONLY
-static int lfs2_rawsetattr(lfs2_t *lfs2, const char *path,
+static int lfs2_setattr_(lfs2_t *lfs2, const char *path,
         uint8_t type, const void *buffer, lfs2_size_t size) {
     if (size > lfs2->attr_max) {
         return LFS2_ERR_NOSPC;
@@ -4099,13 +4173,28 @@ static int lfs2_rawsetattr(lfs2_t *lfs2, const char *path,
 #endif
 
 #ifndef LFS2_READONLY
-static int lfs2_rawremoveattr(lfs2_t *lfs2, const char *path, uint8_t type) {
+static int lfs2_removeattr_(lfs2_t *lfs2, const char *path, uint8_t type) {
     return lfs2_commitattr(lfs2, path, type, NULL, 0x3ff);
 }
 #endif
 
 
 /// Filesystem operations ///
+
+// compile time checks, see lfs2.h for why these limits exist
+#if LFS2_NAME_MAX > 1022
+#error "Invalid LFS2_NAME_MAX, must be <= 1022"
+#endif
+
+#if LFS2_FILE_MAX > 2147483647
+#error "Invalid LFS2_FILE_MAX, must be <= 2147483647"
+#endif
+
+#if LFS2_ATTR_MAX > 1022
+#error "Invalid LFS2_ATTR_MAX, must be <= 1022"
+#endif
+
+// common filesystem initialization
 static int lfs2_init(lfs2_t *lfs2, const struct lfs2_config *cfg) {
     lfs2->cfg = cfg;
     lfs2->block_count = cfg->block_count;  // May be 0
@@ -4126,6 +4215,14 @@ static int lfs2_init(lfs2_t *lfs2, const struct lfs2_config *cfg) {
     // which littlefs currently does not support
     LFS2_ASSERT((bool)0x80000000);
 
+    // check that the required io functions are provided
+    LFS2_ASSERT(lfs2->cfg->read != NULL);
+#ifndef LFS2_READONLY
+    LFS2_ASSERT(lfs2->cfg->prog != NULL);
+    LFS2_ASSERT(lfs2->cfg->erase != NULL);
+    LFS2_ASSERT(lfs2->cfg->sync != NULL);
+#endif
+
     // validate that the lfs2-cfg sizes were initiated properly before
     // performing any arithmetic logics with them
     LFS2_ASSERT(lfs2->cfg->read_size != 0);
@@ -4153,6 +4250,23 @@ static int lfs2_init(lfs2_t *lfs2, const struct lfs2_config *cfg) {
     // wear-leveling.
     LFS2_ASSERT(lfs2->cfg->block_cycles != 0);
 
+    // check that compact_thresh makes sense
+    //
+    // metadata can't be compacted below block_size/2, and metadata can't
+    // exceed a block_size
+    LFS2_ASSERT(lfs2->cfg->compact_thresh == 0
+            || lfs2->cfg->compact_thresh >= lfs2->cfg->block_size/2);
+    LFS2_ASSERT(lfs2->cfg->compact_thresh == (lfs2_size_t)-1
+            || lfs2->cfg->compact_thresh <= lfs2->cfg->block_size);
+
+    // check that metadata_max is a multiple of read_size and prog_size,
+    // and a factor of the block_size
+    LFS2_ASSERT(!lfs2->cfg->metadata_max
+            || lfs2->cfg->metadata_max % lfs2->cfg->read_size == 0);
+    LFS2_ASSERT(!lfs2->cfg->metadata_max
+            || lfs2->cfg->metadata_max % lfs2->cfg->prog_size == 0);
+    LFS2_ASSERT(!lfs2->cfg->metadata_max
+            || lfs2->cfg->block_size % lfs2->cfg->metadata_max == 0);
 
     // setup read cache
     if (lfs2->cfg->read_buffer) {
@@ -4180,15 +4294,14 @@ static int lfs2_init(lfs2_t *lfs2, const struct lfs2_config *cfg) {
     lfs2_cache_zero(lfs2, &lfs2->rcache);
     lfs2_cache_zero(lfs2, &lfs2->pcache);
 
-    // setup lookahead, must be multiple of 64-bits, 32-bit aligned
+    // setup lookahead buffer, note mount finishes initializing this after
+    // we establish a decent pseudo-random seed
     LFS2_ASSERT(lfs2->cfg->lookahead_size > 0);
-    LFS2_ASSERT(lfs2->cfg->lookahead_size % 8 == 0 &&
-            (uintptr_t)lfs2->cfg->lookahead_buffer % 4 == 0);
     if (lfs2->cfg->lookahead_buffer) {
-        lfs2->free.buffer = lfs2->cfg->lookahead_buffer;
+        lfs2->lookahead.buffer = lfs2->cfg->lookahead_buffer;
     } else {
-        lfs2->free.buffer = lfs2_malloc(lfs2->cfg->lookahead_size);
-        if (!lfs2->free.buffer) {
+        lfs2->lookahead.buffer = lfs2_malloc(lfs2->cfg->lookahead_size);
+        if (!lfs2->lookahead.buffer) {
             err = LFS2_ERR_NOMEM;
             goto cleanup;
         }
@@ -4215,6 +4328,27 @@ static int lfs2_init(lfs2_t *lfs2, const struct lfs2_config *cfg) {
 
     LFS2_ASSERT(lfs2->cfg->metadata_max <= lfs2->cfg->block_size);
 
+    LFS2_ASSERT(lfs2->cfg->inline_max == (lfs2_size_t)-1
+            || lfs2->cfg->inline_max <= lfs2->cfg->cache_size);
+    LFS2_ASSERT(lfs2->cfg->inline_max == (lfs2_size_t)-1
+            || lfs2->cfg->inline_max <= lfs2->attr_max);
+    LFS2_ASSERT(lfs2->cfg->inline_max == (lfs2_size_t)-1
+            || lfs2->cfg->inline_max <= ((lfs2->cfg->metadata_max)
+                ? lfs2->cfg->metadata_max
+                : lfs2->cfg->block_size)/8);
+    lfs2->inline_max = lfs2->cfg->inline_max;
+    if (lfs2->inline_max == (lfs2_size_t)-1) {
+        lfs2->inline_max = 0;
+    } else if (lfs2->inline_max == 0) {
+        lfs2->inline_max = lfs2_min(
+                lfs2->cfg->cache_size,
+                lfs2_min(
+                    lfs2->attr_max,
+                    ((lfs2->cfg->metadata_max)
+                        ? lfs2->cfg->metadata_max
+                        : lfs2->cfg->block_size)/8));
+    }
+
     // setup default state
     lfs2->root[0] = LFS2_BLOCK_NULL;
     lfs2->root[1] = LFS2_BLOCK_NULL;
@@ -4245,7 +4379,7 @@ static int lfs2_deinit(lfs2_t *lfs2) {
     }
 
     if (!lfs2->cfg->lookahead_buffer) {
-        lfs2_free(lfs2->free.buffer);
+        lfs2_free(lfs2->lookahead.buffer);
     }
 
     return 0;
@@ -4254,7 +4388,7 @@ static int lfs2_deinit(lfs2_t *lfs2) {
 
 
 #ifndef LFS2_READONLY
-static int lfs2_rawformat(lfs2_t *lfs2, const struct lfs2_config *cfg) {
+static int lfs2_format_(lfs2_t *lfs2, const struct lfs2_config *cfg) {
     int err = 0;
     {
         err = lfs2_init(lfs2, cfg);
@@ -4265,12 +4399,12 @@ static int lfs2_rawformat(lfs2_t *lfs2, const struct lfs2_config *cfg) {
         LFS2_ASSERT(cfg->block_count != 0);
 
         // create free lookahead
-        memset(lfs2->free.buffer, 0, lfs2->cfg->lookahead_size);
-        lfs2->free.off = 0;
-        lfs2->free.size = lfs2_min(8*lfs2->cfg->lookahead_size,
+        memset(lfs2->lookahead.buffer, 0, lfs2->cfg->lookahead_size);
+        lfs2->lookahead.start = 0;
+        lfs2->lookahead.size = lfs2_min(8*lfs2->cfg->lookahead_size,
                 lfs2->block_count);
-        lfs2->free.i = 0;
-        lfs2_alloc_ack(lfs2);
+        lfs2->lookahead.next = 0;
+        lfs2_alloc_ckpoint(lfs2);
 
         // create root dir
         lfs2_mdir_t root;
@@ -4321,7 +4455,31 @@ static int lfs2_rawformat(lfs2_t *lfs2, const struct lfs2_config *cfg) {
 }
 #endif
 
-static int lfs2_rawmount(lfs2_t *lfs2, const struct lfs2_config *cfg) {
+struct lfs2_tortoise_t {
+    lfs2_block_t pair[2];
+    lfs2_size_t i;
+    lfs2_size_t period;
+};
+
+static int lfs2_tortoise_detectcycles(
+    const lfs2_mdir_t *dir, struct lfs2_tortoise_t *tortoise) {
+    // detect cycles with Brent's algorithm
+    if (lfs2_pair_issync(dir->tail, tortoise->pair)) {
+        LFS2_WARN("Cycle detected in tail list");
+        return LFS2_ERR_CORRUPT;
+    }
+    if (tortoise->i == tortoise->period) {
+        tortoise->pair[0] = dir->tail[0];
+        tortoise->pair[1] = dir->tail[1];
+        tortoise->i = 0;
+        tortoise->period *= 2;
+    }
+    tortoise->i += 1;
+
+    return LFS2_ERR_OK;
+}
+
+static int lfs2_mount_(lfs2_t *lfs2, const struct lfs2_config *cfg) {
     int err = lfs2_init(lfs2, cfg);
     if (err) {
         return err;
@@ -4329,23 +4487,16 @@ static int lfs2_rawmount(lfs2_t *lfs2, const struct lfs2_config *cfg) {
 
     // scan directory blocks for superblock and any global updates
     lfs2_mdir_t dir = {.tail = {0, 1}};
-    lfs2_block_t tortoise[2] = {LFS2_BLOCK_NULL, LFS2_BLOCK_NULL};
-    lfs2_size_t tortoise_i = 1;
-    lfs2_size_t tortoise_period = 1;
+    struct lfs2_tortoise_t tortoise = {
+        .pair = {LFS2_BLOCK_NULL, LFS2_BLOCK_NULL},
+        .i = 1,
+        .period = 1,
+    };
     while (!lfs2_pair_isnull(dir.tail)) {
-        // detect cycles with Brent's algorithm
-        if (lfs2_pair_issync(dir.tail, tortoise)) {
-            LFS2_WARN("Cycle detected in tail list");
-            err = LFS2_ERR_CORRUPT;
+        err = lfs2_tortoise_detectcycles(&dir, &tortoise);
+        if (err < 0) {
             goto cleanup;
         }
-        if (tortoise_i == tortoise_period) {
-            tortoise[0] = dir.tail[0];
-            tortoise[1] = dir.tail[1];
-            tortoise_i = 0;
-            tortoise_period *= 2;
-        }
-        tortoise_i += 1;
 
         // fetch next block in tail list
         lfs2_stag_t tag = lfs2_dir_fetchmatch(lfs2, &dir, dir.tail,
@@ -4394,6 +4545,7 @@ static int lfs2_rawmount(lfs2_t *lfs2, const struct lfs2_config *cfg) {
             // found older minor version? set an in-device only bit in the
             // gstate so we know we need to rewrite the superblock before
             // the first write
+            bool needssuperblock = false;
             if (minor_version < lfs2_fs_disk_version_minor(lfs2)) {
                 LFS2_DEBUG("Found older minor version "
                         "v%"PRIu16".%"PRIu16" < v%"PRIu16".%"PRIu16,
@@ -4401,10 +4553,11 @@ static int lfs2_rawmount(lfs2_t *lfs2, const struct lfs2_config *cfg) {
                         minor_version,
                         lfs2_fs_disk_version_major(lfs2),
                         lfs2_fs_disk_version_minor(lfs2));
-                // note this bit is reserved on disk, so fetching more gstate
-                // will not interfere here
-                lfs2_fs_prepsuperblock(lfs2, true);
+                needssuperblock = true;
             }
+            // note this bit is reserved on disk, so fetching more gstate
+            // will not interfere here
+            lfs2_fs_prepsuperblock(lfs2, needssuperblock);
 
             // check superblock configuration
             if (superblock.name_max) {
@@ -4438,6 +4591,9 @@ static int lfs2_rawmount(lfs2_t *lfs2, const struct lfs2_config *cfg) {
                 }
 
                 lfs2->attr_max = superblock.attr_max;
+
+                // we also need to update inline_max in case attr_max changed
+                lfs2->inline_max = lfs2_min(lfs2->inline_max, lfs2->attr_max);
             }
 
             // this is where we get the block_count from disk if block_count=0
@@ -4478,23 +4634,23 @@ static int lfs2_rawmount(lfs2_t *lfs2, const struct lfs2_config *cfg) {
 
     // setup free lookahead, to distribute allocations uniformly across
     // boots, we start the allocator at a random location
-    lfs2->free.off = lfs2->seed % lfs2->block_count;
+    lfs2->lookahead.start = lfs2->seed % lfs2->block_count;
     lfs2_alloc_drop(lfs2);
 
     return 0;
 
 cleanup:
-    lfs2_rawunmount(lfs2);
+    lfs2_unmount_(lfs2);
     return err;
 }
 
-static int lfs2_rawunmount(lfs2_t *lfs2) {
+static int lfs2_unmount_(lfs2_t *lfs2) {
     return lfs2_deinit(lfs2);
 }
 
 
 /// Filesystem filesystem operations ///
-static int lfs2_fs_rawstat(lfs2_t *lfs2, struct lfs2_fsinfo *fsinfo) {
+static int lfs2_fs_stat_(lfs2_t *lfs2, struct lfs2_fsinfo *fsinfo) {
     // if the superblock is up-to-date, we must be on the most recent
     // minor version of littlefs
     if (!lfs2_gstate_needssuperblock(&lfs2->gstate)) {
@@ -4534,7 +4690,7 @@ static int lfs2_fs_rawstat(lfs2_t *lfs2, struct lfs2_fsinfo *fsinfo) {
     return 0;
 }
 
-int lfs2_fs_rawtraverse(lfs2_t *lfs2,
+int lfs2_fs_traverse_(lfs2_t *lfs2,
         int (*cb)(void *data, lfs2_block_t block), void *data,
         bool includeorphans) {
     // iterate over metadata pairs
@@ -4553,22 +4709,17 @@ int lfs2_fs_rawtraverse(lfs2_t *lfs2,
     }
 #endif
 
-    lfs2_block_t tortoise[2] = {LFS2_BLOCK_NULL, LFS2_BLOCK_NULL};
-    lfs2_size_t tortoise_i = 1;
-    lfs2_size_t tortoise_period = 1;
+    struct lfs2_tortoise_t tortoise = {
+        .pair = {LFS2_BLOCK_NULL, LFS2_BLOCK_NULL},
+        .i = 1,
+        .period = 1,
+    };
+    int err = LFS2_ERR_OK;
     while (!lfs2_pair_isnull(dir.tail)) {
-        // detect cycles with Brent's algorithm
-        if (lfs2_pair_issync(dir.tail, tortoise)) {
-            LFS2_WARN("Cycle detected in tail list");
+        err = lfs2_tortoise_detectcycles(&dir, &tortoise);
+        if (err < 0) {
             return LFS2_ERR_CORRUPT;
         }
-        if (tortoise_i == tortoise_period) {
-            tortoise[0] = dir.tail[0];
-            tortoise[1] = dir.tail[1];
-            tortoise_i = 0;
-            tortoise_period *= 2;
-        }
-        tortoise_i += 1;
 
         for (int i = 0; i < 2; i++) {
             int err = cb(data, dir.tail[i]);
@@ -4647,22 +4798,17 @@ static int lfs2_fs_pred(lfs2_t *lfs2,
     // iterate over all directory directory entries
     pdir->tail[0] = 0;
     pdir->tail[1] = 1;
-    lfs2_block_t tortoise[2] = {LFS2_BLOCK_NULL, LFS2_BLOCK_NULL};
-    lfs2_size_t tortoise_i = 1;
-    lfs2_size_t tortoise_period = 1;
+    struct lfs2_tortoise_t tortoise = {
+        .pair = {LFS2_BLOCK_NULL, LFS2_BLOCK_NULL},
+        .i = 1,
+        .period = 1,
+    };
+    int err = LFS2_ERR_OK;
     while (!lfs2_pair_isnull(pdir->tail)) {
-        // detect cycles with Brent's algorithm
-        if (lfs2_pair_issync(pdir->tail, tortoise)) {
-            LFS2_WARN("Cycle detected in tail list");
+        err = lfs2_tortoise_detectcycles(pdir, &tortoise);
+        if (err < 0) {
             return LFS2_ERR_CORRUPT;
         }
-        if (tortoise_i == tortoise_period) {
-            tortoise[0] = pdir->tail[0];
-            tortoise[1] = pdir->tail[1];
-            tortoise_i = 0;
-            tortoise_period *= 2;
-        }
-        tortoise_i += 1;
 
         if (lfs2_pair_cmp(pdir->tail, pair) == 0) {
             return 0;
@@ -4712,22 +4858,17 @@ static lfs2_stag_t lfs2_fs_parent(lfs2_t *lfs2, const lfs2_block_t pair[2],
     // use fetchmatch with callback to find pairs
     parent->tail[0] = 0;
     parent->tail[1] = 1;
-    lfs2_block_t tortoise[2] = {LFS2_BLOCK_NULL, LFS2_BLOCK_NULL};
-    lfs2_size_t tortoise_i = 1;
-    lfs2_size_t tortoise_period = 1;
+    struct lfs2_tortoise_t tortoise = {
+        .pair = {LFS2_BLOCK_NULL, LFS2_BLOCK_NULL},
+        .i = 1,
+        .period = 1,
+    };
+    int err = LFS2_ERR_OK;
     while (!lfs2_pair_isnull(parent->tail)) {
-        // detect cycles with Brent's algorithm
-        if (lfs2_pair_issync(parent->tail, tortoise)) {
-            LFS2_WARN("Cycle detected in tail list");
-            return LFS2_ERR_CORRUPT;
-        }
-        if (tortoise_i == tortoise_period) {
-            tortoise[0] = parent->tail[0];
-            tortoise[1] = parent->tail[1];
-            tortoise_i = 0;
-            tortoise_period *= 2;
+        err = lfs2_tortoise_detectcycles(parent, &tortoise);
+        if (err < 0) {
+            return err;
         }
-        tortoise_i += 1;
 
         lfs2_stag_t tag = lfs2_dir_fetchmatch(lfs2, parent, parent->tail,
                 LFS2_MKTAG(0x7ff, 0, 0x3ff),
@@ -4999,7 +5140,7 @@ static int lfs2_fs_forceconsistency(lfs2_t *lfs2) {
 #endif
 
 #ifndef LFS2_READONLY
-static int lfs2_fs_rawmkconsistent(lfs2_t *lfs2) {
+static int lfs2_fs_mkconsistent_(lfs2_t *lfs2) {
     // lfs2_fs_forceconsistency does most of the work here
     int err = lfs2_fs_forceconsistency(lfs2);
     if (err) {
@@ -5035,9 +5176,9 @@ static int lfs2_fs_size_count(void *p, lfs2_block_t block) {
     return 0;
 }
 
-static lfs2_ssize_t lfs2_fs_rawsize(lfs2_t *lfs2) {
+static lfs2_ssize_t lfs2_fs_size_(lfs2_t *lfs2) {
     lfs2_size_t size = 0;
-    int err = lfs2_fs_rawtraverse(lfs2, lfs2_fs_size_count, &size, false);
+    int err = lfs2_fs_traverse_(lfs2, lfs2_fs_size_count, &size, false);
     if (err) {
         return err;
     }
@@ -5045,41 +5186,118 @@ static lfs2_ssize_t lfs2_fs_rawsize(lfs2_t *lfs2) {
     return size;
 }
 
+// explicit garbage collection
 #ifndef LFS2_READONLY
-static int lfs2_fs_rawgrow(lfs2_t *lfs2, lfs2_size_t block_count) {
-    // shrinking is not supported
-    LFS2_ASSERT(block_count >= lfs2->block_count);
+static int lfs2_fs_gc_(lfs2_t *lfs2) {
+    // force consistency, even if we're not necessarily going to write,
+    // because this function is supposed to take care of janitorial work
+    // isn't it?
+    int err = lfs2_fs_forceconsistency(lfs2);
+    if (err) {
+        return err;
+    }
 
-    if (block_count > lfs2->block_count) {
-        lfs2->block_count = block_count;
+    // try to compact metadata pairs, note we can't really accomplish
+    // anything if compact_thresh doesn't at least leave a prog_size
+    // available
+    if (lfs2->cfg->compact_thresh
+            < lfs2->cfg->block_size - lfs2->cfg->prog_size) {
+        // iterate over all mdirs
+        lfs2_mdir_t mdir = {.tail = {0, 1}};
+        while (!lfs2_pair_isnull(mdir.tail)) {
+            err = lfs2_dir_fetch(lfs2, &mdir, mdir.tail);
+            if (err) {
+                return err;
+            }
 
-        // fetch the root
-        lfs2_mdir_t root;
-        int err = lfs2_dir_fetch(lfs2, &root, lfs2->root);
+            // not erased? exceeds our compaction threshold?
+            if (!mdir.erased || ((lfs2->cfg->compact_thresh == 0)
+                    ? mdir.off > lfs2->cfg->block_size - lfs2->cfg->block_size/8
+                    : mdir.off > lfs2->cfg->compact_thresh)) {
+                // the easiest way to trigger a compaction is to mark
+                // the mdir as unerased and add an empty commit
+                mdir.erased = false;
+                err = lfs2_dir_commit(lfs2, &mdir, NULL, 0);
+                if (err) {
+                    return err;
+                }
+            }
+        }
+    }
+
+    // try to populate the lookahead buffer, unless it's already full
+    if (lfs2->lookahead.size < lfs2_min(
+            8 * lfs2->cfg->lookahead_size,
+            lfs2->block_count)) {
+        err = lfs2_alloc_scan(lfs2);
         if (err) {
             return err;
         }
+    }
 
-        // update the superblock
-        lfs2_superblock_t superblock;
-        lfs2_stag_t tag = lfs2_dir_get(lfs2, &root, LFS2_MKTAG(0x7ff, 0x3ff, 0),
-                LFS2_MKTAG(LFS2_TYPE_INLINESTRUCT, 0, sizeof(superblock)),
-                &superblock);
-        if (tag < 0) {
-            return tag;
-        }
-        lfs2_superblock_fromle32(&superblock);
+    return 0;
+}
+#endif
 
-        superblock.block_count = lfs2->block_count;
+#ifndef LFS2_READONLY
+#ifdef LFS2_SHRINKNONRELOCATING
+static int lfs2_shrink_checkblock(void *data, lfs2_block_t block) {
+    lfs2_size_t threshold = *((lfs2_size_t*)data);
+    if (block >= threshold) {
+        return LFS2_ERR_NOTEMPTY;
+    }
+    return 0;
+}
+#endif
 
-        lfs2_superblock_tole32(&superblock);
-        err = lfs2_dir_commit(lfs2, &root, LFS2_MKATTRS(
-                {tag, &superblock}));
+static int lfs2_fs_grow_(lfs2_t *lfs2, lfs2_size_t block_count) {
+    int err;
+
+    if (block_count == lfs2->block_count) {
+        return 0;
+    }
+
+
+#ifndef LFS2_SHRINKNONRELOCATING
+    // shrinking is not supported
+    LFS2_ASSERT(block_count >= lfs2->block_count);
+#endif
+#ifdef LFS2_SHRINKNONRELOCATING
+    if (block_count < lfs2->block_count) {
+        err = lfs2_fs_traverse_(lfs2, lfs2_shrink_checkblock, &block_count, true);
         if (err) {
             return err;
         }
     }
+#endif
+
+    lfs2->block_count = block_count;
 
+    // fetch the root
+    lfs2_mdir_t root;
+    err = lfs2_dir_fetch(lfs2, &root, lfs2->root);
+    if (err) {
+        return err;
+    }
+
+    // update the superblock
+    lfs2_superblock_t superblock;
+    lfs2_stag_t tag = lfs2_dir_get(lfs2, &root, LFS2_MKTAG(0x7ff, 0x3ff, 0),
+            LFS2_MKTAG(LFS2_TYPE_INLINESTRUCT, 0, sizeof(superblock)),
+            &superblock);
+    if (tag < 0) {
+        return tag;
+    }
+    lfs2_superblock_fromle32(&superblock);
+
+    superblock.block_count = lfs2->block_count;
+
+    lfs2_superblock_tole32(&superblock);
+    err = lfs2_dir_commit(lfs2, &root, LFS2_MKATTRS(
+            {tag, &superblock}));
+    if (err) {
+        return err;
+    }
     return 0;
 }
 #endif
@@ -5451,10 +5669,10 @@ static int lfs21_mount(lfs2_t *lfs2, struct lfs21 *lfs21,
         lfs2->lfs21->root[1] = LFS2_BLOCK_NULL;
 
         // setup free lookahead
-        lfs2->free.off = 0;
-        lfs2->free.size = 0;
-        lfs2->free.i = 0;
-        lfs2_alloc_ack(lfs2);
+        lfs2->lookahead.start = 0;
+        lfs2->lookahead.size = 0;
+        lfs2->lookahead.next = 0;
+        lfs2_alloc_ckpoint(lfs2);
 
         // load superblock
         lfs21_dir_t dir;
@@ -5505,7 +5723,7 @@ static int lfs21_unmount(lfs2_t *lfs2) {
 }
 
 /// v1 migration ///
-static int lfs2_rawmigrate(lfs2_t *lfs2, const struct lfs2_config *cfg) {
+static int lfs2_migrate_(lfs2_t *lfs2, const struct lfs2_config *cfg) {
     struct lfs21 lfs21;
 
     // Indeterminate filesystem size not allowed for migration.
@@ -5759,7 +5977,7 @@ int lfs2_format(lfs2_t *lfs2, const struct lfs2_config *cfg) {
                 ".read=%p, .prog=%p, .erase=%p, .sync=%p, "
                 ".read_size=%"PRIu32", .prog_size=%"PRIu32", "
                 ".block_size=%"PRIu32", .block_count=%"PRIu32", "
-                ".block_cycles=%"PRIu32", .cache_size=%"PRIu32", "
+                ".block_cycles=%"PRId32", .cache_size=%"PRIu32", "
                 ".lookahead_size=%"PRIu32", .read_buffer=%p, "
                 ".prog_buffer=%p, .lookahead_buffer=%p, "
                 ".name_max=%"PRIu32", .file_max=%"PRIu32", "
@@ -5772,7 +5990,7 @@ int lfs2_format(lfs2_t *lfs2, const struct lfs2_config *cfg) {
             cfg->read_buffer, cfg->prog_buffer, cfg->lookahead_buffer,
             cfg->name_max, cfg->file_max, cfg->attr_max);
 
-    err = lfs2_rawformat(lfs2, cfg);
+    err = lfs2_format_(lfs2, cfg);
 
     LFS2_TRACE("lfs2_format -> %d", err);
     LFS2_UNLOCK(cfg);
@@ -5789,7 +6007,7 @@ int lfs2_mount(lfs2_t *lfs2, const struct lfs2_config *cfg) {
                 ".read=%p, .prog=%p, .erase=%p, .sync=%p, "
                 ".read_size=%"PRIu32", .prog_size=%"PRIu32", "
                 ".block_size=%"PRIu32", .block_count=%"PRIu32", "
-                ".block_cycles=%"PRIu32", .cache_size=%"PRIu32", "
+                ".block_cycles=%"PRId32", .cache_size=%"PRIu32", "
                 ".lookahead_size=%"PRIu32", .read_buffer=%p, "
                 ".prog_buffer=%p, .lookahead_buffer=%p, "
                 ".name_max=%"PRIu32", .file_max=%"PRIu32", "
@@ -5802,7 +6020,7 @@ int lfs2_mount(lfs2_t *lfs2, const struct lfs2_config *cfg) {
             cfg->read_buffer, cfg->prog_buffer, cfg->lookahead_buffer,
             cfg->name_max, cfg->file_max, cfg->attr_max);
 
-    err = lfs2_rawmount(lfs2, cfg);
+    err = lfs2_mount_(lfs2, cfg);
 
     LFS2_TRACE("lfs2_mount -> %d", err);
     LFS2_UNLOCK(cfg);
@@ -5816,7 +6034,7 @@ int lfs2_unmount(lfs2_t *lfs2) {
     }
     LFS2_TRACE("lfs2_unmount(%p)", (void*)lfs2);
 
-    err = lfs2_rawunmount(lfs2);
+    err = lfs2_unmount_(lfs2);
 
     LFS2_TRACE("lfs2_unmount -> %d", err);
     LFS2_UNLOCK(lfs2->cfg);
@@ -5831,7 +6049,7 @@ int lfs2_remove(lfs2_t *lfs2, const char *path) {
     }
     LFS2_TRACE("lfs2_remove(%p, \"%s\")", (void*)lfs2, path);
 
-    err = lfs2_rawremove(lfs2, path);
+    err = lfs2_remove_(lfs2, path);
 
     LFS2_TRACE("lfs2_remove -> %d", err);
     LFS2_UNLOCK(lfs2->cfg);
@@ -5847,7 +6065,7 @@ int lfs2_rename(lfs2_t *lfs2, const char *oldpath, const char *newpath) {
     }
     LFS2_TRACE("lfs2_rename(%p, \"%s\", \"%s\")", (void*)lfs2, oldpath, newpath);
 
-    err = lfs2_rawrename(lfs2, oldpath, newpath);
+    err = lfs2_rename_(lfs2, oldpath, newpath);
 
     LFS2_TRACE("lfs2_rename -> %d", err);
     LFS2_UNLOCK(lfs2->cfg);
@@ -5862,7 +6080,7 @@ int lfs2_stat(lfs2_t *lfs2, const char *path, struct lfs2_info *info) {
     }
     LFS2_TRACE("lfs2_stat(%p, \"%s\", %p)", (void*)lfs2, path, (void*)info);
 
-    err = lfs2_rawstat(lfs2, path, info);
+    err = lfs2_stat_(lfs2, path, info);
 
     LFS2_TRACE("lfs2_stat -> %d", err);
     LFS2_UNLOCK(lfs2->cfg);
@@ -5878,7 +6096,7 @@ lfs2_ssize_t lfs2_getattr(lfs2_t *lfs2, const char *path,
     LFS2_TRACE("lfs2_getattr(%p, \"%s\", %"PRIu8", %p, %"PRIu32")",
             (void*)lfs2, path, type, buffer, size);
 
-    lfs2_ssize_t res = lfs2_rawgetattr(lfs2, path, type, buffer, size);
+    lfs2_ssize_t res = lfs2_getattr_(lfs2, path, type, buffer, size);
 
     LFS2_TRACE("lfs2_getattr -> %"PRId32, res);
     LFS2_UNLOCK(lfs2->cfg);
@@ -5895,7 +6113,7 @@ int lfs2_setattr(lfs2_t *lfs2, const char *path,
     LFS2_TRACE("lfs2_setattr(%p, \"%s\", %"PRIu8", %p, %"PRIu32")",
             (void*)lfs2, path, type, buffer, size);
 
-    err = lfs2_rawsetattr(lfs2, path, type, buffer, size);
+    err = lfs2_setattr_(lfs2, path, type, buffer, size);
 
     LFS2_TRACE("lfs2_setattr -> %d", err);
     LFS2_UNLOCK(lfs2->cfg);
@@ -5911,7 +6129,7 @@ int lfs2_removeattr(lfs2_t *lfs2, const char *path, uint8_t type) {
     }
     LFS2_TRACE("lfs2_removeattr(%p, \"%s\", %"PRIu8")", (void*)lfs2, path, type);
 
-    err = lfs2_rawremoveattr(lfs2, path, type);
+    err = lfs2_removeattr_(lfs2, path, type);
 
     LFS2_TRACE("lfs2_removeattr -> %d", err);
     LFS2_UNLOCK(lfs2->cfg);
@@ -5926,10 +6144,10 @@ int lfs2_file_open(lfs2_t *lfs2, lfs2_file_t *file, const char *path, int flags)
         return err;
     }
     LFS2_TRACE("lfs2_file_open(%p, %p, \"%s\", %x)",
-            (void*)lfs2, (void*)file, path, flags);
+            (void*)lfs2, (void*)file, path, (unsigned)flags);
     LFS2_ASSERT(!lfs2_mlist_isopen(lfs2->mlist, (struct lfs2_mlist*)file));
 
-    err = lfs2_file_rawopen(lfs2, file, path, flags);
+    err = lfs2_file_open_(lfs2, file, path, flags);
 
     LFS2_TRACE("lfs2_file_open -> %d", err);
     LFS2_UNLOCK(lfs2->cfg);
@@ -5946,11 +6164,11 @@ int lfs2_file_opencfg(lfs2_t *lfs2, lfs2_file_t *file,
     }
     LFS2_TRACE("lfs2_file_opencfg(%p, %p, \"%s\", %x, %p {"
                  ".buffer=%p, .attrs=%p, .attr_count=%"PRIu32"})",
-            (void*)lfs2, (void*)file, path, flags,
+            (void*)lfs2, (void*)file, path, (unsigned)flags,
             (void*)cfg, cfg->buffer, (void*)cfg->attrs, cfg->attr_count);
     LFS2_ASSERT(!lfs2_mlist_isopen(lfs2->mlist, (struct lfs2_mlist*)file));
 
-    err = lfs2_file_rawopencfg(lfs2, file, path, flags, cfg);
+    err = lfs2_file_opencfg_(lfs2, file, path, flags, cfg);
 
     LFS2_TRACE("lfs2_file_opencfg -> %d", err);
     LFS2_UNLOCK(lfs2->cfg);
@@ -5965,7 +6183,7 @@ int lfs2_file_close(lfs2_t *lfs2, lfs2_file_t *file) {
     LFS2_TRACE("lfs2_file_close(%p, %p)", (void*)lfs2, (void*)file);
     LFS2_ASSERT(lfs2_mlist_isopen(lfs2->mlist, (struct lfs2_mlist*)file));
 
-    err = lfs2_file_rawclose(lfs2, file);
+    err = lfs2_file_close_(lfs2, file);
 
     LFS2_TRACE("lfs2_file_close -> %d", err);
     LFS2_UNLOCK(lfs2->cfg);
@@ -5981,7 +6199,7 @@ int lfs2_file_sync(lfs2_t *lfs2, lfs2_file_t *file) {
     LFS2_TRACE("lfs2_file_sync(%p, %p)", (void*)lfs2, (void*)file);
     LFS2_ASSERT(lfs2_mlist_isopen(lfs2->mlist, (struct lfs2_mlist*)file));
 
-    err = lfs2_file_rawsync(lfs2, file);
+    err = lfs2_file_sync_(lfs2, file);
 
     LFS2_TRACE("lfs2_file_sync -> %d", err);
     LFS2_UNLOCK(lfs2->cfg);
@@ -5999,7 +6217,7 @@ lfs2_ssize_t lfs2_file_read(lfs2_t *lfs2, lfs2_file_t *file,
             (void*)lfs2, (void*)file, buffer, size);
     LFS2_ASSERT(lfs2_mlist_isopen(lfs2->mlist, (struct lfs2_mlist*)file));
 
-    lfs2_ssize_t res = lfs2_file_rawread(lfs2, file, buffer, size);
+    lfs2_ssize_t res = lfs2_file_read_(lfs2, file, buffer, size);
 
     LFS2_TRACE("lfs2_file_read -> %"PRId32, res);
     LFS2_UNLOCK(lfs2->cfg);
@@ -6017,7 +6235,7 @@ lfs2_ssize_t lfs2_file_write(lfs2_t *lfs2, lfs2_file_t *file,
             (void*)lfs2, (void*)file, buffer, size);
     LFS2_ASSERT(lfs2_mlist_isopen(lfs2->mlist, (struct lfs2_mlist*)file));
 
-    lfs2_ssize_t res = lfs2_file_rawwrite(lfs2, file, buffer, size);
+    lfs2_ssize_t res = lfs2_file_write_(lfs2, file, buffer, size);
 
     LFS2_TRACE("lfs2_file_write -> %"PRId32, res);
     LFS2_UNLOCK(lfs2->cfg);
@@ -6035,7 +6253,7 @@ lfs2_soff_t lfs2_file_seek(lfs2_t *lfs2, lfs2_file_t *file,
             (void*)lfs2, (void*)file, off, whence);
     LFS2_ASSERT(lfs2_mlist_isopen(lfs2->mlist, (struct lfs2_mlist*)file));
 
-    lfs2_soff_t res = lfs2_file_rawseek(lfs2, file, off, whence);
+    lfs2_soff_t res = lfs2_file_seek_(lfs2, file, off, whence);
 
     LFS2_TRACE("lfs2_file_seek -> %"PRId32, res);
     LFS2_UNLOCK(lfs2->cfg);
@@ -6052,7 +6270,7 @@ int lfs2_file_truncate(lfs2_t *lfs2, lfs2_file_t *file, lfs2_off_t size) {
             (void*)lfs2, (void*)file, size);
     LFS2_ASSERT(lfs2_mlist_isopen(lfs2->mlist, (struct lfs2_mlist*)file));
 
-    err = lfs2_file_rawtruncate(lfs2, file, size);
+    err = lfs2_file_truncate_(lfs2, file, size);
 
     LFS2_TRACE("lfs2_file_truncate -> %d", err);
     LFS2_UNLOCK(lfs2->cfg);
@@ -6068,7 +6286,7 @@ lfs2_soff_t lfs2_file_tell(lfs2_t *lfs2, lfs2_file_t *file) {
     LFS2_TRACE("lfs2_file_tell(%p, %p)", (void*)lfs2, (void*)file);
     LFS2_ASSERT(lfs2_mlist_isopen(lfs2->mlist, (struct lfs2_mlist*)file));
 
-    lfs2_soff_t res = lfs2_file_rawtell(lfs2, file);
+    lfs2_soff_t res = lfs2_file_tell_(lfs2, file);
 
     LFS2_TRACE("lfs2_file_tell -> %"PRId32, res);
     LFS2_UNLOCK(lfs2->cfg);
@@ -6082,7 +6300,7 @@ int lfs2_file_rewind(lfs2_t *lfs2, lfs2_file_t *file) {
     }
     LFS2_TRACE("lfs2_file_rewind(%p, %p)", (void*)lfs2, (void*)file);
 
-    err = lfs2_file_rawrewind(lfs2, file);
+    err = lfs2_file_rewind_(lfs2, file);
 
     LFS2_TRACE("lfs2_file_rewind -> %d", err);
     LFS2_UNLOCK(lfs2->cfg);
@@ -6097,9 +6315,9 @@ lfs2_soff_t lfs2_file_size(lfs2_t *lfs2, lfs2_file_t *file) {
     LFS2_TRACE("lfs2_file_size(%p, %p)", (void*)lfs2, (void*)file);
     LFS2_ASSERT(lfs2_mlist_isopen(lfs2->mlist, (struct lfs2_mlist*)file));
 
-    lfs2_soff_t res = lfs2_file_rawsize(lfs2, file);
+    lfs2_soff_t res = lfs2_file_size_(lfs2, file);
 
-    LFS2_TRACE("lfs2_file_size -> %"PRId32, res);
+    LFS2_TRACE("lfs2_file_size -> %"PRIu32, res);
     LFS2_UNLOCK(lfs2->cfg);
     return res;
 }
@@ -6112,7 +6330,7 @@ int lfs2_mkdir(lfs2_t *lfs2, const char *path) {
     }
     LFS2_TRACE("lfs2_mkdir(%p, \"%s\")", (void*)lfs2, path);
 
-    err = lfs2_rawmkdir(lfs2, path);
+    err = lfs2_mkdir_(lfs2, path);
 
     LFS2_TRACE("lfs2_mkdir -> %d", err);
     LFS2_UNLOCK(lfs2->cfg);
@@ -6128,7 +6346,7 @@ int lfs2_dir_open(lfs2_t *lfs2, lfs2_dir_t *dir, const char *path) {
     LFS2_TRACE("lfs2_dir_open(%p, %p, \"%s\")", (void*)lfs2, (void*)dir, path);
     LFS2_ASSERT(!lfs2_mlist_isopen(lfs2->mlist, (struct lfs2_mlist*)dir));
 
-    err = lfs2_dir_rawopen(lfs2, dir, path);
+    err = lfs2_dir_open_(lfs2, dir, path);
 
     LFS2_TRACE("lfs2_dir_open -> %d", err);
     LFS2_UNLOCK(lfs2->cfg);
@@ -6142,7 +6360,7 @@ int lfs2_dir_close(lfs2_t *lfs2, lfs2_dir_t *dir) {
     }
     LFS2_TRACE("lfs2_dir_close(%p, %p)", (void*)lfs2, (void*)dir);
 
-    err = lfs2_dir_rawclose(lfs2, dir);
+    err = lfs2_dir_close_(lfs2, dir);
 
     LFS2_TRACE("lfs2_dir_close -> %d", err);
     LFS2_UNLOCK(lfs2->cfg);
@@ -6157,7 +6375,7 @@ int lfs2_dir_read(lfs2_t *lfs2, lfs2_dir_t *dir, struct lfs2_info *info) {
     LFS2_TRACE("lfs2_dir_read(%p, %p, %p)",
             (void*)lfs2, (void*)dir, (void*)info);
 
-    err = lfs2_dir_rawread(lfs2, dir, info);
+    err = lfs2_dir_read_(lfs2, dir, info);
 
     LFS2_TRACE("lfs2_dir_read -> %d", err);
     LFS2_UNLOCK(lfs2->cfg);
@@ -6172,7 +6390,7 @@ int lfs2_dir_seek(lfs2_t *lfs2, lfs2_dir_t *dir, lfs2_off_t off) {
     LFS2_TRACE("lfs2_dir_seek(%p, %p, %"PRIu32")",
             (void*)lfs2, (void*)dir, off);
 
-    err = lfs2_dir_rawseek(lfs2, dir, off);
+    err = lfs2_dir_seek_(lfs2, dir, off);
 
     LFS2_TRACE("lfs2_dir_seek -> %d", err);
     LFS2_UNLOCK(lfs2->cfg);
@@ -6186,7 +6404,7 @@ lfs2_soff_t lfs2_dir_tell(lfs2_t *lfs2, lfs2_dir_t *dir) {
     }
     LFS2_TRACE("lfs2_dir_tell(%p, %p)", (void*)lfs2, (void*)dir);
 
-    lfs2_soff_t res = lfs2_dir_rawtell(lfs2, dir);
+    lfs2_soff_t res = lfs2_dir_tell_(lfs2, dir);
 
     LFS2_TRACE("lfs2_dir_tell -> %"PRId32, res);
     LFS2_UNLOCK(lfs2->cfg);
@@ -6200,7 +6418,7 @@ int lfs2_dir_rewind(lfs2_t *lfs2, lfs2_dir_t *dir) {
     }
     LFS2_TRACE("lfs2_dir_rewind(%p, %p)", (void*)lfs2, (void*)dir);
 
-    err = lfs2_dir_rawrewind(lfs2, dir);
+    err = lfs2_dir_rewind_(lfs2, dir);
 
     LFS2_TRACE("lfs2_dir_rewind -> %d", err);
     LFS2_UNLOCK(lfs2->cfg);
@@ -6214,7 +6432,7 @@ int lfs2_fs_stat(lfs2_t *lfs2, struct lfs2_fsinfo *fsinfo) {
     }
     LFS2_TRACE("lfs2_fs_stat(%p, %p)", (void*)lfs2, (void*)fsinfo);
 
-    err = lfs2_fs_rawstat(lfs2, fsinfo);
+    err = lfs2_fs_stat_(lfs2, fsinfo);
 
     LFS2_TRACE("lfs2_fs_stat -> %d", err);
     LFS2_UNLOCK(lfs2->cfg);
@@ -6228,7 +6446,7 @@ lfs2_ssize_t lfs2_fs_size(lfs2_t *lfs2) {
     }
     LFS2_TRACE("lfs2_fs_size(%p)", (void*)lfs2);
 
-    lfs2_ssize_t res = lfs2_fs_rawsize(lfs2);
+    lfs2_ssize_t res = lfs2_fs_size_(lfs2);
 
     LFS2_TRACE("lfs2_fs_size -> %"PRId32, res);
     LFS2_UNLOCK(lfs2->cfg);
@@ -6243,7 +6461,7 @@ int lfs2_fs_traverse(lfs2_t *lfs2, int (*cb)(void *, lfs2_block_t), void *data)
     LFS2_TRACE("lfs2_fs_traverse(%p, %p, %p)",
             (void*)lfs2, (void*)(uintptr_t)cb, data);
 
-    err = lfs2_fs_rawtraverse(lfs2, cb, data, true);
+    err = lfs2_fs_traverse_(lfs2, cb, data, true);
 
     LFS2_TRACE("lfs2_fs_traverse -> %d", err);
     LFS2_UNLOCK(lfs2->cfg);
@@ -6251,32 +6469,32 @@ int lfs2_fs_traverse(lfs2_t *lfs2, int (*cb)(void *, lfs2_block_t), void *data)
 }
 
 #ifndef LFS2_READONLY
-int lfs2_fs_gc(lfs2_t *lfs2) {
+int lfs2_fs_mkconsistent(lfs2_t *lfs2) {
     int err = LFS2_LOCK(lfs2->cfg);
     if (err) {
         return err;
     }
-    LFS2_TRACE("lfs2_fs_gc(%p)", (void*)lfs2);
+    LFS2_TRACE("lfs2_fs_mkconsistent(%p)", (void*)lfs2);
 
-    err = lfs2_fs_rawgc(lfs2);
+    err = lfs2_fs_mkconsistent_(lfs2);
 
-    LFS2_TRACE("lfs2_fs_gc -> %d", err);
+    LFS2_TRACE("lfs2_fs_mkconsistent -> %d", err);
     LFS2_UNLOCK(lfs2->cfg);
     return err;
 }
 #endif
 
 #ifndef LFS2_READONLY
-int lfs2_fs_mkconsistent(lfs2_t *lfs2) {
+int lfs2_fs_gc(lfs2_t *lfs2) {
     int err = LFS2_LOCK(lfs2->cfg);
     if (err) {
         return err;
     }
-    LFS2_TRACE("lfs2_fs_mkconsistent(%p)", (void*)lfs2);
+    LFS2_TRACE("lfs2_fs_gc(%p)", (void*)lfs2);
 
-    err = lfs2_fs_rawmkconsistent(lfs2);
+    err = lfs2_fs_gc_(lfs2);
 
-    LFS2_TRACE("lfs2_fs_mkconsistent -> %d", err);
+    LFS2_TRACE("lfs2_fs_gc -> %d", err);
     LFS2_UNLOCK(lfs2->cfg);
     return err;
 }
@@ -6290,7 +6508,7 @@ int lfs2_fs_grow(lfs2_t *lfs2, lfs2_size_t block_count) {
     }
     LFS2_TRACE("lfs2_fs_grow(%p, %"PRIu32")", (void*)lfs2, block_count);
 
-    err = lfs2_fs_rawgrow(lfs2, block_count);
+    err = lfs2_fs_grow_(lfs2, block_count);
 
     LFS2_TRACE("lfs2_fs_grow -> %d", err);
     LFS2_UNLOCK(lfs2->cfg);
@@ -6308,7 +6526,7 @@ int lfs2_migrate(lfs2_t *lfs2, const struct lfs2_config *cfg) {
                 ".read=%p, .prog=%p, .erase=%p, .sync=%p, "
                 ".read_size=%"PRIu32", .prog_size=%"PRIu32", "
                 ".block_size=%"PRIu32", .block_count=%"PRIu32", "
-                ".block_cycles=%"PRIu32", .cache_size=%"PRIu32", "
+                ".block_cycles=%"PRId32", .cache_size=%"PRIu32", "
                 ".lookahead_size=%"PRIu32", .read_buffer=%p, "
                 ".prog_buffer=%p, .lookahead_buffer=%p, "
                 ".name_max=%"PRIu32", .file_max=%"PRIu32", "
@@ -6321,7 +6539,7 @@ int lfs2_migrate(lfs2_t *lfs2, const struct lfs2_config *cfg) {
             cfg->read_buffer, cfg->prog_buffer, cfg->lookahead_buffer,
             cfg->name_max, cfg->file_max, cfg->attr_max);
 
-    err = lfs2_rawmigrate(lfs2, cfg);
+    err = lfs2_migrate_(lfs2, cfg);
 
     LFS2_TRACE("lfs2_migrate -> %d", err);
     LFS2_UNLOCK(cfg);
diff --git a/lib/littlefs/lfs2.h b/lib/littlefs/lfs2.h
index 559ccebac9269..aee0619e9326a 100644
--- a/lib/littlefs/lfs2.h
+++ b/lib/littlefs/lfs2.h
@@ -21,7 +21,7 @@ extern "C"
 // Software library version
 // Major (top-nibble), incremented on backwards incompatible changes
 // Minor (bottom-nibble), incremented on feature additions
-#define LFS2_VERSION 0x00020008
+#define LFS2_VERSION 0x0002000b
 #define LFS2_VERSION_MAJOR (0xffff & (LFS2_VERSION >> 16))
 #define LFS2_VERSION_MINOR (0xffff & (LFS2_VERSION >>  0))
 
@@ -52,16 +52,15 @@ typedef uint32_t lfs2_block_t;
 #endif
 
 // Maximum size of a file in bytes, may be redefined to limit to support other
-// drivers. Limited on disk to <= 4294967296. However, above 2147483647 the
-// functions lfs2_file_seek, lfs2_file_size, and lfs2_file_tell will return
-// incorrect values due to using signed integers. Stored in superblock and
-// must be respected by other littlefs drivers.
+// drivers. Limited on disk to <= 2147483647. Stored in superblock and must be
+// respected by other littlefs drivers.
 #ifndef LFS2_FILE_MAX
 #define LFS2_FILE_MAX 2147483647
 #endif
 
 // Maximum size of custom attributes in bytes, may be redefined, but there is
-// no real benefit to using a smaller LFS2_ATTR_MAX. Limited to <= 1022.
+// no real benefit to using a smaller LFS2_ATTR_MAX. Limited to <= 1022. Stored
+// in superblock and must be respected by other littlefs drivers.
 #ifndef LFS2_ATTR_MAX
 #define LFS2_ATTR_MAX 1022
 #endif
@@ -205,7 +204,8 @@ struct lfs2_config {
     // program sizes.
     lfs2_size_t block_size;
 
-    // Number of erasable blocks on the device.
+    // Number of erasable blocks on the device. Defaults to block_count stored
+    // on disk when zero.
     lfs2_size_t block_count;
 
     // Number of erase cycles before littlefs evicts metadata logs and moves
@@ -226,9 +226,20 @@ struct lfs2_config {
     // Size of the lookahead buffer in bytes. A larger lookahead buffer
     // increases the number of blocks found during an allocation pass. The
     // lookahead buffer is stored as a compact bitmap, so each byte of RAM
-    // can track 8 blocks. Must be a multiple of 8.
+    // can track 8 blocks.
     lfs2_size_t lookahead_size;
 
+    // Threshold for metadata compaction during lfs2_fs_gc in bytes. Metadata
+    // pairs that exceed this threshold will be compacted during lfs2_fs_gc.
+    // Defaults to ~88% block_size when zero, though the default may change
+    // in the future.
+    //
+    // Note this only affects lfs2_fs_gc. Normal compactions still only occur
+    // when full.
+    //
+    // Set to -1 to disable metadata compaction during lfs2_fs_gc.
+    lfs2_size_t compact_thresh;
+
     // Optional statically allocated read buffer. Must be cache_size.
     // By default lfs2_malloc is used to allocate this buffer.
     void *read_buffer;
@@ -237,25 +248,24 @@ struct lfs2_config {
     // By default lfs2_malloc is used to allocate this buffer.
     void *prog_buffer;
 
-    // Optional statically allocated lookahead buffer. Must be lookahead_size
-    // and aligned to a 32-bit boundary. By default lfs2_malloc is used to
-    // allocate this buffer.
+    // Optional statically allocated lookahead buffer. Must be lookahead_size.
+    // By default lfs2_malloc is used to allocate this buffer.
     void *lookahead_buffer;
 
     // Optional upper limit on length of file names in bytes. No downside for
     // larger names except the size of the info struct which is controlled by
-    // the LFS2_NAME_MAX define. Defaults to LFS2_NAME_MAX when zero. Stored in
-    // superblock and must be respected by other littlefs drivers.
+    // the LFS2_NAME_MAX define. Defaults to LFS2_NAME_MAX or name_max stored on
+    // disk when zero.
     lfs2_size_t name_max;
 
     // Optional upper limit on files in bytes. No downside for larger files
-    // but must be <= LFS2_FILE_MAX. Defaults to LFS2_FILE_MAX when zero. Stored
-    // in superblock and must be respected by other littlefs drivers.
+    // but must be <= LFS2_FILE_MAX. Defaults to LFS2_FILE_MAX or file_max stored
+    // on disk when zero.
     lfs2_size_t file_max;
 
     // Optional upper limit on custom attributes in bytes. No downside for
     // larger attributes size but must be <= LFS2_ATTR_MAX. Defaults to
-    // LFS2_ATTR_MAX when zero.
+    // LFS2_ATTR_MAX or attr_max stored on disk when zero.
     lfs2_size_t attr_max;
 
     // Optional upper limit on total space given to metadata pairs in bytes. On
@@ -264,6 +274,15 @@ struct lfs2_config {
     // Defaults to block_size when zero.
     lfs2_size_t metadata_max;
 
+    // Optional upper limit on inlined files in bytes. Inlined files live in
+    // metadata and decrease storage requirements, but may be limited to
+    // improve metadata-related performance. Must be <= cache_size, <=
+    // attr_max, and <= block_size/8. Defaults to the largest possible
+    // inline_max when zero.
+    //
+    // Set to -1 to disable inlined files.
+    lfs2_size_t inline_max;
+
 #ifdef LFS2_MULTIVERSION
     // On-disk version to use when writing in the form of 16-bit major version
     // + 16-bit minor version. This limiting metadata to what is supported by
@@ -430,19 +449,20 @@ typedef struct lfs2 {
     lfs2_gstate_t gdisk;
     lfs2_gstate_t gdelta;
 
-    struct lfs2_free {
-        lfs2_block_t off;
+    struct lfs2_lookahead {
+        lfs2_block_t start;
         lfs2_block_t size;
-        lfs2_block_t i;
-        lfs2_block_t ack;
-        uint32_t *buffer;
-    } free;
+        lfs2_block_t next;
+        lfs2_block_t ckpoint;
+        uint8_t *buffer;
+    } lookahead;
 
     const struct lfs2_config *cfg;
     lfs2_size_t block_count;
     lfs2_size_t name_max;
     lfs2_size_t file_max;
     lfs2_size_t attr_max;
+    lfs2_size_t inline_max;
 
 #ifdef LFS2_MIGRATE
     struct lfs21 *lfs21;
@@ -712,18 +732,6 @@ lfs2_ssize_t lfs2_fs_size(lfs2_t *lfs2);
 // Returns a negative error code on failure.
 int lfs2_fs_traverse(lfs2_t *lfs2, int (*cb)(void*, lfs2_block_t), void *data);
 
-// Attempt to proactively find free blocks
-//
-// Calling this function is not required, but may allowing the offloading of
-// the expensive block allocation scan to a less time-critical code path.
-//
-// Note: littlefs currently does not persist any found free blocks to disk.
-// This may change in the future.
-//
-// Returns a negative error code on failure. Finding no free blocks is
-// not an error.
-int lfs2_fs_gc(lfs2_t *lfs2);
-
 #ifndef LFS2_READONLY
 // Attempt to make the filesystem consistent and ready for writing
 //
@@ -736,11 +744,33 @@ int lfs2_fs_gc(lfs2_t *lfs2);
 int lfs2_fs_mkconsistent(lfs2_t *lfs2);
 #endif
 
+#ifndef LFS2_READONLY
+// Attempt any janitorial work
+//
+// This currently:
+// 1. Calls mkconsistent if not already consistent
+// 2. Compacts metadata > compact_thresh
+// 3. Populates the block allocator
+//
+// Though additional janitorial work may be added in the future.
+//
+// Calling this function is not required, but may allow the offloading of
+// expensive janitorial work to a less time-critical code path.
+//
+// Returns a negative error code on failure. Accomplishing nothing is not
+// an error.
+int lfs2_fs_gc(lfs2_t *lfs2);
+#endif
+
 #ifndef LFS2_READONLY
 // Grows the filesystem to a new size, updating the superblock with the new
 // block count.
 //
-// Note: This is irreversible.
+// If LFS2_SHRINKNONRELOCATING is defined, this function will also accept
+// block_counts smaller than the current configuration, after checking
+// that none of the blocks that are being removed are in use.
+// Note that littlefs's pseudorandom block allocation means that
+// this is very unlikely to work in the general case.
 //
 // Returns a negative error code on failure.
 int lfs2_fs_grow(lfs2_t *lfs2, lfs2_size_t block_count);
diff --git a/lib/littlefs/lfs2_util.c b/lib/littlefs/lfs2_util.c
index c9850e78869c3..4fe7e5340ce77 100644
--- a/lib/littlefs/lfs2_util.c
+++ b/lib/littlefs/lfs2_util.c
@@ -11,6 +11,8 @@
 #ifndef LFS2_CONFIG
 
 
+// If user provides their own CRC impl we don't need this
+#ifndef LFS2_CRC
 // Software CRC implementation with small lookup table
 uint32_t lfs2_crc(uint32_t crc, const void *buffer, size_t size) {
     static const uint32_t rtable[16] = {
@@ -29,6 +31,7 @@ uint32_t lfs2_crc(uint32_t crc, const void *buffer, size_t size) {
 
     return crc;
 }
+#endif
 
 
 #endif
diff --git a/lib/littlefs/lfs2_util.h b/lib/littlefs/lfs2_util.h
index dd2cbcc106d84..12c82a630b079 100644
--- a/lib/littlefs/lfs2_util.h
+++ b/lib/littlefs/lfs2_util.h
@@ -8,6 +8,9 @@
 #ifndef LFS2_UTIL_H
 #define LFS2_UTIL_H
 
+#define LFS2_STRINGIZE(x) LFS2_STRINGIZE2(x)
+#define LFS2_STRINGIZE2(x) #x
+
 // Users can override lfs2_util.h with their own configuration by defining
 // LFS2_CONFIG as a header file to include (-DLFS2_CONFIG=lfs2_config.h).
 //
@@ -15,11 +18,26 @@
 // provided by the config file. To start, I would suggest copying lfs2_util.h
 // and modifying as needed.
 #ifdef LFS2_CONFIG
-#define LFS2_STRINGIZE(x) LFS2_STRINGIZE2(x)
-#define LFS2_STRINGIZE2(x) #x
 #include LFS2_STRINGIZE(LFS2_CONFIG)
 #else
 
+// Alternatively, users can provide a header file which defines
+// macros and other things consumed by littlefs.
+//
+// For example, provide my_defines.h, which contains
+// something like:
+//
+// #include <stddef.h>
+// extern void *my_malloc(size_t sz);
+// #define LFS2_MALLOC(sz) my_malloc(sz)
+//
+// And build littlefs with the header by defining LFS2_DEFINES.
+// (-DLFS2_DEFINES=my_defines.h)
+
+#ifdef LFS2_DEFINES
+#include LFS2_STRINGIZE(LFS2_DEFINES)
+#endif
+
 // System includes
 #include <stdint.h>
 #include <stdbool.h>
@@ -177,10 +195,10 @@ static inline uint32_t lfs2_fromle32(uint32_t a) {
     (defined(__BYTE_ORDER__) && defined(__ORDER_BIG_ENDIAN__) && __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__))
     return __builtin_bswap32(a);
 #else
-    return (((uint8_t*)&a)[0] <<  0) |
-           (((uint8_t*)&a)[1] <<  8) |
-           (((uint8_t*)&a)[2] << 16) |
-           (((uint8_t*)&a)[3] << 24);
+    return ((uint32_t)((uint8_t*)&a)[0] <<  0) |
+           ((uint32_t)((uint8_t*)&a)[1] <<  8) |
+           ((uint32_t)((uint8_t*)&a)[2] << 16) |
+           ((uint32_t)((uint8_t*)&a)[3] << 24);
 #endif
 }
 
@@ -200,10 +218,10 @@ static inline uint32_t lfs2_frombe32(uint32_t a) {
     (defined(__BYTE_ORDER__) && defined(__ORDER_BIG_ENDIAN__) && __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__)
     return a;
 #else
-    return (((uint8_t*)&a)[0] << 24) |
-           (((uint8_t*)&a)[1] << 16) |
-           (((uint8_t*)&a)[2] <<  8) |
-           (((uint8_t*)&a)[3] <<  0);
+    return ((uint32_t)((uint8_t*)&a)[0] << 24) |
+           ((uint32_t)((uint8_t*)&a)[1] << 16) |
+           ((uint32_t)((uint8_t*)&a)[2] <<  8) |
+           ((uint32_t)((uint8_t*)&a)[3] <<  0);
 #endif
 }
 
@@ -212,12 +230,22 @@ static inline uint32_t lfs2_tobe32(uint32_t a) {
 }
 
 // Calculate CRC-32 with polynomial = 0x04c11db7
+#ifdef LFS2_CRC
+static inline uint32_t lfs2_crc(uint32_t crc, const void *buffer, size_t size) {
+    return LFS2_CRC(crc, buffer, size);
+}
+#else
 uint32_t lfs2_crc(uint32_t crc, const void *buffer, size_t size);
+#endif
 
 // Allocate memory, only used if buffers are not provided to littlefs
-// Note, memory must be 64-bit aligned
+//
+// littlefs current has no alignment requirements, as it only allocates
+// byte-level buffers.
 static inline void *lfs2_malloc(size_t size) {
-#ifndef LFS2_NO_MALLOC
+#if defined(LFS2_MALLOC)
+    return LFS2_MALLOC(size);
+#elif !defined(LFS2_NO_MALLOC)
     return malloc(size);
 #else
     (void)size;
@@ -227,7 +255,9 @@ static inline void *lfs2_malloc(size_t size) {
 
 // Deallocate memory, only used if buffers are not provided to littlefs
 static inline void lfs2_free(void *p) {
-#ifndef LFS2_NO_MALLOC
+#if defined(LFS2_FREE)
+    LFS2_FREE(p);
+#elif !defined(LFS2_NO_MALLOC)
     free(p);
 #else
     (void)p;
diff --git a/lib/micropython-lib b/lib/micropython-lib
index 5b496e944ec04..6ae440a8a1442 160000
--- a/lib/micropython-lib
+++ b/lib/micropython-lib
@@ -1 +1 @@
-Subproject commit 5b496e944ec045177afa1620920a168410b7f60b
+Subproject commit 6ae440a8a144233e6e703f6759b7e7a0afaa37a4
diff --git a/locale/circuitpython.pot b/locale/circuitpython.pot
index 07623ea94a078..833991ac476e0 100644
--- a/locale/circuitpython.pot
+++ b/locale/circuitpython.pot
@@ -78,6 +78,11 @@ msgid ""
 "%d address pins, %d rgb pins and %d tiles indicate a height of %d, not %d"
 msgstr ""
 
+#: py/emitinlinextensa.c
+#, c-format
+msgid "%d is not a multiple of %d"
+msgstr ""
+
 #: shared-bindings/microcontroller/Pin.c
 msgid "%q and %q contain duplicate pins"
 msgstr ""
@@ -262,10 +267,6 @@ msgstr ""
 msgid "%q out of range"
 msgstr ""
 
-#: py/objmodule.c
-msgid "%q renamed %q"
-msgstr ""
-
 #: py/objrange.c py/objslice.c shared-bindings/random/__init__.c
 msgid "%q step cannot be zero"
 msgstr ""
@@ -963,6 +964,14 @@ msgstr ""
 msgid "ECB only operates on 16 bytes at a time"
 msgstr ""
 
+#: py/asmxtensa.c
+msgid "ERROR: %q %q not word-aligned"
+msgstr ""
+
+#: py/asmxtensa.c
+msgid "ERROR: xtensa %q out of range"
+msgstr ""
+
 #: ports/espressif/common-hal/busio/SPI.c
 #: ports/espressif/common-hal/canio/CAN.c
 #: ports/espressif/common-hal/qspibus/QSPIBus.c
@@ -2627,10 +2636,6 @@ msgstr ""
 msgid "array/bytes required on right side"
 msgstr ""
 
-#: py/asmxtensa.c
-msgid "asm overflow"
-msgstr ""
-
 #: py/compile.c
 msgid "async for/with outside async function"
 msgstr ""
@@ -2844,6 +2849,10 @@ msgstr ""
 msgid "can't create '%q' instances"
 msgstr ""
 
+#: py/objtype.c
+msgid "can't create instance"
+msgstr ""
+
 #: py/compile.c
 msgid "can't declare nonlocal in outer code"
 msgstr ""
@@ -2942,14 +2951,14 @@ msgstr ""
 msgid "cannot convert complex type"
 msgstr ""
 
-#: py/objtype.c
-msgid "cannot create instance"
-msgstr ""
-
 #: extmod/ulab/code/ndarray.c
 msgid "cannot delete array elements"
 msgstr ""
 
+#: py/compile.c
+msgid "cannot emit native code for this architecture"
+msgstr ""
+
 #: extmod/ulab/code/ndarray.c
 msgid "cannot reshape array"
 msgstr ""
@@ -3104,7 +3113,7 @@ msgstr ""
 msgid "div/mod not implemented for uint"
 msgstr ""
 
-#: extmod/ulab/code/numpy/create.c
+#: extmod/ulab/code/numpy/create.c py/objint_longlong.c py/objint_mpz.c
 msgid "divide by zero"
 msgstr ""
 
@@ -3480,6 +3489,10 @@ msgstr ""
 msgid "interval must be in range %s-%s"
 msgstr ""
 
+#: py/emitinlinerv32.c
+msgid "invalid RV32 instruction '%q'"
+msgstr ""
+
 #: py/compile.c
 msgid "invalid arch"
 msgstr ""
@@ -3674,6 +3687,10 @@ msgstr ""
 msgid "mode must be complete, or reduced"
 msgstr ""
 
+#: py/runtime.c
+msgid "module '%q' has no attribute '%q'"
+msgstr ""
+
 #: py/builtinimport.c
 msgid "module not found"
 msgstr ""
@@ -3722,10 +3739,6 @@ msgstr ""
 msgid "native code in .mpy unsupported"
 msgstr ""
 
-#: py/asmthumb.c
-msgid "native method too big"
-msgstr ""
-
 #: py/emitnative.c
 msgid "native yield"
 msgstr ""
@@ -3747,7 +3760,7 @@ msgstr ""
 msgid "negative power with no float support"
 msgstr ""
 
-#: py/objint_mpz.c py/runtime.c
+#: py/objint_longlong.c py/objint_mpz.c py/runtime.c
 msgid "negative shift count"
 msgstr ""
 
@@ -4102,6 +4115,10 @@ msgstr ""
 msgid "real and imaginary parts must be of equal length"
 msgstr ""
 
+#: extmod/modre.c
+msgid "regex too complex"
+msgstr ""
+
 #: py/builtinimport.c
 msgid "relative import"
 msgstr ""
@@ -4111,6 +4128,10 @@ msgstr ""
 msgid "requested length %d but object has length %d"
 msgstr ""
 
+#: py/objint_longlong.c py/parsenum.c
+msgid "result overflows long long storage"
+msgstr ""
+
 #: extmod/ulab/code/ndarray_operators.c
 msgid "results cannot be cast to specified type"
 msgstr ""
@@ -4375,10 +4396,6 @@ msgstr ""
 msgid "type takes 1 or 3 arguments"
 msgstr ""
 
-#: py/objint_longlong.c
-msgid "ulonglong too large"
-msgstr ""
-
 #: py/parse.c
 msgid "unexpected indent"
 msgstr ""
@@ -4400,10 +4417,6 @@ msgstr ""
 msgid "unindent doesn't match any outer indent level"
 msgstr ""
 
-#: py/emitinlinerv32.c
-msgid "unknown RV32 instruction '%q'"
-msgstr ""
-
 #: py/objstr.c
 #, c-format
 msgid "unknown conversion specifier %c"
diff --git a/main.c b/main.c
index c9ed036bf865d..ce058cc49c4b5 100644
--- a/main.c
+++ b/main.c
@@ -1149,7 +1149,7 @@ int __attribute__((used)) main(void) {
             } else {
                 skip_repl = false;
             }
-        } else if (exit_code != 0) {
+        } else if (exit_code != PYEXEC_NORMAL_EXIT) {
             break;
         }
 
@@ -1206,7 +1206,7 @@ size_t gc_get_max_new_split(void) {
     return port_heap_get_largest_free_size();
 }
 
-void NORETURN nlr_jump_fail(void *val) {
+void MP_NORETURN nlr_jump_fail(void *val) {
     reset_into_safe_mode(SAFE_MODE_NLR_JUMP_FAIL);
     while (true) {
     }
@@ -1217,7 +1217,7 @@ bool vm_is_running(void) {
 }
 
 #ifndef NDEBUG
-static void NORETURN __fatal_error(const char *msg) {
+static void MP_NORETURN __fatal_error(const char *msg) {
     #if CIRCUITPY_DEBUG == 0
     reset_into_safe_mode(SAFE_MODE_HARD_FAULT);
     #endif
diff --git a/mpy-cross/main.c b/mpy-cross/main.c
index 989aec68bb519..add07c3d49b3e 100644
--- a/mpy-cross/main.c
+++ b/mpy-cross/main.c
@@ -34,13 +34,19 @@
 #include "py/persistentcode.h"
 #include "py/runtime.h"
 #include "py/gc.h"
-#include "py/stackctrl.h"
+#include "py/parsenum.h"
 #include "genhdr/mpversion.h"
 #ifdef _WIN32
 // CIRCUITPY-CHANGE
 #include "fmode.h"
 #endif
 
+#if MICROPY_EMIT_NATIVE && MICROPY_EMIT_RV32
+#include "py/asmrv32.h"
+
+static asm_rv32_backend_options_t rv32_options = { 0 };
+#endif
+
 // Command line options, with their defaults
 static uint emit_opt = MP_EMIT_OPT_NONE;
 mp_uint_t mp_verbose_flag = 0;
@@ -82,13 +88,20 @@ static int compile_and_save(const char *file, const char *output_file, const cha
             source_name = qstr_from_str(source_file);
         }
 
-        #if MICROPY_PY___FILE__
+        #if MICROPY_MODULE___FILE__
         mp_store_global(MP_QSTR___file__, MP_OBJ_NEW_QSTR(source_name));
         #endif
 
         mp_parse_tree_t parse_tree = mp_parse(lex, MP_PARSE_FILE_INPUT);
         mp_compiled_module_t cm;
         cm.context = m_new_obj(mp_module_context_t);
+        cm.arch_flags = 0;
+        #if MICROPY_EMIT_NATIVE && MICROPY_EMIT_RV32
+        if (mp_dynamic_compiler.native_arch == MP_NATIVE_ARCH_RV32IMC && mp_dynamic_compiler.backend_options != NULL) {
+            cm.arch_flags = ((asm_rv32_backend_options_t *)mp_dynamic_compiler.backend_options)->allowed_extensions;
+        }
+        #endif
+
         mp_compile_to_raw_code(&parse_tree, source_name, false, &cm);
 
         if ((output_file != NULL && strcmp(output_file, "-") == 0) ||
@@ -131,7 +144,10 @@ static int usage(char **argv) {
         "Target specific options:\n"
         "-msmall-int-bits=number : set the maximum bits used to encode a small-int\n"
         "-march=<arch> : set architecture for native emitter;\n"
-        "                x86, x64, armv6, armv6m, armv7m, armv7em, armv7emsp, armv7emdp, xtensa, xtensawin, rv32imc, debug\n"
+        "                x86, x64, armv6, armv6m, armv7m, armv7em, armv7emsp,\n"
+        "                armv7emdp, xtensa, xtensawin, rv32imc, rv64imc, host, debug\n"
+        "-march-flags=<flags> : set architecture-specific flags (can be either a dec/hex/bin value or a string)\n"
+        "                       supported flags for rv32imc: zba\n"
         "\n"
         "Implementation specific options:\n", argv[0]
         );
@@ -212,9 +228,39 @@ static char *backslash_to_forwardslash(char *path) {
     return path;
 }
 
-MP_NOINLINE int main_(int argc, char **argv) {
-    mp_stack_set_limit(40000 * (sizeof(void *) / 4));
+// This will need to be reworked in case mpy-cross needs to set more bits than
+// what its small int representation allows to fit in there.
+static bool parse_integer(const char *value, mp_uint_t *integer) {
+    assert(value && "Attempting to parse a NULL string");
+    assert(integer && "Attempting to store into a NULL integer buffer");
+
+    size_t value_length = strlen(value);
+    int base = 10;
+    if (value_length > 2 && value[0] == '0') {
+        if ((value[1] | 0x20) == 'b') {
+            base = 2;
+        } else if ((value[1] | 0x20) == 'x') {
+            base = 16;
+        } else {
+            return false;
+        }
+    }
+
+    bool valid = false;
+    nlr_buf_t nlr;
+    if (nlr_push(&nlr) == 0) {
+        mp_obj_t parsed = mp_parse_num_integer(value, value_length, base, NULL);
+        if (mp_obj_is_small_int(parsed)) {
+            *integer = MP_OBJ_SMALL_INT_VALUE(parsed);
+            valid = true;
+        }
+        nlr_pop();
+    }
 
+    return valid;
+}
+
+MP_NOINLINE int main_(int argc, char **argv) {
     pre_process_options(argc, argv);
 
     char *heap = malloc(heap_size);
@@ -237,11 +283,13 @@ MP_NOINLINE int main_(int argc, char **argv) {
     // don't support native emitter unless -march is specified
     mp_dynamic_compiler.native_arch = MP_NATIVE_ARCH_NONE;
     mp_dynamic_compiler.nlr_buf_num_regs = 0;
+    mp_dynamic_compiler.backend_options = NULL;
 
     const char *input_file = NULL;
     const char *output_file = NULL;
     const char *source_file = NULL;
     bool option_parsing_active = true;
+    const char *arch_flags = NULL;
 
     // parse main options
     for (int a = 1; a < argc; a++) {
@@ -318,6 +366,9 @@ MP_NOINLINE int main_(int argc, char **argv) {
                 } else if (strcmp(arch, "rv32imc") == 0) {
                     mp_dynamic_compiler.native_arch = MP_NATIVE_ARCH_RV32IMC;
                     mp_dynamic_compiler.nlr_buf_num_regs = MICROPY_NLR_NUM_REGS_RV32I;
+                } else if (strcmp(arch, "rv64imc") == 0) {
+                    mp_dynamic_compiler.native_arch = MP_NATIVE_ARCH_RV64IMC;
+                    mp_dynamic_compiler.nlr_buf_num_regs = MICROPY_NLR_NUM_REGS_RV64I;
                 } else if (strcmp(arch, "debug") == 0) {
                     mp_dynamic_compiler.native_arch = MP_NATIVE_ARCH_DEBUG;
                     mp_dynamic_compiler.nlr_buf_num_regs = 0;
@@ -331,6 +382,9 @@ MP_NOINLINE int main_(int argc, char **argv) {
                     #elif defined(__arm__) && !defined(__thumb2__)
                     mp_dynamic_compiler.native_arch = MP_NATIVE_ARCH_ARMV6;
                     mp_dynamic_compiler.nlr_buf_num_regs = MICROPY_NLR_NUM_REGS_ARM_THUMB_FP;
+                    #elif defined(__riscv) && (__riscv_xlen == 64)
+                    mp_dynamic_compiler.native_arch = MP_NATIVE_ARCH_RV64IMC;
+                    mp_dynamic_compiler.nlr_buf_num_regs = MICROPY_NLR_NUM_REGS_RV64I;
                     #else
                     mp_printf(&mp_stderr_print, "unable to determine host architecture for -march=host\n");
                     exit(1);
@@ -338,6 +392,8 @@ MP_NOINLINE int main_(int argc, char **argv) {
                 } else {
                     return usage(argv);
                 }
+            } else if (strncmp(argv[a], "-march-flags=", sizeof("-march-flags=") - 1) == 0) {
+                arch_flags = argv[a] + sizeof("-march-flags=") - 1;
             } else if (strcmp(argv[a], "--") == 0) {
                 option_parsing_active = false;
             } else {
@@ -352,6 +408,38 @@ MP_NOINLINE int main_(int argc, char **argv) {
         }
     }
 
+    if (arch_flags && mp_dynamic_compiler.native_arch != MP_NATIVE_ARCH_NONE) {
+        bool processed = false;
+        #if MICROPY_EMIT_NATIVE && MICROPY_EMIT_RV32
+        if (mp_dynamic_compiler.native_arch == MP_NATIVE_ARCH_RV32IMC) {
+            mp_dynamic_compiler.backend_options = (void *)&rv32_options;
+            mp_uint_t raw_flags = 0;
+            if (parse_integer(arch_flags, &raw_flags)) {
+                if ((raw_flags & ~((mp_uint_t)RV32_EXT_ALL)) == 0) {
+                    rv32_options.allowed_extensions = raw_flags;
+                    processed = true;
+                }
+            } else if (strncmp(arch_flags, "zba", sizeof("zba") - 1) == 0) {
+                rv32_options.allowed_extensions |= RV32_EXT_ZBA;
+                processed = true;
+            }
+        }
+        #endif
+        if (!processed) {
+            mp_printf(&mp_stderr_print, "unrecognised arch flags\n");
+            exit(1);
+        }
+    }
+
+    #if MICROPY_EMIT_NATIVE
+    if ((MP_STATE_VM(default_emit_opt) == MP_EMIT_OPT_NATIVE_PYTHON
+         || MP_STATE_VM(default_emit_opt) == MP_EMIT_OPT_VIPER)
+        && mp_dynamic_compiler.native_arch == MP_NATIVE_ARCH_NONE) {
+        mp_printf(&mp_stderr_print, "arch not specified\n");
+        exit(1);
+    }
+    #endif
+
     if (input_file == NULL) {
         mp_printf(&mp_stderr_print, "no input file\n");
         exit(1);
@@ -371,7 +459,7 @@ MP_NOINLINE int main_(int argc, char **argv) {
 }
 
 int main(int argc, char **argv) {
-    mp_stack_ctrl_init();
+    mp_cstack_init_with_sp_here(40000 * (sizeof(void *) / 4));
     return main_(argc, argv);
 }
 
diff --git a/mpy-cross/mpconfigport.h b/mpy-cross/mpconfigport.h
index edbd9f87c0558..36bcbc113941c 100644
--- a/mpy-cross/mpconfigport.h
+++ b/mpy-cross/mpconfigport.h
@@ -59,6 +59,7 @@
 #define MICROPY_COMP_CONST_FOLDING  (1)
 #define MICROPY_COMP_MODULE_CONST   (1)
 #define MICROPY_COMP_CONST          (1)
+#define MICROPY_COMP_CONST_FLOAT    (1)
 #define MICROPY_COMP_DOUBLE_TUPLE_ASSIGN (1)
 #define MICROPY_COMP_TRIPLE_TUPLE_ASSIGN (1)
 #define MICROPY_COMP_RETURN_IF_EXPR (1)
@@ -90,11 +91,12 @@
 #define MICROPY_GCREGS_SETJMP (1)
 #endif
 
-#define MICROPY_PY___FILE__         (0)
+#define MICROPY_MODULE___FILE__     (0)
 #define MICROPY_PY_ARRAY            (0)
 #define MICROPY_PY_ATTRTUPLE        (0)
 #define MICROPY_PY_COLLECTIONS      (0)
-#define MICROPY_PY_MATH             (0)
+#define MICROPY_PY_MATH             (MICROPY_COMP_CONST_FLOAT)
+#define MICROPY_PY_MATH_CONSTANTS   (MICROPY_COMP_CONST_FLOAT)
 #define MICROPY_PY_CMATH            (0)
 #define MICROPY_PY_GC               (0)
 #define MICROPY_PY_IO               (0)
@@ -102,23 +104,6 @@
 
 // type definitions for the specific machine
 
-#ifdef __LP64__
-typedef long mp_int_t; // must be pointer size
-typedef unsigned long mp_uint_t; // must be pointer size
-#elif defined(__MINGW32__) && defined(_WIN64)
-#include <stdint.h>
-typedef __int64 mp_int_t;
-typedef unsigned __int64 mp_uint_t;
-#elif defined(_MSC_VER) && defined(_WIN64)
-typedef __int64 mp_int_t;
-typedef unsigned __int64 mp_uint_t;
-#else
-// These are definitions for machines where sizeof(int) == sizeof(void*),
-// regardless for actual size.
-typedef int mp_int_t; // must be pointer size
-typedef unsigned int mp_uint_t; // must be pointer size
-#endif
-
 // Cannot include <sys/types.h>, as it may lead to symbol name clashes
 #if _FILE_OFFSET_BITS == 64 && !defined(__LP64__)
 typedef long long mp_off_t;
@@ -143,7 +128,7 @@ typedef long mp_off_t;
 #ifdef _MSC_VER
 
 #define MP_ENDIANNESS_LITTLE        (1)
-#define NORETURN                    __declspec(noreturn)
+#define MP_NORETURN                 __declspec(noreturn)
 #define MP_NOINLINE                 __declspec(noinline)
 #define MP_ALWAYSINLINE             __forceinline
 #define MP_LIKELY(x)                (x)
diff --git a/mpy-cross/mpy_cross/__init__.py b/mpy-cross/mpy_cross/__init__.py
index 91cd6f99335b3..6d7002a3b89d2 100644
--- a/mpy-cross/mpy_cross/__init__.py
+++ b/mpy-cross/mpy_cross/__init__.py
@@ -25,7 +25,6 @@
 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 # THE SOFTWARE.
 
-from __future__ import print_function
 import os
 import re
 import stat
@@ -44,6 +43,7 @@
     "NATIVE_ARCH_XTENSA": "xtensa",
     "NATIVE_ARCH_XTENSAWIN": "xtensawin",
     "NATIVE_ARCH_RV32IMC": "rv32imc",
+    "NATIVE_ARCH_RV64IMC": "rv64imc",
 }
 
 globals().update(NATIVE_ARCHS)
diff --git a/mpy-cross/mpy_cross/__main__.py b/mpy-cross/mpy_cross/__main__.py
index 2b6b81c333362..fe78a9e077e77 100644
--- a/mpy-cross/mpy_cross/__main__.py
+++ b/mpy-cross/mpy_cross/__main__.py
@@ -25,7 +25,6 @@
 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 # THE SOFTWARE.
 
-from __future__ import print_function
 import argparse
 import sys
 
diff --git a/ports/analog/supervisor/port.c b/ports/analog/supervisor/port.c
index 86d96bc251ba2..ee410a38148e9 100644
--- a/ports/analog/supervisor/port.c
+++ b/ports/analog/supervisor/port.c
@@ -67,7 +67,7 @@ static uint32_t subsec, sec = 0;
 static uint32_t tick_flag = 0;
 
 // defined by cmsis core files
-extern void NVIC_SystemReset(void) NORETURN;
+extern void NVIC_SystemReset(void) MP_NORETURN;
 
 volatile uint32_t system_ticks = 0;
 
diff --git a/ports/atmel-samd/common-hal/alarm/__init__.c b/ports/atmel-samd/common-hal/alarm/__init__.c
index 483aa1a9679ad..38ef58bea7659 100644
--- a/ports/atmel-samd/common-hal/alarm/__init__.c
+++ b/ports/atmel-samd/common-hal/alarm/__init__.c
@@ -133,7 +133,7 @@ void common_hal_alarm_set_deep_sleep_alarms(size_t n_alarms, const mp_obj_t *ala
     _setup_sleep_alarms(true, n_alarms, alarms);
 }
 
-void NORETURN common_hal_alarm_enter_deep_sleep(void) {
+void MP_NORETURN common_hal_alarm_enter_deep_sleep(void) {
     alarm_pin_pinalarm_prepare_for_deep_sleep();
     alarm_time_timealarm_prepare_for_deep_sleep();
     // port_disable_tick(); // TODO: Required for SAMD?
diff --git a/ports/atmel-samd/common-hal/alarm/touch/TouchAlarm.c b/ports/atmel-samd/common-hal/alarm/touch/TouchAlarm.c
index 3c1fbb5ba7b32..de98b7ec85ae6 100644
--- a/ports/atmel-samd/common-hal/alarm/touch/TouchAlarm.c
+++ b/ports/atmel-samd/common-hal/alarm/touch/TouchAlarm.c
@@ -7,6 +7,6 @@
 #include "shared-bindings/alarm/touch/TouchAlarm.h"
 #include "shared-bindings/microcontroller/__init__.h"
 
-NORETURN void common_hal_alarm_touch_touchalarm_construct(alarm_touch_touchalarm_obj_t *self, const mcu_pin_obj_t *pin) {
+MP_NORETURN void common_hal_alarm_touch_touchalarm_construct(alarm_touch_touchalarm_obj_t *self, const mcu_pin_obj_t *pin) {
     mp_raise_NotImplementedError_varg(MP_ERROR_TEXT("%q"), MP_QSTR_TouchAlarm);
 }
diff --git a/ports/atmel-samd/reset.c b/ports/atmel-samd/reset.c
index 9cacd4ab951ae..816e23e3251db 100644
--- a/ports/atmel-samd/reset.c
+++ b/ports/atmel-samd/reset.c
@@ -9,7 +9,7 @@
 #include "reset.h"
 #include "supervisor/filesystem.h"
 
-void NVIC_SystemReset(void) NORETURN;
+void NVIC_SystemReset(void) MP_NORETURN;
 
 void reset(void) {
     filesystem_flush();
diff --git a/ports/atmel-samd/reset.h b/ports/atmel-samd/reset.h
index c74d25fa01ea5..248d43779fdc9 100644
--- a/ports/atmel-samd/reset.h
+++ b/ports/atmel-samd/reset.h
@@ -16,6 +16,6 @@
 
 extern uint32_t _bootloader_dbl_tap;
 
-void reset_to_bootloader(void) NORETURN;
-void reset(void) NORETURN;
+void reset_to_bootloader(void) MP_NORETURN;
+void reset(void) MP_NORETURN;
 bool bootloader_available(void);
diff --git a/ports/atmel-samd/supervisor/port.c b/ports/atmel-samd/supervisor/port.c
index fe7b4a3676c79..288446cf62e71 100644
--- a/ports/atmel-samd/supervisor/port.c
+++ b/ports/atmel-samd/supervisor/port.c
@@ -685,7 +685,7 @@ void port_idle_until_interrupt(void) {
 /**
  * \brief Default interrupt handler for unused IRQs.
  */
-__attribute__((used)) NORETURN void HardFault_Handler(void) {
+__attribute__((used)) MP_NORETURN void HardFault_Handler(void) {
     #ifdef ENABLE_MICRO_TRACE_BUFFER
     // Turn off the micro trace buffer so we don't fill it up in the infinite
     // loop below.
diff --git a/ports/espressif/bindings/espidf/__init__.c b/ports/espressif/bindings/espidf/__init__.c
index 012ed7d9f9adf..897da0eb5717b 100644
--- a/ports/espressif/bindings/espidf/__init__.c
+++ b/ports/espressif/bindings/espidf/__init__.c
@@ -106,7 +106,7 @@ MP_DEFINE_CONST_OBJ_TYPE(
 //|     ...
 //|
 //|
-NORETURN void mp_raise_espidf_MemoryError(void) {
+MP_NORETURN void mp_raise_espidf_MemoryError(void) {
     nlr_raise(mp_obj_new_exception(&mp_type_espidf_MemoryError));
 }
 
diff --git a/ports/espressif/bindings/espidf/__init__.h b/ports/espressif/bindings/espidf/__init__.h
index 7c112abf7368c..92d2e0c276931 100644
--- a/ports/espressif/bindings/espidf/__init__.h
+++ b/ports/espressif/bindings/espidf/__init__.h
@@ -15,9 +15,9 @@
 extern const mp_obj_type_t mp_type_espidf_IDFError;
 extern const mp_obj_type_t mp_type_espidf_MemoryError;
 
-NORETURN void mp_raise_espidf_MemoryError(void);
+MP_NORETURN void mp_raise_espidf_MemoryError(void);
 
-void raise_esp_error(esp_err_t err) NORETURN;
+void raise_esp_error(esp_err_t err) MP_NORETURN;
 #define CHECK_ESP_RESULT(x) do { int res = (x); if (res != ESP_OK) raise_esp_error(res); } while (0)
 
 size_t common_hal_espidf_get_total_psram(void);
diff --git a/ports/espressif/common-hal/alarm/__init__.c b/ports/espressif/common-hal/alarm/__init__.c
index 629f976039fd1..4f8e7e530425a 100644
--- a/ports/espressif/common-hal/alarm/__init__.c
+++ b/ports/espressif/common-hal/alarm/__init__.c
@@ -189,7 +189,7 @@ void common_hal_alarm_set_deep_sleep_alarms(size_t n_alarms, const mp_obj_t *ala
     _setup_sleep_alarms(true, n_alarms, alarms);
 }
 
-void NORETURN common_hal_alarm_enter_deep_sleep(void) {
+void MP_NORETURN common_hal_alarm_enter_deep_sleep(void) {
     alarm_pin_pinalarm_prepare_for_deep_sleep();
     #if CIRCUITPY_ALARM_TOUCH
     alarm_touch_touchalarm_prepare_for_deep_sleep();
diff --git a/ports/espressif/common-hal/microcontroller/__init__.c b/ports/espressif/common-hal/microcontroller/__init__.c
index d23afce4d999e..9b50cd7b5d286 100644
--- a/ports/espressif/common-hal/microcontroller/__init__.c
+++ b/ports/espressif/common-hal/microcontroller/__init__.c
@@ -142,7 +142,7 @@ void common_hal_mcu_on_next_reset(mcu_runmode_t runmode) {
     }
 }
 
-void NORETURN common_hal_mcu_reset(void) {
+void MP_NORETURN common_hal_mcu_reset(void) {
     filesystem_flush(); // TODO: implement as part of flash improvements
     esp_restart();
 }
diff --git a/ports/espressif/supervisor/port.c b/ports/espressif/supervisor/port.c
index b3045026e12d9..d2aafb99f0bd6 100644
--- a/ports/espressif/supervisor/port.c
+++ b/ports/espressif/supervisor/port.c
@@ -103,7 +103,7 @@ static esp_timer_handle_t _sleep_timer;
 
 TaskHandle_t circuitpython_task = NULL;
 
-extern void esp_restart(void) NORETURN;
+extern void esp_restart(void) MP_NORETURN;
 
 static void tick_on_cp_core(void *arg) {
     supervisor_tick();
diff --git a/ports/espressif/tools/update_sdkconfig.py b/ports/espressif/tools/update_sdkconfig.py
index 209b976b881e9..d40614edb75d8 100644
--- a/ports/espressif/tools/update_sdkconfig.py
+++ b/ports/espressif/tools/update_sdkconfig.py
@@ -157,7 +157,7 @@ def sym_default(sym):
     default=False,
     help="Updates the sdkconfigs outside of the board directory.",
 )
-def update(debug, board, update_all):  # noqa: C901: too complex
+def update(debug, board, update_all):  # noqa: C901 too complex
     """Updates related sdkconfig files based on the build directory version that
     was likely modified by menuconfig."""
 
diff --git a/ports/mimxrt10xx/reset.h b/ports/mimxrt10xx/reset.h
index 04c951221e9e5..cae838556bce3 100644
--- a/ports/mimxrt10xx/reset.h
+++ b/ports/mimxrt10xx/reset.h
@@ -16,6 +16,6 @@
 #define DBL_TAP_MAGIC 0xf01669ef // Randomly selected, adjusted to have first and last bit set
 #define DBL_TAP_MAGIC_QUICK_BOOT 0xf02669ef
 
-void reset_to_bootloader(void) NORETURN;
-void reset(void) NORETURN;
+void reset_to_bootloader(void) MP_NORETURN;
+void reset(void) MP_NORETURN;
 bool bootloader_available(void);
diff --git a/ports/nordic/common-hal/alarm/__init__.c b/ports/nordic/common-hal/alarm/__init__.c
index 9753b0321fd06..026e117b9a67a 100644
--- a/ports/nordic/common-hal/alarm/__init__.c
+++ b/ports/nordic/common-hal/alarm/__init__.c
@@ -240,7 +240,7 @@ void common_hal_alarm_set_deep_sleep_alarms(size_t n_alarms, const mp_obj_t *ala
 
 #define PRESCALER_VALUE_IN_DEEP_SLEEP (1024)
 
-void NORETURN common_hal_alarm_enter_deep_sleep(void) {
+void MP_NORETURN common_hal_alarm_enter_deep_sleep(void) {
     alarm_pin_pinalarm_prepare_for_deep_sleep();
     alarm_time_timealarm_prepare_for_deep_sleep();
 
diff --git a/ports/raspberrypi/common-hal/alarm/__init__.c b/ports/raspberrypi/common-hal/alarm/__init__.c
index c47ddc3150515..a72b3a368d407 100644
--- a/ports/raspberrypi/common-hal/alarm/__init__.c
+++ b/ports/raspberrypi/common-hal/alarm/__init__.c
@@ -197,7 +197,7 @@ void common_hal_alarm_set_deep_sleep_alarms(size_t n_alarms, const mp_obj_t *ala
     _setup_sleep_alarms(true, n_alarms, alarms);
 }
 
-void NORETURN common_hal_alarm_enter_deep_sleep(void) {
+void MP_NORETURN common_hal_alarm_enter_deep_sleep(void) {
     bool timealarm_set = alarm_time_timealarm_is_set();
 
     #if CIRCUITPY_CYW43
diff --git a/ports/raspberrypi/common-hal/wifi/Radio.c b/ports/raspberrypi/common-hal/wifi/Radio.c
index 3c22c3548d191..73e7794ecc2dc 100644
--- a/ports/raspberrypi/common-hal/wifi/Radio.c
+++ b/ports/raspberrypi/common-hal/wifi/Radio.c
@@ -48,7 +48,7 @@ static inline void nw_put_le32(uint8_t *buf, uint32_t x) {
     buf[3] = x >> 24;
 }
 
-NORETURN static void ro_attribute(qstr attr) {
+MP_NORETURN static void ro_attribute(qstr attr) {
     mp_raise_NotImplementedError_varg(MP_ERROR_TEXT("%q is read-only for this board"), attr);
 }
 
diff --git a/ports/raspberrypi/common-hal/wifi/__init__.h b/ports/raspberrypi/common-hal/wifi/__init__.h
index 73988e8437987..4005c48a3cde2 100644
--- a/ports/raspberrypi/common-hal/wifi/__init__.h
+++ b/ports/raspberrypi/common-hal/wifi/__init__.h
@@ -11,7 +11,7 @@
 #include "lwip/ip_addr.h"
 
 void wifi_reset(void);
-NORETURN void raise_cyw_error(int err);
+MP_NORETURN void raise_cyw_error(int err);
 #define CHECK_CYW_RESULT(x) do { int res = (x); if (res != 0) raise_cyw_error(res); } while (0)
 
 void ipaddress_ipaddress_to_lwip(mp_obj_t ip_address, ip_addr_t *lwip_ip_address);
diff --git a/ports/raspberrypi/supervisor/port.c b/ports/raspberrypi/supervisor/port.c
index bb6482240a697..0316e34ad951c 100644
--- a/ports/raspberrypi/supervisor/port.c
+++ b/ports/raspberrypi/supervisor/port.c
@@ -588,7 +588,7 @@ void port_idle_until_interrupt(void) {
 /**
  * \brief Default interrupt handler for unused IRQs.
  */
-extern NORETURN void isr_hardfault(void); // provide a prototype to avoid a missing-prototypes diagnostic
+extern MP_NORETURN void isr_hardfault(void); // provide a prototype to avoid a missing-prototypes diagnostic
 __attribute__((used)) void __not_in_flash_func(isr_hardfault)(void) {
     // Only safe mode from core 0 which is running CircuitPython. Core 1 faulting
     // should not be fatal to CP. (Fingers crossed.)
diff --git a/ports/stm/common-hal/alarm/__init__.c b/ports/stm/common-hal/alarm/__init__.c
index 3d6c4466882b4..1be8f8dc10d09 100644
--- a/ports/stm/common-hal/alarm/__init__.c
+++ b/ports/stm/common-hal/alarm/__init__.c
@@ -135,7 +135,7 @@ void common_hal_alarm_set_deep_sleep_alarms(size_t n_alarms, const mp_obj_t *ala
     _setup_sleep_alarms(true, n_alarms, alarms);
 }
 
-void NORETURN common_hal_alarm_enter_deep_sleep(void) {
+void MP_NORETURN common_hal_alarm_enter_deep_sleep(void) {
     alarm_set_wakeup_reason(STM_WAKEUP_UNDEF);
     alarm_pin_pinalarm_prepare_for_deep_sleep();
     alarm_time_timealarm_prepare_for_deep_sleep();
diff --git a/ports/stm/mpconfigport_nanbox.h b/ports/stm/mpconfigport_nanbox.h
deleted file mode 100644
index 164850112e01f..0000000000000
--- a/ports/stm/mpconfigport_nanbox.h
+++ /dev/null
@@ -1,25 +0,0 @@
-// This file is part of the CircuitPython project: https://circuitpython.org
-//
-// SPDX-FileCopyrightText: Copyright (c) 2016 Damien P. George
-//
-// SPDX-License-Identifier: MIT
-
-#pragma once
-
-// select nan-boxing object model
-#define MICROPY_OBJ_REPR (MICROPY_OBJ_REPR_D)
-
-// native emitters don't work with nan-boxing
-#define MICROPY_EMIT_X86 (0)
-#define MICROPY_EMIT_X64 (0)
-#define MICROPY_EMIT_THUMB (0)
-#define MICROPY_EMIT_ARM (0)
-
-#include <stdint.h>
-
-typedef int64_t mp_int_t;
-typedef uint64_t mp_uint_t;
-#define UINT_FMT "%llu"
-#define INT_FMT "%lld"
-
-#include <mpconfigport.h>
diff --git a/ports/stm/supervisor/port.c b/ports/stm/supervisor/port.c
index 3820a046fc4af..1ffc8656a888e 100644
--- a/ports/stm/supervisor/port.c
+++ b/ports/stm/supervisor/port.c
@@ -39,7 +39,7 @@
 
 #include STM32_HAL_H
 
-void NVIC_SystemReset(void) NORETURN;
+void NVIC_SystemReset(void) MP_NORETURN;
 
 #if (CPY_STM32H7) || (CPY_STM32F7)
 #if defined(CIRCUITPY_HW_SDRAM_SIZE)
diff --git a/ports/unix/Makefile b/ports/unix/Makefile
index 6461c310eeb68..32e3b44b2273a 100644
--- a/ports/unix/Makefile
+++ b/ports/unix/Makefile
@@ -27,6 +27,9 @@ FROZEN_MANIFEST ?= variants/manifest.py
 # This should be configured by the mpconfigvariant.mk
 PROG ?= micropython
 
+# For use in test rules below
+ABS_PROG = $(abspath $(BUILD)/$(PROG))
+
 # qstr definitions (must come before including py.mk)
 QSTR_DEFS += qstrdefsport.h
 QSTR_GLOBAL_DEPENDENCIES += $(VARIANT_DIR)/mpconfigvariant.h
@@ -46,6 +49,7 @@ INC += -I$(BUILD)
 
 # compiler settings
 CWARN = -Wall -Werror
+// CIRCUITPY-CHANGE: add  -Wno-missing-field-initializers
 CWARN += -Wextra -Wno-unused-parameter -Wpointer-arith -Wdouble-promotion -Wfloat-conversion -Wno-missing-field-initializers
 CFLAGS += $(INC) $(CWARN) -std=gnu99 -DUNIX $(COPT) -I$(VARIANT_DIR) $(CFLAGS_EXTRA)
 
@@ -53,6 +57,10 @@ CFLAGS += $(INC) $(CWARN) -std=gnu99 -DUNIX $(COPT) -I$(VARIANT_DIR) $(CFLAGS_EX
 # This option has no effect on 64-bit builds.
 CFLAGS += -D_FILE_OFFSET_BITS=64
 
+# Force the use of 64-bits for time_t in C library functions on 32-bit platforms.
+# This option has no effect on 64-bit builds.
+CFLAGS += -D_TIME_BITS=64
+
 # Debugging/Optimization
 ifdef DEBUG
 COPT ?= -Og
@@ -139,7 +147,11 @@ ifeq ($(MICROPY_PY_SOCKET),1)
 CFLAGS += -DMICROPY_PY_SOCKET=1
 endif
 ifeq ($(MICROPY_PY_THREAD),1)
+ifeq ($(MICROPY_PY_THREAD_GIL),1)
+CFLAGS += -DMICROPY_PY_THREAD=1 -DMICROPY_PY_THREAD_GIL=1
+else
 CFLAGS += -DMICROPY_PY_THREAD=1 -DMICROPY_PY_THREAD_GIL=0
+endif
 LDFLAGS += $(LIBPTHREAD)
 endif
 
@@ -225,6 +237,7 @@ $(BUILD)/supervisor/shared/translate/translate.o: $(HEADER_BUILD)/qstrdefs.gener
 
 SHARED_SRC_C += $(addprefix shared/,\
 	runtime/gchelper_generic.c \
+	runtime/pyexec.c \
 	timeutils/timeutils.c \
 	$(SHARED_SRC_C_EXTRA) \
 	)
@@ -280,7 +293,7 @@ print-failures clean-failures:
 TEST_ARGS ?=
 test: $(BUILD)/$(PROG) $(TOP)/tests/run-tests.py
 	$(eval DIRNAME=ports/$(notdir $(CURDIR)))
-	cd $(TOP)/tests && MICROPY_MICROPYTHON=../$(DIRNAME)/$(BUILD)/$(PROG) ./run-tests.py $(TEST_ARGS)
+	cd $(TOP)/tests && MICROPY_MICROPYTHON=../$(DIRNAME)/$(BUILD)/$(PROG) ./run-tests.py
 
 test_full: $(BUILD)/$(PROG) $(TOP)/tests/run-tests.py
 	$(eval DIRNAME=ports/$(notdir $(CURDIR)))
diff --git a/ports/unix/README.md b/ports/unix/README.md
index b7aa6e3fef76d..ee983a882cc83 100644
--- a/ports/unix/README.md
+++ b/ports/unix/README.md
@@ -72,6 +72,14 @@ To run the complete testsuite, use:
 
     $ make test
 
+There are other make targets to interact with the testsuite:
+
+    $ make test//int       # Run all tests matching the pattern "int"
+    $ make test/ports/unix # Run all tests in ports/unix
+    $ make test-failures   # Re-run only the failed tests
+    $ make print-failures  # print the differences for failed tests
+    $ make clean-failures  # delete the .exp and .out files from failed tests
+
 The Unix port comes with a built-in package manager called `mip`, e.g.:
 
     $ ./build-standard/micropython -m mip install hmac
@@ -155,3 +163,21 @@ The default compiler optimisation level is -Os, or -Og if `DEBUG=1` is set.
 Setting the variable `COPT` will explicitly set the optimisation level. For
 example `make [other arguments] COPT=-O0 DEBUG=1` will build a binary with no
 optimisations, assertions enabled, and debug symbols.
+
+### Sanitizers
+
+Sanitizers are extra runtime checks supported by gcc and clang. The CI process
+supports building with the "undefined behavior" (UBSan) or "address" (ASan)
+sanitizers. The script `tools/ci.sh` is the source of truth about how to build
+and run in these modes.
+
+Several classes of checks are disabled via compiler flags:
+
+* In the undefined behavior sanitizer, checks based on the presence of the
+  `non_null` attribute are disabled because the code makes technically incorrect
+  calls like `memset(NULL, 0, 0)`. A future C standard is likely to permit such
+  calls.
+* In the address sanitizer, `detect_stack_use_after_return` is disabled. This
+  check is intended to make sure locals in a "returned from" stack frame are not
+  used. However, this mode interferes with various assumptions that
+  MicroPython's stack checking, NLR, and GC rely on.
diff --git a/ports/unix/coverage.c b/ports/unix/coverage.c
index 7f13f9756f177..49426f0f3e865 100644
--- a/ports/unix/coverage.c
+++ b/ports/unix/coverage.c
@@ -97,6 +97,7 @@ static const mp_rom_map_elem_t rawfile_locals_dict_table[] = {
     { MP_ROM_QSTR(MP_QSTR_write), MP_ROM_PTR(&mp_stream_write_obj) },
     { MP_ROM_QSTR(MP_QSTR_write1), MP_ROM_PTR(&mp_stream_write1_obj) },
     { MP_ROM_QSTR(MP_QSTR_readinto), MP_ROM_PTR(&mp_stream_readinto_obj) },
+    { MP_ROM_QSTR(MP_QSTR_readinto1), MP_ROM_PTR(&mp_stream_readinto1_obj) },
     { MP_ROM_QSTR(MP_QSTR_readline), MP_ROM_PTR(&mp_stream_unbuffered_readline_obj) },
     { MP_ROM_QSTR(MP_QSTR_ioctl), MP_ROM_PTR(&mp_stream_ioctl_obj) },
 };
@@ -171,19 +172,34 @@ static void pairheap_test(size_t nops, int *ops) {
         if (mp_pairheap_is_empty(pairheap_lt, heap)) {
             mp_printf(&mp_plat_print, " -");
         } else {
-            mp_printf(&mp_plat_print, " %d", mp_pairheap_peek(pairheap_lt, heap) - &node[0]);
+            mp_printf(&mp_plat_print, " %d", (int)(mp_pairheap_peek(pairheap_lt, heap) - &node[0]));
             ;
         }
     }
     mp_printf(&mp_plat_print, "\npop all:");
     while (!mp_pairheap_is_empty(pairheap_lt, heap)) {
-        mp_printf(&mp_plat_print, " %d", mp_pairheap_peek(pairheap_lt, heap) - &node[0]);
+        mp_printf(&mp_plat_print, " %d", (int)(mp_pairheap_peek(pairheap_lt, heap) - &node[0]));
         ;
         heap = mp_pairheap_pop(pairheap_lt, heap);
     }
     mp_printf(&mp_plat_print, "\n");
 }
 
+// CIRCUITPY-CHANGE: not turned on in CircuitPython
+#if MICROPY_SCHEDULER_STATIC_NODES
+static mp_sched_node_t mp_coverage_sched_node;
+static bool coverage_sched_function_continue;
+
+static void coverage_sched_function(mp_sched_node_t *node) {
+    (void)node;
+    mp_printf(&mp_plat_print, "scheduled function\n");
+    if (coverage_sched_function_continue) {
+        // Re-scheduling node will cause it to run again next time scheduled functions are run
+        mp_sched_schedule_node(&mp_coverage_sched_node, coverage_sched_function);
+    }
+}
+#endif
+
 // function to run extra tests for things that can't be checked by scripts
 static mp_obj_t extra_coverage(void) {
     // mp_printf (used by ports that don't have a native printf)
@@ -191,10 +207,22 @@ static mp_obj_t extra_coverage(void) {
         mp_printf(&mp_plat_print, "# mp_printf\n");
         mp_printf(&mp_plat_print, "%d %+d % d\n", -123, 123, 123); // sign
         mp_printf(&mp_plat_print, "%05d\n", -123); // negative number with zero padding
-        mp_printf(&mp_plat_print, "%ld\n", 123); // long
-        mp_printf(&mp_plat_print, "%lx\n", 0x123); // long hex
-        mp_printf(&mp_plat_print, "%X\n", 0x1abcdef); // capital hex
-        mp_printf(&mp_plat_print, "%.2s %.3s '%4.4s' '%5.5q' '%.3q'\n", "abc", "abc", "abc", MP_QSTR_True, MP_QSTR_True); // fixed string precision
+        mp_printf(&mp_plat_print, "%ld\n", 123l); // long
+        mp_printf(&mp_plat_print, "%lx\n", 0x123fl); // long hex
+        mp_printf(&mp_plat_print, "%lX\n", 0x123fl); // capital long hex
+        if (sizeof(mp_int_t) == 8) {
+            mp_printf(&mp_plat_print, "%llx\n", LLONG_MAX); // long long hex
+            mp_printf(&mp_plat_print, "%llX\n", LLONG_MAX); // capital long long hex
+            mp_printf(&mp_plat_print, "%llu\n", ULLONG_MAX); // unsigned long long
+        } else {
+            // fake for platforms without narrower mp_int_t
+            mp_printf(&mp_plat_print, "7fffffffffffffff\n");
+            mp_printf(&mp_plat_print, "7FFFFFFFFFFFFFFF\n");
+            mp_printf(&mp_plat_print, "18446744073709551615\n");
+        }
+        mp_printf(&mp_plat_print, "%p\n", (void *)0x789f); // pointer
+        mp_printf(&mp_plat_print, "%P\n", (void *)0x789f); // pointer uppercase
+        mp_printf(&mp_plat_print, "%.2s %.3s '%4.4s' '%5.5q' '%.3q'\n", "abc", "abc", "abc", (qstr)MP_QSTR_True, (qstr)MP_QSTR_True); // fixed string precision
         mp_printf(&mp_plat_print, "%.*s\n", -1, "abc"); // negative string precision
         mp_printf(&mp_plat_print, "%b %b\n", 0, 1); // bools
         #ifndef NDEBUG
@@ -204,10 +232,36 @@ static mp_obj_t extra_coverage(void) {
         #endif
         mp_printf(&mp_plat_print, "%d\n", 0x80000000); // should print signed
         mp_printf(&mp_plat_print, "%u\n", 0x80000000); // should print unsigned
-        mp_printf(&mp_plat_print, "%x\n", 0x80000000); // should print unsigned
-        mp_printf(&mp_plat_print, "%X\n", 0x80000000); // should print unsigned
-        mp_printf(&mp_plat_print, "abc\n%"); // string ends in middle of format specifier
+        mp_printf(&mp_plat_print, "%x\n", 0x8000000f); // should print unsigned
+        mp_printf(&mp_plat_print, "%X\n", 0x8000000f); // should print unsigned
+        // note: storing the string in a variable is enough to prevent the
+        // format string checker from checking this format string. Otherwise,
+        // it would be a compile time diagnostic under the format string
+        // checker.
+        const char msg[] = "abc\n%";
+        mp_printf(&mp_plat_print, msg); // string ends in middle of format specifier
         mp_printf(&mp_plat_print, "%%\n"); // literal % character
+        mp_printf(&mp_plat_print, ".%-3s.\n", "a"); // left adjust
+
+        // Check that all kinds of mp_printf arguments are parsed out
+        // correctly, by having a char argument before and after each main type
+        // of value that can be formatted.
+        mp_printf(&mp_plat_print, "%c%%%c\n", '<', '>');
+        mp_printf(&mp_plat_print, "%c%p%c\n", '<', (void *)0xaaaa, '>');
+        mp_printf(&mp_plat_print, "%c%b%c\n", '<', true, '>');
+        mp_printf(&mp_plat_print, "%c%d%c\n", '<', 0xaaaa, '>');
+        mp_printf(&mp_plat_print, "%c%ld%c\n", '<', 0xaaaal, '>');
+        mp_printf(&mp_plat_print, "%c" INT_FMT "%c\n", '<', (mp_int_t)0xaaaa, '>');
+        mp_printf(&mp_plat_print, "%c%s%c\n", '<', "test", '>');
+        mp_printf(&mp_plat_print, "%c%f%c\n", '<', MICROPY_FLOAT_CONST(1000.), '>');
+        mp_printf(&mp_plat_print, "%c%q%c\n", '<', (qstr)MP_QSTR_True, '>');
+        if (sizeof(mp_int_t) == 8) {
+            mp_printf(&mp_plat_print, "%c%lld%c\n", '<', LLONG_MAX, '>');
+        } else {
+            mp_printf(&mp_plat_print, "<9223372036854775807>\n");
+        }
+
+
     }
 
     // GC
@@ -220,11 +274,11 @@ static mp_obj_t extra_coverage(void) {
         gc_unlock();
 
         // using gc_realloc to resize to 0, which means free the memory
-        void *p = gc_alloc(4, false);
+        void *p = gc_alloc(4, 0);
         mp_printf(&mp_plat_print, "%p\n", gc_realloc(p, 0, false));
 
         // calling gc_nbytes with a non-heap pointer
-        mp_printf(&mp_plat_print, "%p\n", gc_nbytes(NULL));
+        mp_printf(&mp_plat_print, "%d\n", (int)gc_nbytes(NULL));
     }
 
     // GC initialisation and allocation stress test, to check the logic behind ALLOC_TABLE_GAP_BYTE
@@ -285,7 +339,7 @@ static mp_obj_t extra_coverage(void) {
                 }
                 ptrs[i][j] = j;
             }
-            mp_printf(&mp_plat_print, "%d %d\n", i, all_zero);
+            mp_printf(&mp_plat_print, "%d %d\n", (int)i, (int)all_zero);
 
             // hide the pointer from the GC and collect
             ptrs[i] = FLIP_POINTER(ptrs[i]);
@@ -301,7 +355,7 @@ static mp_obj_t extra_coverage(void) {
                     break;
                 }
             }
-            mp_printf(&mp_plat_print, "%d %d\n", i, correct_contents);
+            mp_printf(&mp_plat_print, "%d %d\n", (int)i, (int)correct_contents);
         }
 
         // free the memory blocks
@@ -400,7 +454,7 @@ static mp_obj_t extra_coverage(void) {
         // create a bytearray via mp_obj_new_bytearray
         mp_buffer_info_t bufinfo;
         mp_get_buffer_raise(mp_obj_new_bytearray(4, "data"), &bufinfo, MP_BUFFER_RW);
-        mp_printf(&mp_plat_print, "%.*s\n", bufinfo.len, bufinfo.buf);
+        mp_printf(&mp_plat_print, "%.*s\n", (int)bufinfo.len, bufinfo.buf);
     }
 
     // mpz
@@ -464,6 +518,38 @@ static mp_obj_t extra_coverage(void) {
         mp_int_t value_signed;
         mpz_as_int_checked(&mpz, &value_signed);
         mp_printf(&mp_plat_print, "%d\n", (int)value_signed);
+
+        // hash the zero mpz integer
+        mpz_set_from_int(&mpz, 0);
+        mp_printf(&mp_plat_print, "%d\n", (int)mpz_hash(&mpz));
+
+        // convert the mpz zero integer to int
+        mp_printf(&mp_plat_print, "%d\n", mpz_as_int_checked(&mpz, &value_signed));
+        mp_printf(&mp_plat_print, "%d\n", (int)value_signed);
+
+        // mpz_set_from_float with 0 as argument
+        mpz_set_from_float(&mpz, 0);
+        mp_printf(&mp_plat_print, "%f\n", mpz_as_float(&mpz));
+
+        // convert a large integer value (stored in a mpz) to mp_uint_t and to ll;
+        mp_obj_t obj_bigint = mp_obj_new_int_from_uint((mp_uint_t)0xdeadbeef);
+        mp_printf(&mp_plat_print, "%x\n", (int)mp_obj_get_uint(obj_bigint));
+        obj_bigint = mp_obj_new_int_from_ll(0xc0ffee777c0ffeell);
+        long long value_ll = mp_obj_get_ll(obj_bigint);
+        mp_printf(&mp_plat_print, "%x%08x\n", (uint32_t)(value_ll >> 32), (uint32_t)value_ll);
+
+        // convert a large integer value (stored via a struct object) to uint and to ll
+        // `deadbeef` global is an uctypes.struct defined by extra_coverage.py
+        obj_bigint = mp_load_global(MP_QSTR_deadbeef);
+        mp_printf(&mp_plat_print, "%x\n", (int)mp_obj_get_uint(obj_bigint));
+        value_ll = mp_obj_get_ll(obj_bigint);
+        mp_printf(&mp_plat_print, "%x%08x\n", (uint32_t)(value_ll >> 32), (uint32_t)value_ll);
+
+        // convert a smaller integer value to mp_uint_t and to ll
+        obj_bigint = mp_obj_new_int_from_uint(0xc0ffee);
+        mp_printf(&mp_plat_print, "%x\n", (int)mp_obj_get_uint(obj_bigint));
+        value_ll = mp_obj_get_ll(obj_bigint);
+        mp_printf(&mp_plat_print, "%x%08x\n", (uint32_t)(value_ll >> 32), (uint32_t)value_ll);
     }
 
     // runtime utils
@@ -481,7 +567,7 @@ static mp_obj_t extra_coverage(void) {
         mp_call_function_2_protected(MP_OBJ_FROM_PTR(&mp_builtin_divmod_obj), mp_obj_new_str_from_cstr("abc"), mp_obj_new_str_from_cstr("abc"));
 
         // mp_obj_int_get_checked with mp_obj_int_t that has a value that is a small integer
-        mp_printf(&mp_plat_print, "%d\n", mp_obj_int_get_checked(mp_obj_int_new_mpz()));
+        mp_printf(&mp_plat_print, "%d\n", (int)mp_obj_int_get_checked(MP_OBJ_FROM_PTR(mp_obj_int_new_mpz())));
 
         // mp_obj_int_get_uint_checked with non-negative small-int
         mp_printf(&mp_plat_print, "%d\n", (int)mp_obj_int_get_uint_checked(MP_OBJ_NEW_SMALL_INT(1)));
@@ -506,6 +592,22 @@ static mp_obj_t extra_coverage(void) {
             mp_obj_print_exception(&mp_plat_print, MP_OBJ_FROM_PTR(nlr.ret_val));
         }
 
+        // mp_obj_get_uint from a non-int object (should raise exception)
+        if (nlr_push(&nlr) == 0) {
+            mp_obj_get_uint(mp_const_none);
+            nlr_pop();
+        } else {
+            mp_obj_print_exception(&mp_plat_print, MP_OBJ_FROM_PTR(nlr.ret_val));
+        }
+
+        // mp_obj_int_get_ll from a non-int object (should raise exception)
+        if (nlr_push(&nlr) == 0) {
+            mp_obj_get_ll(mp_const_none);
+            nlr_pop();
+        } else {
+            mp_obj_print_exception(&mp_plat_print, MP_OBJ_FROM_PTR(nlr.ret_val));
+        }
+
         // call mp_obj_new_exception_args (it's a part of the public C API and not used in the core)
         mp_obj_print_exception(&mp_plat_print, mp_obj_new_exception_args(&mp_type_ValueError, 0, NULL));
     }
@@ -515,26 +617,6 @@ static mp_obj_t extra_coverage(void) {
         mp_emitter_warning(MP_PASS_CODE_SIZE, "test");
     }
 
-    // format float
-    {
-        mp_printf(&mp_plat_print, "# format float\n");
-
-        // format with inadequate buffer size
-        char buf[5];
-        mp_format_float(1, buf, sizeof(buf), 'g', 0, '+');
-        mp_printf(&mp_plat_print, "%s\n", buf);
-
-        // format with just enough buffer so that precision must be
-        // set from 0 to 1 twice
-        char buf2[8];
-        mp_format_float(1, buf2, sizeof(buf2), 'g', 0, '+');
-        mp_printf(&mp_plat_print, "%s\n", buf2);
-
-        // format where precision is trimmed to avoid buffer overflow
-        mp_format_float(1, buf2, sizeof(buf2), 'e', 0, '+');
-        mp_printf(&mp_plat_print, "%s\n", buf2);
-    }
-
     // binary
     {
         mp_printf(&mp_plat_print, "# binary\n");
@@ -558,14 +640,26 @@ static mp_obj_t extra_coverage(void) {
         fun_bc.context = &context;
         fun_bc.child_table = NULL;
         fun_bc.bytecode = (const byte *)"\x01"; // just needed for n_state
+        #if MICROPY_PY_SYS_SETTRACE
+        struct _mp_raw_code_t rc = {};
+        fun_bc.rc = &rc;
+        #endif
         mp_code_state_t *code_state = m_new_obj_var(mp_code_state_t, state, mp_obj_t, 1);
         code_state->fun_bc = &fun_bc;
         code_state->ip = (const byte *)"\x00"; // just needed for an invalid opcode
         code_state->sp = &code_state->state[0];
         code_state->exc_sp_idx = 0;
         code_state->old_globals = NULL;
+        #if MICROPY_STACKLESS
+        code_state->prev = NULL;
+        #endif
+        #if MICROPY_PY_SYS_SETTRACE
+        code_state->prev_state = NULL;
+        code_state->frame = NULL;
+        #endif
+
         mp_vm_return_kind_t ret = mp_execute_bytecode(code_state, MP_OBJ_NULL);
-        mp_printf(&mp_plat_print, "%d %d\n", ret, mp_obj_get_type(code_state->state[0]) == &mp_type_NotImplementedError);
+        mp_printf(&mp_plat_print, "%d %d\n", (int)ret, mp_obj_get_type(code_state->state[0]) == &mp_type_NotImplementedError);
     }
 
     // scheduler
@@ -622,9 +716,25 @@ static mp_obj_t extra_coverage(void) {
             mp_obj_print_exception(&mp_plat_print, MP_OBJ_FROM_PTR(nlr.ret_val));
         }
         mp_handle_pending(true);
+
+        // CIRCUITPY-CHANGE: not turned on in CircuitPython
+        #if MICROPY_SCHEDULER_STATIC_NODES
+        coverage_sched_function_continue = true;
+        mp_sched_schedule_node(&mp_coverage_sched_node, coverage_sched_function);
+        for (int i = 0; i < 3; ++i) {
+            mp_printf(&mp_plat_print, "loop\n");
+            mp_handle_pending(true);
+        }
+        // Clear this flag to prevent the function scheduling itself again
+        coverage_sched_function_continue = false;
+        // Will only run the first time through this loop, then not scheduled again
+        for (int i = 0; i < 3; ++i) {
+            mp_handle_pending(true);
+        }
+        #endif
     }
 
-    // CIRCUITPY-CHANGE: ringbuf is different
+    // CIRCUITPY-CHANGE: ringbuf is quite different
     // ringbuf
     {
         #define RINGBUF_SIZE 99
@@ -636,36 +746,36 @@ static mp_obj_t extra_coverage(void) {
         mp_printf(&mp_plat_print, "# ringbuf\n");
 
         // Single-byte put/get with empty ringbuf.
-        mp_printf(&mp_plat_print, "%d %d\n", ringbuf_num_empty(&ringbuf), ringbuf_num_filled(&ringbuf));
+        mp_printf(&mp_plat_print, "%d %d\n", (int)ringbuf_num_empty(&ringbuf), (int)ringbuf_num_filled(&ringbuf));
         ringbuf_put(&ringbuf, 22);
-        mp_printf(&mp_plat_print, "%d %d\n", ringbuf_num_empty(&ringbuf), ringbuf_num_filled(&ringbuf));
+        mp_printf(&mp_plat_print, "%d %d\n", (int)ringbuf_num_empty(&ringbuf), (int)ringbuf_num_filled(&ringbuf));
         mp_printf(&mp_plat_print, "%d\n", ringbuf_get(&ringbuf));
-        mp_printf(&mp_plat_print, "%d %d\n", ringbuf_num_empty(&ringbuf), ringbuf_num_filled(&ringbuf));
+        mp_printf(&mp_plat_print, "%d %d\n", (int)ringbuf_num_empty(&ringbuf), (int)ringbuf_num_filled(&ringbuf));
 
         // Two-byte put/get with empty ringbuf.
         ringbuf_put16(&ringbuf, 0xaa55);
-        mp_printf(&mp_plat_print, "%d %d\n", ringbuf_num_empty(&ringbuf), ringbuf_num_filled(&ringbuf));
+        mp_printf(&mp_plat_print, "%d %d\n", (int)ringbuf_num_empty(&ringbuf), (int)ringbuf_num_filled(&ringbuf));
         mp_printf(&mp_plat_print, "%04x\n", ringbuf_get16(&ringbuf));
-        mp_printf(&mp_plat_print, "%d %d\n", ringbuf_num_empty(&ringbuf), ringbuf_num_filled(&ringbuf));
+        mp_printf(&mp_plat_print, "%d %d\n", (int)ringbuf_num_empty(&ringbuf), (int)ringbuf_num_filled(&ringbuf));
 
         // Two-byte put with full ringbuf.
         for (int i = 0; i < RINGBUF_SIZE; ++i) {
             ringbuf_put(&ringbuf, i);
         }
-        mp_printf(&mp_plat_print, "%d %d\n", ringbuf_num_empty(&ringbuf), ringbuf_num_filled(&ringbuf));
+        mp_printf(&mp_plat_print, "%d %d\n", (int)ringbuf_num_empty(&ringbuf), (int)ringbuf_num_filled(&ringbuf));
         mp_printf(&mp_plat_print, "%d\n", ringbuf_put16(&ringbuf, 0x11bb));
         // Two-byte put with one byte free.
         ringbuf_get(&ringbuf);
-        mp_printf(&mp_plat_print, "%d %d\n", ringbuf_num_empty(&ringbuf), ringbuf_num_filled(&ringbuf));
+        mp_printf(&mp_plat_print, "%d %d\n", (int)ringbuf_num_empty(&ringbuf), (int)ringbuf_num_filled(&ringbuf));
         mp_printf(&mp_plat_print, "%d\n", ringbuf_put16(&ringbuf, 0x3377));
         ringbuf_get(&ringbuf);
-        mp_printf(&mp_plat_print, "%d %d\n", ringbuf_num_empty(&ringbuf), ringbuf_num_filled(&ringbuf));
+        mp_printf(&mp_plat_print, "%d %d\n", (int)ringbuf_num_empty(&ringbuf), (int)ringbuf_num_filled(&ringbuf));
         mp_printf(&mp_plat_print, "%d\n", ringbuf_put16(&ringbuf, 0xcc99));
         for (int i = 0; i < RINGBUF_SIZE - 2; ++i) {
             ringbuf_get(&ringbuf);
         }
         mp_printf(&mp_plat_print, "%04x\n", ringbuf_get16(&ringbuf));
-        mp_printf(&mp_plat_print, "%d %d\n", ringbuf_num_empty(&ringbuf), ringbuf_num_filled(&ringbuf));
+        mp_printf(&mp_plat_print, "%d %d\n", (int)ringbuf_num_empty(&ringbuf), (int)ringbuf_num_filled(&ringbuf));
 
         // Two-byte put with wrap around on first byte:
         ringbuf_clear(&ringbuf);
@@ -777,7 +887,7 @@ static mp_obj_t extra_coverage(void) {
     mp_obj_streamtest_t *s2 = mp_obj_malloc(mp_obj_streamtest_t, &mp_type_stest_textio2);
 
     // return a tuple of data for testing on the Python side
-    mp_obj_t items[] = {(mp_obj_t)&str_no_hash_obj, (mp_obj_t)&bytes_no_hash_obj, MP_OBJ_FROM_PTR(s), MP_OBJ_FROM_PTR(s2)};
+    mp_obj_t items[] = {MP_OBJ_FROM_PTR(&str_no_hash_obj), MP_OBJ_FROM_PTR(&bytes_no_hash_obj), MP_OBJ_FROM_PTR(s), MP_OBJ_FROM_PTR(s2)};
     return mp_obj_new_tuple(MP_ARRAY_SIZE(items), items);
 }
 MP_DEFINE_CONST_FUN_OBJ_0(extra_coverage_obj, extra_coverage);
diff --git a/ports/unix/coveragecpp.cpp b/ports/unix/coveragecpp.cpp
index 377b5acf763ce..8ba308f6468f3 100644
--- a/ports/unix/coveragecpp.cpp
+++ b/ports/unix/coveragecpp.cpp
@@ -1,12 +1,77 @@
 extern "C" {
-// CIRCUITPY-CHANGE: do not include everything: it causes compilation warnings
-#include "py/obj.h"
+// Include the complete public API to verify everything compiles as C++.
+#include <py/gc.h>
+#include <py/obj.h>
+#include <py/objarray.h>
+#include <py/objexcept.h>
+#include <py/objfun.h>
+#include <py/objgenerator.h>
+#include <py/objint.h>
+#include <py/objlist.h>
+#include <py/objmodule.h>
+#include <py/objnamedtuple.h>
+#include <py/objstr.h>
+#include <py/objstringio.h>
+#include <py/objtuple.h>
+#include <py/objtype.h>
+#include <py/runtime.h>
 }
 
+// Invoke all (except one, see below) public API macros which initialize structs to make sure
+// they are C++-compatible, meaning they explicitly initialize all struct members.
+mp_obj_t f0();
+MP_DEFINE_CONST_FUN_OBJ_0(f0_obj, f0);
+mp_obj_t f1(mp_obj_t);
+MP_DEFINE_CONST_FUN_OBJ_1(f1_obj, f1);
+mp_obj_t f2(mp_obj_t, mp_obj_t);
+MP_DEFINE_CONST_FUN_OBJ_2(f2_obj, f2);
+mp_obj_t f3(mp_obj_t, mp_obj_t, mp_obj_t);
+MP_DEFINE_CONST_FUN_OBJ_3(f3_obj, f3);
+mp_obj_t fvar(size_t, const mp_obj_t *);
+MP_DEFINE_CONST_FUN_OBJ_VAR(fvar_obj, 1, fvar);
+mp_obj_t fvarbetween(size_t, const mp_obj_t *);
+MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(fvarbetween_obj, 1, 2, fvarbetween);
+mp_obj_t fkw(size_t, const mp_obj_t *, mp_map_t *);
+MP_DEFINE_CONST_FUN_OBJ_KW(fkw_obj, 1, fkw);
+
+static const mp_rom_map_elem_t table[] = {
+    { MP_ROM_QSTR(MP_QSTR_f0), MP_ROM_PTR(&f0_obj) },
+};
+MP_DEFINE_CONST_MAP(map, table);
+MP_DEFINE_CONST_DICT(dict, table);
+
+static const qstr attrtuple_fields[] = {
+    MP_QSTR_f0,
+};
+MP_DEFINE_ATTRTUPLE(attrtuple, attrtuple_fields, 1, MP_ROM_PTR(&f0_obj));
+
+void nlr_cb(void *);
+void nlr_cb(void *){
+}
+
+// The MP_DEFINE_CONST_OBJ_TYPE macro is not C++-compatible because each of the
+// MP_DEFINE_CONST_OBJ_TYPE_NARGS_X macros only initializes some of _mp_obj_type_t's
+// .slot_index_xxx members but that cannot be fixed to be done in a deterministic way.
+
+
 #if defined(MICROPY_UNIX_COVERAGE)
 
 // Just to test building of C++ code.
 static mp_obj_t extra_cpp_coverage_impl() {
+    MP_DEFINE_NLR_JUMP_CALLBACK_FUNCTION_1(ctx, nlr_cb, (void *) nlr_cb);
+
+    // To avoid 'error: unused variable [-Werror,-Wunused-const-variable]'.
+    (void) ctx;
+    (void) f0_obj;
+    (void) f1_obj;
+    (void) f2_obj;
+    (void) f3_obj;
+    (void) fvar_obj;
+    (void) fvarbetween_obj;
+    (void) fkw_obj;
+    (void) map;
+    (void) dict;
+    (void) attrtuple;
     return mp_const_none;
 }
 
diff --git a/ports/unix/input.c b/ports/unix/input.c
index 31926a5a8e1af..260e9eac8c9db 100644
--- a/ports/unix/input.c
+++ b/ports/unix/input.c
@@ -104,6 +104,9 @@ void prompt_write_history(void) {
     #if MICROPY_USE_READLINE == 1
     char *home = getenv("HOME");
     if (home != NULL) {
+        if (MP_STATE_THREAD(gc_lock_depth) != 0) {
+            return;
+        }
         vstr_t vstr;
         vstr_init(&vstr, 50);
         vstr_printf(&vstr, "%s/.micropython.history", home);
diff --git a/ports/unix/main.c b/ports/unix/main.c
index 259b183eb766d..e42400fe5f9a3 100644
--- a/ports/unix/main.c
+++ b/ports/unix/main.c
@@ -54,9 +54,11 @@
 #include "extmod/vfs_posix.h"
 #include "genhdr/mpversion.h"
 #include "input.h"
+#include "stack_size.h"
+#include "shared/runtime/pyexec.h"
 
 // Command line options, with their defaults
-static bool compile_only = false;
+bool mp_compile_only = false;
 static uint emit_opt = MP_EMIT_OPT_NONE;
 
 #if MICROPY_ENABLE_GC
@@ -90,7 +92,8 @@ static void stderr_print_strn(void *env, const char *str, size_t len) {
 
 const mp_print_t mp_stderr_print = {NULL, stderr_print_strn};
 
-#define FORCED_EXIT (0x100)
+// CIRCUITPY-CHANGE: be consistent about using PYEXEC_FORCED_EXIT
+// #define FORCED_EXIT (0x100)
 // If exc is SystemExit, return value where FORCED_EXIT bit set,
 // and lower 8 bits are SystemExit value. For all other exceptions,
 // return 1.
@@ -103,7 +106,8 @@ static int handle_uncaught_exception(mp_obj_base_t *exc) {
         if (exit_val != mp_const_none && !mp_obj_get_int_maybe(exit_val, &val)) {
             val = 1;
         }
-        return FORCED_EXIT | (val & 255);
+        // CIRCUITPY-CHANGE: be consistent about using PYEXEC_FORCED_EXIT
+        return PYEXEC_FORCED_EXIT | (val & 255);
     }
 
     // Report all other exceptions
@@ -112,8 +116,6 @@ static int handle_uncaught_exception(mp_obj_base_t *exc) {
 }
 
 #define LEX_SRC_STR (1)
-#define LEX_SRC_VSTR (2)
-#define LEX_SRC_FILENAME (3)
 #define LEX_SRC_STDIN (4)
 
 // Returns standard error codes: 0 for success, 1 for all other errors,
@@ -129,19 +131,13 @@ static int execute_from_lexer(int source_kind, const void *source, mp_parse_inpu
         if (source_kind == LEX_SRC_STR) {
             const char *line = source;
             lex = mp_lexer_new_from_str_len(MP_QSTR__lt_stdin_gt_, line, strlen(line), false);
-        } else if (source_kind == LEX_SRC_VSTR) {
-            const vstr_t *vstr = source;
-            lex = mp_lexer_new_from_str_len(MP_QSTR__lt_stdin_gt_, vstr->buf, vstr->len, false);
-        } else if (source_kind == LEX_SRC_FILENAME) {
-            const char *filename = (const char *)source;
-            lex = mp_lexer_new_from_file(qstr_from_str(filename));
         } else { // LEX_SRC_STDIN
             lex = mp_lexer_new_from_fd(MP_QSTR__lt_stdin_gt_, 0, false);
         }
 
         qstr source_name = lex->source_name;
 
-        #if MICROPY_PY___FILE__
+        #if MICROPY_MODULE___FILE__
         if (input_kind == MP_PARSE_FILE_INPUT) {
             mp_store_global(MP_QSTR___file__, MP_OBJ_NEW_QSTR(source_name));
         }
@@ -160,7 +156,7 @@ static int execute_from_lexer(int source_kind, const void *source, mp_parse_inpu
 
         mp_obj_t module_fun = mp_compile(&parse_tree, source_name, is_repl);
 
-        if (!compile_only) {
+        if (!mp_compile_only) {
             // execute it
             mp_call_function_0(module_fun);
         }
@@ -197,92 +193,32 @@ static char *strjoin(const char *s1, int sep_char, const char *s2) {
 #endif
 
 static int do_repl(void) {
-    mp_hal_stdout_tx_str(MICROPY_BANNER_NAME_AND_VERSION);
-    mp_hal_stdout_tx_str("; " MICROPY_BANNER_MACHINE);
-    mp_hal_stdout_tx_str("\nUse Ctrl-D to exit, Ctrl-E for paste mode\n");
-
     #if MICROPY_USE_READLINE == 1
 
-    // use MicroPython supplied readline
+    // use MicroPython supplied readline-based REPL
 
-    vstr_t line;
-    vstr_init(&line, 16);
+    int ret = 0;
     for (;;) {
-        mp_hal_stdio_mode_raw();
-
-    input_restart:
-        vstr_reset(&line);
-        int ret = readline(&line, mp_repl_get_ps1());
-        mp_parse_input_kind_t parse_input_kind = MP_PARSE_SINGLE_INPUT;
-
-        if (ret == CHAR_CTRL_C) {
-            // cancel input
-            mp_hal_stdout_tx_str("\r\n");
-            goto input_restart;
-        } else if (ret == CHAR_CTRL_D) {
-            // EOF
-            printf("\n");
-            mp_hal_stdio_mode_orig();
-            vstr_clear(&line);
-            return 0;
-        } else if (ret == CHAR_CTRL_E) {
-            // paste mode
-            mp_hal_stdout_tx_str("\npaste mode; Ctrl-C to cancel, Ctrl-D to finish\n=== ");
-            vstr_reset(&line);
-            for (;;) {
-                char c = mp_hal_stdin_rx_chr();
-                if (c == CHAR_CTRL_C) {
-                    // cancel everything
-                    mp_hal_stdout_tx_str("\n");
-                    goto input_restart;
-                } else if (c == CHAR_CTRL_D) {
-                    // end of input
-                    mp_hal_stdout_tx_str("\n");
-                    break;
-                } else {
-                    // add char to buffer and echo
-                    vstr_add_byte(&line, c);
-                    if (c == '\r') {
-                        mp_hal_stdout_tx_str("\n=== ");
-                    } else {
-                        mp_hal_stdout_tx_strn(&c, 1);
-                    }
-                }
-            }
-            parse_input_kind = MP_PARSE_FILE_INPUT;
-        } else if (line.len == 0) {
-            if (ret != 0) {
-                printf("\n");
+        if (pyexec_mode_kind == PYEXEC_MODE_RAW_REPL) {
+            if ((ret = pyexec_raw_repl()) != 0) {
+                break;
             }
-            goto input_restart;
         } else {
-            // got a line with non-zero length, see if it needs continuing
-            while (mp_repl_continue_with_input(vstr_null_terminated_str(&line))) {
-                vstr_add_byte(&line, '\n');
-                ret = readline(&line, mp_repl_get_ps2());
-                if (ret == CHAR_CTRL_C) {
-                    // cancel everything
-                    printf("\n");
-                    goto input_restart;
-                } else if (ret == CHAR_CTRL_D) {
-                    // stop entering compound statement
-                    break;
-                }
+            if ((ret = pyexec_friendly_repl()) != 0) {
+                break;
             }
         }
-
-        mp_hal_stdio_mode_orig();
-
-        ret = execute_from_lexer(LEX_SRC_VSTR, &line, parse_input_kind, true);
-        if (ret & FORCED_EXIT) {
-            return ret;
-        }
     }
+    return ret;
 
     #else
 
     // use simple readline
 
+    mp_hal_stdout_tx_str(MICROPY_BANNER_NAME_AND_VERSION);
+    mp_hal_stdout_tx_str("; " MICROPY_BANNER_MACHINE);
+    mp_hal_stdout_tx_str("\nUse Ctrl-D to exit, Ctrl-E for paste mode\n");
+
     for (;;) {
         char *line = prompt((char *)mp_repl_get_ps1());
         if (line == NULL) {
@@ -302,7 +238,8 @@ static int do_repl(void) {
 
         int ret = execute_from_lexer(LEX_SRC_STR, line, MP_PARSE_SINGLE_INPUT, true);
         free(line);
-        if (ret & FORCED_EXIT) {
+        // CIRCUITPY-CHANGE: be consistent about using PYEXEC_FORCED_EXIT
+        if (ret & PYEXEC_FORCED_EXIT) {
             return ret;
         }
     }
@@ -310,12 +247,44 @@ static int do_repl(void) {
     #endif
 }
 
+static inline int convert_pyexec_result(int ret) {
+    #if MICROPY_PYEXEC_ENABLE_EXIT_CODE_HANDLING
+    // With exit code handling enabled:
+    // pyexec returns exit code with PYEXEC_FORCED_EXIT flag set for SystemExit
+    // Unix port expects: 0 for success, non-zero for error/exit
+    if (ret & PYEXEC_FORCED_EXIT) {
+        // SystemExit: extract exit code from lower bits
+        return ret & 0xFF;
+    }
+    // Normal execution or exception: return as-is (0 for success, 1 for exception)
+    return ret;
+    #else
+    // pyexec returns 1 for success, 0 for exception, PYEXEC_FORCED_EXIT for SystemExit
+    // Convert to unix port's expected codes: 0 for success, 1 for exception, FORCED_EXIT|val for SystemExit
+    if (ret == 1) {
+        return 0; // success
+    } else if (ret & PYEXEC_FORCED_EXIT) {
+        return ret; // SystemExit with exit value in lower 8 bits
+    } else {
+        return 1; // exception
+    }
+    #endif
+}
+
 static int do_file(const char *file) {
-    return execute_from_lexer(LEX_SRC_FILENAME, file, MP_PARSE_FILE_INPUT, false);
+    // CIRCUITPY-CHANGE: pyexec_file result arg
+    pyexec_result_t pyexec_result;
+    return convert_pyexec_result(pyexec_file(file, &pyexec_result));
 }
 
 static int do_str(const char *str) {
-    return execute_from_lexer(LEX_SRC_STR, str, MP_PARSE_FILE_INPUT, false);
+    vstr_t vstr;
+    vstr.buf = (char *)str;
+    vstr.len = strlen(str);
+    // CIRCUITPY-CHANGE: pyexec_vstr result arg
+    pyexec_result_t pyexec_result;
+    int ret = pyexec_vstr(&vstr, true, &pyexec_result);
+    return convert_pyexec_result(ret);
 }
 
 static void print_help(char **argv) {
@@ -384,7 +353,7 @@ static void pre_process_options(int argc, char **argv) {
                 }
                 if (0) {
                 } else if (strcmp(argv[a + 1], "compile-only") == 0) {
-                    compile_only = true;
+                    mp_compile_only = true;
                 } else if (strcmp(argv[a + 1], "emit=bytecode") == 0) {
                     emit_opt = MP_EMIT_OPT_BYTECODE;
                 #if MICROPY_EMIT_NATIVE
@@ -456,10 +425,13 @@ static void set_sys_argv(char *argv[], int argc, int start_arg) {
 
 #if MICROPY_PY_SYS_EXECUTABLE
 extern mp_obj_str_t mp_sys_executable_obj;
-static char executable_path[MICROPY_ALLOC_PATH_MAX];
+static char *executable_path = NULL;
 
 static void sys_set_excecutable(char *argv0) {
-    if (realpath(argv0, executable_path)) {
+    if (executable_path == NULL) {
+        executable_path = realpath(argv0, NULL);
+    }
+    if (executable_path != NULL) {
         mp_obj_str_set_data(&mp_sys_executable_obj, (byte *)executable_path, strlen(executable_path));
     }
 }
@@ -479,11 +451,7 @@ int main(int argc, char **argv) {
     #endif
 
     // Define a reasonable stack limit to detect stack overflow.
-    mp_uint_t stack_size = 40000 * (sizeof(void *) / 4);
-    #if defined(__arm__) && !defined(__thumb2__)
-    // ARM (non-Thumb) architectures require more stack.
-    stack_size *= 2;
-    #endif
+    mp_uint_t stack_size = 40000 * UNIX_STACK_MULTIPLIER;
 
     // We should capture stack top ASAP after start, and it should be
     // captured guaranteedly before any other stack variables are allocated.
@@ -619,19 +587,6 @@ MP_NOINLINE int main_(int argc, char **argv) {
     }
     #endif
 
-    // Here is some example code to create a class and instance of that class.
-    // First is the Python, then the C code.
-    //
-    // class TestClass:
-    //     pass
-    // test_obj = TestClass()
-    // test_obj.attr = 42
-    //
-    // mp_obj_t test_class_type, test_class_instance;
-    // test_class_type = mp_obj_new_type(qstr_from_str("TestClass"), mp_const_empty_tuple, mp_obj_new_dict(0));
-    // mp_store_name(qstr_from_str("test_obj"), test_class_instance = mp_call_function_0(test_class_type));
-    // mp_store_attr(test_class_instance, qstr_from_str("attr"), mp_obj_new_int(42));
-
     /*
     printf("bytes:\n");
     printf("    total %d\n", m_get_total_bytes_allocated());
@@ -685,12 +640,18 @@ MP_NOINLINE int main_(int argc, char **argv) {
                 subpkg_tried = false;
 
             reimport:
+                mp_hal_set_interrupt_char(CHAR_CTRL_C);
                 if (nlr_push(&nlr) == 0) {
                     mod = mp_builtin___import__(MP_ARRAY_SIZE(import_args), import_args);
+                    mp_hal_set_interrupt_char(-1);
+                    mp_handle_pending(true);
                     nlr_pop();
                 } else {
                     // uncaught exception
-                    return handle_uncaught_exception(nlr.ret_val) & 0xff;
+                    mp_hal_set_interrupt_char(-1);
+                    mp_handle_pending(false);
+                    ret = handle_uncaught_exception(nlr.ret_val) & 0xff;
+                    break;
                 }
 
                 // If this module is a package, see if it has a `__main__.py`.
@@ -727,11 +688,9 @@ MP_NOINLINE int main_(int argc, char **argv) {
                 return invalid_args();
             }
         } else {
-            char *pathbuf = malloc(PATH_MAX);
-            char *basedir = realpath(argv[a], pathbuf);
+            char *basedir = realpath(argv[a], NULL);
             if (basedir == NULL) {
                 mp_printf(&mp_stderr_print, "%s: can't open file '%s': [Errno %d] %s\n", argv[0], argv[a], errno, strerror(errno));
-                free(pathbuf);
                 // CPython exits with 2 in such case
                 ret = 2;
                 break;
@@ -740,7 +699,7 @@ MP_NOINLINE int main_(int argc, char **argv) {
             // Set base dir of the script as first entry in sys.path.
             char *p = strrchr(basedir, '/');
             mp_obj_list_store(mp_sys_path, MP_OBJ_NEW_SMALL_INT(0), mp_obj_new_str_via_qstr(basedir, p - basedir));
-            free(pathbuf);
+            free(basedir);
 
             set_sys_argv(argv, argc, a);
             ret = do_file(argv[a]);
@@ -780,7 +739,7 @@ MP_NOINLINE int main_(int argc, char **argv) {
     #endif
 
     #if MICROPY_PY_BLUETOOTH
-    void mp_bluetooth_deinit(void);
+    int mp_bluetooth_deinit(void);
     mp_bluetooth_deinit();
     #endif
 
@@ -806,8 +765,20 @@ MP_NOINLINE int main_(int argc, char **argv) {
     #endif
     #endif
 
+    #if MICROPY_PY_SYS_EXECUTABLE && !defined(NDEBUG)
+    // Again, make memory leak detector happy
+    free(executable_path);
+    #endif
+
     // printf("total bytes = %d\n", m_get_total_bytes_allocated());
-    return ret & 0xff;
+
+    // CIRCUITPY-CHANGE: handle PYEXEC_EXCEPTION
+    if (ret & PYEXEC_EXCEPTION) {
+        // Return exit status code 1 so the invoker knows there was an uncaught exception.
+        return 1;
+    } else {
+        return ret & 0xff;
+    }
 }
 
 void nlr_jump_fail(void *val) {
diff --git a/ports/unix/modtime.c b/ports/unix/modtime.c
index fbd94b5ecd129..4f0550dbea765 100644
--- a/ports/unix/modtime.c
+++ b/ports/unix/modtime.c
@@ -34,6 +34,7 @@
 
 #include "py/mphal.h"
 #include "py/runtime.h"
+#include "shared/timeutils/timeutils.h"
 
 #ifdef _WIN32
 static inline int msec_sleep_tv(struct timeval *tv) {
@@ -130,12 +131,7 @@ static mp_obj_t mod_time_gm_local_time(size_t n_args, const mp_obj_t *args, stru
     if (n_args == 0) {
         t = time(NULL);
     } else {
-        #if MICROPY_PY_BUILTINS_FLOAT && MICROPY_FLOAT_IMPL == MICROPY_FLOAT_IMPL_DOUBLE
-        mp_float_t val = mp_obj_get_float(args[0]);
-        t = (time_t)MICROPY_FLOAT_C_FUN(trunc)(val);
-        #else
-        t = mp_obj_get_int(args[0]);
-        #endif
+        t = (time_t)timeutils_obj_get_timestamp(args[0]);
     }
     struct tm *tm = time_func(&t);
 
@@ -193,10 +189,10 @@ static mp_obj_t mod_time_mktime(mp_obj_t tuple) {
         time.tm_isdst = -1; // auto-detect
     }
     time_t ret = mktime(&time);
-    if (ret == -1) {
+    if (ret == (time_t)-1) {
         mp_raise_msg(&mp_type_OverflowError, MP_ERROR_TEXT("invalid mktime usage"));
     }
-    return mp_obj_new_int(ret);
+    return timeutils_obj_from_timestamp(ret);
 }
 MP_DEFINE_CONST_FUN_OBJ_1(mod_time_mktime_obj, mod_time_mktime);
 
diff --git a/ports/unix/mpconfigport.h b/ports/unix/mpconfigport.h
index 4d9fe9f1dc4a2..815be76b4e90c 100644
--- a/ports/unix/mpconfigport.h
+++ b/ports/unix/mpconfigport.h
@@ -32,6 +32,9 @@
 // features to work on Unix-like systems, see mpconfigvariant.h (and
 // mpconfigvariant_common.h) for feature enabling.
 
+// For time_t, needed by MICROPY_TIMESTAMP_IMPL_TIME_T.
+#include <time.h>
+
 // For size_t and ssize_t
 #include <unistd.h>
 
@@ -41,6 +44,7 @@
 // CIRCUITPY-CHANGE
 #define CIRCUITPY_MICROPYTHON_ADVANCED (1)
 #define MICROPY_PY_ASYNC_AWAIT (1)
+#define MICROPY_PY_DOUBLE_TYPECODE (1)
 #define MICROPY_PY_UCTYPES (0)
 
 #ifndef MICROPY_CONFIG_ROM_LEVEL
@@ -78,21 +82,6 @@
     #define MICROPY_EMIT_ARM        (1)
 #endif
 
-// Type definitions for the specific machine based on the word size.
-#ifndef MICROPY_OBJ_REPR
-#ifdef __LP64__
-typedef long mp_int_t; // must be pointer size
-typedef unsigned long mp_uint_t; // must be pointer size
-#else
-// These are definitions for machines where sizeof(int) == sizeof(void*),
-// regardless of actual size.
-typedef int mp_int_t; // must be pointer size
-typedef unsigned int mp_uint_t; // must be pointer size
-#endif
-#else
-// Assume that if we already defined the obj repr then we also defined types.
-#endif
-
 // Cannot include <sys/types.h>, as it may lead to symbol name clashes
 #if _FILE_OFFSET_BITS == 64 && !defined(__LP64__)
 typedef long long mp_off_t;
@@ -135,6 +124,9 @@ typedef long mp_off_t;
 // VFS stat functions should return time values relative to 1970/1/1
 #define MICROPY_EPOCH_IS_1970       (1)
 
+// port modtime functions use time_t
+#define MICROPY_TIMESTAMP_IMPL      (MICROPY_TIMESTAMP_IMPL_TIME_T)
+
 // Assume that select() call, interrupted with a signal, and erroring
 // with EINTR, updates remaining timeout value.
 #define MICROPY_SELECT_REMAINING_TIME (1)
@@ -145,6 +137,9 @@ typedef long mp_off_t;
 #define MICROPY_STACKLESS_STRICT    (0)
 #endif
 
+// Recursive mutex is needed when threading is enabled, regardless of GIL setting.
+#define MICROPY_PY_THREAD_RECURSIVE_MUTEX (MICROPY_PY_THREAD)
+
 // Implementation of the machine module.
 #define MICROPY_PY_MACHINE_INCLUDEFILE "ports/unix/modmachine.c"
 
@@ -172,6 +167,12 @@ typedef long mp_off_t;
 // Enable sys.executable.
 #define MICROPY_PY_SYS_EXECUTABLE (1)
 
+// Enable support for compile-only mode.
+#define MICROPY_PYEXEC_COMPILE_ONLY (1)
+
+// Enable handling of sys.exit() exit codes.
+#define MICROPY_PYEXEC_ENABLE_EXIT_CODE_HANDLING (1)
+
 #define MICROPY_PY_SOCKET_LISTEN_BACKLOG_DEFAULT (SOMAXCONN < 128 ? SOMAXCONN : 128)
 
 // Bare-metal ports don't have stderr. Printing debug to stderr may give tests
diff --git a/ports/unix/mpconfigport.mk b/ports/unix/mpconfigport.mk
index 26c04faf4c5ca..c836663cd2339 100644
--- a/ports/unix/mpconfigport.mk
+++ b/ports/unix/mpconfigport.mk
@@ -14,6 +14,7 @@ MICROPY_PY_BTREE = 0
 
 # _thread module using pthreads
 MICROPY_PY_THREAD = 1
+MICROPY_PY_THREAD_GIL = 0
 
 # Subset of CPython termios module
 MICROPY_PY_TERMIOS = 1
diff --git a/ports/unix/mphalport.h b/ports/unix/mphalport.h
index 7f71217632a8e..d9cd05b3de82b 100644
--- a/ports/unix/mphalport.h
+++ b/ports/unix/mphalport.h
@@ -25,7 +25,6 @@
  */
 #include <errno.h>
 #include <unistd.h>
-// CIRCUITPY-CHANGE: extra include
 #include <stdbool.h>
 
 #ifndef CHAR_CTRL_C
@@ -38,6 +37,20 @@
 #define MICROPY_END_ATOMIC_SECTION(x) (void)x; mp_thread_unix_end_atomic_section()
 #endif
 
+// In lieu of a WFI(), slow down polling from being a tight loop.
+//
+// Note that we don't delay for the full TIMEOUT_MS, as execution
+// can't be woken from the delay.
+#define MICROPY_INTERNAL_WFE(TIMEOUT_MS) \
+    do { \
+        MP_THREAD_GIL_EXIT(); \
+        mp_hal_delay_us(500); \
+        MP_THREAD_GIL_ENTER(); \
+    } while (0)
+
+// The port provides `mp_hal_stdio_mode_raw()` and `mp_hal_stdio_mode_orig()`.
+#define MICROPY_HAL_HAS_STDIO_MODE_SWITCH (1)
+
 // CIRCUITPY-CHANGE: mp_hal_set_interrupt_char(int) instead of char
 void mp_hal_set_interrupt_char(int c);
 bool mp_hal_is_interrupted(void);
@@ -110,3 +123,6 @@ enum {
 
 void mp_hal_get_mac(int idx, uint8_t buf[6]);
 #endif
+
+// Global variable to control compile-only mode.
+extern bool mp_compile_only;
diff --git a/ports/unix/mpthreadport.c b/ports/unix/mpthreadport.c
index 5172645bc147a..a41b3ec9f4701 100644
--- a/ports/unix/mpthreadport.c
+++ b/ports/unix/mpthreadport.c
@@ -31,6 +31,7 @@
 #include "py/runtime.h"
 #include "py/mpthread.h"
 #include "py/gc.h"
+#include "stack_size.h"
 
 #if MICROPY_PY_THREAD
 
@@ -45,8 +46,14 @@
 // potential conflict with other uses of the more commonly used SIGUSR1.
 #ifdef SIGRTMIN
 #define MP_THREAD_GC_SIGNAL (SIGRTMIN + 5)
+#ifdef __ANDROID__
+#define MP_THREAD_TERMINATE_SIGNAL (SIGRTMIN + 6)
+#endif
 #else
 #define MP_THREAD_GC_SIGNAL (SIGUSR1)
+#ifdef __ANDROID__
+#define MP_THREAD_TERMINATE_SIGNAL (SIGUSR2)
+#endif
 #endif
 
 // This value seems to be about right for both 32-bit and 64-bit builds.
@@ -107,6 +114,18 @@ static void mp_thread_gc(int signo, siginfo_t *info, void *context) {
     }
 }
 
+// On Android, pthread_cancel and pthread_setcanceltype are not implemented.
+// To achieve that result a new signal handler responding on either
+// (SIGRTMIN + 6) or SIGUSR2 is installed on every child thread.  The sole
+// purpose of this new signal handler is to terminate the thread in a safe
+// asynchronous manner.
+
+#ifdef __ANDROID__
+static void mp_thread_terminate(int signo, siginfo_t *info, void *context) {
+    pthread_exit(NULL);
+}
+#endif
+
 void mp_thread_init(void) {
     pthread_key_create(&tls_key, NULL);
     pthread_setspecific(tls_key, &mp_state_ctx.thread);
@@ -135,6 +154,14 @@ void mp_thread_init(void) {
     sa.sa_sigaction = mp_thread_gc;
     sigemptyset(&sa.sa_mask);
     sigaction(MP_THREAD_GC_SIGNAL, &sa, NULL);
+
+    // Install a signal handler for asynchronous termination if needed.
+    #if defined(__ANDROID__)
+    sa.sa_flags = SA_SIGINFO;
+    sa.sa_sigaction = mp_thread_terminate;
+    sigemptyset(&sa.sa_mask);
+    sigaction(MP_THREAD_TERMINATE_SIGNAL, &sa, NULL);
+    #endif
 }
 
 void mp_thread_deinit(void) {
@@ -142,7 +169,11 @@ void mp_thread_deinit(void) {
     while (thread->next != NULL) {
         mp_thread_t *th = thread;
         thread = thread->next;
+        #if defined(__ANDROID__)
+        pthread_kill(th->id, MP_THREAD_TERMINATE_SIGNAL);
+        #else
         pthread_cancel(th->id);
+        #endif
         free(th);
     }
     mp_thread_unix_end_atomic_section();
@@ -200,7 +231,9 @@ void mp_thread_start(void) {
     }
     #endif
 
+    #if !defined(__ANDROID__)
     pthread_setcanceltype(PTHREAD_CANCEL_ASYNCHRONOUS, NULL);
+    #endif
     mp_thread_unix_begin_atomic_section();
     for (mp_thread_t *th = thread; th != NULL; th = th->next) {
         if (th->id == pthread_self()) {
@@ -212,14 +245,14 @@ void mp_thread_start(void) {
 }
 
 mp_uint_t mp_thread_create(void *(*entry)(void *), void *arg, size_t *stack_size) {
-    // default stack size is 8k machine-words
+    // default stack size
     if (*stack_size == 0) {
-        *stack_size = 8192 * sizeof(void *);
+        *stack_size = 32768 * UNIX_STACK_MULTIPLIER;
     }
 
     // minimum stack size is set by pthreads
-    if (*stack_size < PTHREAD_STACK_MIN) {
-        *stack_size = PTHREAD_STACK_MIN;
+    if (*stack_size < (size_t)PTHREAD_STACK_MIN) {
+        *stack_size = (size_t)PTHREAD_STACK_MIN;
     }
 
     // ensure there is enough stack to include a stack-overflow margin
diff --git a/ports/unix/stack_size.h b/ports/unix/stack_size.h
new file mode 100644
index 0000000000000..f6159bb69d529
--- /dev/null
+++ b/ports/unix/stack_size.h
@@ -0,0 +1,54 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2025 Angus Gratton
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+#ifndef MICROPY_INCLUDED_UNIX_STACK_SIZE_H
+#define MICROPY_INCLUDED_UNIX_STACK_SIZE_H
+
+#include "py/misc.h"
+
+// Define scaling factors for the stack size (also applies to main thread)
+#ifndef UNIX_STACK_MULTIPLIER
+
+#if defined(__arm__) && !defined(__thumb2__)
+// ARM (non-Thumb) architectures require more stack.
+#define UNIX_STACK_MUL_ARM 2
+#else
+#define UNIX_STACK_MUL_ARM 1
+#endif
+
+#if MP_SANITIZER_BUILD
+// Sanitizer features consume significant stack in some cases
+// This multiplier can probably be removed when using GCC 12 or newer.
+#define UNIX_STACK_MUL_SANITIZERS 4
+#else
+#define UNIX_STACK_MUL_SANITIZERS 1
+#endif
+
+// Double the stack size for 64-bit builds, plus additional scaling
+#define UNIX_STACK_MULTIPLIER ((sizeof(void *) / 4) * UNIX_STACK_MUL_ARM * UNIX_STACK_MUL_SANITIZERS)
+
+#endif // UNIX_STACK_MULTIPLIER
+
+#endif // MICROPY_INCLUDED_UNIX_STACK_SIZE_H
diff --git a/ports/unix/variants/coverage/mpconfigvariant.h b/ports/unix/variants/coverage/mpconfigvariant.h
index ca79d3d0d2b61..03f77ec14c6db 100644
--- a/ports/unix/variants/coverage/mpconfigvariant.h
+++ b/ports/unix/variants/coverage/mpconfigvariant.h
@@ -39,11 +39,22 @@
 
 // Enable additional features.
 #define MICROPY_DEBUG_PARSE_RULE_NAME  (1)
+// CIRCUITPY-CHANGE: off
+#define MICROPY_PY_SYS_SETTRACE        (0)
 #define MICROPY_TRACKED_ALLOC          (1)
 #define MICROPY_WARNINGS_CATEGORY      (1)
 #undef MICROPY_VFS_ROM_IOCTL
 #define MICROPY_VFS_ROM_IOCTL          (1)
 #define MICROPY_PY_CRYPTOLIB_CTR       (1)
+// CIRCUITPY-CHANGE: off
+#define MICROPY_SCHEDULER_STATIC_NODES (0)
+
+// Enable os.uname for attrtuple coverage test
+#define MICROPY_PY_OS_UNAME            (1)
+#define MICROPY_HW_BOARD_NAME          "a machine"
+#define MICROPY_HW_MCU_NAME            MICROPY_PY_SYS_PLATFORM
+// Keep the standard banner message
+#define MICROPY_BANNER_MACHINE MICROPY_PY_SYS_PLATFORM " [" MICROPY_PLATFORM_COMPILER "] version"
 
 // CIRCUITPY-CHANGE: Disable things never used in circuitpython
 #define MICROPY_PY_CRYPTOLIB           (0)
diff --git a/ports/unix/variants/longlong/mpconfigvariant.h b/ports/unix/variants/longlong/mpconfigvariant.h
new file mode 100644
index 0000000000000..d50d360b1fe5c
--- /dev/null
+++ b/ports/unix/variants/longlong/mpconfigvariant.h
@@ -0,0 +1,44 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2016 Damien P. George
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+// This config exists to test that the MICROPY_LONGINT_IMPL_LONGLONG variant
+// (i.e. minimal form of "big integer" that's backed by 64-bit int only) builds
+// and passes tests.
+
+#define MICROPY_LONGINT_IMPL           (MICROPY_LONGINT_IMPL_LONGLONG)
+
+// We build it on top of REPR C, which uses memory-efficient floating point
+// objects encoded directly mp_obj_t (30 bits only).
+// Therefore this variant should be built using MICROPY_FORCE_32BIT=1
+
+#define MICROPY_OBJ_REPR               (MICROPY_OBJ_REPR_C)
+#define MICROPY_FLOAT_IMPL             (MICROPY_FLOAT_IMPL_FLOAT)
+
+// Set base feature level.
+#define MICROPY_CONFIG_ROM_LEVEL (MICROPY_CONFIG_ROM_LEVEL_EXTRA_FEATURES)
+
+// Enable extra Unix features.
+#include "../mpconfigvariant_common.h"
diff --git a/ports/unix/variants/longlong/mpconfigvariant.mk b/ports/unix/variants/longlong/mpconfigvariant.mk
new file mode 100644
index 0000000000000..2d2c3706469fb
--- /dev/null
+++ b/ports/unix/variants/longlong/mpconfigvariant.mk
@@ -0,0 +1,8 @@
+# build interpreter with "bigints" implemented as "longlong"
+
+# otherwise, small int is essentially 64-bit
+MICROPY_FORCE_32BIT := 1
+
+MICROPY_PY_FFI := 0
+
+MPY_TOOL_FLAGS = -mlongint-impl longlong
diff --git a/ports/unix/variants/minimal/mpconfigvariant.h b/ports/unix/variants/minimal/mpconfigvariant.h
index 97ed786b8f409..0e280a8f73058 100644
--- a/ports/unix/variants/minimal/mpconfigvariant.h
+++ b/ports/unix/variants/minimal/mpconfigvariant.h
@@ -49,6 +49,7 @@
 #define MICROPY_COMP_DOUBLE_TUPLE_ASSIGN (1)
 #define MICROPY_ENABLE_COMPILER (1)
 #define MICROPY_ENABLE_EXTERNAL_IMPORT (1)
+#define MICROPY_STACK_CHECK (1)
 #define MICROPY_FULL_CHECKS (1)
 #define MICROPY_HELPER_REPL (1)
 #define MICROPY_KBD_EXCEPTION (1)
@@ -61,6 +62,5 @@
 #define MICROPY_PY_BUILTINS_RANGE_ATTRS (1)
 #define MICROPY_PY_GENERATOR_PEND_THROW (1)
 
-// Enable just the sys and os built-in modules.
-#define MICROPY_PY_SYS (1)
+// Add just the os built-in module.
 #define MICROPY_PY_OS (1)
diff --git a/ports/unix/variants/mpconfigvariant_common.h b/ports/unix/variants/mpconfigvariant_common.h
index 9eeed8797366c..1ac59c95572dd 100644
--- a/ports/unix/variants/mpconfigvariant_common.h
+++ b/ports/unix/variants/mpconfigvariant_common.h
@@ -29,7 +29,7 @@
 
 // Send raise KeyboardInterrupt directly from the signal handler rather than
 // scheduling it into the VM.
-#define MICROPY_ASYNC_KBD_INTR         (1)
+#define MICROPY_ASYNC_KBD_INTR         (!MICROPY_PY_THREAD_GIL)
 
 // Enable helpers for printing debugging information.
 #ifndef MICROPY_DEBUG_PRINTERS
@@ -104,12 +104,6 @@
 #define MICROPY_PY_TIME_CUSTOM_SLEEP   (1)
 #define MICROPY_PY_TIME_INCLUDEFILE    "ports/unix/modtime.c"
 
-#if MICROPY_PY_SSL
-#define MICROPY_PY_HASHLIB_MD5         (1)
-#define MICROPY_PY_HASHLIB_SHA1        (1)
-#define MICROPY_PY_CRYPTOLIB           (1)
-#endif
-
 // The "select" module is enabled by default, but disable select.select().
 #define MICROPY_PY_SELECT_POSIX_OPTIMISATIONS (1)
 #define MICROPY_PY_SELECT_SELECT       (0)
diff --git a/ports/unix/variants/nanbox/mpconfigvariant.h b/ports/unix/variants/nanbox/mpconfigvariant.h
index 7b13b7dc6ce4e..c9e9c1f63d95d 100644
--- a/ports/unix/variants/nanbox/mpconfigvariant.h
+++ b/ports/unix/variants/nanbox/mpconfigvariant.h
@@ -41,10 +41,3 @@
 #define MICROPY_EMIT_X64 (0)
 #define MICROPY_EMIT_THUMB (0)
 #define MICROPY_EMIT_ARM (0)
-
-#include <stdint.h>
-
-typedef int64_t mp_int_t;
-typedef uint64_t mp_uint_t;
-#define UINT_FMT "%llu"
-#define INT_FMT "%lld"
diff --git a/py/argcheck.c b/py/argcheck.c
index 9302dec96c396..155e29bdc15bf 100644
--- a/py/argcheck.c
+++ b/py/argcheck.c
@@ -170,13 +170,13 @@ void mp_arg_parse_all_kw_array(size_t n_pos, size_t n_kw, const mp_obj_t *args,
 }
 
 #if MICROPY_ERROR_REPORTING <= MICROPY_ERROR_REPORTING_TERSE
-NORETURN void mp_arg_error_terse_mismatch(void) {
+MP_NORETURN void mp_arg_error_terse_mismatch(void) {
     mp_raise_TypeError(MP_ERROR_TEXT("argument num/types mismatch"));
 }
 #endif
 
 #if MICROPY_CPYTHON_COMPAT
-NORETURN void mp_arg_error_unimpl_kw(void) {
+MP_NORETURN void mp_arg_error_unimpl_kw(void) {
     mp_raise_NotImplementedError(MP_ERROR_TEXT("keyword argument(s) not implemented - use normal args instead"));
 }
 #endif
@@ -312,6 +312,6 @@ mp_int_t mp_arg_validate_type_int(mp_obj_t obj, qstr arg_name) {
     return an_int;
 }
 
-NORETURN void mp_arg_error_invalid(qstr arg_name) {
+MP_NORETURN void mp_arg_error_invalid(qstr arg_name) {
     mp_raise_ValueError_varg(MP_ERROR_TEXT("Invalid %q"), arg_name);
 }
diff --git a/py/asmarm.c b/py/asmarm.c
index 6fa751b32eb7c..15bc73b61eca6 100644
--- a/py/asmarm.c
+++ b/py/asmarm.c
@@ -36,7 +36,7 @@
 
 #include "py/asmarm.h"
 
-#define SIGNED_FIT24(x) (((x) & 0xff800000) == 0) || (((x) & 0xff000000) == 0xff000000)
+#define REG_TEMP ASM_ARM_REG_R8
 
 // Insert word into instruction flow
 static void emit(asm_arm_t *as, uint op) {
@@ -171,8 +171,8 @@ void asm_arm_entry(asm_arm_t *as, int num_locals) {
         if (as->stack_adjust < 0x100) {
             emit_al(as, asm_arm_op_sub_imm(ASM_ARM_REG_SP, ASM_ARM_REG_SP, as->stack_adjust));
         } else {
-            asm_arm_mov_reg_i32_optimised(as, ASM_ARM_REG_R8, as->stack_adjust);
-            emit_al(as, asm_arm_op_sub_reg(ASM_ARM_REG_SP, ASM_ARM_REG_SP, ASM_ARM_REG_R8));
+            asm_arm_mov_reg_i32_optimised(as, REG_TEMP, as->stack_adjust);
+            emit_al(as, asm_arm_op_sub_reg(ASM_ARM_REG_SP, ASM_ARM_REG_SP, REG_TEMP));
         }
     }
 }
@@ -182,8 +182,8 @@ void asm_arm_exit(asm_arm_t *as) {
         if (as->stack_adjust < 0x100) {
             emit_al(as, asm_arm_op_add_imm(ASM_ARM_REG_SP, ASM_ARM_REG_SP, as->stack_adjust));
         } else {
-            asm_arm_mov_reg_i32_optimised(as, ASM_ARM_REG_R8, as->stack_adjust);
-            emit_al(as, asm_arm_op_add_reg(ASM_ARM_REG_SP, ASM_ARM_REG_SP, ASM_ARM_REG_R8));
+            asm_arm_mov_reg_i32_optimised(as, REG_TEMP, as->stack_adjust);
+            emit_al(as, asm_arm_op_add_reg(ASM_ARM_REG_SP, ASM_ARM_REG_SP, REG_TEMP));
         }
     }
 
@@ -293,10 +293,10 @@ void asm_arm_orr_reg_reg_reg(asm_arm_t *as, uint rd, uint rn, uint rm) {
 
 void asm_arm_mov_reg_local_addr(asm_arm_t *as, uint rd, int local_num) {
     if (local_num >= 0x40) {
-        // mov r8, #local_num*4
-        // add rd, sp, r8
-        asm_arm_mov_reg_i32_optimised(as, ASM_ARM_REG_R8, local_num << 2);
-        emit_al(as, asm_arm_op_add_reg(rd, ASM_ARM_REG_SP, ASM_ARM_REG_R8));
+        // mov temp, #local_num*4
+        // add rd, sp, temp
+        asm_arm_mov_reg_i32_optimised(as, REG_TEMP, local_num << 2);
+        emit_al(as, asm_arm_op_add_reg(rd, ASM_ARM_REG_SP, REG_TEMP));
     } else {
         // add rd, sp, #local_num*4
         emit_al(as, asm_arm_op_add_imm(rd, ASM_ARM_REG_SP, local_num << 2));
@@ -333,14 +333,22 @@ void asm_arm_asr_reg_reg(asm_arm_t *as, uint rd, uint rs) {
     emit_al(as, 0x1a00050 | (rd << 12) | (rs << 8) | rd);
 }
 
-void asm_arm_ldr_reg_reg(asm_arm_t *as, uint rd, uint rn, uint byte_offset) {
-    // ldr rd, [rn, #off]
-    emit_al(as, 0x5900000 | (rn << 16) | (rd << 12) | byte_offset);
+void asm_arm_ldr_reg_reg_offset(asm_arm_t *as, uint rd, uint rn, uint byte_offset) {
+    if (byte_offset < 0x1000) {
+        // ldr rd, [rn, #off]
+        emit_al(as, 0x5900000 | (rn << 16) | (rd << 12) | byte_offset);
+    } else {
+        // mov temp, #off
+        // ldr rd, [rn, temp]
+        asm_arm_mov_reg_i32_optimised(as, REG_TEMP, byte_offset);
+        emit_al(as, 0x7900000 | (rn << 16) | (rd << 12) | REG_TEMP);
+    }
 }
 
-void asm_arm_ldrh_reg_reg(asm_arm_t *as, uint rd, uint rn) {
-    // ldrh rd, [rn]
-    emit_al(as, 0x1d000b0 | (rn << 16) | (rd << 12));
+void asm_arm_ldrh_reg_reg_reg(asm_arm_t *as, uint rd, uint rm, uint rn) {
+    // ldrh doesn't support scaled register index
+    emit_al(as, 0x1a00080 | (REG_TEMP << 12) | rn); // mov temp, rn, lsl #1
+    emit_al(as, 0x19000b0 | (rm << 16) | (rd << 12) | REG_TEMP); // ldrh rd, [rm, temp];
 }
 
 void asm_arm_ldrh_reg_reg_offset(asm_arm_t *as, uint rd, uint rn, uint byte_offset) {
@@ -348,31 +356,69 @@ void asm_arm_ldrh_reg_reg_offset(asm_arm_t *as, uint rd, uint rn, uint byte_offs
         // ldrh rd, [rn, #off]
         emit_al(as, 0x1d000b0 | (rn << 16) | (rd << 12) | ((byte_offset & 0xf0) << 4) | (byte_offset & 0xf));
     } else {
-        // mov r8, #off
-        // ldrh rd, [rn, r8]
-        asm_arm_mov_reg_i32_optimised(as, ASM_ARM_REG_R8, byte_offset);
-        emit_al(as, 0x19000b0 | (rn << 16) | (rd << 12) | ASM_ARM_REG_R8);
+        // mov temp, #off
+        // ldrh rd, [rn, temp]
+        asm_arm_mov_reg_i32_optimised(as, REG_TEMP, byte_offset);
+        emit_al(as, 0x19000b0 | (rn << 16) | (rd << 12) | REG_TEMP);
     }
 }
 
-void asm_arm_ldrb_reg_reg(asm_arm_t *as, uint rd, uint rn) {
-    // ldrb rd, [rn]
-    emit_al(as, 0x5d00000 | (rn << 16) | (rd << 12));
+void asm_arm_ldrb_reg_reg_reg(asm_arm_t *as, uint rd, uint rm, uint rn) {
+    // ldrb rd, [rm, rn]
+    emit_al(as, 0x7d00000 | (rm << 16) | (rd << 12) | rn);
+}
+
+void asm_arm_ldrb_reg_reg_offset(asm_arm_t *as, uint rd, uint rn, uint byte_offset) {
+    if (byte_offset < 0x1000) {
+        // ldrb rd, [rn, #off]
+        emit_al(as, 0x5d00000 | (rn << 16) | (rd << 12) | byte_offset);
+    } else {
+        // mov temp, #off
+        // ldrb rd, [rn, temp]
+        asm_arm_mov_reg_i32_optimised(as, REG_TEMP, byte_offset);
+        emit_al(as, 0x7d00000 | (rn << 16) | (rd << 12) | REG_TEMP);
+    }
 }
 
-void asm_arm_str_reg_reg(asm_arm_t *as, uint rd, uint rm, uint byte_offset) {
-    // str rd, [rm, #off]
-    emit_al(as, 0x5800000 | (rm << 16) | (rd << 12) | byte_offset);
+void asm_arm_ldr_reg_reg_reg(asm_arm_t *as, uint rd, uint rm, uint rn) {
+    // ldr rd, [rm, rn, lsl #2]
+    emit_al(as, 0x7900100 | (rm << 16) | (rd << 12) | rn);
 }
 
-void asm_arm_strh_reg_reg(asm_arm_t *as, uint rd, uint rm) {
-    // strh rd, [rm]
-    emit_al(as, 0x1c000b0 | (rm << 16) | (rd << 12));
+void asm_arm_str_reg_reg_offset(asm_arm_t *as, uint rd, uint rm, uint byte_offset) {
+    if (byte_offset < 0x1000) {
+        // str rd, [rm, #off]
+        emit_al(as, 0x5800000 | (rm << 16) | (rd << 12) | byte_offset);
+    } else {
+        // mov temp, #off
+        // str rd, [rm, temp]
+        asm_arm_mov_reg_i32_optimised(as, REG_TEMP, byte_offset);
+        emit_al(as, 0x7800000 | (rm << 16) | (rd << 12) | REG_TEMP);
+    }
 }
 
-void asm_arm_strb_reg_reg(asm_arm_t *as, uint rd, uint rm) {
-    // strb rd, [rm]
-    emit_al(as, 0x5c00000 | (rm << 16) | (rd << 12));
+void asm_arm_strh_reg_reg_offset(asm_arm_t *as, uint rd, uint rn, uint byte_offset) {
+    if (byte_offset < 0x100) {
+        // strh rd, [rn, #off]
+        emit_al(as, 0x1c000b0 | (rn << 16) | (rd << 12) | ((byte_offset & 0xf0) << 4) | (byte_offset & 0xf));
+    } else {
+        // mov temp, #off
+        // strh rd, [rn, temp]
+        asm_arm_mov_reg_i32_optimised(as, REG_TEMP, byte_offset);
+        emit_al(as, 0x18000b0 | (rn << 16) | (rd << 12) | REG_TEMP);
+    }
+}
+
+void asm_arm_strb_reg_reg_offset(asm_arm_t *as, uint rd, uint rm, uint byte_offset) {
+    if (byte_offset < 0x1000) {
+        // strb rd, [rm, #off]
+        emit_al(as, 0x5c00000 | (rm << 16) | (rd << 12) | byte_offset);
+    } else {
+        // mov temp, #off
+        // strb rd, [rm, temp]
+        asm_arm_mov_reg_i32_optimised(as, REG_TEMP, byte_offset);
+        emit_al(as, 0x7c00000 | (rm << 16) | (rd << 12) | REG_TEMP);
+    }
 }
 
 void asm_arm_str_reg_reg_reg(asm_arm_t *as, uint rd, uint rm, uint rn) {
@@ -382,8 +428,8 @@ void asm_arm_str_reg_reg_reg(asm_arm_t *as, uint rd, uint rm, uint rn) {
 
 void asm_arm_strh_reg_reg_reg(asm_arm_t *as, uint rd, uint rm, uint rn) {
     // strh doesn't support scaled register index
-    emit_al(as, 0x1a00080 | (ASM_ARM_REG_R8 << 12) | rn); // mov r8, rn, lsl #1
-    emit_al(as, 0x18000b0 | (rm << 16) | (rd << 12) | ASM_ARM_REG_R8); // strh rd, [rm, r8]
+    emit_al(as, 0x1a00080 | (REG_TEMP << 12) | rn); // mov temp, rn, lsl #1
+    emit_al(as, 0x18000b0 | (rm << 16) | (rd << 12) | REG_TEMP); // strh rd, [rm, temp]
 }
 
 void asm_arm_strb_reg_reg_reg(asm_arm_t *as, uint rd, uint rm, uint rn) {
@@ -398,7 +444,7 @@ void asm_arm_bcc_label(asm_arm_t *as, int cond, uint label) {
     rel -= 8; // account for instruction prefetch, PC is 8 bytes ahead of this instruction
     rel >>= 2; // in ARM mode the branch target is 32-bit aligned, so the 2 LSB are omitted
 
-    if (SIGNED_FIT24(rel)) {
+    if (MP_FIT_SIGNED(24, rel)) {
         emit(as, cond | 0xa000000 | (rel & 0xffffff));
     } else {
         printf("asm_arm_bcc: branch does not fit in 24 bits\n");
diff --git a/py/asmarm.h b/py/asmarm.h
index a0e057fce4450..f3fd586a37530 100644
--- a/py/asmarm.h
+++ b/py/asmarm.h
@@ -109,13 +109,18 @@ void asm_arm_lsr_reg_reg(asm_arm_t *as, uint rd, uint rs);
 void asm_arm_asr_reg_reg(asm_arm_t *as, uint rd, uint rs);
 
 // memory
-void asm_arm_ldr_reg_reg(asm_arm_t *as, uint rd, uint rn, uint byte_offset);
-void asm_arm_ldrh_reg_reg(asm_arm_t *as, uint rd, uint rn);
+void asm_arm_ldr_reg_reg_offset(asm_arm_t *as, uint rd, uint rn, uint byte_offset);
 void asm_arm_ldrh_reg_reg_offset(asm_arm_t *as, uint rd, uint rn, uint byte_offset);
-void asm_arm_ldrb_reg_reg(asm_arm_t *as, uint rd, uint rn);
-void asm_arm_str_reg_reg(asm_arm_t *as, uint rd, uint rm, uint byte_offset);
-void asm_arm_strh_reg_reg(asm_arm_t *as, uint rd, uint rm);
-void asm_arm_strb_reg_reg(asm_arm_t *as, uint rd, uint rm);
+void asm_arm_ldrb_reg_reg_offset(asm_arm_t *as, uint rd, uint rn, uint byte_offset);
+void asm_arm_str_reg_reg_offset(asm_arm_t *as, uint rd, uint rm, uint byte_offset);
+void asm_arm_strh_reg_reg_offset(asm_arm_t *as, uint rd, uint rm, uint byte_offset);
+void asm_arm_strb_reg_reg_offset(asm_arm_t *as, uint rd, uint rm, uint byte_offset);
+
+// load from array
+void asm_arm_ldr_reg_reg_reg(asm_arm_t *as, uint rd, uint rm, uint rn);
+void asm_arm_ldrh_reg_reg_reg(asm_arm_t *as, uint rd, uint rm, uint rn);
+void asm_arm_ldrb_reg_reg_reg(asm_arm_t *as, uint rd, uint rm, uint rn);
+
 // store to array
 void asm_arm_str_reg_reg_reg(asm_arm_t *as, uint rd, uint rm, uint rn);
 void asm_arm_strh_reg_reg_reg(asm_arm_t *as, uint rd, uint rm, uint rn);
@@ -160,12 +165,12 @@ void asm_arm_bx_reg(asm_arm_t *as, uint reg_src);
 // Holds a pointer to mp_fun_table
 #define REG_FUN_TABLE ASM_ARM_REG_FUN_TABLE
 
-#define ASM_T               asm_arm_t
-#define ASM_END_PASS        asm_arm_end_pass
-#define ASM_ENTRY           asm_arm_entry
-#define ASM_EXIT            asm_arm_exit
+#define ASM_T                           asm_arm_t
+#define ASM_END_PASS                    asm_arm_end_pass
+#define ASM_ENTRY(as, num_locals, name) asm_arm_entry((as), (num_locals))
+#define ASM_EXIT                        asm_arm_exit
 
-#define ASM_JUMP            asm_arm_b_label
+#define ASM_JUMP                        asm_arm_b_label
 #define ASM_JUMP_IF_REG_ZERO(as, reg, label, bool_test) \
     do { \
         asm_arm_cmp_reg_i8(as, reg, 0); \
@@ -203,18 +208,28 @@ void asm_arm_bx_reg(asm_arm_t *as, uint reg_src);
 #define ASM_SUB_REG_REG(as, reg_dest, reg_src) asm_arm_sub_reg_reg_reg((as), (reg_dest), (reg_dest), (reg_src))
 #define ASM_MUL_REG_REG(as, reg_dest, reg_src) asm_arm_mul_reg_reg_reg((as), (reg_dest), (reg_dest), (reg_src))
 
-#define ASM_LOAD_REG_REG(as, reg_dest, reg_base) asm_arm_ldr_reg_reg((as), (reg_dest), (reg_base), 0)
-#define ASM_LOAD_REG_REG_OFFSET(as, reg_dest, reg_base, word_offset) asm_arm_ldr_reg_reg((as), (reg_dest), (reg_base), 4 * (word_offset))
-#define ASM_LOAD8_REG_REG(as, reg_dest, reg_base) asm_arm_ldrb_reg_reg((as), (reg_dest), (reg_base))
-#define ASM_LOAD16_REG_REG(as, reg_dest, reg_base) asm_arm_ldrh_reg_reg((as), (reg_dest), (reg_base))
-#define ASM_LOAD16_REG_REG_OFFSET(as, reg_dest, reg_base, uint16_offset) asm_arm_ldrh_reg_reg_offset((as), (reg_dest), (reg_base), 2 * (uint16_offset))
-#define ASM_LOAD32_REG_REG(as, reg_dest, reg_base) asm_arm_ldr_reg_reg((as), (reg_dest), (reg_base), 0)
-
-#define ASM_STORE_REG_REG(as, reg_value, reg_base) asm_arm_str_reg_reg((as), (reg_value), (reg_base), 0)
-#define ASM_STORE_REG_REG_OFFSET(as, reg_dest, reg_base, word_offset) asm_arm_str_reg_reg((as), (reg_dest), (reg_base), 4 * (word_offset))
-#define ASM_STORE8_REG_REG(as, reg_value, reg_base) asm_arm_strb_reg_reg((as), (reg_value), (reg_base))
-#define ASM_STORE16_REG_REG(as, reg_value, reg_base) asm_arm_strh_reg_reg((as), (reg_value), (reg_base))
-#define ASM_STORE32_REG_REG(as, reg_value, reg_base) asm_arm_str_reg_reg((as), (reg_value), (reg_base), 0)
+#define ASM_LOAD_REG_REG_OFFSET(as, reg_dest, reg_base, word_offset) ASM_LOAD32_REG_REG_OFFSET((as), (reg_dest), (reg_base), (word_offset))
+#define ASM_LOAD8_REG_REG(as, reg_dest, reg_base) ASM_LOAD8_REG_REG_OFFSET((as), (reg_dest), (reg_base), 0)
+#define ASM_LOAD8_REG_REG_OFFSET(as, reg_dest, reg_base, byte_offset) asm_arm_ldrb_reg_reg_offset((as), (reg_dest), (reg_base), (byte_offset))
+#define ASM_LOAD16_REG_REG(as, reg_dest, reg_base) ASM_LOAD16_REG_REG_OFFSET((as), (reg_dest), (reg_base), 0)
+#define ASM_LOAD16_REG_REG_OFFSET(as, reg_dest, reg_base, halfword_offset) asm_arm_ldrh_reg_reg_offset((as), (reg_dest), (reg_base), 2 * (halfword_offset))
+#define ASM_LOAD32_REG_REG(as, reg_dest, reg_base) ASM_LOAD32_REG_REG_OFFSET((as), (reg_dest), (reg_base), 0)
+#define ASM_LOAD32_REG_REG_OFFSET(as, reg_dest, reg_base, word_offset) asm_arm_ldr_reg_reg_offset((as), (reg_dest), (reg_base), 4 * (word_offset))
+
+#define ASM_STORE_REG_REG_OFFSET(as, reg_value, reg_base, word_offset) ASM_STORE32_REG_REG_OFFSET((as), (reg_value), (reg_base), (word_offset))
+#define ASM_STORE8_REG_REG(as, reg_value, reg_base) ASM_STORE8_REG_REG_OFFSET((as), (reg_value), (reg_base), 0)
+#define ASM_STORE8_REG_REG_OFFSET(as, reg_value, reg_base, byte_offset) asm_arm_strb_reg_reg_offset((as), (reg_value), (reg_base), (byte_offset))
+#define ASM_STORE16_REG_REG(as, reg_value, reg_base) ASM_STORE16_REG_REG_OFFSET((as), (reg_value), (reg_base), 0)
+#define ASM_STORE16_REG_REG_OFFSET(as, reg_value, reg_base, halfword_offset) asm_arm_strh_reg_reg_offset((as), (reg_value), (reg_base), 2 * (halfword_offset))
+#define ASM_STORE32_REG_REG(as, reg_value, reg_base) ASM_STORE32_REG_REG_OFFSET((as), (reg_value), (reg_base), 0)
+#define ASM_STORE32_REG_REG_OFFSET(as, reg_value, reg_base, word_offset) asm_arm_str_reg_reg_offset((as), (reg_value), (reg_base), 4 * (word_offset))
+
+#define ASM_LOAD8_REG_REG_REG(as, reg_dest, reg_base, reg_index) asm_arm_ldrb_reg_reg_reg((as), (reg_dest), (reg_base), (reg_index))
+#define ASM_LOAD16_REG_REG_REG(as, reg_dest, reg_base, reg_index) asm_arm_ldrh_reg_reg_reg((as), (reg_dest), (reg_base), (reg_index))
+#define ASM_LOAD32_REG_REG_REG(as, reg_dest, reg_base, reg_index) asm_arm_ldr_reg_reg_reg((as), (reg_dest), (reg_base), (reg_index))
+#define ASM_STORE8_REG_REG_REG(as, reg_val, reg_base, reg_index) asm_arm_strb_reg_reg_reg((as), (reg_val), (reg_base), (reg_index))
+#define ASM_STORE16_REG_REG_REG(as, reg_val, reg_base, reg_index) asm_arm_strh_reg_reg_reg((as), (reg_val), (reg_base), (reg_index))
+#define ASM_STORE32_REG_REG_REG(as, reg_val, reg_base, reg_index) asm_arm_str_reg_reg_reg((as), (reg_val), (reg_base), (reg_index))
 
 #endif // GENERIC_ASM_API
 
diff --git a/py/asmbase.c b/py/asmbase.c
index 3fce543a7f485..07dbf4430f9db 100644
--- a/py/asmbase.c
+++ b/py/asmbase.c
@@ -53,7 +53,7 @@ void mp_asm_base_start_pass(mp_asm_base_t *as, int pass) {
     } else {
         // allocating executable RAM is platform specific
         MP_PLAT_ALLOC_EXEC(as->code_offset, (void **)&as->code_base, &as->code_size);
-        assert(as->code_base != NULL);
+        assert(as->code_size == 0 || as->code_base != NULL);
     }
     as->pass = pass;
     as->suppress = false;
@@ -102,7 +102,7 @@ void mp_asm_base_label_assign(mp_asm_base_t *as, size_t label) {
 
 // align must be a multiple of 2
 void mp_asm_base_align(mp_asm_base_t *as, unsigned int align) {
-    as->code_offset = (as->code_offset + align - 1) & (~(align - 1));
+    as->code_offset = (as->code_offset + align - 1) & (~(size_t)(align - 1));
 }
 
 // this function assumes a little endian machine
diff --git a/py/asmrv32.c b/py/asmrv32.c
index c24d05a1384d4..1d0cea6c02616 100644
--- a/py/asmrv32.c
+++ b/py/asmrv32.c
@@ -36,6 +36,8 @@
 #if MICROPY_EMIT_RV32
 
 #include "py/asmrv32.h"
+#include "py/mpstate.h"
+#include "py/persistentcode.h"
 
 #if MICROPY_DEBUG_VERBOSE
 #define DEBUG_PRINT (1)
@@ -450,18 +452,24 @@ void asm_rv32_emit_mov_reg_local_addr(asm_rv32_t *state, mp_uint_t rd, mp_uint_t
     asm_rv32_opcode_cadd(state, rd, ASM_RV32_REG_SP);
 }
 
-void asm_rv32_emit_load_reg_reg_offset(asm_rv32_t *state, mp_uint_t rd, mp_uint_t rs, mp_int_t offset) {
-    mp_int_t scaled_offset = offset * sizeof(ASM_WORD_SIZE);
+static const uint8_t RV32_LOAD_OPCODE_TABLE[3] = {
+    0x04, 0x05, 0x02
+};
 
-    if (scaled_offset >= 0 && RV32_IS_IN_C_REGISTER_WINDOW(rd) && RV32_IS_IN_C_REGISTER_WINDOW(rs) && FIT_UNSIGNED(scaled_offset, 6)) {
+void asm_rv32_emit_load_reg_reg_offset(asm_rv32_t *state, mp_uint_t rd, mp_uint_t rs, int32_t offset, mp_uint_t operation_size) {
+    assert(operation_size <= 2 && "Operation size value out of range.");
+
+    int32_t scaled_offset = offset << operation_size;
+
+    if (scaled_offset >= 0 && operation_size == 2 && RV32_IS_IN_C_REGISTER_WINDOW(rd) && RV32_IS_IN_C_REGISTER_WINDOW(rs) && MP_FIT_UNSIGNED(6, scaled_offset)) {
         // c.lw rd', offset(rs')
         asm_rv32_opcode_clw(state, RV32_MAP_IN_C_REGISTER_WINDOW(rd), RV32_MAP_IN_C_REGISTER_WINDOW(rs), scaled_offset);
         return;
     }
 
-    if (FIT_SIGNED(scaled_offset, 12)) {
-        // lw rd, offset(rs)
-        asm_rv32_opcode_lw(state, rd, rs, scaled_offset);
+    if (MP_FIT_SIGNED(12, scaled_offset)) {
+        // lbu|lhu|lw rd, offset(rs)
+        asm_rv32_emit_word_opcode(state, RV32_ENCODE_TYPE_I(0x03, RV32_LOAD_OPCODE_TABLE[operation_size], rd, rs, scaled_offset));
         return;
     }
 
@@ -469,12 +477,12 @@ void asm_rv32_emit_load_reg_reg_offset(asm_rv32_t *state, mp_uint_t rd, mp_uint_
     mp_uint_t lower = 0;
     split_immediate(scaled_offset, &upper, &lower);
 
-    // lui   rd, HI(offset) ; Or c.lui if possible
-    // c.add rd, rs
-    // lw    rd, LO(offset)(rd)
+    // lui        rd, HI(offset) ; Or c.lui if possible
+    // c.add      rd, rs
+    // lbu|lhu|lw rd, LO(offset)(rd)
     load_upper_immediate(state, rd, upper);
     asm_rv32_opcode_cadd(state, rd, rs);
-    asm_rv32_opcode_lw(state, rd, rd, lower);
+    asm_rv32_emit_word_opcode(state, RV32_ENCODE_TYPE_I(0x03, RV32_LOAD_OPCODE_TABLE[operation_size], rd, rd, lower));
 }
 
 void asm_rv32_emit_jump(asm_rv32_t *state, mp_uint_t label) {
@@ -497,12 +505,20 @@ void asm_rv32_emit_jump(asm_rv32_t *state, mp_uint_t label) {
     asm_rv32_opcode_jalr(state, ASM_RV32_REG_ZERO, REG_TEMP2, lower);
 }
 
-void asm_rv32_emit_store_reg_reg_offset(asm_rv32_t *state, mp_uint_t rd, mp_uint_t rs, mp_int_t offset) {
-    mp_int_t scaled_offset = offset * ASM_WORD_SIZE;
+void asm_rv32_emit_store_reg_reg_offset(asm_rv32_t *state, mp_uint_t rd, mp_uint_t rs, int32_t offset, mp_uint_t operation_size) {
+    assert(operation_size <= 2 && "Operation size value out of range.");
 
-    if (FIT_SIGNED(scaled_offset, 12)) {
-        // sw rd, offset(rs)
-        asm_rv32_opcode_sw(state, rd, rs, scaled_offset);
+    int32_t scaled_offset = offset << operation_size;
+
+    if (scaled_offset >= 0 && operation_size == 2 && RV32_IS_IN_C_REGISTER_WINDOW(rd) && RV32_IS_IN_C_REGISTER_WINDOW(rs) && MP_FIT_UNSIGNED(6, scaled_offset)) {
+        // c.sw rd', offset(rs')
+        asm_rv32_opcode_csw(state, RV32_MAP_IN_C_REGISTER_WINDOW(rd), RV32_MAP_IN_C_REGISTER_WINDOW(rs), scaled_offset);
+        return;
+    }
+
+    if (MP_FIT_SIGNED(12, scaled_offset)) {
+        // sb|sh|sw rd, offset(rs)
+        asm_rv32_emit_word_opcode(state, RV32_ENCODE_TYPE_S(0x23, operation_size, rs, rd, scaled_offset));
         return;
     }
 
@@ -510,12 +526,12 @@ void asm_rv32_emit_store_reg_reg_offset(asm_rv32_t *state, mp_uint_t rd, mp_uint
     mp_uint_t lower = 0;
     split_immediate(scaled_offset, &upper, &lower);
 
-    // lui   temporary, HI(offset) ; Or c.lui if possible
-    // c.add temporary, rs
-    // sw    rd, LO(offset)(temporary)
+    // lui      temporary, HI(offset) ; Or c.lui if possible
+    // c.add    temporary, rs
+    // sb|sh|sw rd, LO(offset)(temporary)
     load_upper_immediate(state, REG_TEMP2, upper);
     asm_rv32_opcode_cadd(state, REG_TEMP2, rs);
-    asm_rv32_opcode_sw(state, rd, REG_TEMP2, lower);
+    asm_rv32_emit_word_opcode(state, RV32_ENCODE_TYPE_S(0x23, operation_size, REG_TEMP2, rd, lower));
 }
 
 void asm_rv32_emit_mov_reg_pcrel(asm_rv32_t *state, mp_uint_t rd, mp_uint_t label) {
@@ -530,27 +546,6 @@ void asm_rv32_emit_mov_reg_pcrel(asm_rv32_t *state, mp_uint_t rd, mp_uint_t labe
     asm_rv32_opcode_addi(state, rd, rd, lower);
 }
 
-void asm_rv32_emit_load16_reg_reg_offset(asm_rv32_t *state, mp_uint_t rd, mp_uint_t rs, mp_int_t offset) {
-    mp_int_t scaled_offset = offset * sizeof(uint16_t);
-
-    if (FIT_SIGNED(scaled_offset, 12)) {
-        // lhu rd, offset(rs)
-        asm_rv32_opcode_lhu(state, rd, rs, scaled_offset);
-        return;
-    }
-
-    mp_uint_t upper = 0;
-    mp_uint_t lower = 0;
-    split_immediate(scaled_offset, &upper, &lower);
-
-    // lui   rd, HI(offset) ; Or c.lui if possible
-    // c.add rd, rs
-    // lhu   rd, LO(offset)(rd)
-    load_upper_immediate(state, rd, upper);
-    asm_rv32_opcode_cadd(state, rd, rs);
-    asm_rv32_opcode_lhu(state, rd, rd, lower);
-}
-
 void asm_rv32_emit_optimised_xor(asm_rv32_t *state, mp_uint_t rd, mp_uint_t rs) {
     if (rs == rd) {
         // c.li rd, 0
@@ -562,14 +557,39 @@ void asm_rv32_emit_optimised_xor(asm_rv32_t *state, mp_uint_t rd, mp_uint_t rs)
     asm_rv32_opcode_xor(state, rd, rd, rs);
 }
 
+static bool asm_rv32_allow_zba_opcodes(void) {
+    return asm_rv32_allowed_extensions() & RV32_EXT_ZBA;
+}
+
+static void asm_rv32_fix_up_scaled_reg_reg_reg(asm_rv32_t *state, mp_uint_t rs1, mp_uint_t rs2, mp_uint_t operation_size) {
+    assert(operation_size <= 2 && "Operation size value out of range.");
+
+    if (operation_size > 0 && asm_rv32_allow_zba_opcodes()) {
+        // sh{1,2}add rs1, rs2, rs1
+        asm_rv32_emit_word_opcode(state, RV32_ENCODE_TYPE_R(0x33, 1 << operation_size, 0x10, rs1, rs2, rs1));
+    } else {
+        if (operation_size > 0) {
+            asm_rv32_opcode_cslli(state, rs2, operation_size);
+        }
+        asm_rv32_opcode_cadd(state, rs1, rs2);
+    }
+}
+
+void asm_rv32_emit_load_reg_reg_reg(asm_rv32_t *state, mp_uint_t rd, mp_uint_t rs1, mp_uint_t rs2, mp_uint_t operation_size) {
+    asm_rv32_fix_up_scaled_reg_reg_reg(state, rs1, rs2, operation_size);
+    asm_rv32_emit_load_reg_reg_offset(state, rd, rs1, 0, operation_size);
+}
+
+void asm_rv32_emit_store_reg_reg_reg(asm_rv32_t *state, mp_uint_t rd, mp_uint_t rs1, mp_uint_t rs2, mp_uint_t operation_size) {
+    asm_rv32_fix_up_scaled_reg_reg_reg(state, rs1, rs2, operation_size);
+    asm_rv32_emit_store_reg_reg_offset(state, rd, rs1, 0, operation_size);
+}
+
 void asm_rv32_meta_comparison_eq(asm_rv32_t *state, mp_uint_t rs1, mp_uint_t rs2, mp_uint_t rd) {
-    // c.li rd, 1       ;
-    // beq  rs1, rs2, 6 ; PC + 0
-    // c.li rd, 0       ; PC + 4
-    // ...              ; PC + 6
-    asm_rv32_opcode_cli(state, rd, 1);
-    asm_rv32_opcode_beq(state, rs1, rs2, 6);
-    asm_rv32_opcode_cli(state, rd, 0);
+    // sub   rd, rs1, rs2
+    // sltiu rd, rd, 1
+    asm_rv32_opcode_sub(state, rd, rs1, rs2);
+    asm_rv32_opcode_sltiu(state, rd, rd, 1);
 }
 
 void asm_rv32_meta_comparison_ne(asm_rv32_t *state, mp_uint_t rs1, mp_uint_t rs2, mp_uint_t rd) {
@@ -580,26 +600,15 @@ void asm_rv32_meta_comparison_ne(asm_rv32_t *state, mp_uint_t rs1, mp_uint_t rs2
 }
 
 void asm_rv32_meta_comparison_lt(asm_rv32_t *state, mp_uint_t rs1, mp_uint_t rs2, mp_uint_t rd, bool unsigned_comparison) {
-    // slt(u) rd, rs1, rs2
-    if (unsigned_comparison) {
-        asm_rv32_opcode_sltu(state, rd, rs1, rs2);
-    } else {
-        asm_rv32_opcode_slt(state, rd, rs1, rs2);
-    }
+    // slt|sltu rd, rs1, rs2
+    asm_rv32_emit_word_opcode(state, RV32_ENCODE_TYPE_R(0x33, (0x02 | (unsigned_comparison ? 1 : 0)), 0x00, rd, rs1, rs2));
 }
 
 void asm_rv32_meta_comparison_le(asm_rv32_t *state, mp_uint_t rs1, mp_uint_t rs2, mp_uint_t rd, bool unsigned_comparison) {
-    // c.li   rd, 1        ;
-    // beq    rs1, rs2, 8  ; PC + 0
-    // slt(u) rd, rs1, rs2 ; PC + 4
-    // ...                 ; PC + 8
-    asm_rv32_opcode_cli(state, rd, 1);
-    asm_rv32_opcode_beq(state, rs1, rs2, 8);
-    if (unsigned_comparison) {
-        asm_rv32_opcode_sltu(state, rd, rs1, rs2);
-    } else {
-        asm_rv32_opcode_slt(state, rd, rs1, rs2);
-    }
+    // slt[u] rd, rs2, rs1
+    // xori   rd, rd, 1
+    asm_rv32_meta_comparison_lt(state, rs2, rs1, rd, unsigned_comparison);
+    asm_rv32_opcode_xori(state, rd, rd, 1);
 }
 
 #endif // MICROPY_EMIT_RV32
diff --git a/py/asmrv32.h b/py/asmrv32.h
index b09f48eb12f66..6f709daa11bce 100644
--- a/py/asmrv32.h
+++ b/py/asmrv32.h
@@ -122,6 +122,18 @@ typedef struct _asm_rv32_t {
     mp_uint_t locals_stack_offset;
 } asm_rv32_t;
 
+enum {
+    RV32_EXT_NONE = 0,
+    RV32_EXT_ZBA = 1 << 0,
+
+    RV32_EXT_ALL = RV32_EXT_ZBA
+};
+
+typedef struct _asm_rv32_backend_options_t {
+    // This is a bitmask holding a combination of RV32_EXT_* entries.
+    uint8_t allowed_extensions;
+} asm_rv32_backend_options_t;
+
 void asm_rv32_entry(asm_rv32_t *state, mp_uint_t locals);
 void asm_rv32_exit(asm_rv32_t *state);
 void asm_rv32_end_pass(asm_rv32_t *state);
@@ -583,6 +595,24 @@ static inline void asm_rv32_opcode_remu(asm_rv32_t *state, mp_uint_t rd, mp_uint
     asm_rv32_emit_word_opcode(state, RV32_ENCODE_TYPE_R(0x33, 0x07, 0x01, rd, rs1, rs2));
 }
 
+// SH1ADD RD, RS1, RS2
+static inline void asm_rv32_opcode_sh1add(asm_rv32_t *state, mp_uint_t rd, mp_uint_t rs1, mp_uint_t rs2) {
+    // R: 0010000 ..... ..... 010 ..... 0110011
+    asm_rv32_emit_word_opcode(state, RV32_ENCODE_TYPE_R(0x33, 0x02, 0x10, rd, rs1, rs2));
+}
+
+// SH2ADD RD, RS1, RS2
+static inline void asm_rv32_opcode_sh2add(asm_rv32_t *state, mp_uint_t rd, mp_uint_t rs1, mp_uint_t rs2) {
+    // R: 0010000 ..... ..... 100 ..... 0110011
+    asm_rv32_emit_word_opcode(state, RV32_ENCODE_TYPE_R(0x33, 0x04, 0x10, rd, rs1, rs2));
+}
+
+// SH3ADD RD, RS1, RS2
+static inline void asm_rv32_opcode_sh3add(asm_rv32_t *state, mp_uint_t rd, mp_uint_t rs1, mp_uint_t rs2) {
+    // R: 0010000 ..... ..... 110 ..... 0110011
+    asm_rv32_emit_word_opcode(state, RV32_ENCODE_TYPE_R(0x33, 0x06, 0x10, rd, rs1, rs2));
+}
+
 // SLL RD, RS1, RS2
 static inline void asm_rv32_opcode_sll(asm_rv32_t *state, mp_uint_t rd, mp_uint_t rs1, mp_uint_t rs2) {
     // R: 0000000 ..... ..... 001 ..... 0110011
@@ -679,6 +709,19 @@ static inline void asm_rv32_opcode_xori(asm_rv32_t *state, mp_uint_t rd, mp_uint
     asm_rv32_emit_word_opcode(state, RV32_ENCODE_TYPE_I(0x13, 0x04, rd, rs, immediate));
 }
 
+#define MICROPY_RV32_EXTENSIONS \
+    (MICROPY_EMIT_RV32_ZBA ? RV32_EXT_ZBA : 0)
+
+static inline uint8_t asm_rv32_allowed_extensions(void) {
+    uint8_t extensions = MICROPY_RV32_EXTENSIONS;
+    #if MICROPY_DYNAMIC_COMPILER
+    if (mp_dynamic_compiler.backend_options != NULL) {
+        extensions |= ((asm_rv32_backend_options_t *)mp_dynamic_compiler.backend_options)->allowed_extensions;
+    }
+    #endif
+    return extensions;
+}
+
 #define ASM_WORD_SIZE (4)
 #define ASM_HALFWORD_SIZE (2)
 
@@ -702,6 +745,8 @@ void asm_rv32_meta_comparison_lt(asm_rv32_t *state, mp_uint_t rs1, mp_uint_t rs2
 void asm_rv32_meta_comparison_le(asm_rv32_t *state, mp_uint_t rs1, mp_uint_t rs2, mp_uint_t rd, bool unsigned_comparison);
 
 void asm_rv32_emit_optimised_load_immediate(asm_rv32_t *state, mp_uint_t rd, mp_int_t immediate);
+void asm_rv32_emit_load_reg_reg_reg(asm_rv32_t *state, mp_uint_t rd, mp_uint_t rs1, mp_uint_t rs2, mp_uint_t operation_size);
+void asm_rv32_emit_store_reg_reg_reg(asm_rv32_t *state, mp_uint_t rd, mp_uint_t rs1, mp_uint_t rs2, mp_uint_t operation_size);
 
 #ifdef GENERIC_ASM_API
 
@@ -709,17 +754,16 @@ void asm_rv32_emit_call_ind(asm_rv32_t *state, mp_uint_t index);
 void asm_rv32_emit_jump(asm_rv32_t *state, mp_uint_t label);
 void asm_rv32_emit_jump_if_reg_eq(asm_rv32_t *state, mp_uint_t rs1, mp_uint_t rs2, mp_uint_t label);
 void asm_rv32_emit_jump_if_reg_nonzero(asm_rv32_t *state, mp_uint_t rs, mp_uint_t label);
-void asm_rv32_emit_load16_reg_reg_offset(asm_rv32_t *state, mp_uint_t rd, mp_uint_t rs, mp_int_t offset);
-void asm_rv32_emit_load_reg_reg_offset(asm_rv32_t *state, mp_uint_t rd, mp_uint_t rs, mp_int_t offset);
+void asm_rv32_emit_load_reg_reg_offset(asm_rv32_t *state, mp_uint_t rd, mp_uint_t rs, int32_t offset, mp_uint_t operation_size);
 void asm_rv32_emit_mov_local_reg(asm_rv32_t *state, mp_uint_t local, mp_uint_t rs);
 void asm_rv32_emit_mov_reg_local_addr(asm_rv32_t *state, mp_uint_t rd, mp_uint_t local);
 void asm_rv32_emit_mov_reg_local(asm_rv32_t *state, mp_uint_t rd, mp_uint_t local);
 void asm_rv32_emit_mov_reg_pcrel(asm_rv32_t *state, mp_uint_t rd, mp_uint_t label);
 void asm_rv32_emit_optimised_xor(asm_rv32_t *state, mp_uint_t rd, mp_uint_t rs);
-void asm_rv32_emit_store_reg_reg_offset(asm_rv32_t *state, mp_uint_t source, mp_uint_t base, mp_int_t offset);
+void asm_rv32_emit_store_reg_reg_offset(asm_rv32_t *state, mp_uint_t source, mp_uint_t base, int32_t offset, mp_uint_t operation_size);
 
 #define ASM_T asm_rv32_t
-#define ASM_ENTRY(state, labels) asm_rv32_entry(state, labels)
+#define ASM_ENTRY(state, labels, name) asm_rv32_entry(state, labels)
 #define ASM_EXIT(state) asm_rv32_exit(state)
 #define ASM_END_PASS(state) asm_rv32_end_pass(state)
 
@@ -732,12 +776,13 @@ void asm_rv32_emit_store_reg_reg_offset(asm_rv32_t *state, mp_uint_t source, mp_
 #define ASM_JUMP_IF_REG_NONZERO(state, rs, label, bool_test) asm_rv32_emit_jump_if_reg_nonzero(state, rs, label)
 #define ASM_JUMP_IF_REG_ZERO(state, rs, label, bool_test) asm_rv32_emit_jump_if_reg_eq(state, rs, ASM_RV32_REG_ZERO, label)
 #define ASM_JUMP_REG(state, rs) asm_rv32_opcode_cjr(state, rs)
-#define ASM_LOAD16_REG_REG_OFFSET(state, rd, rs, offset) asm_rv32_emit_load16_reg_reg_offset(state, rd, rs, offset)
-#define ASM_LOAD16_REG_REG(state, rd, rs) asm_rv32_opcode_lhu(state, rd, rs, 0)
-#define ASM_LOAD32_REG_REG(state, rd, rs) ASM_LOAD_REG_REG_OFFSET(state, rd, rs, 0)
-#define ASM_LOAD8_REG_REG(state, rd, rs) asm_rv32_opcode_lbu(state, rd, rs, 0)
-#define ASM_LOAD_REG_REG_OFFSET(state, rd, rs, offset) asm_rv32_emit_load_reg_reg_offset(state, rd, rs, offset)
-#define ASM_LOAD_REG_REG(state, rd, rs) ASM_LOAD32_REG_REG(state, rd, rs)
+#define ASM_LOAD_REG_REG_OFFSET(state, rd, rs, offset) ASM_LOAD32_REG_REG_OFFSET(state, rd, rs, offset)
+#define ASM_LOAD8_REG_REG(state, rd, rs) ASM_LOAD8_REG_REG_OFFSET(state, rd, rs, 0)
+#define ASM_LOAD16_REG_REG(state, rd, rs) ASM_LOAD16_REG_REG_OFFSET(state, rd, rs, 0)
+#define ASM_LOAD32_REG_REG(state, rd, rs) ASM_LOAD32_REG_REG_OFFSET(state, rd, rs, 0)
+#define ASM_LOAD8_REG_REG_OFFSET(state, rd, rs, offset) asm_rv32_emit_load_reg_reg_offset(state, rd, rs, offset, 0)
+#define ASM_LOAD16_REG_REG_OFFSET(state, rd, rs, offset) asm_rv32_emit_load_reg_reg_offset(state, rd, rs, offset, 1)
+#define ASM_LOAD32_REG_REG_OFFSET(state, rd, rs, offset) asm_rv32_emit_load_reg_reg_offset(state, rd, rs, offset, 2)
 #define ASM_LSL_REG_REG(state, rd, rs) asm_rv32_opcode_sll(state, rd, rd, rs)
 #define ASM_LSR_REG_REG(state, rd, rs) asm_rv32_opcode_srl(state, rd, rd, rs)
 #define ASM_MOV_LOCAL_REG(state, local, rs) asm_rv32_emit_mov_local_reg(state, local, rs)
@@ -750,14 +795,22 @@ void asm_rv32_emit_store_reg_reg_offset(asm_rv32_t *state, mp_uint_t source, mp_
 #define ASM_NEG_REG(state, rd) asm_rv32_opcode_sub(state, rd, ASM_RV32_REG_ZERO, rd)
 #define ASM_NOT_REG(state, rd) asm_rv32_opcode_xori(state, rd, rd, -1)
 #define ASM_OR_REG_REG(state, rd, rs) asm_rv32_opcode_or(state, rd, rd, rs)
-#define ASM_STORE16_REG_REG(state, rs1, rs2) asm_rv32_opcode_sh(state, rs1, rs2, 0)
-#define ASM_STORE32_REG_REG(state, rs1, rs2) ASM_STORE_REG_REG_OFFSET(state, rs1, rs2, 0)
-#define ASM_STORE8_REG_REG(state, rs1, rs2) asm_rv32_opcode_sb(state, rs1, rs2, 0)
-#define ASM_STORE_REG_REG_OFFSET(state, rd, rs, offset) asm_rv32_emit_store_reg_reg_offset(state, rd, rs, offset)
-#define ASM_STORE_REG_REG(state, rs1, rs2) ASM_STORE32_REG_REG(state, rs1, rs2)
+#define ASM_STORE_REG_REG_OFFSET(state, rd, rs, offset) ASM_STORE32_REG_REG_OFFSET(state, rd, rs, offset)
+#define ASM_STORE8_REG_REG(state, rs1, rs2) ASM_STORE8_REG_REG_OFFSET(state, rs1, rs2, 0)
+#define ASM_STORE16_REG_REG(state, rs1, rs2) ASM_STORE16_REG_REG_OFFSET(state, rs1, rs2, 0)
+#define ASM_STORE32_REG_REG(state, rs1, rs2) ASM_STORE32_REG_REG_OFFSET(state, rs1, rs2, 0)
+#define ASM_STORE8_REG_REG_OFFSET(state, rd, rs, offset) asm_rv32_emit_store_reg_reg_offset(state, rd, rs, offset, 0)
+#define ASM_STORE16_REG_REG_OFFSET(state, rd, rs, offset) asm_rv32_emit_store_reg_reg_offset(state, rd, rs, offset, 1)
+#define ASM_STORE32_REG_REG_OFFSET(state, rd, rs, offset) asm_rv32_emit_store_reg_reg_offset(state, rd, rs, offset, 2)
 #define ASM_SUB_REG_REG(state, rd, rs) asm_rv32_opcode_sub(state, rd, rd, rs)
 #define ASM_XOR_REG_REG(state, rd, rs) asm_rv32_emit_optimised_xor(state, rd, rs)
 #define ASM_CLR_REG(state, rd)
+#define ASM_LOAD8_REG_REG_REG(state, rd, rs1, rs2) asm_rv32_emit_load_reg_reg_reg(state, rd, rs1, rs2, 0)
+#define ASM_LOAD16_REG_REG_REG(state, rd, rs1, rs2) asm_rv32_emit_load_reg_reg_reg(state, rd, rs1, rs2, 1)
+#define ASM_LOAD32_REG_REG_REG(state, rd, rs1, rs2) asm_rv32_emit_load_reg_reg_reg(state, rd, rs1, rs2, 2)
+#define ASM_STORE8_REG_REG_REG(state, rd, rs1, rs2) asm_rv32_emit_store_reg_reg_reg(state, rd, rs1, rs2, 0)
+#define ASM_STORE16_REG_REG_REG(state, rd, rs1, rs2) asm_rv32_emit_store_reg_reg_reg(state, rd, rs1, rs2, 1)
+#define ASM_STORE32_REG_REG_REG(state, rd, rs1, rs2) asm_rv32_emit_store_reg_reg_reg(state, rd, rs1, rs2, 2)
 
 #endif
 
diff --git a/py/asmthumb.c b/py/asmthumb.c
index 420815e80269a..58cc7aea88085 100644
--- a/py/asmthumb.c
+++ b/py/asmthumb.c
@@ -37,7 +37,6 @@
 #include "py/asmthumb.h"
 #include "py/misc.h"
 
-#define UNSIGNED_FIT5(x) ((uint32_t)(x) < 32)
 #define UNSIGNED_FIT7(x) ((uint32_t)(x) < 128)
 #define UNSIGNED_FIT8(x) (((x) & 0xffffff00) == 0)
 #define UNSIGNED_FIT16(x) (((x) & 0xffff0000) == 0)
@@ -52,12 +51,6 @@
 #define OP_SUB_W_RRI_HI(reg_src) (0xf2a0 | (reg_src))
 #define OP_SUB_W_RRI_LO(reg_dest, imm11) ((imm11 << 4 & 0x7000) | reg_dest << 8 | (imm11 & 0xff))
 
-#define OP_LDR_W_HI(reg_base) (0xf8d0 | (reg_base))
-#define OP_LDR_W_LO(reg_dest, imm12) ((reg_dest) << 12 | (imm12))
-
-#define OP_LDRH_W_HI(reg_base) (0xf8b0 | (reg_base))
-#define OP_LDRH_W_LO(reg_dest, imm12) ((reg_dest) << 12 | (imm12))
-
 static inline byte *asm_thumb_get_cur_to_write_bytes(asm_thumb_t *as, int n) {
     return mp_asm_base_get_cur_to_write_bytes(&as->base, n);
 }
@@ -274,9 +267,8 @@ bool asm_thumb_b_n_label(asm_thumb_t *as, uint label) {
 
 #define OP_BCC_N(cond, byte_offset) (0xd000 | ((cond) << 8) | (((byte_offset) >> 1) & 0x00ff))
 
-// all these bit-arithmetic operations need coverage testing!
-#define OP_BCC_W_HI(cond, byte_offset) (0xf000 | ((cond) << 6) | (((byte_offset) >> 10) & 0x0400) | (((byte_offset) >> 14) & 0x003f))
-#define OP_BCC_W_LO(byte_offset) (0x8000 | ((byte_offset) & 0x2000) | (((byte_offset) >> 1) & 0x0fff))
+#define OP_BCC_W_HI(cond, byte_offset) (0xf000 | ((cond) << 6) | (((byte_offset) >> 10) & 0x0400) | (((byte_offset) >> 12) & 0x003f))
+#define OP_BCC_W_LO(byte_offset) (0x8000 | (((byte_offset) >> 5) & 0x2000) | (((byte_offset) >> 8) & 0x0800) | (((byte_offset) >> 1) & 0x07ff))
 
 bool asm_thumb_bcc_nw_label(asm_thumb_t *as, int cond, uint label, bool wide) {
     mp_uint_t dest = get_label_dest(as, label);
@@ -432,11 +424,6 @@ void asm_thumb_mov_reg_pcrel(asm_thumb_t *as, uint rlo_dest, uint label) {
     asm_thumb_add_reg_reg(as, rlo_dest, ASM_THUMB_REG_R15); // 2 bytes
 }
 
-// ARMv7-M only
-static inline void asm_thumb_ldr_reg_reg_i12(asm_thumb_t *as, uint reg_dest, uint reg_base, uint word_offset) {
-    asm_thumb_op32(as, OP_LDR_W_HI(reg_base), OP_LDR_W_LO(reg_dest, word_offset * 4));
-}
-
 // emits code for: reg_dest = reg_base + offset << offset_shift
 static void asm_thumb_add_reg_reg_offset(asm_thumb_t *as, uint reg_dest, uint reg_base, uint offset, uint offset_shift) {
     if (reg_dest < ASM_THUMB_REG_R8 && reg_base < ASM_THUMB_REG_R8) {
@@ -450,12 +437,12 @@ static void asm_thumb_add_reg_reg_offset(asm_thumb_t *as, uint reg_dest, uint re
             asm_thumb_lsl_rlo_rlo_i5(as, reg_dest, reg_dest, offset_shift);
             asm_thumb_add_rlo_rlo_rlo(as, reg_dest, reg_dest, reg_base);
         } else if (reg_dest != reg_base) {
-            asm_thumb_mov_rlo_i16(as, reg_dest, offset << offset_shift);
-            asm_thumb_add_rlo_rlo_rlo(as, reg_dest, reg_dest, reg_dest);
+            asm_thumb_mov_reg_i32_optimised(as, reg_dest, offset << offset_shift);
+            asm_thumb_add_rlo_rlo_rlo(as, reg_dest, reg_dest, reg_base);
         } else {
             uint reg_other = reg_dest ^ 7;
             asm_thumb_op16(as, OP_PUSH_RLIST((1 << reg_other)));
-            asm_thumb_mov_rlo_i16(as, reg_other, offset << offset_shift);
+            asm_thumb_mov_reg_i32_optimised(as, reg_other, offset << offset_shift);
             asm_thumb_add_rlo_rlo_rlo(as, reg_dest, reg_dest, reg_other);
             asm_thumb_op16(as, OP_POP_RLIST((1 << reg_other)));
         }
@@ -464,30 +451,50 @@ static void asm_thumb_add_reg_reg_offset(asm_thumb_t *as, uint reg_dest, uint re
     }
 }
 
-void asm_thumb_ldr_reg_reg_i12_optimised(asm_thumb_t *as, uint reg_dest, uint reg_base, uint word_offset) {
-    if (reg_dest < ASM_THUMB_REG_R8 && reg_base < ASM_THUMB_REG_R8 && UNSIGNED_FIT5(word_offset)) {
-        asm_thumb_ldr_rlo_rlo_i5(as, reg_dest, reg_base, word_offset);
-    } else if (asm_thumb_allow_armv7m(as)) {
-        asm_thumb_ldr_reg_reg_i12(as, reg_dest, reg_base, word_offset);
+#define OP_LDR_STR_W_HI(operation_size, reg) ((0xf880 | (operation_size) << 5) | (reg))
+#define OP_LDR_STR_W_LO(reg, imm12) (((reg) << 12) | (imm12))
+
+#define OP_LDR 0x01
+#define OP_STR 0x00
+
+#define OP_LDR_W 0x10
+#define OP_STR_W 0x00
+
+static const uint8_t OP_LDR_STR_TABLE[3] = {
+    0x0E, 0x10, 0x0C
+};
+
+void asm_thumb_load_reg_reg_offset(asm_thumb_t *as, uint reg_dest, uint reg_base, uint offset, uint operation_size) {
+    assert(operation_size <= 2 && "Operation size out of range.");
+
+    if (MP_FIT_UNSIGNED(5, offset) && (reg_dest < ASM_THUMB_REG_R8) && (reg_base < ASM_THUMB_REG_R8)) {
+        // Can use T1 encoding
+        asm_thumb_op16(as, ((OP_LDR_STR_TABLE[operation_size] | OP_LDR) << 11) | (offset << 6) | (reg_base << 3) | reg_dest);
+    } else if (asm_thumb_allow_armv7m(as) && MP_FIT_UNSIGNED(12, offset << operation_size)) {
+        // Can use T3 encoding
+        asm_thumb_op32(as, (OP_LDR_STR_W_HI(operation_size, reg_base) | OP_LDR_W), OP_LDR_STR_W_LO(reg_dest, (offset << operation_size)));
     } else {
-        asm_thumb_add_reg_reg_offset(as, reg_dest, reg_base, word_offset - 31, 2);
-        asm_thumb_ldr_rlo_rlo_i5(as, reg_dest, reg_dest, 31);
+        // Must use the generic sequence
+        asm_thumb_add_reg_reg_offset(as, reg_dest, reg_base, offset - 31, operation_size);
+        asm_thumb_op16(as, ((OP_LDR_STR_TABLE[operation_size] | OP_LDR) << 11) | (31 << 6) | (reg_dest << 3) | (reg_dest));
     }
 }
 
-// ARMv7-M only
-static inline void asm_thumb_ldrh_reg_reg_i12(asm_thumb_t *as, uint reg_dest, uint reg_base, uint uint16_offset) {
-    asm_thumb_op32(as, OP_LDRH_W_HI(reg_base), OP_LDRH_W_LO(reg_dest, uint16_offset * 2));
-}
+void asm_thumb_store_reg_reg_offset(asm_thumb_t *as, uint reg_src, uint reg_base, uint offset, uint operation_size) {
+    assert(operation_size <= 2 && "Operation size out of range.");
 
-void asm_thumb_ldrh_reg_reg_i12_optimised(asm_thumb_t *as, uint reg_dest, uint reg_base, uint uint16_offset) {
-    if (reg_dest < ASM_THUMB_REG_R8 && reg_base < ASM_THUMB_REG_R8 && UNSIGNED_FIT5(uint16_offset)) {
-        asm_thumb_ldrh_rlo_rlo_i5(as, reg_dest, reg_base, uint16_offset);
-    } else if (asm_thumb_allow_armv7m(as)) {
-        asm_thumb_ldrh_reg_reg_i12(as, reg_dest, reg_base, uint16_offset);
+    if (MP_FIT_UNSIGNED(5, offset) && (reg_src < ASM_THUMB_REG_R8) && (reg_base < ASM_THUMB_REG_R8)) {
+        // Can use T1 encoding
+        asm_thumb_op16(as, ((OP_LDR_STR_TABLE[operation_size] | OP_STR) << 11) | (offset << 6) | (reg_base << 3) | reg_src);
+    } else if (asm_thumb_allow_armv7m(as) && MP_FIT_UNSIGNED(12, offset << operation_size)) {
+        // Can use T3 encoding
+        asm_thumb_op32(as, (OP_LDR_STR_W_HI(operation_size, reg_base) | OP_STR_W), OP_LDR_STR_W_LO(reg_src, (offset << operation_size)));
     } else {
-        asm_thumb_add_reg_reg_offset(as, reg_dest, reg_base, uint16_offset - 31, 1);
-        asm_thumb_ldrh_rlo_rlo_i5(as, reg_dest, reg_dest, 31);
+        // Must use the generic sequence
+        asm_thumb_op16(as, OP_PUSH_RLIST(1 << reg_base));
+        asm_thumb_add_reg_reg_offset(as, reg_base, reg_base, offset - 31, operation_size);
+        asm_thumb_op16(as, ((OP_LDR_STR_TABLE[operation_size] | OP_STR) << 11) | (31 << 6) | (reg_base << 3) | reg_src);
+        asm_thumb_op16(as, OP_POP_RLIST(1 << reg_base));
     }
 }
 
@@ -495,6 +502,7 @@ void asm_thumb_ldrh_reg_reg_i12_optimised(asm_thumb_t *as, uint reg_dest, uint r
 #define OP_BW_HI(byte_offset) (0xf000 | (((byte_offset) >> 12) & 0x07ff))
 #define OP_BW_LO(byte_offset) (0xb800 | (((byte_offset) >> 1) & 0x07ff))
 
+// In Thumb1 mode, this may clobber r1.
 void asm_thumb_b_label(asm_thumb_t *as, uint label) {
     mp_uint_t dest = get_label_dest(as, label);
     mp_int_t rel = dest - as->base.code_offset;
@@ -514,19 +522,40 @@ void asm_thumb_b_label(asm_thumb_t *as, uint label) {
     if (asm_thumb_allow_armv7m(as)) {
         asm_thumb_op32(as, OP_BW_HI(rel), OP_BW_LO(rel));
     } else {
+        // this code path has to be the same instruction size irrespective of the value of rel
+        bool need_align = as->base.code_offset & 2u;
         if (SIGNED_FIT12(rel)) {
-            // this code path has to be the same number of instructions irrespective of rel
             asm_thumb_op16(as, OP_B_N(rel));
-        } else {
             asm_thumb_op16(as, ASM_THUMB_OP_NOP);
-            if (dest != (mp_uint_t)-1) {
-                // we have an actual branch > 12 bits; this is not handled yet
-                mp_raise_NotImplementedError(MP_ERROR_TEXT("native method too big"));
+            asm_thumb_op16(as, ASM_THUMB_OP_NOP);
+            asm_thumb_op16(as, ASM_THUMB_OP_NOP);
+            if (need_align) {
+                asm_thumb_op16(as, ASM_THUMB_OP_NOP);
+            }
+        } else {
+            // do a large jump using:
+            //     (nop)
+            //     ldr r1, [pc, _data]
+            //     add pc, r1
+            // _data: .word rel
+            //
+            // note: can't use r0 as a temporary because native code can have the return value
+            // in that register and use a large jump to get to the exit point of the function
+
+            rel -= 2; // account for the "ldr r1, [pc, _data]"
+            if (need_align) {
+                asm_thumb_op16(as, ASM_THUMB_OP_NOP);
+                rel -= 2; // account for this nop
             }
+            asm_thumb_ldr_rlo_pcrel_i8(as, ASM_THUMB_REG_R1, 0);
+            asm_thumb_add_reg_reg(as, ASM_THUMB_REG_R15, ASM_THUMB_REG_R1);
+            asm_thumb_op16(as, rel & 0xffff);
+            asm_thumb_op16(as, rel >> 16);
         }
     }
 }
 
+// In Thumb1 mode, this may clobber r1.
 void asm_thumb_bcc_label(asm_thumb_t *as, int cond, uint label) {
     mp_uint_t dest = get_label_dest(as, label);
     mp_int_t rel = dest - as->base.code_offset;
@@ -547,8 +576,15 @@ void asm_thumb_bcc_label(asm_thumb_t *as, int cond, uint label) {
         asm_thumb_op32(as, OP_BCC_W_HI(cond, rel), OP_BCC_W_LO(rel));
     } else {
         // reverse the sense of the branch to jump over a longer branch
-        asm_thumb_op16(as, OP_BCC_N(cond ^ 1, 0));
+        size_t code_offset_start = as->base.code_offset;
+        byte *c = asm_thumb_get_cur_to_write_bytes(as, 2);
         asm_thumb_b_label(as, label);
+        size_t bytes_to_skip = as->base.code_offset - code_offset_start;
+        uint16_t op = OP_BCC_N(cond ^ 1, bytes_to_skip - 4);
+        if (c != NULL) {
+            c[0] = op;
+            c[1] = op >> 8;
+        }
     }
 }
 
@@ -569,7 +605,7 @@ void asm_thumb_b_rel12(asm_thumb_t *as, int rel) {
 
 void asm_thumb_bl_ind(asm_thumb_t *as, uint fun_id, uint reg_temp) {
     // Load ptr to function from table, indexed by fun_id, then call it
-    asm_thumb_ldr_reg_reg_i12_optimised(as, reg_temp, ASM_THUMB_REG_FUN_TABLE, fun_id);
+    asm_thumb_load_reg_reg_offset(as, reg_temp, ASM_THUMB_REG_FUN_TABLE, fun_id, 2);
     asm_thumb_op16(as, OP_BLX(reg_temp));
 }
 
diff --git a/py/asmthumb.h b/py/asmthumb.h
index 0584ed3227aad..cb786694f0b78 100644
--- a/py/asmthumb.h
+++ b/py/asmthumb.h
@@ -251,6 +251,50 @@ static inline void asm_thumb_bx_reg(asm_thumb_t *as, uint r_src) {
     asm_thumb_format_5(as, ASM_THUMB_FORMAT_5_BX, 0, r_src);
 }
 
+// FORMAT 7: load/store with register offset
+// FORMAT 8: load/store sign-extended byte/halfword
+
+#define ASM_THUMB_FORMAT_7_LDR (0x5800)
+#define ASM_THUMB_FORMAT_7_STR (0x5000)
+#define ASM_THUMB_FORMAT_7_WORD_TRANSFER (0x0000)
+#define ASM_THUMB_FORMAT_7_BYTE_TRANSFER (0x0400)
+#define ASM_THUMB_FORMAT_8_LDRH (0x5A00)
+#define ASM_THUMB_FORMAT_8_STRH (0x5200)
+
+#define ASM_THUMB_FORMAT_7_8_ENCODE(op, rlo_dest, rlo_base, rlo_index) \
+    ((op) | ((rlo_index) << 6) | ((rlo_base) << 3) | ((rlo_dest)))
+
+static inline void asm_thumb_format_7_8(asm_thumb_t *as, uint op, uint rlo_dest, uint rlo_base, uint rlo_index) {
+    assert(rlo_dest < ASM_THUMB_REG_R8);
+    assert(rlo_base < ASM_THUMB_REG_R8);
+    assert(rlo_index < ASM_THUMB_REG_R8);
+    asm_thumb_op16(as, ASM_THUMB_FORMAT_7_8_ENCODE(op, rlo_dest, rlo_base, rlo_index));
+}
+
+static inline void asm_thumb_ldrb_rlo_rlo_rlo(asm_thumb_t *as, uint rlo_dest, uint rlo_base, uint rlo_index) {
+    asm_thumb_format_7_8(as, ASM_THUMB_FORMAT_7_LDR | ASM_THUMB_FORMAT_7_BYTE_TRANSFER, rlo_dest, rlo_base, rlo_index);
+}
+
+static inline void asm_thumb_ldrh_rlo_rlo_rlo(asm_thumb_t *as, uint rlo_dest, uint rlo_base, uint rlo_index) {
+    asm_thumb_format_7_8(as, ASM_THUMB_FORMAT_8_LDRH, rlo_dest, rlo_base, rlo_index);
+}
+
+static inline void asm_thumb_ldr_rlo_rlo_rlo(asm_thumb_t *as, uint rlo_dest, uint rlo_base, uint rlo_index) {
+    asm_thumb_format_7_8(as, ASM_THUMB_FORMAT_7_LDR | ASM_THUMB_FORMAT_7_WORD_TRANSFER, rlo_dest, rlo_base, rlo_index);
+}
+
+static inline void asm_thumb_strb_rlo_rlo_rlo(asm_thumb_t *as, uint rlo_src, uint rlo_base, uint rlo_index) {
+    asm_thumb_format_7_8(as, ASM_THUMB_FORMAT_7_STR | ASM_THUMB_FORMAT_7_BYTE_TRANSFER, rlo_src, rlo_base, rlo_index);
+}
+
+static inline void asm_thumb_strh_rlo_rlo_rlo(asm_thumb_t *as, uint rlo_dest, uint rlo_base, uint rlo_index) {
+    asm_thumb_format_7_8(as, ASM_THUMB_FORMAT_8_STRH, rlo_dest, rlo_base, rlo_index);
+}
+
+static inline void asm_thumb_str_rlo_rlo_rlo(asm_thumb_t *as, uint rlo_src, uint rlo_base, uint rlo_index) {
+    asm_thumb_format_7_8(as, ASM_THUMB_FORMAT_7_STR | ASM_THUMB_FORMAT_7_WORD_TRANSFER, rlo_src, rlo_base, rlo_index);
+}
+
 // FORMAT 9: load/store with immediate offset
 // For word transfers the offset must be aligned, and >>2
 
@@ -273,24 +317,6 @@ static inline void asm_thumb_format_9_10(asm_thumb_t *as, uint op, uint rlo_dest
     asm_thumb_op16(as, ASM_THUMB_FORMAT_9_10_ENCODE(op, rlo_dest, rlo_base, offset));
 }
 
-static inline void asm_thumb_str_rlo_rlo_i5(asm_thumb_t *as, uint rlo_src, uint rlo_base, uint word_offset) {
-    asm_thumb_format_9_10(as, ASM_THUMB_FORMAT_9_STR | ASM_THUMB_FORMAT_9_WORD_TRANSFER, rlo_src, rlo_base, word_offset);
-}
-static inline void asm_thumb_strb_rlo_rlo_i5(asm_thumb_t *as, uint rlo_src, uint rlo_base, uint byte_offset) {
-    asm_thumb_format_9_10(as, ASM_THUMB_FORMAT_9_STR | ASM_THUMB_FORMAT_9_BYTE_TRANSFER, rlo_src, rlo_base, byte_offset);
-}
-static inline void asm_thumb_strh_rlo_rlo_i5(asm_thumb_t *as, uint rlo_src, uint rlo_base, uint uint16_offset) {
-    asm_thumb_format_9_10(as, ASM_THUMB_FORMAT_10_STRH, rlo_src, rlo_base, uint16_offset);
-}
-static inline void asm_thumb_ldr_rlo_rlo_i5(asm_thumb_t *as, uint rlo_dest, uint rlo_base, uint word_offset) {
-    asm_thumb_format_9_10(as, ASM_THUMB_FORMAT_9_LDR | ASM_THUMB_FORMAT_9_WORD_TRANSFER, rlo_dest, rlo_base, word_offset);
-}
-static inline void asm_thumb_ldrb_rlo_rlo_i5(asm_thumb_t *as, uint rlo_dest, uint rlo_base, uint byte_offset) {
-    asm_thumb_format_9_10(as, ASM_THUMB_FORMAT_9_LDR | ASM_THUMB_FORMAT_9_BYTE_TRANSFER, rlo_dest, rlo_base, byte_offset);
-}
-static inline void asm_thumb_ldrh_rlo_rlo_i5(asm_thumb_t *as, uint rlo_dest, uint rlo_base, uint uint16_offset) {
-    asm_thumb_format_9_10(as, ASM_THUMB_FORMAT_10_LDRH, rlo_dest, rlo_base, uint16_offset);
-}
 static inline void asm_thumb_lsl_rlo_rlo_i5(asm_thumb_t *as, uint rlo_dest, uint rlo_src, uint shift) {
     asm_thumb_format_1(as, ASM_THUMB_FORMAT_1_LSL, rlo_dest, rlo_src, shift);
 }
@@ -338,8 +364,10 @@ void asm_thumb_mov_reg_local(asm_thumb_t *as, uint rlo_dest, int local_num); //
 void asm_thumb_mov_reg_local_addr(asm_thumb_t *as, uint rlo_dest, int local_num); // convenience
 void asm_thumb_mov_reg_pcrel(asm_thumb_t *as, uint rlo_dest, uint label);
 
-void asm_thumb_ldr_reg_reg_i12_optimised(asm_thumb_t *as, uint reg_dest, uint reg_base, uint word_offset); // convenience
-void asm_thumb_ldrh_reg_reg_i12_optimised(asm_thumb_t *as, uint reg_dest, uint reg_base, uint uint16_offset); // convenience
+// Generate optimised load dest, [src, #offset] sequence
+void asm_thumb_load_reg_reg_offset(asm_thumb_t *as, uint reg_dest, uint reg_base, uint offset, uint operation_size);
+// Generate optimised store src, [dest, #offset] sequence
+void asm_thumb_store_reg_reg_offset(asm_thumb_t *as, uint reg_src, uint reg_base, uint offset, uint operation_size);
 
 void asm_thumb_b_label(asm_thumb_t *as, uint label); // convenience: picks narrow or wide branch
 void asm_thumb_bcc_label(asm_thumb_t *as, int cc, uint label); // convenience: picks narrow or wide branch
@@ -376,12 +404,12 @@ void asm_thumb_b_rel12(asm_thumb_t *as, int rel);
 
 #define REG_FUN_TABLE ASM_THUMB_REG_FUN_TABLE
 
-#define ASM_T               asm_thumb_t
-#define ASM_END_PASS        asm_thumb_end_pass
-#define ASM_ENTRY           asm_thumb_entry
-#define ASM_EXIT            asm_thumb_exit
+#define ASM_T                           asm_thumb_t
+#define ASM_END_PASS                    asm_thumb_end_pass
+#define ASM_ENTRY(as, num_locals, name) asm_thumb_entry((as), (num_locals))
+#define ASM_EXIT                        asm_thumb_exit
 
-#define ASM_JUMP            asm_thumb_b_label
+#define ASM_JUMP                        asm_thumb_b_label
 #define ASM_JUMP_IF_REG_ZERO(as, reg, label, bool_test) \
     do { \
         asm_thumb_cmp_rlo_i8(as, reg, 0); \
@@ -419,18 +447,44 @@ void asm_thumb_b_rel12(asm_thumb_t *as, int rel);
 #define ASM_SUB_REG_REG(as, reg_dest, reg_src) asm_thumb_sub_rlo_rlo_rlo((as), (reg_dest), (reg_dest), (reg_src))
 #define ASM_MUL_REG_REG(as, reg_dest, reg_src) asm_thumb_format_4((as), ASM_THUMB_FORMAT_4_MUL, (reg_dest), (reg_src))
 
-#define ASM_LOAD_REG_REG(as, reg_dest, reg_base) asm_thumb_ldr_rlo_rlo_i5((as), (reg_dest), (reg_base), 0)
-#define ASM_LOAD_REG_REG_OFFSET(as, reg_dest, reg_base, word_offset) asm_thumb_ldr_reg_reg_i12_optimised((as), (reg_dest), (reg_base), (word_offset))
-#define ASM_LOAD8_REG_REG(as, reg_dest, reg_base) asm_thumb_ldrb_rlo_rlo_i5((as), (reg_dest), (reg_base), 0)
-#define ASM_LOAD16_REG_REG(as, reg_dest, reg_base) asm_thumb_ldrh_rlo_rlo_i5((as), (reg_dest), (reg_base), 0)
-#define ASM_LOAD16_REG_REG_OFFSET(as, reg_dest, reg_base, uint16_offset) asm_thumb_ldrh_reg_reg_i12_optimised((as), (reg_dest), (reg_base), (uint16_offset))
-#define ASM_LOAD32_REG_REG(as, reg_dest, reg_base) asm_thumb_ldr_rlo_rlo_i5((as), (reg_dest), (reg_base), 0)
-
-#define ASM_STORE_REG_REG(as, reg_src, reg_base) asm_thumb_str_rlo_rlo_i5((as), (reg_src), (reg_base), 0)
-#define ASM_STORE_REG_REG_OFFSET(as, reg_src, reg_base, word_offset) asm_thumb_str_rlo_rlo_i5((as), (reg_src), (reg_base), (word_offset))
-#define ASM_STORE8_REG_REG(as, reg_src, reg_base) asm_thumb_strb_rlo_rlo_i5((as), (reg_src), (reg_base), 0)
-#define ASM_STORE16_REG_REG(as, reg_src, reg_base) asm_thumb_strh_rlo_rlo_i5((as), (reg_src), (reg_base), 0)
-#define ASM_STORE32_REG_REG(as, reg_src, reg_base) asm_thumb_str_rlo_rlo_i5((as), (reg_src), (reg_base), 0)
+#define ASM_LOAD_REG_REG_OFFSET(as, reg_dest, reg_base, word_offset) ASM_LOAD32_REG_REG_OFFSET((as), (reg_dest), (reg_base), (word_offset))
+#define ASM_LOAD8_REG_REG(as, reg_dest, reg_base) ASM_LOAD8_REG_REG_OFFSET((as), (reg_dest), (reg_base), 0)
+#define ASM_LOAD8_REG_REG_OFFSET(as, reg_dest, reg_base, byte_offset) asm_thumb_load_reg_reg_offset((as), (reg_dest), (reg_base), (byte_offset), 0)
+#define ASM_LOAD16_REG_REG(as, reg_dest, reg_base) ASM_LOAD16_REG_REG_OFFSET((as), (reg_dest), (reg_base), 0)
+#define ASM_LOAD16_REG_REG_OFFSET(as, reg_dest, reg_base, halfword_offset) asm_thumb_load_reg_reg_offset((as), (reg_dest), (reg_base), (halfword_offset), 1)
+#define ASM_LOAD32_REG_REG(as, reg_dest, reg_base) ASM_LOAD32_REG_REG_OFFSET((as), (reg_dest), (reg_base), 0)
+#define ASM_LOAD32_REG_REG_OFFSET(as, reg_dest, reg_base, word_offset) asm_thumb_load_reg_reg_offset((as), (reg_dest), (reg_base), (word_offset), 2)
+
+#define ASM_STORE_REG_REG_OFFSET(as, reg_src, reg_base, word_offset) ASM_STORE32_REG_REG_OFFSET((as), (reg_src), (reg_base), (word_offset))
+#define ASM_STORE8_REG_REG(as, reg_src, reg_base) ASM_STORE8_REG_REG_OFFSET((as), (reg_src), (reg_base), 0)
+#define ASM_STORE8_REG_REG_OFFSET(as, reg_src, reg_base, byte_offset) asm_thumb_store_reg_reg_offset((as), (reg_src), (reg_base), (byte_offset), 0)
+#define ASM_STORE16_REG_REG(as, reg_src, reg_base) ASM_STORE16_REG_REG_OFFSET((as), (reg_src), (reg_base), 0)
+#define ASM_STORE16_REG_REG_OFFSET(as, reg_src, reg_base, halfword_offset) asm_thumb_store_reg_reg_offset((as), (reg_src), (reg_base), (halfword_offset), 1)
+#define ASM_STORE32_REG_REG(as, reg_src, reg_base) ASM_STORE32_REG_REG_OFFSET((as), (reg_src), (reg_base), 0)
+#define ASM_STORE32_REG_REG_OFFSET(as, reg_src, reg_base, word_offset) asm_thumb_store_reg_reg_offset((as), (reg_src), (reg_base), (word_offset), 2)
+
+#define ASM_LOAD8_REG_REG_REG(as, reg_dest, reg_base, reg_index) asm_thumb_ldrb_rlo_rlo_rlo((as), (reg_dest), (reg_base), (reg_index))
+#define ASM_LOAD16_REG_REG_REG(as, reg_dest, reg_base, reg_index) \
+    do { \
+        asm_thumb_lsl_rlo_rlo_i5((as), (reg_index), (reg_index), 1); \
+        asm_thumb_ldrh_rlo_rlo_rlo((as), (reg_dest), (reg_base), (reg_index)); \
+    } while (0)
+#define ASM_LOAD32_REG_REG_REG(as, reg_dest, reg_base, reg_index) \
+    do { \
+        asm_thumb_lsl_rlo_rlo_i5((as), (reg_index), (reg_index), 2); \
+        asm_thumb_ldr_rlo_rlo_rlo((as), (reg_dest), (reg_base), (reg_index)); \
+    } while (0)
+#define ASM_STORE8_REG_REG_REG(as, reg_val, reg_base, reg_index) asm_thumb_strb_rlo_rlo_rlo((as), (reg_val), (reg_base), (reg_index))
+#define ASM_STORE16_REG_REG_REG(as, reg_val, reg_base, reg_index) \
+    do { \
+        asm_thumb_lsl_rlo_rlo_i5((as), (reg_index), (reg_index), 1); \
+        asm_thumb_strh_rlo_rlo_rlo((as), (reg_val), (reg_base), (reg_index)); \
+    } while (0)
+#define ASM_STORE32_REG_REG_REG(as, reg_val, reg_base, reg_index) \
+    do { \
+        asm_thumb_lsl_rlo_rlo_i5((as), (reg_index), (reg_index), 2); \
+        asm_thumb_str_rlo_rlo_rlo((as), (reg_val), (reg_base), (reg_index)); \
+    } while (0)
 
 #endif // GENERIC_ASM_API
 
diff --git a/py/asmx64.h b/py/asmx64.h
index 03070b5f63d3b..1e8cb0c905f2b 100644
--- a/py/asmx64.h
+++ b/py/asmx64.h
@@ -155,12 +155,12 @@ void asm_x64_call_ind(asm_x64_t *as, size_t fun_id, int temp_r32);
 // Holds a pointer to mp_fun_table
 #define REG_FUN_TABLE ASM_X64_REG_FUN_TABLE
 
-#define ASM_T               asm_x64_t
-#define ASM_END_PASS        asm_x64_end_pass
-#define ASM_ENTRY           asm_x64_entry
-#define ASM_EXIT            asm_x64_exit
+#define ASM_T                           asm_x64_t
+#define ASM_END_PASS                    asm_x64_end_pass
+#define ASM_ENTRY(as, num_locals, name) asm_x64_entry((as), (num_locals))
+#define ASM_EXIT                        asm_x64_exit
 
-#define ASM_JUMP            asm_x64_jmp_label
+#define ASM_JUMP                        asm_x64_jmp_label
 #define ASM_JUMP_IF_REG_ZERO(as, reg, label, bool_test) \
     do { \
         if (bool_test) { \
@@ -206,18 +206,21 @@ void asm_x64_call_ind(asm_x64_t *as, size_t fun_id, int temp_r32);
 #define ASM_SUB_REG_REG(as, reg_dest, reg_src) asm_x64_sub_r64_r64((as), (reg_dest), (reg_src))
 #define ASM_MUL_REG_REG(as, reg_dest, reg_src) asm_x64_mul_r64_r64((as), (reg_dest), (reg_src))
 
-#define ASM_LOAD_REG_REG(as, reg_dest, reg_base) asm_x64_mov_mem64_to_r64((as), (reg_base), 0, (reg_dest))
-#define ASM_LOAD_REG_REG_OFFSET(as, reg_dest, reg_base, word_offset) asm_x64_mov_mem64_to_r64((as), (reg_base), 8 * (word_offset), (reg_dest))
-#define ASM_LOAD8_REG_REG(as, reg_dest, reg_base) asm_x64_mov_mem8_to_r64zx((as), (reg_base), 0, (reg_dest))
-#define ASM_LOAD16_REG_REG(as, reg_dest, reg_base) asm_x64_mov_mem16_to_r64zx((as), (reg_base), 0, (reg_dest))
-#define ASM_LOAD16_REG_REG_OFFSET(as, reg_dest, reg_base, uint16_offset) asm_x64_mov_mem16_to_r64zx((as), (reg_base), 2 * (uint16_offset), (reg_dest))
-#define ASM_LOAD32_REG_REG(as, reg_dest, reg_base) asm_x64_mov_mem32_to_r64zx((as), (reg_base), 0, (reg_dest))
-
-#define ASM_STORE_REG_REG(as, reg_src, reg_base) asm_x64_mov_r64_to_mem64((as), (reg_src), (reg_base), 0)
-#define ASM_STORE_REG_REG_OFFSET(as, reg_src, reg_base, word_offset) asm_x64_mov_r64_to_mem64((as), (reg_src), (reg_base), 8 * (word_offset))
-#define ASM_STORE8_REG_REG(as, reg_src, reg_base) asm_x64_mov_r8_to_mem8((as), (reg_src), (reg_base), 0)
-#define ASM_STORE16_REG_REG(as, reg_src, reg_base) asm_x64_mov_r16_to_mem16((as), (reg_src), (reg_base), 0)
-#define ASM_STORE32_REG_REG(as, reg_src, reg_base) asm_x64_mov_r32_to_mem32((as), (reg_src), (reg_base), 0)
+#define ASM_LOAD_REG_REG_OFFSET(as, reg_dest, reg_base, qword_offset) asm_x64_mov_mem64_to_r64((as), (reg_base), 8 * (qword_offset), (reg_dest))
+#define ASM_LOAD8_REG_REG(as, reg_dest, reg_base) ASM_LOAD8_REG_REG_OFFSET((as), (reg_dest), (reg_base), 0)
+#define ASM_LOAD8_REG_REG_OFFSET(as, reg_dest, reg_base, byte_offset) asm_x64_mov_mem8_to_r64zx((as), (reg_base), (byte_offset), (reg_dest))
+#define ASM_LOAD16_REG_REG(as, reg_dest, reg_base) ASM_LOAD16_REG_REG_OFFSET((as), (reg_dest), (reg_base), 0)
+#define ASM_LOAD16_REG_REG_OFFSET(as, reg_dest, reg_base, word_offset) asm_x64_mov_mem16_to_r64zx((as), (reg_base), 2 * (word_offset), (reg_dest))
+#define ASM_LOAD32_REG_REG(as, reg_dest, reg_base) ASM_LOAD32_REG_REG_OFFSET((as), (reg_dest), (reg_base), 0)
+#define ASM_LOAD32_REG_REG_OFFSET(as, reg_dest, reg_base, dword_offset) asm_x64_mov_mem32_to_r64zx((as), (reg_base), 4 * (dword_offset), (reg_dest))
+
+#define ASM_STORE_REG_REG_OFFSET(as, reg_src, reg_base, qword_offset) asm_x64_mov_r64_to_mem64((as), (reg_src), (reg_base), 8 * (qword_offset))
+#define ASM_STORE8_REG_REG(as, reg_src, reg_base) ASM_STORE8_REG_REG_OFFSET((as), (reg_src), (reg_base), 0)
+#define ASM_STORE8_REG_REG_OFFSET(as, reg_src, reg_base, byte_offset) asm_x64_mov_r8_to_mem8((as), (reg_src), (reg_base), (byte_offset))
+#define ASM_STORE16_REG_REG(as, reg_src, reg_base) ASM_STORE16_REG_REG_OFFSET((as), (reg_src), (reg_base), 0)
+#define ASM_STORE16_REG_REG_OFFSET(as, reg_src, reg_base, word_offset) asm_x64_mov_r16_to_mem16((as), (reg_src), (reg_base), 2 * (word_offset))
+#define ASM_STORE32_REG_REG(as, reg_src, reg_base) ASM_STORE32_REG_REG_OFFSET((as), (reg_src), (reg_base), 0)
+#define ASM_STORE32_REG_REG_OFFSET(as, reg_src, reg_base, dword_offset) asm_x64_mov_r32_to_mem32((as), (reg_src), (reg_base), 4 * (dword_offset))
 
 #endif // GENERIC_ASM_API
 
diff --git a/py/asmx86.h b/py/asmx86.h
index 7796d69762617..f5d37228a2f04 100644
--- a/py/asmx86.h
+++ b/py/asmx86.h
@@ -150,12 +150,12 @@ void asm_x86_call_ind(asm_x86_t *as, size_t fun_id, mp_uint_t n_args, int temp_r
 // Holds a pointer to mp_fun_table
 #define REG_FUN_TABLE ASM_X86_REG_FUN_TABLE
 
-#define ASM_T               asm_x86_t
-#define ASM_END_PASS        asm_x86_end_pass
-#define ASM_ENTRY           asm_x86_entry
-#define ASM_EXIT            asm_x86_exit
+#define ASM_T                           asm_x86_t
+#define ASM_END_PASS                    asm_x86_end_pass
+#define ASM_ENTRY(as, num_locals, name) asm_x86_entry((as), (num_locals))
+#define ASM_EXIT                        asm_x86_exit
 
-#define ASM_JUMP            asm_x86_jmp_label
+#define ASM_JUMP                        asm_x86_jmp_label
 #define ASM_JUMP_IF_REG_ZERO(as, reg, label, bool_test) \
     do { \
         if (bool_test) { \
@@ -201,18 +201,21 @@ void asm_x86_call_ind(asm_x86_t *as, size_t fun_id, mp_uint_t n_args, int temp_r
 #define ASM_SUB_REG_REG(as, reg_dest, reg_src) asm_x86_sub_r32_r32((as), (reg_dest), (reg_src))
 #define ASM_MUL_REG_REG(as, reg_dest, reg_src) asm_x86_mul_r32_r32((as), (reg_dest), (reg_src))
 
-#define ASM_LOAD_REG_REG(as, reg_dest, reg_base) asm_x86_mov_mem32_to_r32((as), (reg_base), 0, (reg_dest))
-#define ASM_LOAD_REG_REG_OFFSET(as, reg_dest, reg_base, word_offset) asm_x86_mov_mem32_to_r32((as), (reg_base), 4 * (word_offset), (reg_dest))
-#define ASM_LOAD8_REG_REG(as, reg_dest, reg_base) asm_x86_mov_mem8_to_r32zx((as), (reg_base), 0, (reg_dest))
-#define ASM_LOAD16_REG_REG(as, reg_dest, reg_base) asm_x86_mov_mem16_to_r32zx((as), (reg_base), 0, (reg_dest))
-#define ASM_LOAD16_REG_REG_OFFSET(as, reg_dest, reg_base, uint16_offset) asm_x86_mov_mem16_to_r32zx((as), (reg_base), 2 * (uint16_offset), (reg_dest))
-#define ASM_LOAD32_REG_REG(as, reg_dest, reg_base) asm_x86_mov_mem32_to_r32((as), (reg_base), 0, (reg_dest))
-
-#define ASM_STORE_REG_REG(as, reg_src, reg_base) asm_x86_mov_r32_to_mem32((as), (reg_src), (reg_base), 0)
-#define ASM_STORE_REG_REG_OFFSET(as, reg_src, reg_base, word_offset) asm_x86_mov_r32_to_mem32((as), (reg_src), (reg_base), 4 * (word_offset))
-#define ASM_STORE8_REG_REG(as, reg_src, reg_base) asm_x86_mov_r8_to_mem8((as), (reg_src), (reg_base), 0)
-#define ASM_STORE16_REG_REG(as, reg_src, reg_base) asm_x86_mov_r16_to_mem16((as), (reg_src), (reg_base), 0)
-#define ASM_STORE32_REG_REG(as, reg_src, reg_base) asm_x86_mov_r32_to_mem32((as), (reg_src), (reg_base), 0)
+#define ASM_LOAD_REG_REG_OFFSET(as, reg_dest, reg_base, dword_offset) ASM_LOAD32_REG_REG_OFFSET((as), (reg_dest), (reg_base), (dword_offset))
+#define ASM_LOAD8_REG_REG(as, reg_dest, reg_base) ASM_LOAD8_REG_REG_OFFSET((as), (reg_dest), (reg_base), 0)
+#define ASM_LOAD8_REG_REG_OFFSET(as, reg_dest, reg_base, byte_offset) asm_x86_mov_mem8_to_r32zx((as), (reg_base), (byte_offset), (reg_dest))
+#define ASM_LOAD16_REG_REG(as, reg_dest, reg_base) ASM_LOAD16_REG_REG_OFFSET((as), (reg_dest), (reg_base), 0)
+#define ASM_LOAD16_REG_REG_OFFSET(as, reg_dest, reg_base, word_offset) asm_x86_mov_mem16_to_r32zx((as), (reg_base), 2 * (word_offset), (reg_dest))
+#define ASM_LOAD32_REG_REG(as, reg_dest, reg_base) ASM_LOAD32_REG_REG_OFFSET((as), (reg_dest), (reg_base), 0)
+#define ASM_LOAD32_REG_REG_OFFSET(as, reg_dest, reg_base, dword_offset) asm_x86_mov_mem32_to_r32((as), (reg_base), 4 * (dword_offset), (reg_dest))
+
+#define ASM_STORE_REG_REG_OFFSET(as, reg_src, reg_base, dword_offset) ASM_STORE32_REG_REG_OFFSET((as), (reg_src), (reg_base), (dword_offset))
+#define ASM_STORE8_REG_REG(as, reg_src, reg_base) ASM_STORE8_REG_REG_OFFSET((as), (reg_src), (reg_base), 0)
+#define ASM_STORE8_REG_REG_OFFSET(as, reg_src, reg_base, byte_offset) asm_x86_mov_r8_to_mem8((as), (reg_src), (reg_base), (byte_offset))
+#define ASM_STORE16_REG_REG(as, reg_src, reg_base) ASM_STORE16_REG_REG_OFFSET((as), (reg_src), (reg_base), 0)
+#define ASM_STORE16_REG_REG_OFFSET(as, reg_src, reg_base, word_offset) asm_x86_mov_r16_to_mem16((as), (reg_src), (reg_base), 2 * (word_offset))
+#define ASM_STORE32_REG_REG(as, reg_src, reg_base) ASM_STORE32_REG_REG_OFFSET((as), (reg_src), (reg_base), 0)
+#define ASM_STORE32_REG_REG_OFFSET(as, reg_src, reg_base, dword_offset) asm_x86_mov_r32_to_mem32((as), (reg_src), (reg_base), 4 * (dword_offset))
 
 #endif // GENERIC_ASM_API
 
diff --git a/py/asmxtensa.c b/py/asmxtensa.c
index 0fbe351dcf3c7..bc3e717d9f3a0 100644
--- a/py/asmxtensa.c
+++ b/py/asmxtensa.c
@@ -34,9 +34,20 @@
 
 #include "py/asmxtensa.h"
 
+#if N_XTENSAWIN
+#define REG_TEMP ASM_XTENSA_REG_TEMPORARY_WIN
+#else
+#define REG_TEMP ASM_XTENSA_REG_TEMPORARY
+#endif
+
 #define WORD_SIZE (4)
+#define SIGNED_FIT6(x) ((((x) & 0xffffffe0) == 0) || (((x) & 0xffffffe0) == 0xffffffe0))
 #define SIGNED_FIT8(x) ((((x) & 0xffffff80) == 0) || (((x) & 0xffffff80) == 0xffffff80))
 #define SIGNED_FIT12(x) ((((x) & 0xfffff800) == 0) || (((x) & 0xfffff800) == 0xfffff800))
+#define SIGNED_FIT18(x) ((((x) & 0xfffe0000) == 0) || (((x) & 0xfffe0000) == 0xfffe0000))
+
+#define ET_OUT_OF_RANGE MP_ERROR_TEXT("ERROR: xtensa %q out of range")
+#define ET_NOT_ALIGNED MP_ERROR_TEXT("ERROR: %q %q not word-aligned")
 
 void asm_xtensa_end_pass(asm_xtensa_t *as) {
     as->num_const = as->cur_const;
@@ -47,9 +58,9 @@ void asm_xtensa_end_pass(asm_xtensa_t *as) {
     if (as->base.pass == MP_ASM_PASS_EMIT) {
         uint8_t *d = as->base.code_base;
         printf("XTENSA ASM:");
-        for (int i = 0; i < ((as->base.code_size + 15) & ~15); ++i) {
+        for (size_t i = 0; i < ((as->base.code_size + 15) & ~15); ++i) {
             if (i % 16 == 0) {
-                printf("\n%08x:", (uint32_t)&d[i]);
+                printf("\n%p:", &d[i]);
             }
             if (i % 2 == 0) {
                 printf(" ");
@@ -62,10 +73,12 @@ void asm_xtensa_end_pass(asm_xtensa_t *as) {
 }
 
 void asm_xtensa_entry(asm_xtensa_t *as, int num_locals) {
-    // jump over the constants
-    asm_xtensa_op_j(as, as->num_const * WORD_SIZE + 4 - 4);
-    mp_asm_base_get_cur_to_write_bytes(&as->base, 1); // padding/alignment byte
-    as->const_table = (uint32_t *)mp_asm_base_get_cur_to_write_bytes(&as->base, as->num_const * 4);
+    if (as->num_const > 0) {
+        // jump over the constants
+        asm_xtensa_op_j(as, as->num_const * WORD_SIZE + 4 - 4);
+        mp_asm_base_get_cur_to_write_bytes(&as->base, 1); // padding/alignment byte
+        as->const_table = (uint32_t *)mp_asm_base_get_cur_to_write_bytes(&as->base, as->num_const * 4);
+    }
 
     // adjust the stack-pointer to store a0, a12, a13, a14, a15 and locals, 16-byte aligned
     as->stack_adjust = (((ASM_XTENSA_NUM_REGS_SAVED + num_locals) * WORD_SIZE) + 15) & ~15;
@@ -146,22 +159,60 @@ void asm_xtensa_j_label(asm_xtensa_t *as, uint label) {
     asm_xtensa_op_j(as, rel);
 }
 
+static bool calculate_branch_displacement(asm_xtensa_t *as, uint label, ptrdiff_t *displacement) {
+    assert(displacement != NULL && "Displacement pointer is NULL");
+
+    uint32_t label_offset = get_label_dest(as, label);
+    *displacement = (ptrdiff_t)(label_offset - as->base.code_offset - 4);
+    return (label_offset != (uint32_t)-1) && (*displacement < 0);
+}
+
 void asm_xtensa_bccz_reg_label(asm_xtensa_t *as, uint cond, uint reg, uint label) {
-    uint32_t dest = get_label_dest(as, label);
-    int32_t rel = dest - as->base.code_offset - 4;
-    if (as->base.pass == MP_ASM_PASS_EMIT && !SIGNED_FIT12(rel)) {
-        printf("ERROR: xtensa bccz out of range\n");
+    ptrdiff_t rel = 0;
+    bool can_emit_short_jump = calculate_branch_displacement(as, label, &rel);
+
+    if (can_emit_short_jump && SIGNED_FIT12(rel)) {
+        // Backwards BCCZ opcodes with an offset that fits in 12 bits can
+        // be emitted without any change.
+        asm_xtensa_op_bccz(as, cond, reg, rel);
+        return;
     }
-    asm_xtensa_op_bccz(as, cond, reg, rel);
+
+    // Range is effectively extended to 18 bits, as a more complex jump code
+    // sequence is emitted.
+    if (as->base.pass == MP_ASM_PASS_EMIT && !SIGNED_FIT18(rel - 6)) {
+        mp_raise_msg_varg(&mp_type_RuntimeError, ET_OUT_OF_RANGE, MP_QSTR_bccz);
+    }
+
+    // ~BCCZ skip ; +0  <- Condition is flipped here (EQ -> NE, etc.)
+    //  J    addr ; +3
+    // skip:      ; +6
+    asm_xtensa_op_bccz(as, cond ^ 1, reg, 6 - 4);
+    asm_xtensa_op_j(as, rel - 3);
 }
 
 void asm_xtensa_bcc_reg_reg_label(asm_xtensa_t *as, uint cond, uint reg1, uint reg2, uint label) {
-    uint32_t dest = get_label_dest(as, label);
-    int32_t rel = dest - as->base.code_offset - 4;
-    if (as->base.pass == MP_ASM_PASS_EMIT && !SIGNED_FIT8(rel)) {
-        printf("ERROR: xtensa bcc out of range\n");
+    ptrdiff_t rel = 0;
+    bool can_emit_short_jump = calculate_branch_displacement(as, label, &rel);
+
+    if (can_emit_short_jump && SIGNED_FIT8(rel)) {
+        // Backwards BCC opcodes with an offset that fits in 8 bits can
+        // be emitted without any change.
+        asm_xtensa_op_bcc(as, cond, reg1, reg2, rel);
+        return;
+    }
+
+    // Range is effectively extended to 18 bits, as a more complex jump code
+    // sequence is emitted.
+    if (as->base.pass == MP_ASM_PASS_EMIT && !SIGNED_FIT18(rel - 6)) {
+        mp_raise_msg_varg(&mp_type_RuntimeError, ET_OUT_OF_RANGE, MP_QSTR_bcc);
     }
-    asm_xtensa_op_bcc(as, cond, reg1, reg2, rel);
+
+    // ~BCC skip ; +0  <- Condition is flipped here (EQ -> NE, etc.)
+    //  J   addr ; +3
+    // skip:     ; +6
+    asm_xtensa_op_bcc(as, cond ^ 8, reg1, reg2, 6 - 4);
+    asm_xtensa_op_j(as, rel - 3);
 }
 
 // convenience function; reg_dest must be different from reg_src[12]
@@ -179,6 +230,8 @@ size_t asm_xtensa_mov_reg_i32(asm_xtensa_t *as, uint reg_dest, uint32_t i32) {
     // store the constant in the table
     if (as->const_table != NULL) {
         as->const_table[as->cur_const] = i32;
+    } else {
+        assert((as->base.pass != MP_ASM_PASS_EMIT) && "Constants table was not built.");
     }
     ++as->cur_const;
     return loc;
@@ -240,17 +293,53 @@ void asm_xtensa_l32i_optimised(asm_xtensa_t *as, uint reg_dest, uint reg_base, u
     } else if (word_offset < 256) {
         asm_xtensa_op_l32i(as, reg_dest, reg_base, word_offset);
     } else {
-        mp_raise_msg(&mp_type_RuntimeError, MP_ERROR_TEXT("asm overflow"));
+        asm_xtensa_mov_reg_i32_optimised(as, reg_dest, word_offset * 4);
+        asm_xtensa_op_add_n(as, reg_dest, reg_base, reg_dest);
+        asm_xtensa_op_l32i_n(as, reg_dest, reg_dest, 0);
     }
 }
 
-void asm_xtensa_s32i_optimised(asm_xtensa_t *as, uint reg_src, uint reg_base, uint word_offset) {
-    if (word_offset < 16) {
-        asm_xtensa_op_s32i_n(as, reg_src, reg_base, word_offset);
-    } else if (word_offset < 256) {
-        asm_xtensa_op_s32i(as, reg_src, reg_base, word_offset);
+void asm_xtensa_load_reg_reg_offset(asm_xtensa_t *as, uint reg_dest, uint reg_base, uint offset, uint operation_size) {
+    assert(operation_size <= 2 && "Operation size value out of range.");
+
+    if (operation_size == 2 && MP_FIT_UNSIGNED(4, offset)) {
+        asm_xtensa_op_l32i_n(as, reg_dest, reg_base, offset);
+        return;
+    }
+
+    if (MP_FIT_UNSIGNED(8, offset)) {
+        asm_xtensa_op24(as, ASM_XTENSA_ENCODE_RRI8(2, operation_size, reg_base, reg_dest, offset));
+        return;
+    }
+
+    asm_xtensa_mov_reg_i32_optimised(as, reg_dest, offset << operation_size);
+    asm_xtensa_op_add_n(as, reg_dest, reg_base, reg_dest);
+    if (operation_size == 2) {
+        asm_xtensa_op_l32i_n(as, reg_dest, reg_dest, 0);
     } else {
-        mp_raise_msg(&mp_type_RuntimeError, MP_ERROR_TEXT("asm overflow"));
+        asm_xtensa_op24(as, ASM_XTENSA_ENCODE_RRI8(2, operation_size, reg_dest, reg_dest, 0));
+    }
+}
+
+void asm_xtensa_store_reg_reg_offset(asm_xtensa_t *as, uint reg_src, uint reg_base, uint offset, uint operation_size) {
+    assert(operation_size <= 2 && "Operation size value out of range.");
+
+    if (operation_size == 2 && MP_FIT_UNSIGNED(4, offset)) {
+        asm_xtensa_op_s32i_n(as, reg_src, reg_base, offset);
+        return;
+    }
+
+    if (MP_FIT_UNSIGNED(8, offset)) {
+        asm_xtensa_op24(as, ASM_XTENSA_ENCODE_RRI8(2, 0x04 | operation_size, reg_base, reg_src, offset));
+        return;
+    }
+
+    asm_xtensa_mov_reg_i32_optimised(as, REG_TEMP, offset << operation_size);
+    asm_xtensa_op_add_n(as, REG_TEMP, reg_base, REG_TEMP);
+    if (operation_size == 2) {
+        asm_xtensa_op_s32i_n(as, reg_src, REG_TEMP, 0);
+    } else {
+        asm_xtensa_op24(as, ASM_XTENSA_ENCODE_RRI8(2, 0x04 | operation_size, REG_TEMP, reg_src, 0));
     }
 }
 
@@ -264,4 +353,47 @@ void asm_xtensa_call_ind_win(asm_xtensa_t *as, uint idx) {
     asm_xtensa_op_callx8(as, ASM_XTENSA_REG_A8);
 }
 
+void asm_xtensa_bit_branch(asm_xtensa_t *as, mp_uint_t reg, mp_uint_t bit, mp_uint_t label, mp_uint_t condition) {
+    uint32_t dest = get_label_dest(as, label);
+    int32_t rel = dest - as->base.code_offset - 4;
+    if (as->base.pass == MP_ASM_PASS_EMIT && !SIGNED_FIT8(rel)) {
+        mp_raise_msg_varg(&mp_type_RuntimeError, ET_OUT_OF_RANGE, MP_QSTR_bit_branch);
+    }
+    asm_xtensa_op24(as, ASM_XTENSA_ENCODE_RRI8(7, condition | ((bit >> 4) & 0x01), reg, bit & 0x0F, rel & 0xFF));
+}
+
+void asm_xtensa_call0(asm_xtensa_t *as, mp_uint_t label) {
+    uint32_t dest = get_label_dest(as, label);
+    int32_t rel = dest - as->base.code_offset - 3;
+    if (as->base.pass == MP_ASM_PASS_EMIT) {
+        if ((dest & 0x03) != 0) {
+            mp_raise_msg_varg(&mp_type_RuntimeError, ET_NOT_ALIGNED, MP_QSTR_call0, MP_QSTR_target);
+        }
+        if ((rel & 0x03) != 0) {
+            mp_raise_msg_varg(&mp_type_RuntimeError, ET_NOT_ALIGNED, MP_QSTR_call0, MP_QSTR_location);
+        }
+        if (!SIGNED_FIT18(rel)) {
+            mp_raise_msg_varg(&mp_type_RuntimeError, ET_OUT_OF_RANGE, MP_QSTR_call0);
+        }
+    }
+    asm_xtensa_op_call0(as, rel);
+}
+
+void asm_xtensa_l32r(asm_xtensa_t *as, mp_uint_t reg, mp_uint_t label) {
+    uint32_t dest = get_label_dest(as, label);
+    int32_t rel = dest - as->base.code_offset;
+    if (as->base.pass == MP_ASM_PASS_EMIT) {
+        if ((dest & 0x03) != 0) {
+            mp_raise_msg_varg(&mp_type_RuntimeError, ET_NOT_ALIGNED, MP_QSTR_l32r, MP_QSTR_target);
+        }
+        if ((rel & 0x03) != 0) {
+            mp_raise_msg_varg(&mp_type_RuntimeError, ET_NOT_ALIGNED, MP_QSTR_l32r, MP_QSTR_location);
+        }
+        if (!SIGNED_FIT18(rel) || (rel >= 0)) {
+            mp_raise_msg_varg(&mp_type_RuntimeError, ET_OUT_OF_RANGE, MP_QSTR_l32r);
+        }
+    }
+    asm_xtensa_op_l32r(as, reg, as->base.code_offset, dest);
+}
+
 #endif // MICROPY_EMIT_XTENSA || MICROPY_EMIT_INLINE_XTENSA || MICROPY_EMIT_XTENSAWIN
diff --git a/py/asmxtensa.h b/py/asmxtensa.h
index a8c39206bd008..ed98c9d730516 100644
--- a/py/asmxtensa.h
+++ b/py/asmxtensa.h
@@ -64,9 +64,11 @@
 #define ASM_XTENSA_REG_A14 (14)
 #define ASM_XTENSA_REG_A15 (15)
 
-// for bccz
+// for bccz and bcci
 #define ASM_XTENSA_CCZ_EQ (0)
 #define ASM_XTENSA_CCZ_NE (1)
+#define ASM_XTENSA_CCZ_LT (2)
+#define ASM_XTENSA_CCZ_GE (3)
 
 // for bcc and setcc
 #define ASM_XTENSA_CC_NONE  (0)
@@ -291,15 +293,24 @@ void asm_xtensa_mov_local_reg(asm_xtensa_t *as, int local_num, uint reg_src);
 void asm_xtensa_mov_reg_local(asm_xtensa_t *as, uint reg_dest, int local_num);
 void asm_xtensa_mov_reg_local_addr(asm_xtensa_t *as, uint reg_dest, int local_num);
 void asm_xtensa_mov_reg_pcrel(asm_xtensa_t *as, uint reg_dest, uint label);
-void asm_xtensa_l32i_optimised(asm_xtensa_t *as, uint reg_dest, uint reg_base, uint word_offset);
-void asm_xtensa_s32i_optimised(asm_xtensa_t *as, uint reg_src, uint reg_base, uint word_offset);
+void asm_xtensa_load_reg_reg_offset(asm_xtensa_t *as, uint reg_dest, uint reg_base, uint offset, uint operation_size);
+void asm_xtensa_store_reg_reg_offset(asm_xtensa_t *as, uint reg_src, uint reg_base, uint offset, uint operation_size);
 void asm_xtensa_call_ind(asm_xtensa_t *as, uint idx);
 void asm_xtensa_call_ind_win(asm_xtensa_t *as, uint idx);
+void asm_xtensa_bit_branch(asm_xtensa_t *as, mp_uint_t reg, mp_uint_t bit, mp_uint_t label, mp_uint_t condition);
+void asm_xtensa_immediate_branch(asm_xtensa_t *as, mp_uint_t reg, mp_uint_t immediate, mp_uint_t label, mp_uint_t cond);
+void asm_xtensa_call0(asm_xtensa_t *as, mp_uint_t label);
+void asm_xtensa_l32r(asm_xtensa_t *as, mp_uint_t reg, mp_uint_t label);
 
 // Holds a pointer to mp_fun_table
 #define ASM_XTENSA_REG_FUN_TABLE ASM_XTENSA_REG_A15
 #define ASM_XTENSA_REG_FUN_TABLE_WIN ASM_XTENSA_REG_A7
 
+// Internal temporary register (currently aliased to REG_ARG_5 for xtensa,
+// and to REG_TEMP2 for xtensawin).
+#define ASM_XTENSA_REG_TEMPORARY ASM_XTENSA_REG_A6
+#define ASM_XTENSA_REG_TEMPORARY_WIN ASM_XTENSA_REG_A12
+
 // CIRCUITPY-CHANGE: prevent #if warning
 #if defined(GENERIC_ASM_API) && GENERIC_ASM_API
 
@@ -330,9 +341,9 @@ void asm_xtensa_call_ind_win(asm_xtensa_t *as, uint idx);
 #define ASM_NUM_REGS_SAVED ASM_XTENSA_NUM_REGS_SAVED
 #define REG_FUN_TABLE ASM_XTENSA_REG_FUN_TABLE
 
-#define ASM_ENTRY(as, nlocal)   asm_xtensa_entry((as), (nlocal))
-#define ASM_EXIT(as)            asm_xtensa_exit((as))
-#define ASM_CALL_IND(as, idx)   asm_xtensa_call_ind((as), (idx))
+#define ASM_ENTRY(as, nlocal, name)   asm_xtensa_entry((as), (nlocal))
+#define ASM_EXIT(as)                  asm_xtensa_exit((as))
+#define ASM_CALL_IND(as, idx)         asm_xtensa_call_ind((as), (idx))
 
 #else
 // Configuration for windowed calls with window size 8
@@ -360,9 +371,9 @@ void asm_xtensa_call_ind_win(asm_xtensa_t *as, uint idx);
 #define ASM_NUM_REGS_SAVED ASM_XTENSA_NUM_REGS_SAVED_WIN
 #define REG_FUN_TABLE ASM_XTENSA_REG_FUN_TABLE_WIN
 
-#define ASM_ENTRY(as, nlocal)   asm_xtensa_entry_win((as), (nlocal))
-#define ASM_EXIT(as)            asm_xtensa_exit_win((as))
-#define ASM_CALL_IND(as, idx)   asm_xtensa_call_ind_win((as), (idx))
+#define ASM_ENTRY(as, nlocal, name)   asm_xtensa_entry_win((as), (nlocal))
+#define ASM_EXIT(as)                  asm_xtensa_exit_win((as))
+#define ASM_CALL_IND(as, idx)         asm_xtensa_call_ind_win((as), (idx))
 
 #endif
 
@@ -408,16 +419,51 @@ void asm_xtensa_call_ind_win(asm_xtensa_t *as, uint idx);
 #define ASM_SUB_REG_REG(as, reg_dest, reg_src) asm_xtensa_op_sub((as), (reg_dest), (reg_dest), (reg_src))
 #define ASM_MUL_REG_REG(as, reg_dest, reg_src) asm_xtensa_op_mull((as), (reg_dest), (reg_dest), (reg_src))
 
-#define ASM_LOAD_REG_REG_OFFSET(as, reg_dest, reg_base, word_offset) asm_xtensa_l32i_optimised((as), (reg_dest), (reg_base), (word_offset))
-#define ASM_LOAD8_REG_REG(as, reg_dest, reg_base) asm_xtensa_op_l8ui((as), (reg_dest), (reg_base), 0)
-#define ASM_LOAD16_REG_REG(as, reg_dest, reg_base) asm_xtensa_op_l16ui((as), (reg_dest), (reg_base), 0)
-#define ASM_LOAD16_REG_REG_OFFSET(as, reg_dest, reg_base, uint16_offset) asm_xtensa_op_l16ui((as), (reg_dest), (reg_base), (uint16_offset))
-#define ASM_LOAD32_REG_REG(as, reg_dest, reg_base) asm_xtensa_op_l32i_n((as), (reg_dest), (reg_base), 0)
+#define ASM_LOAD_REG_REG_OFFSET(as, reg_dest, reg_base, word_offset) ASM_LOAD32_REG_REG_OFFSET((as), (reg_dest), (reg_base), (word_offset))
+#define ASM_LOAD8_REG_REG(as, reg_dest, reg_base) ASM_LOAD8_REG_REG_OFFSET((as), (reg_dest), (reg_base), 0)
+#define ASM_LOAD8_REG_REG_OFFSET(as, reg_dest, reg_base, byte_offset) asm_xtensa_load_reg_reg_offset((as), (reg_dest), (reg_base), (byte_offset), 0)
+#define ASM_LOAD8_REG_REG_REG(as, reg_dest, reg_base, reg_index) \
+    do { \
+        asm_xtensa_op_add_n((as), (reg_base), (reg_index), (reg_base)); \
+        asm_xtensa_op_l8ui((as), (reg_dest), (reg_base), 0); \
+    } while (0)
+#define ASM_LOAD16_REG_REG(as, reg_dest, reg_base) ASM_LOAD16_REG_REG_OFFSET((as), (reg_dest), (reg_base), 0)
+#define ASM_LOAD16_REG_REG_OFFSET(as, reg_dest, reg_base, halfword_offset) asm_xtensa_load_reg_reg_offset((as), (reg_dest), (reg_base), (halfword_offset), 1)
+#define ASM_LOAD16_REG_REG_REG(as, reg_dest, reg_base, reg_index) \
+    do { \
+        asm_xtensa_op_addx2((as), (reg_base), (reg_index), (reg_base)); \
+        asm_xtensa_op_l16ui((as), (reg_dest), (reg_base), 0); \
+    } while (0)
+#define ASM_LOAD32_REG_REG(as, reg_dest, reg_base) ASM_LOAD32_REG_REG_OFFSET((as), (reg_dest), (reg_base), 0)
+#define ASM_LOAD32_REG_REG_OFFSET(as, reg_dest, reg_base, word_offset) asm_xtensa_load_reg_reg_offset((as), (reg_dest), (reg_base), (word_offset), 2)
+#define ASM_LOAD32_REG_REG_REG(as, reg_dest, reg_base, reg_index) \
+    do { \
+        asm_xtensa_op_addx4((as), (reg_base), (reg_index), (reg_base)); \
+        asm_xtensa_op_l32i_n((as), (reg_dest), (reg_base), 0); \
+    } while (0)
 
-#define ASM_STORE_REG_REG_OFFSET(as, reg_dest, reg_base, word_offset) asm_xtensa_s32i_optimised((as), (reg_dest), (reg_base), (word_offset))
-#define ASM_STORE8_REG_REG(as, reg_src, reg_base) asm_xtensa_op_s8i((as), (reg_src), (reg_base), 0)
-#define ASM_STORE16_REG_REG(as, reg_src, reg_base) asm_xtensa_op_s16i((as), (reg_src), (reg_base), 0)
-#define ASM_STORE32_REG_REG(as, reg_src, reg_base) asm_xtensa_op_s32i_n((as), (reg_src), (reg_base), 0)
+#define ASM_STORE_REG_REG_OFFSET(as, reg_dest, reg_base, word_offset) ASM_STORE32_REG_REG_OFFSET((as), (reg_dest), (reg_base), (word_offset))
+#define ASM_STORE8_REG_REG(as, reg_src, reg_base) ASM_STORE8_REG_REG_OFFSET((as), (reg_src), (reg_base), 0)
+#define ASM_STORE8_REG_REG_OFFSET(as, reg_src, reg_base, byte_offset) asm_xtensa_store_reg_reg_offset((as), (reg_src), (reg_base), (byte_offset), 0)
+#define ASM_STORE8_REG_REG_REG(as, reg_val, reg_base, reg_index) \
+    do { \
+        asm_xtensa_op_add_n((as), (reg_base), (reg_index), (reg_base)); \
+        asm_xtensa_op_s8i((as), (reg_val), (reg_base), 0); \
+    } while (0)
+#define ASM_STORE16_REG_REG(as, reg_src, reg_base) ASM_STORE16_REG_REG_OFFSET((as), (reg_src), (reg_base), 0)
+#define ASM_STORE16_REG_REG_OFFSET(as, reg_src, reg_base, halfword_offset) asm_xtensa_store_reg_reg_offset((as), (reg_src), (reg_base), (halfword_offset), 1)
+#define ASM_STORE16_REG_REG_REG(as, reg_val, reg_base, reg_index) \
+    do { \
+        asm_xtensa_op_addx2((as), (reg_base), (reg_index), (reg_base)); \
+        asm_xtensa_op_s16i((as), (reg_val), (reg_base), 0); \
+    } while (0)
+#define ASM_STORE32_REG_REG(as, reg_src, reg_base) ASM_STORE32_REG_REG_OFFSET((as), (reg_src), (reg_base), 0)
+#define ASM_STORE32_REG_REG_OFFSET(as, reg_dest, reg_base, word_offset) asm_xtensa_store_reg_reg_offset((as), (reg_dest), (reg_base), (word_offset), 2)
+#define ASM_STORE32_REG_REG_REG(as, reg_val, reg_base, reg_index) \
+    do { \
+        asm_xtensa_op_addx4((as), (reg_base), (reg_index), (reg_base)); \
+        asm_xtensa_op_s32i_n((as), (reg_val), (reg_base), 0); \
+    } while (0)
 
 #endif // GENERIC_ASM_API
 
diff --git a/py/bc.c b/py/bc.c
index c2956030e38e1..4caa022e3d8b4 100644
--- a/py/bc.c
+++ b/py/bc.c
@@ -88,7 +88,7 @@ const byte *mp_decode_uint_skip(const byte *ptr) {
     return ptr;
 }
 
-static NORETURN void fun_pos_args_mismatch(mp_obj_fun_bc_t *f, size_t expected, size_t given) {
+static MP_NORETURN void fun_pos_args_mismatch(mp_obj_fun_bc_t *f, size_t expected, size_t given) {
     #if MICROPY_ERROR_REPORTING <= MICROPY_ERROR_REPORTING_TERSE
     // generic message, used also for other argument issues
     (void)f;
diff --git a/py/bc.h b/py/bc.h
index 7658f66414f17..3b7a6fe1c960b 100644
--- a/py/bc.h
+++ b/py/bc.h
@@ -226,6 +226,7 @@ typedef struct _mp_compiled_module_t {
     bool has_native;
     size_t n_qstr;
     size_t n_obj;
+    size_t arch_flags;
     #endif
 } mp_compiled_module_t;
 
@@ -303,7 +304,7 @@ static inline void mp_module_context_alloc_tables(mp_module_context_t *context,
     size_t nq = (n_qstr * sizeof(qstr_short_t) + sizeof(mp_uint_t) - 1) / sizeof(mp_uint_t);
     size_t no = n_obj;
     // CIRCUITPY-CHANGE
-    mp_uint_t *mem = m_malloc_items(nq + no);
+    mp_uint_t *mem = (mp_uint_t *)m_malloc_items(nq + no);
     context->constants.qstr_table = (qstr_short_t *)mem;
     context->constants.obj_table = (mp_obj_t *)(mem + nq);
     #else
@@ -316,25 +317,35 @@ static inline void mp_module_context_alloc_tables(mp_module_context_t *context,
     #endif
 }
 
+typedef struct _mp_code_lineinfo_t {
+    size_t bc_increment;
+    size_t line_increment;
+} mp_code_lineinfo_t;
+
+static inline mp_code_lineinfo_t mp_bytecode_decode_lineinfo(const byte **line_info) {
+    mp_code_lineinfo_t result;
+    size_t c = (*line_info)[0];
+    if ((c & 0x80) == 0) {
+        // 0b0LLBBBBB encoding
+        result.bc_increment = c & 0x1f;
+        result.line_increment = c >> 5;
+        *line_info += 1;
+    } else {
+        // 0b1LLLBBBB 0bLLLLLLLL encoding (l's LSB in second byte)
+        result.bc_increment = c & 0xf;
+        result.line_increment = ((c << 4) & 0x700) | (*line_info)[1];
+        *line_info += 2;
+    }
+    return result;
+}
+
 static inline size_t mp_bytecode_get_source_line(const byte *line_info, const byte *line_info_top, size_t bc_offset) {
     size_t source_line = 1;
     while (line_info < line_info_top) {
-        size_t c = *line_info;
-        size_t b, l;
-        if ((c & 0x80) == 0) {
-            // 0b0LLBBBBB encoding
-            b = c & 0x1f;
-            l = c >> 5;
-            line_info += 1;
-        } else {
-            // 0b1LLLBBBB 0bLLLLLLLL encoding (l's LSB in second byte)
-            b = c & 0xf;
-            l = ((c << 4) & 0x700) | line_info[1];
-            line_info += 2;
-        }
-        if (bc_offset >= b) {
-            bc_offset -= b;
-            source_line += l;
+        mp_code_lineinfo_t decoded = mp_bytecode_decode_lineinfo(&line_info);
+        if (bc_offset >= decoded.bc_increment) {
+            bc_offset -= decoded.bc_increment;
+            source_line += decoded.line_increment;
         } else {
             // found source line corresponding to bytecode offset
             break;
diff --git a/py/binary.c b/py/binary.c
index 728f29815cd78..180a13beec7bf 100644
--- a/py/binary.c
+++ b/py/binary.c
@@ -71,8 +71,7 @@ size_t mp_binary_get_size(char struct_type, char val_type, size_t *palign) {
                 case 'Q':
                     size = 8;
                     break;
-                    // CIRCUITPY-CHANGE: non-standard typecodes can be turned off
-                #if MICROPY_NONSTANDARD_TYPECODES
+                #if MICROPY_PY_STRUCT_UNSAFE_TYPECODES
                 case 'P':
                 case 'O':
                 case 'S':
@@ -128,8 +127,7 @@ size_t mp_binary_get_size(char struct_type, char val_type, size_t *palign) {
                     align = alignof(long long);
                     size = sizeof(long long);
                     break;
-                    // CIRCUITPY-CHANGE: non-standard typecodes can be turned off
-                #if MICROPY_NONSTANDARD_TYPECODES
+                #if MICROPY_PY_STRUCT_UNSAFE_TYPECODES
                 case 'P':
                 case 'O':
                 case 'S':
@@ -208,7 +206,7 @@ static float mp_decode_half_float(uint16_t hf) {
         ++e;
     }
 
-    fpu.i = ((hf & 0x8000) << 16) | (e << 23) | (m << 13);
+    fpu.i = ((hf & 0x8000u) << 16) | (e << 23) | (m << 13);
     return fpu.f;
 }
 
@@ -289,20 +287,17 @@ mp_obj_t mp_binary_get_val_array(char typecode, void *p, size_t index) {
         #if MICROPY_PY_BUILTINS_FLOAT
         case 'f':
             return mp_obj_new_float_from_f(((float *)p)[index]);
-        #if MICROPY_PY_DOUBLE_TYPECODE
         case 'd':
             return mp_obj_new_float_from_d(((double *)p)[index]);
         #endif
-        #endif
-            // CIRCUITPY-CHANGE: non-standard typecodes can be turned off
-            #if MICROPY_NONSTANDARD_TYPECODES
-        // Extension to CPython: array of objects
+            // Extension to CPython: array of objects
+        #if MICROPY_PY_STRUCT_UNSAFE_TYPECODES
         case 'O':
             return ((mp_obj_t *)p)[index];
         // Extension to CPython: array of pointers
         case 'P':
             return mp_obj_new_int((mp_int_t)(uintptr_t)((void **)p)[index]);
-            #endif
+        #endif
     }
     return MP_OBJ_NEW_SMALL_INT(val);
 }
@@ -352,14 +347,11 @@ mp_obj_t mp_binary_get_val(char struct_type, char val_type, byte *p_base, byte *
 
     long long val = mp_binary_get_int(size, is_signed(val_type), (struct_type == '>'), p);
 
-    // CIRCUITPY-CHANGE: non-standard typecodes can be turned off
-    if (MICROPY_NONSTANDARD_TYPECODES && (val_type == 'O')) {
+    if (MICROPY_PY_STRUCT_UNSAFE_TYPECODES && val_type == 'O') {
         return (mp_obj_t)(mp_uint_t)val;
-    #if MICROPY_NONSTANDARD_TYPECODES
-    } else if (val_type == 'S') {
+    } else if (MICROPY_PY_STRUCT_UNSAFE_TYPECODES && val_type == 'S') {
         const char *s_val = (const char *)(uintptr_t)(mp_uint_t)val;
         return mp_obj_new_str_from_cstr(s_val);
-    #endif
     #if MICROPY_PY_BUILTINS_FLOAT
     } else if (val_type == 'e') {
         return mp_obj_new_float_from_f(mp_decode_half_float(val));
@@ -369,7 +361,6 @@ mp_obj_t mp_binary_get_val(char struct_type, char val_type, byte *p_base, byte *
             float f;
         } fpu = {val};
         return mp_obj_new_float_from_f(fpu.f);
-    #if MICROPY_PY_DOUBLE_TYPECODE
     } else if (val_type == 'd') {
         union {
             uint64_t i;
@@ -377,7 +368,6 @@ mp_obj_t mp_binary_get_val(char struct_type, char val_type, byte *p_base, byte *
         } fpu = {val};
         return mp_obj_new_float_from_d(fpu.f);
     #endif
-    #endif
     } else if (is_signed(val_type)) {
         if ((long long)MP_SMALL_INT_MIN <= val && val <= (long long)MP_SMALL_INT_MAX) {
             return mp_obj_new_int((mp_int_t)val);
@@ -430,8 +420,7 @@ void mp_binary_set_val(char struct_type, char val_type, mp_obj_t val_in, byte *p
 
     mp_uint_t val;
     switch (val_type) {
-        // CIRCUITPY-CHANGE: non-standard typecodes can be turned off
-        #if MICROPY_NONSTANDARD_TYPECODES
+        #if MICROPY_PY_STRUCT_UNSAFE_TYPECODES
         case 'O':
             val = (mp_uint_t)val_in;
             break;
@@ -449,6 +438,7 @@ void mp_binary_set_val(char struct_type, char val_type, mp_obj_t val_in, byte *p
             val = fp_sp.i;
             break;
         }
+            // CIRCUITPY-CHANGE
         #if MICROPY_PY_DOUBLE_TYPECODE
         case 'd': {
             union {
@@ -507,14 +497,11 @@ void mp_binary_set_val_array(char typecode, void *p, size_t index, mp_obj_t val_
         case 'f':
             ((float *)p)[index] = mp_obj_get_float_to_f(val_in);
             break;
-        #if MICROPY_PY_DOUBLE_TYPECODE
         case 'd':
             ((double *)p)[index] = mp_obj_get_float_to_d(val_in);
             break;
         #endif
-        #endif
-        // CIRCUITPY-CHANGE: non-standard typecodes can be turned off
-        #if MICROPY_NONSTANDARD_TYPECODES
+        #if MICROPY_PY_STRUCT_UNSAFE_TYPECODES
         // Extension to CPython: array of objects
         case 'O':
             ((mp_obj_t *)p)[index] = val_in;
@@ -582,18 +569,15 @@ void mp_binary_set_val_array_from_int(char typecode, void *p, size_t index, mp_i
         case 'f':
             ((float *)p)[index] = (float)val;
             break;
-        #if MICROPY_PY_DOUBLE_TYPECODE
         case 'd':
             ((double *)p)[index] = (double)val;
             break;
         #endif
-        #endif
-            // CIRCUITPY-CHANGE: non-standard typecodes can be turned off
-            #if MICROPY_NONSTANDARD_TYPECODES
-        // Extension to CPython: array of pointers
+            // Extension to CPython: array of pointers
+        #if MICROPY_PY_STRUCT_UNSAFE_TYPECODES
         case 'P':
             ((void **)p)[index] = (void *)(uintptr_t)val;
             break;
-            #endif
+        #endif
     }
 }
diff --git a/py/builtin.h b/py/builtin.h
index 6efe3e8facabd..388bc8470053d 100644
--- a/py/builtin.h
+++ b/py/builtin.h
@@ -138,6 +138,7 @@ extern const mp_obj_module_t mp_module_sys;
 extern const mp_obj_module_t mp_module_errno;
 extern const mp_obj_module_t mp_module_uctypes;
 extern const mp_obj_module_t mp_module_machine;
+extern const mp_obj_module_t mp_module_math;
 
 extern const char MICROPY_PY_BUILTINS_HELP_TEXT[];
 
diff --git a/py/builtinhelp.c b/py/builtinhelp.c
index d041d6915a63a..9ab2a12d21455 100644
--- a/py/builtinhelp.c
+++ b/py/builtinhelp.c
@@ -162,9 +162,8 @@ static void mp_help_print_obj(const mp_obj_t obj) {
     }
     if (map != NULL) {
         for (uint i = 0; i < map->alloc; i++) {
-            mp_obj_t key = map->table[i].key;
-            if (key != MP_OBJ_NULL) {
-                mp_help_print_info_about_object(key, map->table[i].value);
+            if (mp_map_slot_is_filled(map, i)) {
+                mp_help_print_info_about_object(map->table[i].key, map->table[i].value);
             }
         }
     }
diff --git a/py/builtinimport.c b/py/builtinimport.c
index e4e06d8e2cc8b..8fcac22ccb491 100644
--- a/py/builtinimport.c
+++ b/py/builtinimport.c
@@ -118,7 +118,7 @@ static mp_import_stat_t stat_module(vstr_t *path) {
 // path (i.e. "<entry>/mod_name(.py)").
 static mp_import_stat_t stat_top_level(qstr mod_name, vstr_t *dest) {
     DEBUG_printf("stat_top_level: '%s'\n", qstr_str(mod_name));
-    #if MICROPY_PY_SYS
+    #if MICROPY_PY_SYS && MICROPY_PY_SYS_PATH
     size_t path_num;
     mp_obj_t *path_items;
     mp_obj_get_array(mp_sys_path, &path_num, &path_items);
@@ -155,7 +155,7 @@ static mp_import_stat_t stat_top_level(qstr mod_name, vstr_t *dest) {
 
 #if MICROPY_MODULE_FROZEN_STR || MICROPY_ENABLE_COMPILER
 static void do_load_from_lexer(mp_module_context_t *context, mp_lexer_t *lex) {
-    #if MICROPY_PY___FILE__
+    #if MICROPY_MODULE___FILE__
     qstr source_name = lex->source_name;
     mp_store_attr(MP_OBJ_FROM_PTR(&context->module), MP_QSTR___file__, MP_OBJ_NEW_QSTR(source_name));
     #endif
@@ -168,7 +168,7 @@ static void do_load_from_lexer(mp_module_context_t *context, mp_lexer_t *lex) {
 
 #if (MICROPY_HAS_FILE_READER && MICROPY_PERSISTENT_CODE_LOAD) || MICROPY_MODULE_FROZEN_MPY
 static void do_execute_proto_fun(const mp_module_context_t *context, mp_proto_fun_t proto_fun, qstr source_name) {
-    #if MICROPY_PY___FILE__
+    #if MICROPY_MODULE___FILE__
     mp_store_attr(MP_OBJ_FROM_PTR(&context->module), MP_QSTR___file__, MP_OBJ_NEW_QSTR(source_name));
     #else
     (void)source_name;
@@ -227,7 +227,7 @@ static void do_load(mp_module_context_t *module_obj, vstr_t *file) {
         if (frozen_type == MP_FROZEN_MPY) {
             const mp_frozen_module_t *frozen = modref;
             module_obj->constants = frozen->constants;
-            #if MICROPY_PY___FILE__
+            #if MICROPY_MODULE___FILE__
             qstr frozen_file_qstr = qstr_from_str(file_str + frozen_path_prefix_len);
             #else
             qstr frozen_file_qstr = MP_QSTRnull;
@@ -270,7 +270,7 @@ static void do_load(mp_module_context_t *module_obj, vstr_t *file) {
 
 // Convert a relative (to the current module) import, going up "level" levels,
 // into an absolute import.
-static void evaluate_relative_import(mp_int_t level, const char **module_name, size_t *module_name_len) {
+static void evaluate_relative_import(mp_int_t level, const char **module_name, size_t *module_name_len, mp_obj_t globals) {
     // What we want to do here is to take the name of the current module,
     // remove <level> trailing components, and concatenate the passed-in
     // module name.
@@ -279,7 +279,7 @@ static void evaluate_relative_import(mp_int_t level, const char **module_name, s
     // module's position in the package hierarchy."
     // http://legacy.python.org/dev/peps/pep-0328/#relative-imports-and-name
 
-    mp_obj_t current_module_name_obj = mp_obj_dict_get(MP_OBJ_FROM_PTR(mp_globals_get()), MP_OBJ_NEW_QSTR(MP_QSTR___name__));
+    mp_obj_t current_module_name_obj = mp_obj_dict_get(globals, MP_OBJ_NEW_QSTR(MP_QSTR___name__));
     assert(current_module_name_obj != MP_OBJ_NULL);
 
     #if MICROPY_MODULE_OVERRIDE_MAIN_IMPORT && MICROPY_CPYTHON_COMPAT
@@ -287,12 +287,12 @@ static void evaluate_relative_import(mp_int_t level, const char **module_name, s
         // This is a module loaded by -m command-line switch (e.g. unix port),
         // and so its __name__ has been set to "__main__". Get its real name
         // that we stored during import in the __main__ attribute.
-        current_module_name_obj = mp_obj_dict_get(MP_OBJ_FROM_PTR(mp_globals_get()), MP_OBJ_NEW_QSTR(MP_QSTR___main__));
+        current_module_name_obj = mp_obj_dict_get(globals, MP_OBJ_NEW_QSTR(MP_QSTR___main__));
     }
     #endif
 
     // If we have a __path__ in the globals dict, then we're a package.
-    bool is_pkg = mp_map_lookup(&mp_globals_get()->map, MP_OBJ_NEW_QSTR(MP_QSTR___path__), MP_MAP_LOOKUP);
+    bool is_pkg = mp_map_lookup(mp_obj_dict_get_map(globals), MP_OBJ_NEW_QSTR(MP_QSTR___path__), MP_MAP_LOOKUP);
 
     #if DEBUG_PRINT
     DEBUG_printf("Current module/package: ");
@@ -370,7 +370,7 @@ static mp_obj_t process_import_at_level(qstr full_mod_name, qstr level_mod_name,
     // Immediately return if the module at this level is already loaded.
     mp_map_elem_t *elem;
 
-    #if MICROPY_PY_SYS
+    #if MICROPY_PY_SYS && MICROPY_PY_SYS_PATH
     // If sys.path is empty, the intention is to force using a built-in. This
     // means we should also ignore any loaded modules with the same name
     // which may have come from the filesystem.
@@ -406,6 +406,7 @@ static mp_obj_t process_import_at_level(qstr full_mod_name, qstr level_mod_name,
         // all the locations in sys.path.
         stat = stat_top_level(level_mod_name, &path);
 
+        #if MICROPY_HAVE_REGISTERED_EXTENSIBLE_MODULES
         // If filesystem failed, now try and see if it matches an extensible
         // built-in module.
         if (stat == MP_IMPORT_STAT_NO_EXIST) {
@@ -414,6 +415,7 @@ static mp_obj_t process_import_at_level(qstr full_mod_name, qstr level_mod_name,
                 return module_obj;
             }
         }
+        #endif
     } else {
         DEBUG_printf("Searching for sub-module\n");
 
@@ -577,10 +579,19 @@ mp_obj_t mp_builtin___import___default(size_t n_args, const mp_obj_t *args) {
     const char *module_name = mp_obj_str_get_data(module_name_obj, &module_name_len);
 
     if (level != 0) {
+        // This is the dict with all global symbols.
+        mp_obj_t globals = MP_OBJ_FROM_PTR(mp_globals_get());
+        if (n_args >= 2 && args[1] != mp_const_none) {
+            globals = args[1];
+            if (!mp_obj_is_type(globals, &mp_type_dict)) {
+                mp_raise_TypeError(NULL);
+            }
+        }
+
         // Turn "foo.bar" with level=3 into "<current module 3 components>.foo.bar".
         // Current module name is extracted from globals().__name__.
-        evaluate_relative_import(level, &module_name, &module_name_len);
         // module_name is now an absolute module path.
+        evaluate_relative_import(level, &module_name, &module_name_len, globals);
     }
 
     if (module_name_len == 0) {
@@ -656,11 +667,13 @@ mp_obj_t mp_builtin___import___default(size_t n_args, const mp_obj_t *args) {
     if (module_obj != MP_OBJ_NULL) {
         return module_obj;
     }
+    #if MICROPY_HAVE_REGISTERED_EXTENSIBLE_MODULES
     // Now try as an extensible built-in (e.g. `time`).
     module_obj = mp_module_get_builtin(module_name_qstr, true);
     if (module_obj != MP_OBJ_NULL) {
         return module_obj;
     }
+    #endif
 
     // Couldn't find the module, so fail
     #if MICROPY_ERROR_REPORTING <= MICROPY_ERROR_REPORTING_TERSE
diff --git a/py/circuitpy_mpconfig.h b/py/circuitpy_mpconfig.h
index 3918296636afa..4b23784c5416c 100644
--- a/py/circuitpy_mpconfig.h
+++ b/py/circuitpy_mpconfig.h
@@ -17,6 +17,10 @@
 // Always 1: defined in circuitpy_mpconfig.mk
 // #define CIRCUITPY (1)
 
+#ifndef MP_SSIZE_MAX
+#define MP_SSIZE_MAX (0x7fffffff)
+#endif
+
 // REPR_C encodes qstrs, 31-bit ints, and 30-bit floats in a single 32-bit word.
 #ifndef MICROPY_OBJ_REPR
 #define MICROPY_OBJ_REPR            (MICROPY_OBJ_REPR_C)
@@ -42,10 +46,14 @@ extern void common_hal_mcu_enable_interrupts(void);
 #define MICROPY_PY_BLUETOOTH             (0)
 #define MICROPY_PY_LWIP_SLIP             (0)
 #define MICROPY_PY_OS_DUPTERM            (0)
+#define MICROPY_PYEXEC_COMPILE_ONLY      (0)
 #define MICROPY_ROM_TEXT_COMPRESSION     (0)
 #define MICROPY_VFS_LFS1                 (0)
 #define MICROPY_VFS_LFS2                 (0)
 
+// Always turn on exit code handling
+#define MICROPY_PYEXEC_ENABLE_EXIT_CODE_HANDLING (1)
+
 #ifndef MICROPY_GCREGS_SETJMP
 #define MICROPY_GCREGS_SETJMP            (0)
 #endif
@@ -88,7 +96,6 @@ extern void common_hal_mcu_enable_interrupts(void);
 #define MICROPY_MEM_STATS                (0)
 #define MICROPY_MODULE_BUILTIN_INIT      (1)
 #define MICROPY_MODULE_BUILTIN_SUBPACKAGES (1)
-#define MICROPY_NONSTANDARD_TYPECODES    (0)
 #define MICROPY_OPT_COMPUTED_GOTO        (1)
 #define MICROPY_OPT_COMPUTED_GOTO_SAVE_SPACE (CIRCUITPY_COMPUTED_GOTO_SAVE_SPACE)
 #define MICROPY_OPT_LOAD_ATTR_FAST_PATH  (CIRCUITPY_OPT_LOAD_ATTR_FAST_PATH)
@@ -141,6 +148,7 @@ extern void common_hal_mcu_enable_interrupts(void);
 #define MICROPY_PY_RE                   (CIRCUITPY_RE)
 // Supplanted by shared-bindings/struct
 #define MICROPY_PY_STRUCT                (0)
+#define MICROPY_PY_STRUCT_UNSAFE_TYPECODES (0)
 #define MICROPY_PY_SYS                   (CIRCUITPY_SYS)
 #define MICROPY_PY_SYS_MAXSIZE           (1)
 #define MICROPY_PY_SYS_STDFILES          (1)
@@ -193,21 +201,6 @@ extern void common_hal_mcu_enable_interrupts(void);
 // Track stack usage. Expose results via ustack module.
 #define MICROPY_MAX_STACK_USAGE       (0)
 
-#define UINT_FMT "%u"
-#define INT_FMT "%d"
-#ifdef __LP64__
-typedef long mp_int_t; // must be pointer size
-typedef unsigned long mp_uint_t; // must be pointer size
-#else
-// These are definitions for machines where sizeof(int) == sizeof(void*),
-// regardless of actual size.
-typedef int mp_int_t; // must be pointer size
-typedef unsigned int mp_uint_t; // must be pointer size
-#endif
-#if __GNUC__ >= 10 // on recent gcc versions we can check that this is so
-_Static_assert(sizeof(mp_int_t) == sizeof(void *));
-_Static_assert(sizeof(mp_uint_t) == sizeof(void *));
-#endif
 typedef long mp_off_t;
 
 #define MP_PLAT_PRINT_STRN(str, len) mp_hal_stdout_tx_strn_cooked(str, len)
@@ -303,12 +296,10 @@ typedef long mp_off_t;
 
 #ifdef LONGINT_IMPL_MPZ
 #define MICROPY_LONGINT_IMPL (MICROPY_LONGINT_IMPL_MPZ)
-#define MP_SSIZE_MAX (0x7fffffff)
 #endif
 
 #ifdef LONGINT_IMPL_LONGLONG
 #define MICROPY_LONGINT_IMPL (MICROPY_LONGINT_IMPL_LONGLONG)
-#define MP_SSIZE_MAX (0x7fffffff)
 #endif
 
 #ifndef MICROPY_PY_REVERSE_SPECIAL_METHODS
diff --git a/py/compile.c b/py/compile.c
index c7dd2fd476136..c8704131234f1 100644
--- a/py/compile.c
+++ b/py/compile.c
@@ -103,6 +103,7 @@ static const emit_method_table_t *emit_native_table[] = {
     &emit_native_xtensa_method_table,
     &emit_native_xtensawin_method_table,
     &emit_native_rv32_method_table,
+    NULL,
     &emit_native_debug_method_table,
 };
 
@@ -3295,7 +3296,9 @@ static void compile_scope_inline_asm(compiler_t *comp, scope_t *scope, pass_kind
         }
 
         // check structure of parse node
-        assert(MP_PARSE_NODE_IS_STRUCT(pns2->nodes[0]));
+        if (!MP_PARSE_NODE_IS_STRUCT(pns2->nodes[0])) {
+            goto not_an_instruction;
+        }
         if (!MP_PARSE_NODE_IS_NULL(pns2->nodes[1])) {
             goto not_an_instruction;
         }
@@ -3587,6 +3590,13 @@ void mp_compile_to_raw_code(mp_parse_tree_t *parse_tree, qstr source_file, bool
                 case MP_EMIT_OPT_NATIVE_PYTHON:
                 case MP_EMIT_OPT_VIPER:
                     if (emit_native == NULL) {
+                        // The check looks like this to work around a false
+                        // warning in GCC 13 (and possibly later), where it
+                        // assumes that the check will always fail.
+                        if ((uintptr_t)NATIVE_EMITTER_TABLE == (uintptr_t)NULL) {
+                            comp->compile_error = mp_obj_new_exception_msg(&mp_type_NotImplementedError, MP_ERROR_TEXT("cannot emit native code for this architecture"));
+                            goto emit_finished;
+                        }
                         emit_native = NATIVE_EMITTER(new)(&comp->emit_common, &comp->compile_error, &comp->next_label, max_num_labels);
                     }
                     comp->emit_method_table = NATIVE_EMITTER_TABLE;
@@ -3619,6 +3629,10 @@ void mp_compile_to_raw_code(mp_parse_tree_t *parse_tree, qstr source_file, bool
         }
     }
 
+    #if MICROPY_EMIT_NATIVE
+emit_finished:
+    #endif
+
     if (comp->compile_error != MP_OBJ_NULL) {
         // if there is no line number for the error then use the line
         // number for the start of this scope
diff --git a/py/cstack.h b/py/cstack.h
index b12a18e13fcad..bcd919d31f932 100644
--- a/py/cstack.h
+++ b/py/cstack.h
@@ -35,7 +35,7 @@
 
 void mp_cstack_init_with_sp_here(size_t stack_size);
 
-inline static void mp_cstack_init_with_top(void *top, size_t stack_size) {
+static inline void mp_cstack_init_with_top(void *top, size_t stack_size) {
     MP_STATE_THREAD(stack_top) = (char *)top;
 
     #if MICROPY_STACK_CHECK
@@ -54,7 +54,7 @@ void mp_cstack_check(void);
 
 #else
 
-inline static void mp_cstack_check(void) {
+static inline void mp_cstack_check(void) {
     // No-op when stack checking is disabled
 }
 
diff --git a/py/dynruntime.h b/py/dynruntime.h
index e87cf6591c4b6..ab155a1387579 100644
--- a/py/dynruntime.h
+++ b/py/dynruntime.h
@@ -70,7 +70,7 @@
 #define m_realloc(ptr, new_num_bytes)   (m_realloc_dyn((ptr), (new_num_bytes)))
 #define m_realloc_maybe(ptr, new_num_bytes, allow_move) (m_realloc_maybe_dyn((ptr), (new_num_bytes), (allow_move)))
 
-static NORETURN inline void m_malloc_fail_dyn(size_t num_bytes) {
+static MP_NORETURN inline void m_malloc_fail_dyn(size_t num_bytes) {
     mp_fun_table.raise_msg(
         mp_fun_table.load_global(MP_QSTR_MemoryError),
         "memory allocation failed");
@@ -289,7 +289,7 @@ static inline void *mp_obj_malloc_helper_dyn(size_t num_bytes, const mp_obj_type
 
 #define nlr_raise(o)                            (mp_raise_dyn(o))
 #define mp_raise_type_arg(type, arg)            (mp_raise_dyn(mp_obj_new_exception_arg1_dyn((type), (arg))))
-// CIRCUITPY-CHANGE: use str
+// CIRCUITPY-CHANGE: use mp_raise_msg_str
 #define mp_raise_msg(type, msg)                 (mp_fun_table.raise_msg_str((type), (msg)))
 #define mp_raise_OSError(er)                    (mp_raise_OSError_dyn(er))
 #define mp_raise_NotImplementedError(msg)       (mp_raise_msg(&mp_type_NotImplementedError, (msg)))
@@ -301,14 +301,14 @@ static inline mp_obj_t mp_obj_new_exception_arg1_dyn(const mp_obj_type_t *exc_ty
     return mp_call_function_n_kw(MP_OBJ_FROM_PTR(exc_type), 1, 0, &args[0]);
 }
 
-static NORETURN inline void mp_raise_dyn(mp_obj_t o) {
+static MP_NORETURN inline void mp_raise_dyn(mp_obj_t o) {
     mp_fun_table.raise(o);
     for (;;) {
     }
 }
 
 // CIRCUITPY-CHANGE: new routine
-static NORETURN inline void mp_raise_arg1(const mp_obj_type_t *exc_type, mp_obj_t arg) {
+static MP_NORETURN inline void mp_raise_arg1(const mp_obj_type_t *exc_type, mp_obj_t arg) {
     mp_fun_table.raise(mp_obj_new_exception_arg1_dyn(exc_type, arg));
     for (;;) {
     }
diff --git a/py/dynruntime.mk b/py/dynruntime.mk
index 807befb464a84..030728cfc9adf 100644
--- a/py/dynruntime.mk
+++ b/py/dynruntime.mk
@@ -63,14 +63,14 @@ else ifeq ($(ARCH),armv6m)
 # thumb
 CROSS = arm-none-eabi-
 CFLAGS_ARCH += -mthumb -mcpu=cortex-m0
-MICROPY_FLOAT_IMPL ?= none
+MICROPY_FLOAT_IMPL ?= float
 
 else ifeq ($(ARCH),armv7m)
 
 # thumb
 CROSS = arm-none-eabi-
 CFLAGS_ARCH += -mthumb -mcpu=cortex-m3
-MICROPY_FLOAT_IMPL ?= none
+MICROPY_FLOAT_IMPL ?= float
 
 else ifeq ($(ARCH),armv7emsp)
 
@@ -124,6 +124,10 @@ else
 $(error architecture '$(ARCH)' not supported)
 endif
 
+ifneq ($(findstring -musl,$(shell $(CROSS)gcc -dumpmachine)),)
+USE_MUSL := 1
+endif
+
 MICROPY_FLOAT_IMPL_UPPER = $(shell echo $(MICROPY_FLOAT_IMPL) | tr '[:lower:]' '[:upper:]')
 CFLAGS += $(CFLAGS_ARCH) -DMICROPY_FLOAT_IMPL=MICROPY_FLOAT_IMPL_$(MICROPY_FLOAT_IMPL_UPPER)
 
@@ -147,6 +151,8 @@ ifeq ($(LINK_RUNTIME),1)
 # distribution.
 ifeq ($(USE_PICOLIBC),1)
 LIBM_NAME := libc.a
+else ifeq ($(USE_MUSL),1)
+LIBM_NAME := libc.a
 else
 LIBM_NAME := libm.a
 endif
@@ -166,6 +172,9 @@ endif
 endif
 MPY_LD_FLAGS += $(addprefix -l, $(LIBGCC_PATH) $(LIBM_PATH))
 endif
+ifneq ($(MPY_EXTERN_SYM_FILE),)
+MPY_LD_FLAGS += --externs "$(realpath $(MPY_EXTERN_SYM_FILE))"
+endif
 
 CFLAGS += $(CFLAGS_EXTRA)
 
diff --git a/py/emitcommon.c b/py/emitcommon.c
index a9eb6e2021fc8..1369c544c54f5 100644
--- a/py/emitcommon.c
+++ b/py/emitcommon.c
@@ -25,6 +25,7 @@
  */
 
 #include <assert.h>
+#include <math.h>
 
 #include "py/emit.h"
 #include "py/nativeglue.h"
@@ -72,7 +73,25 @@ static bool strictly_equal(mp_obj_t a, mp_obj_t b) {
         }
         return true;
     } else {
-        return mp_obj_equal(a, b);
+        if (!mp_obj_equal(a, b)) {
+            return false;
+        }
+        #if MICROPY_PY_BUILTINS_FLOAT && MICROPY_COMP_CONST_FLOAT
+        if (a_type == &mp_type_float) {
+            mp_float_t a_val = mp_obj_float_get(a);
+            // CIRCUITPY-CHANGE: ignore float equal warning
+            #pragma GCC diagnostic push
+            #pragma GCC diagnostic ignored "-Wfloat-equal"
+            if (a_val == (mp_float_t)0.0) {
+                // Although 0.0 == -0.0, they are not strictly_equal and
+                // must be stored as two different constants in .mpy files
+                mp_float_t b_val = mp_obj_float_get(b);
+                return signbit(a_val) == signbit(b_val);
+            }
+            #pragma GCC diagnostic pop
+        }
+        #endif
+        return true;
     }
 }
 
diff --git a/py/emitglue.c b/py/emitglue.c
index 8cc14bdc54eb5..c6ad3e3bc3845 100644
--- a/py/emitglue.c
+++ b/py/emitglue.c
@@ -32,6 +32,7 @@
 #include <assert.h>
 
 #include "py/emitglue.h"
+#include "py/mphal.h"
 #include "py/runtime0.h"
 #include "py/bc.h"
 #include "py/objfun.h"
@@ -133,6 +134,9 @@ void mp_emit_glue_assign_native(mp_raw_code_t *rc, mp_raw_code_kind_t kind, cons
         "mcr p15, 0, r0, c7, c7, 0\n" // invalidate I-cache and D-cache
         : : : "r0", "cc");
     #endif
+    #elif (MICROPY_EMIT_RV32 || MICROPY_EMIT_INLINE_RV32) && defined(MP_HAL_CLEAN_DCACHE)
+    // Flush the D-cache.
+    MP_HAL_CLEAN_DCACHE(fun_data, fun_len);
     #endif
 
     rc->kind = kind;
diff --git a/py/emitinlinerv32.c b/py/emitinlinerv32.c
index a539242b84d95..e81b152087de3 100644
--- a/py/emitinlinerv32.c
+++ b/py/emitinlinerv32.c
@@ -196,7 +196,6 @@ typedef enum {
     CALL_R,   // Opcode Register
     CALL_RL,  // Opcode Register, Label
     CALL_N,   // Opcode
-    CALL_I,   // Opcode Immediate
     CALL_RII, // Opcode Register, Register, Immediate
     CALL_RIR, // Opcode Register, Immediate(Register)
     CALL_COUNT
@@ -210,7 +209,6 @@ typedef enum {
 #define U (1 << 2) // Unsigned immediate
 #define Z (1 << 3) // Non-zero
 
-typedef void (*call_l_t)(asm_rv32_t *state, mp_uint_t label_index);
 typedef void (*call_ri_t)(asm_rv32_t *state, mp_uint_t rd, mp_int_t immediate);
 typedef void (*call_rri_t)(asm_rv32_t *state, mp_uint_t rd, mp_uint_t rs1, mp_int_t immediate);
 typedef void (*call_rii_t)(asm_rv32_t *state, mp_uint_t rd, mp_uint_t immediate1, mp_int_t immediate2);
@@ -225,7 +223,7 @@ typedef struct _opcode_t {
     uint16_t argument1_mask : 4;
     uint16_t argument2_mask : 4;
     uint16_t argument3_mask : 4;
-    uint16_t arguments_count : 2;
+    uint16_t parse_nodes : 2;
     // 2 bits available here
     uint32_t calling_convention : 4;
     uint32_t argument1_kind : 4;
@@ -234,7 +232,8 @@ typedef struct _opcode_t {
     uint32_t argument2_shift : 4;
     uint32_t argument3_kind : 4;
     uint32_t argument3_shift : 4;
-    // 4 bits available here
+    uint32_t required_extensions : 1;
+    // 3 bits available here
     void *emitter;
 } opcode_t;
 
@@ -297,88 +296,91 @@ static const uint32_t OPCODE_MASKS[] = {
 };
 
 static const opcode_t OPCODES[] = {
-    { MP_QSTR_add,        MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_FFFFFFFF, 3, CALL_RRR, R,  0, R,   0,  R,  0, asm_rv32_opcode_add       },
-    { MP_QSTR_addi,       MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_00000FFF, 3, CALL_RRI, R,  0, R,   0,  I,  0, asm_rv32_opcode_addi      },
-    { MP_QSTR_and_,       MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_FFFFFFFF, 3, CALL_RRR, R,  0, R,   0,  R,  0, asm_rv32_opcode_and       },
-    { MP_QSTR_andi,       MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_00000FFF, 3, CALL_RRI, R,  0, R,   0,  I,  0, asm_rv32_opcode_andi      },
-    { MP_QSTR_auipc,      MASK_FFFFFFFF, MASK_FFFFF000, MASK_NOT_USED, 2, CALL_RI,  R,  0, I,   12, N,  0, asm_rv32_opcode_auipc     },
-    { MP_QSTR_beq,        MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_00001FFE, 3, CALL_RRL, R,  0, R,   0,  L,  0, asm_rv32_opcode_beq       },
-    { MP_QSTR_bge,        MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_00001FFE, 3, CALL_RRL, R,  0, R,   0,  L,  0, asm_rv32_opcode_bge       },
-    { MP_QSTR_bgeu,       MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_00001FFE, 3, CALL_RRL, R,  0, R,   0,  L,  0, asm_rv32_opcode_bgeu      },
-    { MP_QSTR_blt,        MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_00001FFE, 3, CALL_RRL, R,  0, R,   0,  L,  0, asm_rv32_opcode_blt       },
-    { MP_QSTR_bltu,       MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_00001FFE, 3, CALL_RRL, R,  0, R,   0,  L,  0, asm_rv32_opcode_bltu      },
-    { MP_QSTR_bne,        MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_00001FFE, 3, CALL_RRL, R,  0, R,   0,  L,  0, asm_rv32_opcode_bne       },
-    { MP_QSTR_csrrc,      MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_00000FFF, 3, CALL_RRI, R,  0, R,   0,  IU, 0, asm_rv32_opcode_csrrc     },
-    { MP_QSTR_csrrs,      MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_00000FFF, 3, CALL_RRI, R,  0, R,   0,  IU, 0, asm_rv32_opcode_csrrs     },
-    { MP_QSTR_csrrw,      MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_00000FFF, 3, CALL_RRI, R,  0, R,   0,  IU, 0, asm_rv32_opcode_csrrw     },
-    { MP_QSTR_csrrci,     MASK_FFFFFFFF, MASK_00000FFF, MASK_0000001F, 3, CALL_RII, R,  0, IU,  0,  IU, 0, asm_rv32_opcode_csrrci    },
-    { MP_QSTR_csrrsi,     MASK_FFFFFFFF, MASK_00000FFF, MASK_0000001F, 3, CALL_RII, R,  0, IU,  0,  IU, 0, asm_rv32_opcode_csrrsi    },
-    { MP_QSTR_csrrwi,     MASK_FFFFFFFF, MASK_00000FFF, MASK_0000001F, 3, CALL_RII, R,  0, IU,  0,  IU, 0, asm_rv32_opcode_csrrwi    },
-    { MP_QSTR_c_add,      MASK_FFFFFFFE, MASK_FFFFFFFE, MASK_NOT_USED, 2, CALL_RR,  R,  0, R,   0,  N,  0, asm_rv32_opcode_cadd      },
-    { MP_QSTR_c_addi,     MASK_FFFFFFFE, MASK_0000003F, MASK_NOT_USED, 2, CALL_RI,  R,  0, IZ,  0,  N,  0, asm_rv32_opcode_caddi     },
-    { MP_QSTR_c_addi4spn, MASK_0000FF00, MASK_000003FC, MASK_NOT_USED, 2, CALL_RI,  R,  0, IUZ, 0,  N,  0, asm_rv32_opcode_caddi4spn },
-    { MP_QSTR_c_and,      MASK_0000FF00, MASK_0000FF00, MASK_NOT_USED, 2, CALL_RR,  RC, 0, RC,  0,  N,  0, asm_rv32_opcode_cand      },
-    { MP_QSTR_c_andi,     MASK_0000FF00, MASK_0000003F, MASK_NOT_USED, 2, CALL_RI,  RC, 0, I,   0,  N,  0, asm_rv32_opcode_candi     },
-    { MP_QSTR_c_beqz,     MASK_0000FF00, MASK_000001FE, MASK_NOT_USED, 2, CALL_RL,  RC, 0, L,   0,  N,  0, asm_rv32_opcode_cbeqz     },
-    { MP_QSTR_c_bnez,     MASK_0000FF00, MASK_000001FE, MASK_NOT_USED, 2, CALL_RL,  RC, 0, L,   0,  N,  0, asm_rv32_opcode_cbnez     },
-    { MP_QSTR_c_ebreak,   MASK_NOT_USED, MASK_NOT_USED, MASK_NOT_USED, 0, CALL_N,   N,  0, N,   0,  N,  0, asm_rv32_opcode_cebreak   },
-    { MP_QSTR_c_j,        MASK_00000FFE, MASK_NOT_USED, MASK_NOT_USED, 1, CALL_L,   L,  0, N,   0,  N,  0, asm_rv32_opcode_cj        },
-    { MP_QSTR_c_jal,      MASK_00000FFE, MASK_NOT_USED, MASK_NOT_USED, 1, CALL_L,   L,  0, N,   0,  N,  0, asm_rv32_opcode_cjal      },
-    { MP_QSTR_c_jalr,     MASK_FFFFFFFE, MASK_NOT_USED, MASK_NOT_USED, 1, CALL_R,   R,  0, N,   0,  N,  0, asm_rv32_opcode_cjalr     },
-    { MP_QSTR_c_jr,       MASK_FFFFFFFE, MASK_NOT_USED, MASK_NOT_USED, 1, CALL_R,   R,  0, N,   0,  N,  0, asm_rv32_opcode_cjr       },
-    { MP_QSTR_c_li,       MASK_FFFFFFFE, MASK_0000003F, MASK_NOT_USED, 2, CALL_RI,  R,  0, I,   0,  N,  0, asm_rv32_opcode_cli       },
-    { MP_QSTR_c_lui,      MASK_FFFFFFFA, MASK_0001F800, MASK_NOT_USED, 2, CALL_RI,  R,  0, IUZ, 12, N,  0, asm_rv32_opcode_clui      },
-    { MP_QSTR_c_lw,       MASK_0000FF00, MASK_0000007C, MASK_0000FF00, 3, CALL_RIR, RC, 0, I,   0,  RC, 0, asm_rv32_opcode_clw       },
-    { MP_QSTR_c_lwsp,     MASK_FFFFFFFE, MASK_000000FC, MASK_NOT_USED, 2, CALL_RI,  R,  0, I,   0,  N,  0, asm_rv32_opcode_clwsp     },
-    { MP_QSTR_c_mv,       MASK_FFFFFFFE, MASK_FFFFFFFE, MASK_NOT_USED, 2, CALL_RR,  R,  0, R,   0,  N,  0, asm_rv32_opcode_cmv       },
-    { MP_QSTR_c_nop,      MASK_NOT_USED, MASK_NOT_USED, MASK_NOT_USED, 0, CALL_N,   N,  0, N,   0,  N,  0, asm_rv32_opcode_cnop      },
-    { MP_QSTR_c_or,       MASK_0000FF00, MASK_0000FF00, MASK_NOT_USED, 2, CALL_RR,  RC, 0, RC,  0,  N,  0, asm_rv32_opcode_cor       },
-    { MP_QSTR_c_slli,     MASK_FFFFFFFE, MASK_0000001F, MASK_NOT_USED, 2, CALL_RI,  R,  0, IU,  0,  N,  0, asm_rv32_opcode_cslli     },
-    { MP_QSTR_c_srai,     MASK_0000FF00, MASK_0000001F, MASK_NOT_USED, 2, CALL_RI,  RC, 0, IU,  0,  N,  0, asm_rv32_opcode_csrai     },
-    { MP_QSTR_c_srli,     MASK_0000FF00, MASK_0000001F, MASK_NOT_USED, 2, CALL_RI,  RC, 0, IU,  0,  N,  0, asm_rv32_opcode_csrli     },
-    { MP_QSTR_c_sub,      MASK_0000FF00, MASK_0000FF00, MASK_NOT_USED, 2, CALL_RR,  RC, 0, RC,  0,  N,  0, asm_rv32_opcode_csub      },
-    { MP_QSTR_c_sw,       MASK_0000FF00, MASK_0000007C, MASK_0000FF00, 3, CALL_RIR, RC, 0, I,   0,  RC, 0, asm_rv32_opcode_csw       },
-    { MP_QSTR_c_swsp,     MASK_FFFFFFFF, MASK_000000FC, MASK_NOT_USED, 2, CALL_RI,  R,  0, I,   0,  N,  0, asm_rv32_opcode_cswsp     },
-    { MP_QSTR_c_xor,      MASK_0000FF00, MASK_0000FF00, MASK_NOT_USED, 2, CALL_RR,  RC, 0, RC,  0,  N,  0, asm_rv32_opcode_cxor      },
-    { MP_QSTR_div,        MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_FFFFFFFF, 3, CALL_RRR, R,  0, R,   0,  R,  0, asm_rv32_opcode_div       },
-    { MP_QSTR_divu,       MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_FFFFFFFF, 3, CALL_RRR, R,  0, R,   0,  R,  0, asm_rv32_opcode_divu      },
-    { MP_QSTR_ebreak,     MASK_NOT_USED, MASK_NOT_USED, MASK_NOT_USED, 0, CALL_N,   N,  0, N,   0,  N,  0, asm_rv32_opcode_ebreak    },
-    { MP_QSTR_ecall,      MASK_NOT_USED, MASK_NOT_USED, MASK_NOT_USED, 0, CALL_N,   N,  0, N,   0,  N,  0, asm_rv32_opcode_ecall     },
-    { MP_QSTR_jal,        MASK_FFFFFFFF, MASK_001FFFFE, MASK_NOT_USED, 2, CALL_RL,  R,  0, L,   0,  N,  0, asm_rv32_opcode_jal       },
-    { MP_QSTR_jalr,       MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_00000FFF, 3, CALL_RRI, R,  0, R,   0,  I,  0, asm_rv32_opcode_jalr      },
-    { MP_QSTR_la,         MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_NOT_USED, 2, CALL_RL,  R,  0, L,   0,  N,  0, opcode_la                 },
-    { MP_QSTR_lb,         MASK_FFFFFFFF, MASK_00000FFF, MASK_FFFFFFFF, 3, CALL_RIR, R,  0, I,   0,  R,  0, asm_rv32_opcode_lb        },
-    { MP_QSTR_lbu,        MASK_FFFFFFFF, MASK_00000FFF, MASK_FFFFFFFF, 3, CALL_RIR, R,  0, I,   0,  R,  0, asm_rv32_opcode_lbu       },
-    { MP_QSTR_lh,         MASK_FFFFFFFF, MASK_00000FFF, MASK_FFFFFFFF, 3, CALL_RIR, R,  0, I,   0,  R,  0, asm_rv32_opcode_lh        },
-    { MP_QSTR_lhu,        MASK_FFFFFFFF, MASK_00000FFF, MASK_FFFFFFFF, 3, CALL_RIR, R,  0, I,   0,  R,  0, asm_rv32_opcode_lhu       },
-    { MP_QSTR_li,         MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_NOT_USED, 2, CALL_RI,  R,  0, I,   0,  N,  0, opcode_li                 },
-    { MP_QSTR_lui,        MASK_FFFFFFFF, MASK_FFFFF000, MASK_NOT_USED, 2, CALL_RI,  R,  0, I,   12, N,  0, asm_rv32_opcode_lui       },
-    { MP_QSTR_lw,         MASK_FFFFFFFF, MASK_00000FFF, MASK_FFFFFFFF, 3, CALL_RIR, R,  0, I,   0,  R,  0, asm_rv32_opcode_lw        },
-    { MP_QSTR_mv,         MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_NOT_USED, 2, CALL_RR,  R,  0, R,   0,  N,  0, asm_rv32_opcode_cmv       },
-    { MP_QSTR_mul,        MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_FFFFFFFF, 3, CALL_RRR, R,  0, R,   0,  R,  0, asm_rv32_opcode_mul       },
-    { MP_QSTR_mulh,       MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_FFFFFFFF, 3, CALL_RRR, R,  0, R,   0,  R,  0, asm_rv32_opcode_mulh      },
-    { MP_QSTR_mulhsu,     MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_FFFFFFFF, 3, CALL_RRR, R,  0, R,   0,  R,  0, asm_rv32_opcode_mulhsu    },
-    { MP_QSTR_mulhu,      MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_FFFFFFFF, 3, CALL_RRR, R,  0, R,   0,  R,  0, asm_rv32_opcode_mulhu     },
-    { MP_QSTR_or_,        MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_FFFFFFFF, 3, CALL_RRR, R,  0, R,   0,  R,  0, asm_rv32_opcode_or        },
-    { MP_QSTR_ori,        MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_00000FFF, 3, CALL_RRI, R,  0, R,   0,  I,  0, asm_rv32_opcode_ori       },
-    { MP_QSTR_rem,        MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_FFFFFFFF, 3, CALL_RRR, R,  0, R,   0,  R,  0, asm_rv32_opcode_rem       },
-    { MP_QSTR_remu,       MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_FFFFFFFF, 3, CALL_RRR, R,  0, R,   0,  R,  0, asm_rv32_opcode_remu      },
-    { MP_QSTR_sb,         MASK_FFFFFFFF, MASK_00000FFF, MASK_FFFFFFFF, 3, CALL_RIR, R,  0, I,   0,  R,  0, asm_rv32_opcode_sb        },
-    { MP_QSTR_sh,         MASK_FFFFFFFF, MASK_00000FFF, MASK_FFFFFFFF, 3, CALL_RIR, R,  0, I,   0,  R,  0, asm_rv32_opcode_sh        },
-    { MP_QSTR_sll,        MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_FFFFFFFF, 3, CALL_RRR, R,  0, R,   0,  R,  0, asm_rv32_opcode_sll       },
-    { MP_QSTR_slli,       MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_0000001F, 3, CALL_RRI, R,  0, R,   0,  IU, 0, asm_rv32_opcode_slli      },
-    { MP_QSTR_slt,        MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_FFFFFFFF, 3, CALL_RRR, R,  0, R,   0,  R,  0, asm_rv32_opcode_slt       },
-    { MP_QSTR_slti,       MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_00000FFF, 3, CALL_RRI, R,  0, R,   0,  I,  0, asm_rv32_opcode_slti      },
-    { MP_QSTR_sltiu,      MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_00000FFF, 3, CALL_RRI, R,  0, R,   0,  I,  0, asm_rv32_opcode_sltiu     },
-    { MP_QSTR_sltu,       MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_FFFFFFFF, 3, CALL_RRR, R,  0, R,   0,  R,  0, asm_rv32_opcode_sltu      },
-    { MP_QSTR_sra,        MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_FFFFFFFF, 3, CALL_RRR, R,  0, R,   0,  R,  0, asm_rv32_opcode_sra       },
-    { MP_QSTR_srai,       MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_0000001F, 3, CALL_RRI, R,  0, R,   0,  IU, 0, asm_rv32_opcode_srai      },
-    { MP_QSTR_srl,        MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_FFFFFFFF, 3, CALL_RRR, R,  0, R,   0,  R,  0, asm_rv32_opcode_srl       },
-    { MP_QSTR_srli,       MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_0000001F, 3, CALL_RRI, R,  0, R,   0,  IU, 0, asm_rv32_opcode_srli      },
-    { MP_QSTR_sub,        MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_FFFFFFFF, 3, CALL_RRR, R,  0, R,   0,  R,  0, asm_rv32_opcode_sub       },
-    { MP_QSTR_sw,         MASK_FFFFFFFF, MASK_00000FFF, MASK_FFFFFFFF, 3, CALL_RIR, R,  0, I,   0,  R,  0, asm_rv32_opcode_sw        },
-    { MP_QSTR_xor,        MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_FFFFFFFF, 3, CALL_RRR, R,  0, R,   0,  R,  0, asm_rv32_opcode_xor       },
-    { MP_QSTR_xori,       MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_00000FFF, 3, CALL_RRI, R,  0, R,   0,  I,  0, asm_rv32_opcode_xori      },
+    { MP_QSTR_add,        MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_FFFFFFFF, 3, CALL_RRR, R,  0, R,   0,  R,  0, RV32_EXT_NONE, asm_rv32_opcode_add       },
+    { MP_QSTR_addi,       MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_00000FFF, 3, CALL_RRI, R,  0, R,   0,  I,  0, RV32_EXT_NONE, asm_rv32_opcode_addi      },
+    { MP_QSTR_and_,       MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_FFFFFFFF, 3, CALL_RRR, R,  0, R,   0,  R,  0, RV32_EXT_NONE, asm_rv32_opcode_and       },
+    { MP_QSTR_andi,       MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_00000FFF, 3, CALL_RRI, R,  0, R,   0,  I,  0, RV32_EXT_NONE, asm_rv32_opcode_andi      },
+    { MP_QSTR_auipc,      MASK_FFFFFFFF, MASK_FFFFF000, MASK_NOT_USED, 2, CALL_RI,  R,  0, I,   12, N,  0, RV32_EXT_NONE, asm_rv32_opcode_auipc     },
+    { MP_QSTR_beq,        MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_00001FFE, 3, CALL_RRL, R,  0, R,   0,  L,  0, RV32_EXT_NONE, asm_rv32_opcode_beq       },
+    { MP_QSTR_bge,        MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_00001FFE, 3, CALL_RRL, R,  0, R,   0,  L,  0, RV32_EXT_NONE, asm_rv32_opcode_bge       },
+    { MP_QSTR_bgeu,       MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_00001FFE, 3, CALL_RRL, R,  0, R,   0,  L,  0, RV32_EXT_NONE, asm_rv32_opcode_bgeu      },
+    { MP_QSTR_blt,        MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_00001FFE, 3, CALL_RRL, R,  0, R,   0,  L,  0, RV32_EXT_NONE, asm_rv32_opcode_blt       },
+    { MP_QSTR_bltu,       MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_00001FFE, 3, CALL_RRL, R,  0, R,   0,  L,  0, RV32_EXT_NONE, asm_rv32_opcode_bltu      },
+    { MP_QSTR_bne,        MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_00001FFE, 3, CALL_RRL, R,  0, R,   0,  L,  0, RV32_EXT_NONE, asm_rv32_opcode_bne       },
+    { MP_QSTR_csrrc,      MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_00000FFF, 3, CALL_RRI, R,  0, R,   0,  IU, 0, RV32_EXT_NONE, asm_rv32_opcode_csrrc     },
+    { MP_QSTR_csrrs,      MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_00000FFF, 3, CALL_RRI, R,  0, R,   0,  IU, 0, RV32_EXT_NONE, asm_rv32_opcode_csrrs     },
+    { MP_QSTR_csrrw,      MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_00000FFF, 3, CALL_RRI, R,  0, R,   0,  IU, 0, RV32_EXT_NONE, asm_rv32_opcode_csrrw     },
+    { MP_QSTR_csrrci,     MASK_FFFFFFFF, MASK_00000FFF, MASK_0000001F, 3, CALL_RII, R,  0, IU,  0,  IU, 0, RV32_EXT_NONE, asm_rv32_opcode_csrrci    },
+    { MP_QSTR_csrrsi,     MASK_FFFFFFFF, MASK_00000FFF, MASK_0000001F, 3, CALL_RII, R,  0, IU,  0,  IU, 0, RV32_EXT_NONE, asm_rv32_opcode_csrrsi    },
+    { MP_QSTR_csrrwi,     MASK_FFFFFFFF, MASK_00000FFF, MASK_0000001F, 3, CALL_RII, R,  0, IU,  0,  IU, 0, RV32_EXT_NONE, asm_rv32_opcode_csrrwi    },
+    { MP_QSTR_c_add,      MASK_FFFFFFFE, MASK_FFFFFFFE, MASK_NOT_USED, 2, CALL_RR,  R,  0, R,   0,  N,  0, RV32_EXT_NONE, asm_rv32_opcode_cadd      },
+    { MP_QSTR_c_addi,     MASK_FFFFFFFE, MASK_0000003F, MASK_NOT_USED, 2, CALL_RI,  R,  0, IZ,  0,  N,  0, RV32_EXT_NONE, asm_rv32_opcode_caddi     },
+    { MP_QSTR_c_addi4spn, MASK_0000FF00, MASK_000003FC, MASK_NOT_USED, 2, CALL_RI,  R,  0, IUZ, 0,  N,  0, RV32_EXT_NONE, asm_rv32_opcode_caddi4spn },
+    { MP_QSTR_c_and,      MASK_0000FF00, MASK_0000FF00, MASK_NOT_USED, 2, CALL_RR,  RC, 0, RC,  0,  N,  0, RV32_EXT_NONE, asm_rv32_opcode_cand      },
+    { MP_QSTR_c_andi,     MASK_0000FF00, MASK_0000003F, MASK_NOT_USED, 2, CALL_RI,  RC, 0, I,   0,  N,  0, RV32_EXT_NONE, asm_rv32_opcode_candi     },
+    { MP_QSTR_c_beqz,     MASK_0000FF00, MASK_000001FE, MASK_NOT_USED, 2, CALL_RL,  RC, 0, L,   0,  N,  0, RV32_EXT_NONE, asm_rv32_opcode_cbeqz     },
+    { MP_QSTR_c_bnez,     MASK_0000FF00, MASK_000001FE, MASK_NOT_USED, 2, CALL_RL,  RC, 0, L,   0,  N,  0, RV32_EXT_NONE, asm_rv32_opcode_cbnez     },
+    { MP_QSTR_c_ebreak,   MASK_NOT_USED, MASK_NOT_USED, MASK_NOT_USED, 0, CALL_N,   N,  0, N,   0,  N,  0, RV32_EXT_NONE, asm_rv32_opcode_cebreak   },
+    { MP_QSTR_c_j,        MASK_00000FFE, MASK_NOT_USED, MASK_NOT_USED, 1, CALL_L,   L,  0, N,   0,  N,  0, RV32_EXT_NONE, asm_rv32_opcode_cj        },
+    { MP_QSTR_c_jal,      MASK_00000FFE, MASK_NOT_USED, MASK_NOT_USED, 1, CALL_L,   L,  0, N,   0,  N,  0, RV32_EXT_NONE, asm_rv32_opcode_cjal      },
+    { MP_QSTR_c_jalr,     MASK_FFFFFFFE, MASK_NOT_USED, MASK_NOT_USED, 1, CALL_R,   R,  0, N,   0,  N,  0, RV32_EXT_NONE, asm_rv32_opcode_cjalr     },
+    { MP_QSTR_c_jr,       MASK_FFFFFFFE, MASK_NOT_USED, MASK_NOT_USED, 1, CALL_R,   R,  0, N,   0,  N,  0, RV32_EXT_NONE, asm_rv32_opcode_cjr       },
+    { MP_QSTR_c_li,       MASK_FFFFFFFE, MASK_0000003F, MASK_NOT_USED, 2, CALL_RI,  R,  0, I,   0,  N,  0, RV32_EXT_NONE, asm_rv32_opcode_cli       },
+    { MP_QSTR_c_lui,      MASK_FFFFFFFA, MASK_0001F800, MASK_NOT_USED, 2, CALL_RI,  R,  0, IUZ, 12, N,  0, RV32_EXT_NONE, asm_rv32_opcode_clui      },
+    { MP_QSTR_c_lw,       MASK_0000FF00, MASK_0000007C, MASK_0000FF00, 2, CALL_RIR, RC, 0, I,   0,  RC, 0, RV32_EXT_NONE, asm_rv32_opcode_clw       },
+    { MP_QSTR_c_lwsp,     MASK_FFFFFFFE, MASK_000000FC, MASK_NOT_USED, 2, CALL_RI,  R,  0, I,   0,  N,  0, RV32_EXT_NONE, asm_rv32_opcode_clwsp     },
+    { MP_QSTR_c_mv,       MASK_FFFFFFFE, MASK_FFFFFFFE, MASK_NOT_USED, 2, CALL_RR,  R,  0, R,   0,  N,  0, RV32_EXT_NONE, asm_rv32_opcode_cmv       },
+    { MP_QSTR_c_nop,      MASK_NOT_USED, MASK_NOT_USED, MASK_NOT_USED, 0, CALL_N,   N,  0, N,   0,  N,  0, RV32_EXT_NONE, asm_rv32_opcode_cnop      },
+    { MP_QSTR_c_or,       MASK_0000FF00, MASK_0000FF00, MASK_NOT_USED, 2, CALL_RR,  RC, 0, RC,  0,  N,  0, RV32_EXT_NONE, asm_rv32_opcode_cor       },
+    { MP_QSTR_c_slli,     MASK_FFFFFFFE, MASK_0000001F, MASK_NOT_USED, 2, CALL_RI,  R,  0, IU,  0,  N,  0, RV32_EXT_NONE, asm_rv32_opcode_cslli     },
+    { MP_QSTR_c_srai,     MASK_0000FF00, MASK_0000001F, MASK_NOT_USED, 2, CALL_RI,  RC, 0, IU,  0,  N,  0, RV32_EXT_NONE, asm_rv32_opcode_csrai     },
+    { MP_QSTR_c_srli,     MASK_0000FF00, MASK_0000001F, MASK_NOT_USED, 2, CALL_RI,  RC, 0, IU,  0,  N,  0, RV32_EXT_NONE, asm_rv32_opcode_csrli     },
+    { MP_QSTR_c_sub,      MASK_0000FF00, MASK_0000FF00, MASK_NOT_USED, 2, CALL_RR,  RC, 0, RC,  0,  N,  0, RV32_EXT_NONE, asm_rv32_opcode_csub      },
+    { MP_QSTR_c_sw,       MASK_0000FF00, MASK_0000007C, MASK_0000FF00, 2, CALL_RIR, RC, 0, I,   0,  RC, 0, RV32_EXT_NONE, asm_rv32_opcode_csw       },
+    { MP_QSTR_c_swsp,     MASK_FFFFFFFF, MASK_000000FC, MASK_NOT_USED, 2, CALL_RI,  R,  0, I,   0,  N,  0, RV32_EXT_NONE, asm_rv32_opcode_cswsp     },
+    { MP_QSTR_c_xor,      MASK_0000FF00, MASK_0000FF00, MASK_NOT_USED, 2, CALL_RR,  RC, 0, RC,  0,  N,  0, RV32_EXT_NONE, asm_rv32_opcode_cxor      },
+    { MP_QSTR_div,        MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_FFFFFFFF, 3, CALL_RRR, R,  0, R,   0,  R,  0, RV32_EXT_NONE, asm_rv32_opcode_div       },
+    { MP_QSTR_divu,       MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_FFFFFFFF, 3, CALL_RRR, R,  0, R,   0,  R,  0, RV32_EXT_NONE, asm_rv32_opcode_divu      },
+    { MP_QSTR_ebreak,     MASK_NOT_USED, MASK_NOT_USED, MASK_NOT_USED, 0, CALL_N,   N,  0, N,   0,  N,  0, RV32_EXT_NONE, asm_rv32_opcode_ebreak    },
+    { MP_QSTR_ecall,      MASK_NOT_USED, MASK_NOT_USED, MASK_NOT_USED, 0, CALL_N,   N,  0, N,   0,  N,  0, RV32_EXT_NONE, asm_rv32_opcode_ecall     },
+    { MP_QSTR_jal,        MASK_FFFFFFFF, MASK_001FFFFE, MASK_NOT_USED, 2, CALL_RL,  R,  0, L,   0,  N,  0, RV32_EXT_NONE, asm_rv32_opcode_jal       },
+    { MP_QSTR_jalr,       MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_00000FFF, 3, CALL_RRI, R,  0, R,   0,  I,  0, RV32_EXT_NONE, asm_rv32_opcode_jalr      },
+    { MP_QSTR_la,         MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_NOT_USED, 2, CALL_RL,  R,  0, L,   0,  N,  0, RV32_EXT_NONE, opcode_la                 },
+    { MP_QSTR_lb,         MASK_FFFFFFFF, MASK_00000FFF, MASK_FFFFFFFF, 2, CALL_RIR, R,  0, I,   0,  R,  0, RV32_EXT_NONE, asm_rv32_opcode_lb        },
+    { MP_QSTR_lbu,        MASK_FFFFFFFF, MASK_00000FFF, MASK_FFFFFFFF, 2, CALL_RIR, R,  0, I,   0,  R,  0, RV32_EXT_NONE, asm_rv32_opcode_lbu       },
+    { MP_QSTR_lh,         MASK_FFFFFFFF, MASK_00000FFF, MASK_FFFFFFFF, 2, CALL_RIR, R,  0, I,   0,  R,  0, RV32_EXT_NONE, asm_rv32_opcode_lh        },
+    { MP_QSTR_lhu,        MASK_FFFFFFFF, MASK_00000FFF, MASK_FFFFFFFF, 2, CALL_RIR, R,  0, I,   0,  R,  0, RV32_EXT_NONE, asm_rv32_opcode_lhu       },
+    { MP_QSTR_li,         MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_NOT_USED, 2, CALL_RI,  R,  0, I,   0,  N,  0, RV32_EXT_NONE, opcode_li                 },
+    { MP_QSTR_lui,        MASK_FFFFFFFF, MASK_FFFFF000, MASK_NOT_USED, 2, CALL_RI,  R,  0, I,   12, N,  0, RV32_EXT_NONE, asm_rv32_opcode_lui       },
+    { MP_QSTR_lw,         MASK_FFFFFFFF, MASK_00000FFF, MASK_FFFFFFFF, 2, CALL_RIR, R,  0, I,   0,  R,  0, RV32_EXT_NONE, asm_rv32_opcode_lw        },
+    { MP_QSTR_mv,         MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_NOT_USED, 2, CALL_RR,  R,  0, R,   0,  N,  0, RV32_EXT_NONE, asm_rv32_opcode_cmv       },
+    { MP_QSTR_mul,        MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_FFFFFFFF, 3, CALL_RRR, R,  0, R,   0,  R,  0, RV32_EXT_NONE, asm_rv32_opcode_mul       },
+    { MP_QSTR_mulh,       MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_FFFFFFFF, 3, CALL_RRR, R,  0, R,   0,  R,  0, RV32_EXT_NONE, asm_rv32_opcode_mulh      },
+    { MP_QSTR_mulhsu,     MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_FFFFFFFF, 3, CALL_RRR, R,  0, R,   0,  R,  0, RV32_EXT_NONE, asm_rv32_opcode_mulhsu    },
+    { MP_QSTR_mulhu,      MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_FFFFFFFF, 3, CALL_RRR, R,  0, R,   0,  R,  0, RV32_EXT_NONE, asm_rv32_opcode_mulhu     },
+    { MP_QSTR_or_,        MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_FFFFFFFF, 3, CALL_RRR, R,  0, R,   0,  R,  0, RV32_EXT_NONE, asm_rv32_opcode_or        },
+    { MP_QSTR_ori,        MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_00000FFF, 3, CALL_RRI, R,  0, R,   0,  I,  0, RV32_EXT_NONE, asm_rv32_opcode_ori       },
+    { MP_QSTR_rem,        MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_FFFFFFFF, 3, CALL_RRR, R,  0, R,   0,  R,  0, RV32_EXT_NONE, asm_rv32_opcode_rem       },
+    { MP_QSTR_remu,       MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_FFFFFFFF, 3, CALL_RRR, R,  0, R,   0,  R,  0, RV32_EXT_NONE, asm_rv32_opcode_remu      },
+    { MP_QSTR_sb,         MASK_FFFFFFFF, MASK_00000FFF, MASK_FFFFFFFF, 2, CALL_RIR, R,  0, I,   0,  R,  0, RV32_EXT_NONE, asm_rv32_opcode_sb        },
+    { MP_QSTR_sh,         MASK_FFFFFFFF, MASK_00000FFF, MASK_FFFFFFFF, 2, CALL_RIR, R,  0, I,   0,  R,  0, RV32_EXT_NONE, asm_rv32_opcode_sh        },
+    { MP_QSTR_sh1add,     MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_FFFFFFFF, 3, CALL_RRR, R,  0, R,   0,  R,  0, RV32_EXT_ZBA,  asm_rv32_opcode_sh1add    },
+    { MP_QSTR_sh2add,     MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_FFFFFFFF, 3, CALL_RRR, R,  0, R,   0,  R,  0, RV32_EXT_ZBA,  asm_rv32_opcode_sh2add    },
+    { MP_QSTR_sh3add,     MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_FFFFFFFF, 3, CALL_RRR, R,  0, R,   0,  R,  0, RV32_EXT_ZBA,  asm_rv32_opcode_sh3add    },
+    { MP_QSTR_sll,        MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_FFFFFFFF, 3, CALL_RRR, R,  0, R,   0,  R,  0, RV32_EXT_NONE, asm_rv32_opcode_sll       },
+    { MP_QSTR_slli,       MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_0000001F, 3, CALL_RRI, R,  0, R,   0,  IU, 0, RV32_EXT_NONE, asm_rv32_opcode_slli      },
+    { MP_QSTR_slt,        MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_FFFFFFFF, 3, CALL_RRR, R,  0, R,   0,  R,  0, RV32_EXT_NONE, asm_rv32_opcode_slt       },
+    { MP_QSTR_slti,       MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_00000FFF, 3, CALL_RRI, R,  0, R,   0,  I,  0, RV32_EXT_NONE, asm_rv32_opcode_slti      },
+    { MP_QSTR_sltiu,      MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_00000FFF, 3, CALL_RRI, R,  0, R,   0,  I,  0, RV32_EXT_NONE, asm_rv32_opcode_sltiu     },
+    { MP_QSTR_sltu,       MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_FFFFFFFF, 3, CALL_RRR, R,  0, R,   0,  R,  0, RV32_EXT_NONE, asm_rv32_opcode_sltu      },
+    { MP_QSTR_sra,        MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_FFFFFFFF, 3, CALL_RRR, R,  0, R,   0,  R,  0, RV32_EXT_NONE, asm_rv32_opcode_sra       },
+    { MP_QSTR_srai,       MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_0000001F, 3, CALL_RRI, R,  0, R,   0,  IU, 0, RV32_EXT_NONE, asm_rv32_opcode_srai      },
+    { MP_QSTR_srl,        MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_FFFFFFFF, 3, CALL_RRR, R,  0, R,   0,  R,  0, RV32_EXT_NONE, asm_rv32_opcode_srl       },
+    { MP_QSTR_srli,       MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_0000001F, 3, CALL_RRI, R,  0, R,   0,  IU, 0, RV32_EXT_NONE, asm_rv32_opcode_srli      },
+    { MP_QSTR_sub,        MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_FFFFFFFF, 3, CALL_RRR, R,  0, R,   0,  R,  0, RV32_EXT_NONE, asm_rv32_opcode_sub       },
+    { MP_QSTR_sw,         MASK_FFFFFFFF, MASK_00000FFF, MASK_FFFFFFFF, 2, CALL_RIR, R,  0, I,   0,  R,  0, RV32_EXT_NONE, asm_rv32_opcode_sw        },
+    { MP_QSTR_xor,        MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_FFFFFFFF, 3, CALL_RRR, R,  0, R,   0,  R,  0, RV32_EXT_NONE, asm_rv32_opcode_xor       },
+    { MP_QSTR_xori,       MASK_FFFFFFFF, MASK_FFFFFFFF, MASK_00000FFF, 3, CALL_RRI, R,  0, R,   0,  I,  0, RV32_EXT_NONE, asm_rv32_opcode_xori      },
 };
 
 #undef RC
@@ -388,9 +390,9 @@ static const opcode_t OPCODES[] = {
 
 // These two checks assume the bitmasks are contiguous.
 
-static bool is_in_signed_mask(mp_uint_t mask, mp_uint_t value) {
-    mp_uint_t leading_zeroes = mp_clz(mask);
-    if (leading_zeroes == 0 || leading_zeroes > 32) {
+static bool is_in_signed_mask(uint32_t mask, mp_uint_t value) {
+    uint32_t leading_zeroes = mp_clz(mask);
+    if (leading_zeroes == 0) {
         return true;
     }
     mp_uint_t positive_mask = ~(mask & ~(1U << (31 - leading_zeroes)));
@@ -435,9 +437,9 @@ static bool validate_integer(mp_uint_t value, mp_uint_t mask, mp_uint_t flags) {
 #define ET_WRONG_ARGUMENTS_COUNT MP_ERROR_TEXT("opcode '%q': expecting %d arguments")
 #define ET_OUT_OF_RANGE          MP_ERROR_TEXT("opcode '%q' argument %d: out of range")
 
-static bool validate_argument(emit_inline_asm_t *emit, qstr opcode_qstr,
-    const opcode_t *opcode, mp_parse_node_t node, mp_uint_t node_index) {
+static bool serialise_argument(emit_inline_asm_t *emit, const opcode_t *opcode, mp_parse_node_t node, mp_uint_t node_index, mp_uint_t *serialised) {
     assert((node_index < 3) && "Invalid argument node number.");
+    assert(serialised && "Serialised value pointer is NULL.");
 
     uint32_t kind = 0;
     uint32_t shift = 0;
@@ -466,17 +468,19 @@ static bool validate_argument(emit_inline_asm_t *emit, qstr opcode_qstr,
             break;
     }
 
+    mp_uint_t serialised_value = 0;
+
     switch (kind & 0x03) {
         case N:
             assert(mask == OPCODE_MASKS[MASK_NOT_USED] && "Invalid mask index for missing operand.");
-            return true;
+            break;
 
         case R: {
             mp_uint_t register_index;
             if (!parse_register_node(node, &register_index, false)) {
                 emit_inline_rv32_error_exc(emit,
                     mp_obj_new_exception_msg_varg(&mp_type_SyntaxError,
-                        ET_WRONG_ARGUMENT_KIND, opcode_qstr, node_index + 1, MP_QSTR_register));
+                        ET_WRONG_ARGUMENT_KIND, opcode->qstring, node_index + 1, MP_QSTR_register));
                 return false;
             }
 
@@ -484,11 +488,11 @@ static bool validate_argument(emit_inline_asm_t *emit, qstr opcode_qstr,
                 emit_inline_rv32_error_exc(emit,
                     mp_obj_new_exception_msg_varg(&mp_type_SyntaxError,
                         MP_ERROR_TEXT("opcode '%q' argument %d: unknown register"),
-                        opcode_qstr, node_index + 1));
+                        opcode->qstring, node_index + 1));
                 return false;
             }
 
-            return true;
+            serialised_value = (kind & C) ? RV32_MAP_IN_C_REGISTER_WINDOW(register_index) : register_index;
         }
         break;
 
@@ -497,7 +501,7 @@ static bool validate_argument(emit_inline_asm_t *emit, qstr opcode_qstr,
             if (!mp_parse_node_get_int_maybe(node, &object)) {
                 emit_inline_rv32_error_exc(emit,
                     mp_obj_new_exception_msg_varg(&mp_type_SyntaxError,
-                        ET_WRONG_ARGUMENT_KIND, opcode_qstr, node_index + 1, MP_QSTR_integer));
+                        ET_WRONG_ARGUMENT_KIND, opcode->qstring, node_index + 1, MP_QSTR_integer));
                 return false;
             }
 
@@ -516,7 +520,7 @@ static bool validate_argument(emit_inline_asm_t *emit, qstr opcode_qstr,
                 goto zero_immediate;
             }
 
-            return true;
+            serialised_value = immediate;
         }
         break;
 
@@ -524,7 +528,7 @@ static bool validate_argument(emit_inline_asm_t *emit, qstr opcode_qstr,
             if (!MP_PARSE_NODE_IS_ID(node)) {
                 emit_inline_rv32_error_exc(emit,
                     mp_obj_new_exception_msg_varg(&mp_type_SyntaxError,
-                        ET_WRONG_ARGUMENT_KIND, opcode_qstr, node_index + 1, MP_QSTR_label));
+                        ET_WRONG_ARGUMENT_KIND, opcode->qstring, node_index + 1, MP_QSTR_label));
                 return false;
             }
 
@@ -534,7 +538,7 @@ static bool validate_argument(emit_inline_asm_t *emit, qstr opcode_qstr,
                 emit_inline_rv32_error_exc(emit,
                     mp_obj_new_exception_msg_varg(&mp_type_SyntaxError,
                         MP_ERROR_TEXT("opcode '%q' argument %d: undefined label '%q'"),
-                        opcode_qstr, node_index + 1, qstring));
+                        opcode->qstring, node_index + 1, qstring));
                 return false;
             }
 
@@ -548,43 +552,45 @@ static bool validate_argument(emit_inline_asm_t *emit, qstr opcode_qstr,
                     goto out_of_range;
                 }
             }
-            return true;
+
+            serialised_value = displacement;
         }
         break;
 
         default:
             assert(!"Unknown argument kind");
+            MP_UNREACHABLE;
             break;
     }
 
-    return false;
+    *serialised = serialised_value;
+    return true;
 
 out_of_range:
     emit_inline_rv32_error_exc(emit,
-        mp_obj_new_exception_msg_varg(&mp_type_SyntaxError, ET_OUT_OF_RANGE, opcode_qstr, node_index + 1));
+        mp_obj_new_exception_msg_varg(&mp_type_SyntaxError, ET_OUT_OF_RANGE, opcode->qstring, node_index + 1));
     return false;
 
 zero_immediate:
     emit_inline_rv32_error_exc(emit,
         mp_obj_new_exception_msg_varg(&mp_type_SyntaxError,
             MP_ERROR_TEXT("opcode '%q' argument %d: must not be zero"),
-            opcode_qstr, node_index + 1));
+            opcode->qstring, node_index + 1));
     return false;
 }
 
-static bool parse_register_offset_node(emit_inline_asm_t *emit, qstr opcode_qstr, const opcode_t *opcode_data, mp_parse_node_t node, mp_uint_t node_index, mp_parse_node_t *register_node, mp_parse_node_t *offset_node, bool *negative) {
-    assert(register_node != NULL && "Register node pointer is NULL.");
-    assert(offset_node != NULL && "Offset node pointer is NULL.");
-    assert(negative != NULL && "Negative pointer is NULL.");
+static bool serialise_register_offset_node(emit_inline_asm_t *emit, const opcode_t *opcode_data, mp_parse_node_t node, mp_uint_t node_index, mp_uint_t *offset, mp_uint_t *base) {
+    assert(offset && "Attempting to store the offset value into NULL.");
+    assert(base && "Attempting to store the base register into NULL.");
 
     if (!MP_PARSE_NODE_IS_STRUCT_KIND(node, PN_atom_expr_normal) && !MP_PARSE_NODE_IS_STRUCT_KIND(node, PN_factor_2)) {
         goto invalid_structure;
     }
     mp_parse_node_struct_t *node_struct = (mp_parse_node_struct_t *)node;
-    *negative = false;
+    bool negative = false;
     if (MP_PARSE_NODE_IS_STRUCT_KIND(node, PN_factor_2)) {
         if (MP_PARSE_NODE_IS_TOKEN_KIND(node_struct->nodes[0], MP_TOKEN_OP_MINUS)) {
-            *negative = true;
+            negative = true;
         } else {
             if (!MP_PARSE_NODE_IS_TOKEN_KIND(node_struct->nodes[0], MP_TOKEN_OP_PLUS)) {
                 goto invalid_structure;
@@ -596,186 +602,97 @@ static bool parse_register_offset_node(emit_inline_asm_t *emit, qstr opcode_qstr
         node_struct = (mp_parse_node_struct_t *)node_struct->nodes[1];
     }
 
-    if (*negative) {
+    if (negative) {
         // If the value is negative, RULE_atom_expr_normal's first token will be the
         // offset stripped of its negative marker; range check will then fail if the
         // default method is used, so a custom check is used instead.
         mp_obj_t object;
         if (!mp_parse_node_get_int_maybe(node_struct->nodes[0], &object)) {
             emit_inline_rv32_error_exc(emit,
-                mp_obj_new_exception_msg_varg(&mp_type_SyntaxError, ET_WRONG_ARGUMENT_KIND, opcode_qstr, 2, MP_QSTR_integer));
+                mp_obj_new_exception_msg_varg(&mp_type_SyntaxError, ET_WRONG_ARGUMENT_KIND, opcode_data->qstring, 2, MP_QSTR_integer));
             return false;
         }
         mp_uint_t value = mp_obj_get_int_truncated(object);
         value = (~value + 1) & (mp_uint_t)-1;
         if (!validate_integer(value << opcode_data->argument2_shift, OPCODE_MASKS[opcode_data->argument2_mask], opcode_data->argument2_kind)) {
             emit_inline_rv32_error_exc(emit,
-                mp_obj_new_exception_msg_varg(&mp_type_SyntaxError, ET_OUT_OF_RANGE, opcode_qstr, 2));
+                mp_obj_new_exception_msg_varg(&mp_type_SyntaxError, ET_OUT_OF_RANGE, opcode_data->qstring, 2));
             return false;
         }
+        *offset = value;
     } else {
-        if (!validate_argument(emit, opcode_qstr, opcode_data, node_struct->nodes[0], 1)) {
+        if (!serialise_argument(emit, opcode_data, node_struct->nodes[0], 1, offset)) {
             return false;
         }
     }
 
-    *offset_node = node_struct->nodes[0];
     node_struct = (mp_parse_node_struct_t *)node_struct->nodes[1];
-    if (!validate_argument(emit, opcode_qstr, opcode_data, node_struct->nodes[0], 2)) {
+    if (!serialise_argument(emit, opcode_data, node_struct->nodes[0], 2, base)) {
         return false;
     }
-    *register_node = node_struct->nodes[0];
     return true;
 
 invalid_structure:
     emit_inline_rv32_error_exc(emit,
         mp_obj_new_exception_msg_varg(&mp_type_SyntaxError,
-            ET_WRONG_ARGUMENT_KIND, opcode_qstr, node_index + 1, MP_QSTR_offset));
+            ET_WRONG_ARGUMENT_KIND, opcode_data->qstring, node_index + 1, MP_QSTR_offset));
     return false;
 }
 
-static void handle_opcode(emit_inline_asm_t *emit, qstr opcode, const opcode_t *opcode_data, mp_parse_node_t *arguments) {
-    mp_uint_t rd = 0;
-    mp_uint_t rs1 = 0;
-    mp_uint_t rs2 = 0;
-
+static void handle_opcode(emit_inline_asm_t *emit, const opcode_t *opcode_data, mp_uint_t *arguments) {
     switch (opcode_data->calling_convention) {
-        case CALL_RRR: {
-            parse_register_node(arguments[0], &rd, opcode_data->argument1_kind & C);
-            parse_register_node(arguments[1], &rs1, opcode_data->argument2_kind & C);
-            parse_register_node(arguments[2], &rs2, opcode_data->argument3_kind & C);
-            ((call_rrr_t)opcode_data->emitter)(&emit->as, rd, rs1, rs2);
+        case CALL_RRR:
+            ((call_rrr_t)opcode_data->emitter)(&emit->as, arguments[0], arguments[1], arguments[2]);
             break;
-        }
 
-        case CALL_RR: {
-            parse_register_node(arguments[0], &rd, opcode_data->argument1_kind & C);
-            parse_register_node(arguments[1], &rs1, opcode_data->argument2_kind & C);
-            ((call_rr_t)opcode_data->emitter)(&emit->as, rd, rs1);
+        case CALL_RR:
+            ((call_rr_t)opcode_data->emitter)(&emit->as, arguments[0], arguments[1]);
             break;
-        }
 
-        case CALL_RRI: {
-            parse_register_node(arguments[0], &rd, opcode_data->argument1_kind & C);
-            parse_register_node(arguments[1], &rs1, opcode_data->argument2_kind & C);
-            mp_obj_t object;
-            mp_parse_node_get_int_maybe(arguments[2], &object);
-            mp_uint_t immediate = mp_obj_get_int_truncated(object) << opcode_data->argument3_shift;
-            ((call_rri_t)opcode_data->emitter)(&emit->as, rd, rs1, immediate);
+        case CALL_RRI:
+            ((call_rri_t)opcode_data->emitter)(&emit->as, arguments[0], arguments[1], arguments[2]);
             break;
-        }
 
-        case CALL_RI: {
-            parse_register_node(arguments[0], &rd, opcode_data->argument1_kind & C);
-            mp_obj_t object;
-            mp_parse_node_get_int_maybe(arguments[1], &object);
-            mp_uint_t immediate = mp_obj_get_int_truncated(object) << opcode_data->argument2_shift;
-            ((call_ri_t)opcode_data->emitter)(&emit->as, rd, immediate);
+        case CALL_RI:
+            ((call_ri_t)opcode_data->emitter)(&emit->as, arguments[0], arguments[1]);
             break;
-        }
 
-        case CALL_R: {
-            parse_register_node(arguments[0], &rd, opcode_data->argument1_kind & C);
-            ((call_r_t)opcode_data->emitter)(&emit->as, rd);
+        case CALL_R:
+            ((call_r_t)opcode_data->emitter)(&emit->as, arguments[0]);
             break;
-        }
 
-        case CALL_RRL: {
-            parse_register_node(arguments[0], &rd, opcode_data->argument1_kind & C);
-            parse_register_node(arguments[1], &rs1, opcode_data->argument2_kind & C);
-            qstr qstring;
-            mp_uint_t label_index = lookup_label(emit, arguments[2], &qstring);
-            ptrdiff_t displacement = label_code_offset(emit, label_index);
-            ((call_rri_t)opcode_data->emitter)(&emit->as, rd, rs1, displacement);
+        case CALL_RRL:
+            ((call_rri_t)opcode_data->emitter)(&emit->as, arguments[0], arguments[1], (ptrdiff_t)arguments[2]);
             break;
-        }
 
-        case CALL_RL: {
-            parse_register_node(arguments[0], &rd, opcode_data->argument1_kind & C);
-            qstr qstring;
-            mp_uint_t label_index = lookup_label(emit, arguments[1], &qstring);
-            ptrdiff_t displacement = label_code_offset(emit, label_index);
-            ((call_ri_t)opcode_data->emitter)(&emit->as, rd, displacement);
+        case CALL_RL:
+            ((call_ri_t)opcode_data->emitter)(&emit->as, arguments[0], (ptrdiff_t)arguments[1]);
             break;
-        }
 
-        case CALL_L: {
-            qstr qstring;
-            mp_uint_t label_index = lookup_label(emit, arguments[0], &qstring);
-            ptrdiff_t displacement = label_code_offset(emit, label_index);
-            ((call_i_t)opcode_data->emitter)(&emit->as, displacement);
+        case CALL_L:
+            ((call_i_t)opcode_data->emitter)(&emit->as, (ptrdiff_t)arguments[0]);
             break;
-        }
 
         case CALL_N:
             ((call_n_t)opcode_data->emitter)(&emit->as);
             break;
 
-        case CALL_I: {
-            mp_obj_t object;
-            mp_parse_node_get_int_maybe(arguments[0], &object);
-            mp_uint_t immediate = mp_obj_get_int_truncated(object) << opcode_data->argument1_shift;
-            ((call_i_t)opcode_data->emitter)(&emit->as, immediate);
+        case CALL_RII:
+            ((call_rii_t)opcode_data->emitter)(&emit->as, arguments[0], arguments[1], arguments[2]);
             break;
-        }
-
-        case CALL_RII: {
-            parse_register_node(arguments[0], &rd, opcode_data->argument1_kind & C);
-            mp_obj_t object;
-            mp_parse_node_get_int_maybe(arguments[1], &object);
-            mp_uint_t immediate1 = mp_obj_get_int_truncated(object) << opcode_data->argument2_shift;
-            mp_parse_node_get_int_maybe(arguments[2], &object);
-            mp_uint_t immediate2 = mp_obj_get_int_truncated(object) << opcode_data->argument3_shift;
-            ((call_rii_t)opcode_data->emitter)(&emit->as, rd, immediate1, immediate2);
-            break;
-        }
 
         case CALL_RIR:
-            assert(!"Should not get here.");
+            // The last two arguments indices are swapped on purpose.
+            ((call_rri_t)opcode_data->emitter)(&emit->as, arguments[0], arguments[2], arguments[1]);
             break;
 
         default:
             assert(!"Unhandled call convention.");
+            MP_UNREACHABLE;
             break;
     }
 }
 
-static bool handle_load_store_opcode_with_offset(emit_inline_asm_t *emit, qstr opcode, const opcode_t *opcode_data, mp_parse_node_t *argument_nodes) {
-    mp_parse_node_t nodes[3] = {0};
-    if (!validate_argument(emit, opcode, opcode_data, argument_nodes[0], 0)) {
-        return false;
-    }
-    nodes[0] = argument_nodes[0];
-    bool negative = false;
-    if (!parse_register_offset_node(emit, opcode, opcode_data, argument_nodes[1], 1, &nodes[1], &nodes[2], &negative)) {
-        return false;
-    }
-
-    mp_uint_t rd = 0;
-    mp_uint_t rs1 = 0;
-    if (!parse_register_node(nodes[0], &rd, opcode_data->argument1_kind & C)) {
-        return false;
-    }
-    if (!parse_register_node(nodes[1], &rs1, opcode_data->argument3_kind & C)) {
-        return false;
-    }
-
-    mp_obj_t object;
-    mp_parse_node_get_int_maybe(nodes[2], &object);
-    mp_uint_t immediate = mp_obj_get_int_truncated(object) << opcode_data->argument2_shift;
-    if (negative) {
-        immediate = (~immediate + 1) & (mp_uint_t)-1;
-    }
-    if (!is_in_signed_mask(OPCODE_MASKS[opcode_data->argument2_mask], immediate)) {
-        emit_inline_rv32_error_exc(emit,
-            mp_obj_new_exception_msg_varg(&mp_type_SyntaxError, ET_OUT_OF_RANGE, opcode, 2));
-        return false;
-    }
-
-    ((call_rri_t)opcode_data->emitter)(&emit->as, rd, rs1, immediate);
-    return true;
-}
-
 static void emit_inline_rv32_opcode(emit_inline_asm_t *emit, qstr opcode, mp_uint_t arguments_count, mp_parse_node_t *argument_nodes) {
     const opcode_t *opcode_data = NULL;
     for (mp_uint_t index = 0; index < MP_ARRAY_SIZE(OPCODES); index++) {
@@ -785,10 +702,9 @@ static void emit_inline_rv32_opcode(emit_inline_asm_t *emit, qstr opcode, mp_uin
         }
     }
 
-    if (!opcode_data) {
-        emit_inline_rv32_error_exc(emit,
-            mp_obj_new_exception_msg_varg(&mp_type_SyntaxError,
-                MP_ERROR_TEXT("unknown RV32 instruction '%q'"), opcode));
+    if (!opcode_data || (asm_rv32_allowed_extensions() & opcode_data->required_extensions) != opcode_data->required_extensions) {
+        emit_inline_rv32_error_exc(emit, mp_obj_new_exception_msg_varg(&mp_type_SyntaxError,
+            MP_ERROR_TEXT("invalid RV32 instruction '%q'"), opcode));
         return;
     }
 
@@ -796,36 +712,36 @@ static void emit_inline_rv32_opcode(emit_inline_asm_t *emit, qstr opcode, mp_uin
     assert((opcode_data->argument2_mask < MP_ARRAY_SIZE(OPCODE_MASKS)) && "Argument #2 opcode mask index out of bounds.");
     assert((opcode_data->argument3_mask < MP_ARRAY_SIZE(OPCODE_MASKS)) && "Argument #3 opcode mask index out of bounds.");
     assert((opcode_data->calling_convention < CALL_COUNT) && "Calling convention index out of bounds.");
-    if (opcode_data->calling_convention != CALL_RIR) {
-        if (opcode_data->arguments_count != arguments_count) {
-            emit_inline_rv32_error_exc(emit,
-                mp_obj_new_exception_msg_varg(&mp_type_SyntaxError,
-                    ET_WRONG_ARGUMENTS_COUNT, opcode, opcode_data->arguments_count));
-            return;
-        }
-        if (opcode_data->arguments_count >= 1 && !validate_argument(emit, opcode, opcode_data, argument_nodes[0], 0)) {
+    mp_uint_t serialised_arguments[3] = { 0 };
+    if (arguments_count != opcode_data->parse_nodes) {
+        emit_inline_rv32_error_exc(emit,
+            mp_obj_new_exception_msg_varg(&mp_type_SyntaxError,
+                ET_WRONG_ARGUMENTS_COUNT, opcode, opcode_data->parse_nodes));
+        return;
+    }
+
+    if (opcode_data->parse_nodes >= 1 && !serialise_argument(emit, opcode_data, argument_nodes[0], 0, &serialised_arguments[0])) {
+        return;
+    }
+    if (opcode_data->calling_convention == CALL_RIR) {
+        // "register, offset(base)" calls require some preprocessing to
+        // split the offset and base nodes - not to mention that if the offset
+        // is negative, the parser won't see the offset as a single node but as
+        // a sequence of the minus sign token followed by the number itself.
+
+        if (!serialise_register_offset_node(emit, opcode_data, argument_nodes[1], 1, &serialised_arguments[1], &serialised_arguments[2])) {
             return;
         }
-        if (opcode_data->arguments_count >= 2 && !validate_argument(emit, opcode, opcode_data, argument_nodes[1], 1)) {
+    } else {
+        if (opcode_data->parse_nodes >= 2 && !serialise_argument(emit, opcode_data, argument_nodes[1], 1, &serialised_arguments[1])) {
             return;
         }
-        if (opcode_data->arguments_count >= 3 && !validate_argument(emit, opcode, opcode_data, argument_nodes[2], 2)) {
+        if (opcode_data->parse_nodes >= 3 && !serialise_argument(emit, opcode_data, argument_nodes[2], 2, &serialised_arguments[2])) {
             return;
         }
-        handle_opcode(emit, opcode, opcode_data, argument_nodes);
-        return;
-    }
-
-    assert((opcode_data->argument2_kind & U) == 0 && "Offset must not be unsigned.");
-    assert((opcode_data->argument2_kind & Z) == 0 && "Offset can be zero.");
-
-    if (arguments_count != 2) {
-        emit_inline_rv32_error_exc(emit,
-            mp_obj_new_exception_msg_varg(&mp_type_SyntaxError, ET_WRONG_ARGUMENTS_COUNT, opcode, 2));
-        return;
     }
 
-    handle_load_store_opcode_with_offset(emit, opcode, opcode_data, argument_nodes);
+    handle_opcode(emit, opcode_data, serialised_arguments);
 }
 
 #undef N
diff --git a/py/emitinlinextensa.c b/py/emitinlinextensa.c
index fed259cfc6b20..d0eb3d566fce3 100644
--- a/py/emitinlinextensa.c
+++ b/py/emitinlinextensa.c
@@ -173,7 +173,7 @@ static int get_arg_label(emit_inline_asm_t *emit, const char *op, mp_parse_node_
 #define RRI8_B (2)
 
 typedef struct _opcode_table_3arg_t {
-    uint16_t name; // actually a qstr, which should fit in 16 bits
+    qstr_short_t name;
     uint8_t type;
     uint8_t a0 : 4;
     uint8_t a1 : 4;
@@ -187,6 +187,13 @@ static const opcode_table_3arg_t opcode_table_3arg[] = {
     {MP_QSTR_add, RRR, 0, 8},
     {MP_QSTR_sub, RRR, 0, 12},
     {MP_QSTR_mull, RRR, 2, 8},
+    {MP_QSTR_addx2, RRR, 0, 9},
+    {MP_QSTR_addx4, RRR, 0, 10},
+    {MP_QSTR_addx8, RRR, 0, 11},
+    {MP_QSTR_subx2, RRR, 0, 13},
+    {MP_QSTR_subx4, RRR, 0, 14},
+    {MP_QSTR_subx8, RRR, 0, 15},
+    {MP_QSTR_src, RRR, 1, 8},
 
     // load/store/addi opcodes: reg, reg, imm
     // upper nibble of type encodes the range of the immediate arg
@@ -208,21 +215,62 @@ static const opcode_table_3arg_t opcode_table_3arg[] = {
     {MP_QSTR_bge, RRI8_B, ASM_XTENSA_CC_GE, 0},
     {MP_QSTR_bgeu, RRI8_B, ASM_XTENSA_CC_GEU, 0},
     {MP_QSTR_blt, RRI8_B, ASM_XTENSA_CC_LT, 0},
+    {MP_QSTR_bltu, RRI8_B, ASM_XTENSA_CC_LTU, 0},
     {MP_QSTR_bnall, RRI8_B, ASM_XTENSA_CC_NALL, 0},
     {MP_QSTR_bne, RRI8_B, ASM_XTENSA_CC_NE, 0},
     {MP_QSTR_bnone, RRI8_B, ASM_XTENSA_CC_NONE, 0},
 };
 
+// The index of the first four qstrs matches the CCZ condition value to be
+// embedded into the opcode.
+static const qstr_short_t BCCZ_OPCODES[] = {
+    MP_QSTR_beqz, MP_QSTR_bnez, MP_QSTR_bltz, MP_QSTR_bgez,
+    MP_QSTR_beqz_n, MP_QSTR_bnez_n
+};
+
+#if MICROPY_EMIT_INLINE_XTENSA_UNCOMMON_OPCODES
+typedef struct _single_opcode_t {
+    qstr_short_t name;
+    uint16_t value;
+} single_opcode_t;
+
+static const single_opcode_t NOARGS_OPCODES[] = {
+    {MP_QSTR_dsync, 0x2030},
+    {MP_QSTR_esync, 0x2020},
+    {MP_QSTR_extw,  0x20D0},
+    {MP_QSTR_ill,   0x0000},
+    {MP_QSTR_isync, 0x2000},
+    {MP_QSTR_memw,  0x20C0},
+    {MP_QSTR_rsync, 0x2010},
+};
+#endif
+
 static void emit_inline_xtensa_op(emit_inline_asm_t *emit, qstr op, mp_uint_t n_args, mp_parse_node_t *pn_args) {
     size_t op_len;
     const char *op_str = (const char *)qstr_data(op, &op_len);
 
     if (n_args == 0) {
-        if (op == MP_QSTR_ret_n) {
+        if (op == MP_QSTR_ret_n || op == MP_QSTR_ret) {
             asm_xtensa_op_ret_n(&emit->as);
-        } else {
-            goto unknown_op;
+            return;
+        } else if (op == MP_QSTR_nop) {
+            asm_xtensa_op24(&emit->as, 0x20F0);
+            return;
+        } else if (op == MP_QSTR_nop_n) {
+            asm_xtensa_op16(&emit->as, 0xF03D);
+            return;
         }
+        #if MICROPY_EMIT_INLINE_XTENSA_UNCOMMON_OPCODES
+        for (size_t index = 0; index < MP_ARRAY_SIZE(NOARGS_OPCODES); index++) {
+            const single_opcode_t *opcode = &NOARGS_OPCODES[index];
+            if (op == opcode->name) {
+                asm_xtensa_op24(&emit->as, opcode->value);
+                return;
+            }
+        }
+        #endif
+
+        goto unknown_op;
 
     } else if (n_args == 1) {
         if (op == MP_QSTR_callx0) {
@@ -234,19 +282,45 @@ static void emit_inline_xtensa_op(emit_inline_asm_t *emit, qstr op, mp_uint_t n_
         } else if (op == MP_QSTR_jx) {
             uint r0 = get_arg_reg(emit, op_str, pn_args[0]);
             asm_xtensa_op_jx(&emit->as, r0);
+        } else if (op == MP_QSTR_ssl) {
+            mp_uint_t r0 = get_arg_reg(emit, op_str, pn_args[0]);
+            asm_xtensa_op_ssl(&emit->as, r0);
+        } else if (op == MP_QSTR_ssr) {
+            mp_uint_t r0 = get_arg_reg(emit, op_str, pn_args[0]);
+            asm_xtensa_op_ssr(&emit->as, r0);
+        } else if (op == MP_QSTR_ssai) {
+            mp_uint_t sa = get_arg_i(emit, op_str, pn_args[0], 0, 31);
+            asm_xtensa_op24(&emit->as, ASM_XTENSA_ENCODE_RRR(0, 0, 4, 4, sa & 0x0F, (sa >> 4) & 0x01));
+        } else if (op == MP_QSTR_ssa8b) {
+            mp_uint_t r0 = get_arg_reg(emit, op_str, pn_args[0]);
+            asm_xtensa_op24(&emit->as, ASM_XTENSA_ENCODE_RRR(0, 0, 4, 3, r0, 0));
+        } else if (op == MP_QSTR_ssa8l) {
+            mp_uint_t r0 = get_arg_reg(emit, op_str, pn_args[0]);
+            asm_xtensa_op24(&emit->as, ASM_XTENSA_ENCODE_RRR(0, 0, 4, 2, r0, 0));
+        } else if (op == MP_QSTR_call0) {
+            mp_uint_t label = get_arg_label(emit, op_str, pn_args[0]);
+            asm_xtensa_call0(&emit->as, label);
+        #if MICROPY_EMIT_INLINE_XTENSA_UNCOMMON_OPCODES
+        } else if (op == MP_QSTR_fsync) {
+            mp_uint_t imm3 = get_arg_i(emit, op_str, pn_args[0], 0, 7);
+            asm_xtensa_op24(&emit->as, ASM_XTENSA_ENCODE_RRR(0, 0, 0, 2, 8 | imm3, 0));
+        } else if (op == MP_QSTR_ill_n) {
+            asm_xtensa_op16(&emit->as, 0xF06D);
+        #endif
         } else {
             goto unknown_op;
         }
 
     } else if (n_args == 2) {
         uint r0 = get_arg_reg(emit, op_str, pn_args[0]);
-        if (op == MP_QSTR_beqz) {
-            int label = get_arg_label(emit, op_str, pn_args[1]);
-            asm_xtensa_bccz_reg_label(&emit->as, ASM_XTENSA_CCZ_EQ, r0, label);
-        } else if (op == MP_QSTR_bnez) {
-            int label = get_arg_label(emit, op_str, pn_args[1]);
-            asm_xtensa_bccz_reg_label(&emit->as, ASM_XTENSA_CCZ_NE, r0, label);
-        } else if (op == MP_QSTR_mov || op == MP_QSTR_mov_n) {
+        for (size_t index = 0; index < MP_ARRAY_SIZE(BCCZ_OPCODES); index++) {
+            if (op == BCCZ_OPCODES[index]) {
+                mp_uint_t label = get_arg_label(emit, op_str, pn_args[1]);
+                asm_xtensa_bccz_reg_label(&emit->as, index & 0x03, r0, label);
+                return;
+            }
+        }
+        if (op == MP_QSTR_mov || op == MP_QSTR_mov_n) {
             // we emit mov.n for both "mov" and "mov_n" opcodes
             uint r1 = get_arg_reg(emit, op_str, pn_args[1]);
             asm_xtensa_op_mov_n(&emit->as, r0, r1);
@@ -254,7 +328,53 @@ static void emit_inline_xtensa_op(emit_inline_asm_t *emit, qstr op, mp_uint_t n_
             // for convenience we emit l32r if the integer doesn't fit in movi
             uint32_t imm = get_arg_i(emit, op_str, pn_args[1], 0, 0);
             asm_xtensa_mov_reg_i32(&emit->as, r0, imm);
-        } else {
+        } else if (op == MP_QSTR_abs_) {
+            mp_uint_t r1 = get_arg_reg(emit, op_str, pn_args[1]);
+            asm_xtensa_op24(&emit->as, ASM_XTENSA_ENCODE_RRR(0, 0, 6, r0, 1, r1));
+        } else if (op == MP_QSTR_neg) {
+            mp_uint_t r1 = get_arg_reg(emit, op_str, pn_args[1]);
+            asm_xtensa_op24(&emit->as, ASM_XTENSA_ENCODE_RRR(0, 0, 6, r0, 0, r1));
+        } else if (op == MP_QSTR_sll) {
+            mp_uint_t r1 = get_arg_reg(emit, op_str, pn_args[1]);
+            asm_xtensa_op24(&emit->as, ASM_XTENSA_ENCODE_RRR(0, 1, 10, r0, r1, 0));
+        } else if (op == MP_QSTR_sra) {
+            mp_uint_t r1 = get_arg_reg(emit, op_str, pn_args[1]);
+            asm_xtensa_op24(&emit->as, ASM_XTENSA_ENCODE_RRR(0, 1, 11, r0, 0, r1));
+        } else if (op == MP_QSTR_srl) {
+            mp_uint_t r1 = get_arg_reg(emit, op_str, pn_args[1]);
+            asm_xtensa_op24(&emit->as, ASM_XTENSA_ENCODE_RRR(0, 1, 9, r0, 0, r1));
+        } else if (op == MP_QSTR_nsa) {
+            mp_uint_t r1 = get_arg_reg(emit, op_str, pn_args[1]);
+            asm_xtensa_op24(&emit->as, ASM_XTENSA_ENCODE_RRR(0, 0, 4, 14, r1, r0));
+        } else if (op == MP_QSTR_nsau) {
+            mp_uint_t r1 = get_arg_reg(emit, op_str, pn_args[1]);
+            asm_xtensa_op24(&emit->as, ASM_XTENSA_ENCODE_RRR(0, 0, 4, 15, r1, r0));
+        } else if (op == MP_QSTR_l32r) {
+            mp_uint_t label = get_arg_label(emit, op_str, pn_args[1]);
+            asm_xtensa_l32r(&emit->as, r0, label);
+        } else if (op == MP_QSTR_movi_n) {
+            mp_int_t imm = get_arg_i(emit, op_str, pn_args[1], -32, 95);
+            asm_xtensa_op_movi_n(&emit->as, r0, imm);
+        } else
+        #if MICROPY_EMIT_INLINE_XTENSA_UNCOMMON_OPCODES
+        if (op == MP_QSTR_rsr) {
+            mp_uint_t sr = get_arg_i(emit, op_str, pn_args[1], 0, 255);
+            asm_xtensa_op24(&emit->as, ASM_XTENSA_ENCODE_RSR(0, 3, 0, sr, r0));
+        } else if (op == MP_QSTR_rur) {
+            mp_uint_t imm8 = get_arg_i(emit, op_str, pn_args[1], 0, 255);
+            asm_xtensa_op24(&emit->as, ASM_XTENSA_ENCODE_RRR(0, 3, 14, r0, (imm8 >> 4) & 0x0F, imm8 & 0x0F));
+        } else if (op == MP_QSTR_wsr) {
+            mp_uint_t sr = get_arg_i(emit, op_str, pn_args[1], 0, 255);
+            asm_xtensa_op24(&emit->as, ASM_XTENSA_ENCODE_RSR(0, 3, 1, sr, r0));
+        } else if (op == MP_QSTR_wur) {
+            mp_uint_t sr = get_arg_i(emit, op_str, pn_args[1], 0, 255);
+            asm_xtensa_op24(&emit->as, ASM_XTENSA_ENCODE_RSR(0, 3, 15, sr, r0));
+        } else if (op == MP_QSTR_xsr) {
+            mp_uint_t sr = get_arg_i(emit, op_str, pn_args[1], 0, 255);
+            asm_xtensa_op24(&emit->as, ASM_XTENSA_ENCODE_RSR(0, 1, 6, sr, r0));
+        } else
+        #endif
+        {
             goto unknown_op;
         }
 
@@ -288,7 +408,72 @@ static void emit_inline_xtensa_op(emit_inline_asm_t *emit, qstr op, mp_uint_t n_
                 return;
             }
         }
-        goto unknown_op;
+
+        if (op == MP_QSTR_add_n) {
+            mp_uint_t r0 = get_arg_reg(emit, op_str, pn_args[0]);
+            mp_uint_t r1 = get_arg_reg(emit, op_str, pn_args[1]);
+            mp_uint_t r2 = get_arg_reg(emit, op_str, pn_args[2]);
+            asm_xtensa_op16(&emit->as, ASM_XTENSA_ENCODE_RRRN(10, r0, r1, r2));
+        } else if (op == MP_QSTR_addi_n) {
+            mp_uint_t r0 = get_arg_reg(emit, op_str, pn_args[0]);
+            mp_uint_t r1 = get_arg_reg(emit, op_str, pn_args[1]);
+            mp_int_t imm4 = get_arg_i(emit, op_str, pn_args[2], -1, 15);
+            asm_xtensa_op16(&emit->as, ASM_XTENSA_ENCODE_RRRN(11, r0, r1, (imm4 != 0 ? imm4 : -1)));
+        } else if (op == MP_QSTR_addmi) {
+            mp_uint_t r0 = get_arg_reg(emit, op_str, pn_args[0]);
+            mp_uint_t r1 = get_arg_reg(emit, op_str, pn_args[1]);
+            mp_int_t imm8 = get_arg_i(emit, op_str, pn_args[2], -128 * 256, 127 * 256);
+            if ((imm8 & 0xFF) != 0) {
+                emit_inline_xtensa_error_exc(emit, mp_obj_new_exception_msg_varg(&mp_type_SyntaxError, MP_ERROR_TEXT("%d is not a multiple of %d"), imm8, 256));
+            } else {
+                asm_xtensa_op24(&emit->as, ASM_XTENSA_ENCODE_RRI8(2, 13, r1, r0, imm8 >> 8));
+            }
+        } else if (op == MP_QSTR_bbci) {
+            mp_uint_t r0 = get_arg_reg(emit, op_str, pn_args[0]);
+            mp_uint_t bit = get_arg_i(emit, op_str, pn_args[1], 0, 31);
+            mp_int_t label = get_arg_label(emit, op_str, pn_args[2]);
+            asm_xtensa_bit_branch(&emit->as, r0, bit, label, 6);
+        } else if (op == MP_QSTR_bbsi) {
+            mp_uint_t r0 = get_arg_reg(emit, op_str, pn_args[0]);
+            mp_uint_t bit = get_arg_i(emit, op_str, pn_args[1], 0, 31);
+            mp_uint_t label = get_arg_label(emit, op_str, pn_args[2]);
+            asm_xtensa_bit_branch(&emit->as, r0, bit, label, 14);
+        } else if (op == MP_QSTR_slli) {
+            mp_uint_t r0 = get_arg_reg(emit, op_str, pn_args[0]);
+            mp_uint_t r1 = get_arg_reg(emit, op_str, pn_args[1]);
+            mp_uint_t bits = 32 - get_arg_i(emit, op_str, pn_args[2], 1, 31);
+            asm_xtensa_op24(&emit->as, ASM_XTENSA_ENCODE_RRR(0, 1, 0 | ((bits >> 4) & 0x01), r0, r1, bits & 0x0F));
+        } else if (op == MP_QSTR_srai) {
+            mp_uint_t r0 = get_arg_reg(emit, op_str, pn_args[0]);
+            mp_uint_t r1 = get_arg_reg(emit, op_str, pn_args[1]);
+            mp_uint_t bits = get_arg_i(emit, op_str, pn_args[2], 0, 31);
+            asm_xtensa_op24(&emit->as, ASM_XTENSA_ENCODE_RRR(0, 1, 2 | ((bits >> 4) & 0x01), r0, bits & 0x0F, r1));
+        } else if (op == MP_QSTR_srli) {
+            mp_uint_t r0 = get_arg_reg(emit, op_str, pn_args[0]);
+            mp_uint_t r1 = get_arg_reg(emit, op_str, pn_args[1]);
+            mp_uint_t bits = get_arg_i(emit, op_str, pn_args[2], 0, 15);
+            asm_xtensa_op24(&emit->as, ASM_XTENSA_ENCODE_RRR(0, 1, 4, r0, bits, r1));
+        } else if (op == MP_QSTR_l32i_n) {
+            mp_uint_t r0 = get_arg_reg(emit, op_str, pn_args[0]);
+            mp_uint_t r1 = get_arg_reg(emit, op_str, pn_args[1]);
+            mp_uint_t imm = get_arg_i(emit, op_str, pn_args[2], 0, 60);
+            if ((imm & 0x03) != 0) {
+                emit_inline_xtensa_error_exc(emit, mp_obj_new_exception_msg_varg(&mp_type_SyntaxError, MP_ERROR_TEXT("%d is not a multiple of %d"), imm, 4));
+            } else {
+                asm_xtensa_op_l32i_n(&emit->as, r0, r1, imm >> 2);
+            }
+        } else if (op == MP_QSTR_s32i_n) {
+            mp_uint_t r0 = get_arg_reg(emit, op_str, pn_args[0]);
+            mp_uint_t r1 = get_arg_reg(emit, op_str, pn_args[1]);
+            mp_uint_t imm = get_arg_i(emit, op_str, pn_args[2], 0, 60);
+            if ((imm & 0x03) != 0) {
+                emit_inline_xtensa_error_exc(emit, mp_obj_new_exception_msg_varg(&mp_type_SyntaxError, MP_ERROR_TEXT("%d is not a multiple of %d"), imm, 4));
+            } else {
+                asm_xtensa_op_s32i_n(&emit->as, r0, r1, imm >> 2);
+            }
+        } else {
+            goto unknown_op;
+        }
 
     } else {
         goto unknown_op;
diff --git a/py/emitnative.c b/py/emitnative.c
index a888418e5dfed..6f12200f7e171 100644
--- a/py/emitnative.c
+++ b/py/emitnative.c
@@ -222,12 +222,6 @@ static const uint8_t reg_local_table[MAX_REGS_FOR_LOCAL_VARS] = {REG_LOCAL_1, RE
         *emit->error_slot = mp_obj_new_exception_msg_varg(&mp_type_ViperTypeError, __VA_ARGS__); \
 } while (0)
 
-#if N_RV32
-#define FIT_SIGNED(value, bits)                                                                                     \
-    ((((value) & ~((1U << ((bits) - 1)) - 1)) == 0) ||                                      \
-    (((value) & ~((1U << ((bits) - 1)) - 1)) == ~((1U << ((bits) - 1)) - 1)))
-#endif
-
 typedef enum {
     STACK_VALUE,
     STACK_REG,
@@ -335,12 +329,27 @@ struct _emit_t {
 #define ASM_CLR_REG(state, rd) ASM_XOR_REG_REG(state, rd, rd)
 #endif
 
+#if N_RV32
+#define ASM_MOV_LOCAL_MP_OBJ_NULL(as, local_num, reg_temp) \
+    ASM_MOV_LOCAL_REG(as, local_num, REG_ZERO)
+#else
+#define ASM_MOV_LOCAL_MP_OBJ_NULL(as, local_num, reg_temp) \
+    ASM_MOV_REG_IMM(as, reg_temp, (mp_uint_t)MP_OBJ_NULL); \
+    ASM_MOV_LOCAL_REG(as, local_num, reg_temp)
+#endif
+
 static void emit_load_reg_with_object(emit_t *emit, int reg, mp_obj_t obj);
 static void emit_native_global_exc_entry(emit_t *emit);
 static void emit_native_global_exc_exit(emit_t *emit);
 static void emit_native_load_const_obj(emit_t *emit, mp_obj_t obj);
 
 emit_t *EXPORT_FUN(new)(mp_emit_common_t * emit_common, mp_obj_t *error_slot, uint *label_slot, mp_uint_t max_num_labels) {
+    // Generated code performing exception handling assumes that MP_OBJ_NULL
+    // equals to 0 to simplify some checks, leveraging dedicated opcodes for
+    // comparisons against 0.  If this assumption does not hold true anymore
+    // then generated code won't work correctly.
+    MP_STATIC_ASSERT(MP_OBJ_NULL == 0);
+
     emit_t *emit = m_new0(emit_t, 1);
     emit->emit_common = emit_common;
     emit->error_slot = error_slot;
@@ -467,6 +476,30 @@ static void emit_native_start_pass(emit_t *emit, pass_kind_t pass, scope_t *scop
         emit->stack_info[i].vtype = VTYPE_UNBOUND;
     }
 
+    char *qualified_name = NULL;
+
+    #if N_DEBUG
+    scope_t *current_scope = scope;
+    vstr_t *qualified_name_vstr = vstr_new(qstr_len(current_scope->simple_name));
+    size_t fragment_length = 0;
+    const byte *fragment_pointer;
+    for (;;) {
+        fragment_pointer = qstr_data(current_scope->simple_name, &fragment_length);
+        vstr_hint_size(qualified_name_vstr, fragment_length);
+        memmove(qualified_name_vstr->buf + fragment_length, qualified_name_vstr->buf, qualified_name_vstr->len);
+        memcpy(qualified_name_vstr->buf, fragment_pointer, fragment_length);
+        qualified_name_vstr->len += fragment_length;
+        if (current_scope->parent == NULL || current_scope->parent->simple_name == MP_QSTR__lt_module_gt_) {
+            break;
+        }
+        vstr_ins_char(qualified_name_vstr, 0, '.');
+        current_scope = current_scope->parent;
+    }
+    qualified_name = vstr_null_terminated_str(qualified_name_vstr);
+    #else
+    (void)qualified_name;
+    #endif
+
     mp_asm_base_start_pass(&emit->as->base, pass == MP_PASS_EMIT ? MP_ASM_PASS_EMIT : MP_ASM_PASS_COMPUTE);
 
     // generate code for entry to function
@@ -513,7 +546,7 @@ static void emit_native_start_pass(emit_t *emit, pass_kind_t pass, scope_t *scop
         }
 
         // Entry to function
-        ASM_ENTRY(emit->as, emit->stack_start + emit->n_state - num_locals_in_regs);
+        ASM_ENTRY(emit->as, emit->stack_start + emit->n_state - num_locals_in_regs, qualified_name);
 
         #if N_X86
         asm_x86_mov_arg_to_r32(emit->as, 0, REG_PARENT_ARG_1);
@@ -584,7 +617,7 @@ static void emit_native_start_pass(emit_t *emit, pass_kind_t pass, scope_t *scop
 
         if (emit->scope->scope_flags & MP_SCOPE_FLAG_GENERATOR) {
             mp_asm_base_data(&emit->as->base, ASM_WORD_SIZE, (uintptr_t)emit->start_offset);
-            ASM_ENTRY(emit->as, emit->code_state_start);
+            ASM_ENTRY(emit->as, emit->code_state_start, qualified_name);
 
             // Reset the state size for the state pointed to by REG_GENERATOR_STATE
             emit->code_state_start = 0;
@@ -616,7 +649,7 @@ static void emit_native_start_pass(emit_t *emit, pass_kind_t pass, scope_t *scop
             emit->stack_start = emit->code_state_start + SIZEOF_CODE_STATE;
 
             // Allocate space on C-stack for code_state structure, which includes state
-            ASM_ENTRY(emit->as, emit->stack_start + emit->n_state);
+            ASM_ENTRY(emit->as, emit->stack_start + emit->n_state, qualified_name);
 
             // Prepare incoming arguments for call to mp_setup_code_state
 
@@ -682,6 +715,10 @@ static void emit_native_start_pass(emit_t *emit, pass_kind_t pass, scope_t *scop
             }
         }
     }
+
+    #if N_DEBUG
+    vstr_free(qualified_name_vstr);
+    #endif
 }
 
 static inline void emit_native_write_code_info_byte(emit_t *emit, byte val) {
@@ -1311,8 +1348,7 @@ static void emit_native_global_exc_entry(emit_t *emit) {
 
             // Check LOCAL_IDX_THROW_VAL for any injected value
             ASM_MOV_REG_LOCAL(emit->as, REG_ARG_1, LOCAL_IDX_THROW_VAL(emit));
-            ASM_MOV_REG_IMM(emit->as, REG_ARG_2, (mp_uint_t)MP_OBJ_NULL);
-            ASM_MOV_LOCAL_REG(emit->as, LOCAL_IDX_THROW_VAL(emit), REG_ARG_2);
+            ASM_MOV_LOCAL_MP_OBJ_NULL(emit->as, LOCAL_IDX_THROW_VAL(emit), REG_ARG_2);
             emit_call(emit, MP_F_NATIVE_RAISE);
         }
     }
@@ -1579,87 +1615,50 @@ static void emit_native_load_subscr(emit_t *emit) {
             switch (vtype_base) {
                 case VTYPE_PTR8: {
                     // pointer to 8-bit memory
-                    // TODO optimise to use thumb ldrb r1, [r2, r3]
+                    #ifdef ASM_LOAD8_REG_REG_OFFSET
+                    ASM_LOAD8_REG_REG_OFFSET(emit->as, REG_RET, reg_base, index_value);
+                    #else
                     if (index_value != 0) {
                         // index is non-zero
-                        #if N_THUMB
-                        if (index_value > 0 && index_value < 32) {
-                            asm_thumb_ldrb_rlo_rlo_i5(emit->as, REG_RET, reg_base, index_value);
-                            break;
-                        }
-                        #elif N_RV32
-                        if (FIT_SIGNED(index_value, 12)) {
-                            asm_rv32_opcode_lbu(emit->as, REG_RET, reg_base, index_value);
-                            break;
-                        }
-                        #elif N_XTENSA || N_XTENSAWIN
-                        if (index_value > 0 && index_value < 256) {
-                            asm_xtensa_op_l8ui(emit->as, REG_RET, reg_base, index_value);
-                            break;
-                        }
-                        #endif
                         need_reg_single(emit, reg_index, 0);
                         ASM_MOV_REG_IMM(emit->as, reg_index, index_value);
                         ASM_ADD_REG_REG(emit->as, reg_index, reg_base); // add index to base
                         reg_base = reg_index;
                     }
                     ASM_LOAD8_REG_REG(emit->as, REG_RET, reg_base); // load from (base+index)
+                    #endif
                     break;
                 }
                 case VTYPE_PTR16: {
                     // pointer to 16-bit memory
+                    #ifdef ASM_LOAD16_REG_REG_OFFSET
+                    ASM_LOAD16_REG_REG_OFFSET(emit->as, REG_RET, reg_base, index_value);
+                    #else
                     if (index_value != 0) {
                         // index is a non-zero immediate
-                        #if N_THUMB
-                        if (index_value > 0 && index_value < 32) {
-                            asm_thumb_ldrh_rlo_rlo_i5(emit->as, REG_RET, reg_base, index_value);
-                            break;
-                        }
-                        #elif N_RV32
-                        if (FIT_SIGNED(index_value, 11)) {
-                            asm_rv32_opcode_lhu(emit->as, REG_RET, reg_base, index_value << 1);
-                            break;
-                        }
-                        #elif N_XTENSA || N_XTENSAWIN
-                        if (index_value > 0 && index_value < 256) {
-                            asm_xtensa_op_l16ui(emit->as, REG_RET, reg_base, index_value);
-                            break;
-                        }
-                        #endif
                         need_reg_single(emit, reg_index, 0);
                         ASM_MOV_REG_IMM(emit->as, reg_index, index_value << 1);
                         ASM_ADD_REG_REG(emit->as, reg_index, reg_base); // add 2*index to base
                         reg_base = reg_index;
                     }
                     ASM_LOAD16_REG_REG(emit->as, REG_RET, reg_base); // load from (base+2*index)
+                    #endif
                     break;
                 }
                 case VTYPE_PTR32: {
                     // pointer to 32-bit memory
+                    #ifdef ASM_LOAD32_REG_REG_OFFSET
+                    ASM_LOAD32_REG_REG_OFFSET(emit->as, REG_RET, reg_base, index_value);
+                    #else
                     if (index_value != 0) {
                         // index is a non-zero immediate
-                        #if N_THUMB
-                        if (index_value > 0 && index_value < 32) {
-                            asm_thumb_ldr_rlo_rlo_i5(emit->as, REG_RET, reg_base, index_value);
-                            break;
-                        }
-                        #elif N_RV32
-                        if (FIT_SIGNED(index_value, 10)) {
-                            asm_rv32_opcode_lw(emit->as, REG_RET, reg_base, index_value << 2);
-                            break;
-                        }
-                        #elif N_XTENSA || N_XTENSAWIN
-                        if (index_value > 0 && index_value < 256) {
-                            asm_xtensa_l32i_optimised(emit->as, REG_RET, reg_base, index_value);
-                            break;
-                        }
-                        #endif
                         need_reg_single(emit, reg_index, 0);
                         ASM_MOV_REG_IMM(emit->as, reg_index, index_value << 2);
                         ASM_ADD_REG_REG(emit->as, reg_index, reg_base); // add 4*index to base
                         reg_base = reg_index;
                     }
                     ASM_LOAD32_REG_REG(emit->as, REG_RET, reg_base); // load from (base+4*index)
+                    #endif
                     break;
                 }
                 default:
@@ -1680,40 +1679,36 @@ static void emit_native_load_subscr(emit_t *emit) {
             switch (vtype_base) {
                 case VTYPE_PTR8: {
                     // pointer to 8-bit memory
-                    // TODO optimise to use thumb ldrb r1, [r2, r3]
+                    #ifdef ASM_LOAD8_REG_REG_REG
+                    ASM_LOAD8_REG_REG_REG(emit->as, REG_RET, REG_ARG_1, reg_index);
+                    #else
                     ASM_ADD_REG_REG(emit->as, REG_ARG_1, reg_index); // add index to base
                     ASM_LOAD8_REG_REG(emit->as, REG_RET, REG_ARG_1); // store value to (base+index)
+                    #endif
                     break;
                 }
                 case VTYPE_PTR16: {
                     // pointer to 16-bit memory
-                    #if N_XTENSA || N_XTENSAWIN
-                    asm_xtensa_op_addx2(emit->as, REG_ARG_1, reg_index, REG_ARG_1);
-                    asm_xtensa_op_l16ui(emit->as, REG_RET, REG_ARG_1, 0);
-                    break;
-                    #endif
+                    #ifdef ASM_LOAD16_REG_REG_REG
+                    ASM_LOAD16_REG_REG_REG(emit->as, REG_RET, REG_ARG_1, reg_index);
+                    #else
                     ASM_ADD_REG_REG(emit->as, REG_ARG_1, reg_index); // add index to base
                     ASM_ADD_REG_REG(emit->as, REG_ARG_1, reg_index); // add index to base
                     ASM_LOAD16_REG_REG(emit->as, REG_RET, REG_ARG_1); // load from (base+2*index)
+                    #endif
                     break;
                 }
                 case VTYPE_PTR32: {
                     // pointer to word-size memory
-                    #if N_RV32
-                    asm_rv32_opcode_slli(emit->as, REG_TEMP2, reg_index, 2);
-                    asm_rv32_opcode_cadd(emit->as, REG_ARG_1, REG_TEMP2);
-                    asm_rv32_opcode_lw(emit->as, REG_RET, REG_ARG_1, 0);
-                    break;
-                    #elif N_XTENSA || N_XTENSAWIN
-                    asm_xtensa_op_addx4(emit->as, REG_ARG_1, reg_index, REG_ARG_1);
-                    asm_xtensa_op_l32i_n(emit->as, REG_RET, REG_ARG_1, 0);
-                    break;
-                    #endif
+                    #ifdef ASM_LOAD32_REG_REG_REG
+                    ASM_LOAD32_REG_REG_REG(emit->as, REG_RET, REG_ARG_1, reg_index);
+                    #else
                     ASM_ADD_REG_REG(emit->as, REG_ARG_1, reg_index); // add index to base
                     ASM_ADD_REG_REG(emit->as, REG_ARG_1, reg_index); // add index to base
                     ASM_ADD_REG_REG(emit->as, REG_ARG_1, reg_index); // add index to base
                     ASM_ADD_REG_REG(emit->as, REG_ARG_1, reg_index); // add index to base
                     ASM_LOAD32_REG_REG(emit->as, REG_RET, REG_ARG_1); // load from (base+4*index)
+                    #endif
                     break;
                 }
                 default:
@@ -1856,92 +1851,47 @@ static void emit_native_store_subscr(emit_t *emit) {
             switch (vtype_base) {
                 case VTYPE_PTR8: {
                     // pointer to 8-bit memory
-                    // TODO optimise to use thumb strb r1, [r2, r3]
+                    #ifdef ASM_STORE8_REG_REG_OFFSET
+                    ASM_STORE8_REG_REG_OFFSET(emit->as, reg_value, reg_base, index_value);
+                    #else
                     if (index_value != 0) {
                         // index is non-zero
-                        #if N_THUMB
-                        if (index_value > 0 && index_value < 32) {
-                            asm_thumb_strb_rlo_rlo_i5(emit->as, reg_value, reg_base, index_value);
-                            break;
-                        }
-                        #elif N_RV32
-                        if (FIT_SIGNED(index_value, 12)) {
-                            asm_rv32_opcode_sb(emit->as, reg_value, reg_base, index_value);
-                            break;
-                        }
-                        #elif N_XTENSA || N_XTENSAWIN
-                        if (index_value > 0 && index_value < 256) {
-                            asm_xtensa_op_s8i(emit->as, REG_RET, reg_base, index_value);
-                            break;
-                        }
-                        #endif
                         ASM_MOV_REG_IMM(emit->as, reg_index, index_value);
-                        #if N_ARM
-                        asm_arm_strb_reg_reg_reg(emit->as, reg_value, reg_base, reg_index);
-                        return;
-                        #endif
                         ASM_ADD_REG_REG(emit->as, reg_index, reg_base); // add index to base
                         reg_base = reg_index;
                     }
                     ASM_STORE8_REG_REG(emit->as, reg_value, reg_base); // store value to (base+index)
+                    #endif
                     break;
                 }
                 case VTYPE_PTR16: {
                     // pointer to 16-bit memory
+                    #ifdef ASM_STORE16_REG_REG_OFFSET
+                    ASM_STORE16_REG_REG_OFFSET(emit->as, reg_value, reg_base, index_value);
+                    #else
                     if (index_value != 0) {
                         // index is a non-zero immediate
-                        #if N_THUMB
-                        if (index_value > 0 && index_value < 32) {
-                            asm_thumb_strh_rlo_rlo_i5(emit->as, reg_value, reg_base, index_value);
-                            break;
-                        }
-                        #elif N_RV32
-                        if (FIT_SIGNED(index_value, 11)) {
-                            asm_rv32_opcode_sh(emit->as, reg_value, reg_base, index_value << 1);
-                            break;
-                        }
-                        #elif N_XTENSA || N_XTENSAWIN
-                        if (index_value > 0 && index_value < 256) {
-                            asm_xtensa_op_s16i(emit->as, REG_RET, reg_base, index_value);
-                            break;
-                        }
-                        #endif
                         ASM_MOV_REG_IMM(emit->as, reg_index, index_value << 1);
                         ASM_ADD_REG_REG(emit->as, reg_index, reg_base); // add 2*index to base
                         reg_base = reg_index;
                     }
                     ASM_STORE16_REG_REG(emit->as, reg_value, reg_base); // store value to (base+2*index)
+                    #endif
                     break;
                 }
                 case VTYPE_PTR32: {
                     // pointer to 32-bit memory
+                    #ifdef ASM_STORE32_REG_REG_OFFSET
+                    ASM_STORE32_REG_REG_OFFSET(emit->as, reg_value, reg_base, index_value);
+                    #else
                     if (index_value != 0) {
                         // index is a non-zero immediate
-                        #if N_THUMB
-                        if (index_value > 0 && index_value < 32) {
-                            asm_thumb_str_rlo_rlo_i5(emit->as, reg_value, reg_base, index_value);
-                            break;
-                        }
-                        #elif N_RV32
-                        if (FIT_SIGNED(index_value, 10)) {
-                            asm_rv32_opcode_sw(emit->as, reg_value, reg_base, index_value << 2);
-                            break;
-                        }
-                        #elif N_XTENSA || N_XTENSAWIN
-                        if (index_value > 0 && index_value < 256) {
-                            asm_xtensa_s32i_optimised(emit->as, REG_RET, reg_base, index_value);
-                            break;
-                        }
-                        #elif N_ARM
-                        ASM_MOV_REG_IMM(emit->as, reg_index, index_value);
-                        asm_arm_str_reg_reg_reg(emit->as, reg_value, reg_base, reg_index);
-                        return;
-                        #endif
                         ASM_MOV_REG_IMM(emit->as, reg_index, index_value << 2);
                         ASM_ADD_REG_REG(emit->as, reg_index, reg_base); // add 4*index to base
                         reg_base = reg_index;
                     }
                     ASM_STORE32_REG_REG(emit->as, reg_value, reg_base); // store value to (base+4*index)
+                    #endif
                     break;
                 }
                 default:
@@ -1972,50 +1922,36 @@ static void emit_native_store_subscr(emit_t *emit) {
             switch (vtype_base) {
                 case VTYPE_PTR8: {
                     // pointer to 8-bit memory
-                    // TODO optimise to use thumb strb r1, [r2, r3]
-                    #if N_ARM
-                    asm_arm_strb_reg_reg_reg(emit->as, reg_value, REG_ARG_1, reg_index);
-                    break;
-                    #endif
+                    #ifdef ASM_STORE8_REG_REG_REG
+                    ASM_STORE8_REG_REG_REG(emit->as, reg_value, REG_ARG_1, reg_index);
+                    #else
                     ASM_ADD_REG_REG(emit->as, REG_ARG_1, reg_index); // add index to base
                     ASM_STORE8_REG_REG(emit->as, reg_value, REG_ARG_1); // store value to (base+index)
+                    #endif
                     break;
                 }
                 case VTYPE_PTR16: {
                     // pointer to 16-bit memory
-                    #if N_ARM
-                    asm_arm_strh_reg_reg_reg(emit->as, reg_value, REG_ARG_1, reg_index);
-                    break;
-                    #elif N_XTENSA || N_XTENSAWIN
-                    asm_xtensa_op_addx2(emit->as, REG_ARG_1, reg_index, REG_ARG_1);
-                    asm_xtensa_op_s16i(emit->as, reg_value, REG_ARG_1, 0);
-                    break;
-                    #endif
+                    #ifdef ASM_STORE16_REG_REG_REG
+                    ASM_STORE16_REG_REG_REG(emit->as, reg_value, REG_ARG_1, reg_index);
+                    #else
                     ASM_ADD_REG_REG(emit->as, REG_ARG_1, reg_index); // add index to base
                     ASM_ADD_REG_REG(emit->as, REG_ARG_1, reg_index); // add index to base
                     ASM_STORE16_REG_REG(emit->as, reg_value, REG_ARG_1); // store value to (base+2*index)
+                    #endif
                     break;
                 }
                 case VTYPE_PTR32: {
                     // pointer to 32-bit memory
-                    #if N_ARM
-                    asm_arm_str_reg_reg_reg(emit->as, reg_value, REG_ARG_1, reg_index);
-                    break;
-                    #elif N_RV32
-                    asm_rv32_opcode_slli(emit->as, REG_TEMP2, reg_index, 2);
-                    asm_rv32_opcode_cadd(emit->as, REG_ARG_1, REG_TEMP2);
-                    asm_rv32_opcode_sw(emit->as, reg_value, REG_ARG_1, 0);
-                    break;
-                    #elif N_XTENSA || N_XTENSAWIN
-                    asm_xtensa_op_addx4(emit->as, REG_ARG_1, reg_index, REG_ARG_1);
-                    asm_xtensa_op_s32i_n(emit->as, reg_value, REG_ARG_1, 0);
-                    break;
-                    #endif
+                    #ifdef ASM_STORE32_REG_REG_REG
+                    ASM_STORE32_REG_REG_REG(emit->as, reg_value, REG_ARG_1, reg_index);
+                    #else
                     ASM_ADD_REG_REG(emit->as, REG_ARG_1, reg_index); // add index to base
                     ASM_ADD_REG_REG(emit->as, REG_ARG_1, reg_index); // add index to base
                     ASM_ADD_REG_REG(emit->as, REG_ARG_1, reg_index); // add index to base
                     ASM_ADD_REG_REG(emit->as, REG_ARG_1, reg_index); // add index to base
                     ASM_STORE32_REG_REG(emit->as, reg_value, REG_ARG_1); // store value to (base+4*index)
+                    #endif
                     break;
                 }
                 default:
@@ -2328,8 +2264,7 @@ static void emit_native_with_cleanup(emit_t *emit, mp_uint_t label) {
 
     // Replace exception with MP_OBJ_NULL.
     emit_native_label_assign(emit, *emit->label_slot);
-    ASM_MOV_REG_IMM(emit->as, REG_TEMP0, (mp_uint_t)MP_OBJ_NULL);
-    ASM_MOV_LOCAL_REG(emit->as, LOCAL_IDX_EXC_VAL(emit), REG_TEMP0);
+    ASM_MOV_LOCAL_MP_OBJ_NULL(emit->as, LOCAL_IDX_EXC_VAL(emit), REG_TEMP0);
 
     // end of with cleanup nlr_catch block
     emit_native_label_assign(emit, *emit->label_slot + 1);
@@ -2436,8 +2371,7 @@ static void emit_native_for_iter_end(emit_t *emit) {
 static void emit_native_pop_except_jump(emit_t *emit, mp_uint_t label, bool within_exc_handler) {
     if (within_exc_handler) {
         // Cancel any active exception so subsequent handlers don't see it
-        ASM_MOV_REG_IMM(emit->as, REG_TEMP0, (mp_uint_t)MP_OBJ_NULL);
-        ASM_MOV_LOCAL_REG(emit->as, LOCAL_IDX_EXC_VAL(emit), REG_TEMP0);
+        ASM_MOV_LOCAL_MP_OBJ_NULL(emit->as, LOCAL_IDX_EXC_VAL(emit), REG_TEMP0);
     } else {
         emit_native_leave_exc_stack(emit, false);
     }
@@ -3122,8 +3056,7 @@ static void emit_native_yield(emit_t *emit, int kind) {
     if (kind == MP_EMIT_YIELD_VALUE) {
         // Check LOCAL_IDX_THROW_VAL for any injected value
         ASM_MOV_REG_LOCAL(emit->as, REG_ARG_1, LOCAL_IDX_THROW_VAL(emit));
-        ASM_MOV_REG_IMM(emit->as, REG_ARG_2, (mp_uint_t)MP_OBJ_NULL);
-        ASM_MOV_LOCAL_REG(emit->as, LOCAL_IDX_THROW_VAL(emit), REG_ARG_2);
+        ASM_MOV_LOCAL_MP_OBJ_NULL(emit->as, LOCAL_IDX_THROW_VAL(emit), REG_ARG_2);
         emit_call(emit, MP_F_NATIVE_RAISE);
     } else {
         // Label loop entry
diff --git a/py/emitndebug.c b/py/emitndebug.c
index bd896a75c8ddf..e49c5cdbffa7b 100644
--- a/py/emitndebug.c
+++ b/py/emitndebug.c
@@ -108,8 +108,8 @@ static void asm_debug_end_pass(asm_debug_t *as) {
     (void)as;
 }
 
-static void asm_debug_entry(asm_debug_t *as, int num_locals) {
-    asm_debug_printf(as, "ENTRY(num_locals=%d)\n", num_locals);
+static void asm_debug_entry(asm_debug_t *as, int num_locals, char *name) {
+    asm_debug_printf(as, "ENTRY(%s, num_locals=%d)\n", name != NULL ? name : "?", num_locals);
 }
 
 static void asm_debug_exit(asm_debug_t *as) {
@@ -195,8 +195,8 @@ static void asm_debug_setcc_reg_reg_reg(asm_debug_t *as, int op, int reg1, int r
 
 #define ASM_T               asm_debug_t
 #define ASM_END_PASS        asm_debug_end_pass
-#define ASM_ENTRY(as, num_locals) \
-    asm_debug_entry(as, num_locals)
+#define ASM_ENTRY(as, num_locals, name) \
+    asm_debug_entry(as, num_locals, name)
 #define ASM_EXIT(as) \
     asm_debug_exit(as)
 
@@ -251,8 +251,6 @@ static void asm_debug_setcc_reg_reg_reg(asm_debug_t *as, int op, int reg1, int r
 #define ASM_MUL_REG_REG(as, reg_dest, reg_src) \
     asm_debug_reg_reg(as, "mul", reg_dest, reg_src)
 
-#define ASM_LOAD_REG_REG(as, reg_dest, reg_base) \
-    asm_debug_reg_reg(as, "load", reg_dest, reg_base)
 #define ASM_LOAD_REG_REG_OFFSET(as, reg_dest, reg_base, word_offset) \
     asm_debug_reg_reg_offset(as, "load", reg_dest, reg_base, word_offset)
 #define ASM_LOAD8_REG_REG(as, reg_dest, reg_base) \
@@ -264,8 +262,6 @@ static void asm_debug_setcc_reg_reg_reg(asm_debug_t *as, int op, int reg1, int r
 #define ASM_LOAD32_REG_REG(as, reg_dest, reg_base) \
     asm_debug_reg_reg(as, "load32", reg_dest, reg_base)
 
-#define ASM_STORE_REG_REG(as, reg_src, reg_base) \
-    asm_debug_reg_reg(as, "store", reg_src, reg_base)
 #define ASM_STORE_REG_REG_OFFSET(as, reg_src, reg_base, word_offset) \
     asm_debug_reg_reg_offset(as, "store", reg_src, reg_base, word_offset)
 #define ASM_STORE8_REG_REG(as, reg_src, reg_base) \
diff --git a/py/formatfloat.c b/py/formatfloat.c
index b4348122ff428..1ea34f84bf7fb 100644
--- a/py/formatfloat.c
+++ b/py/formatfloat.c
@@ -33,394 +33,537 @@
 #include <stdint.h>
 #include <math.h>
 #include "py/formatfloat.h"
+#include "py/parsenum.h"
 
 /***********************************************************************
 
   Routine for converting a arbitrary floating
   point number into a string.
 
-  The code in this function was inspired from Fred Bayer's pdouble.c.
-  Since pdouble.c was released as Public Domain, I'm releasing this
-  code as public domain as well.
+  The code in this function was inspired from Dave Hylands's previous
+  version, which was itself inspired from Fred Bayer's pdouble.c.
 
   The original code can be found in https://github.com/dhylands/format-float
 
-  Dave Hylands
-
 ***********************************************************************/
 
-#if MICROPY_FLOAT_IMPL == MICROPY_FLOAT_IMPL_FLOAT
-// 1 sign bit, 8 exponent bits, and 23 mantissa bits.
-// exponent values 0 and 255 are reserved, exponent can be 1 to 254.
-// exponent is stored with a bias of 127.
-// The min and max floats are on the order of 1x10^37 and 1x10^-37
-
-#define FPTYPE float
-#define FPCONST(x) x##F
-#define FPROUND_TO_ONE 0.9999995F
-#define FPDECEXP 32
-#define FPMIN_BUF_SIZE 6 // +9e+99
+// Float formatting debug code is intended for use in ports/unix only,
+// as it uses the libc float printing function as a reference.
+#define DEBUG_FLOAT_FORMATTING 0
+
+#if DEBUG_FLOAT_FORMATTING
+#define DEBUG_PRINTF(...) fprintf(stderr, __VA_ARGS__)
+#else
+#define DEBUG_PRINTF(...)
+#endif
+
+#if MICROPY_FLOAT_FORMAT_IMPL == MICROPY_FLOAT_FORMAT_IMPL_EXACT || MICROPY_FLOAT_IMPL == MICROPY_FLOAT_IMPL_DOUBLE
+#define MP_FFUINT_FMT "%lu"
+#else
+#define MP_FFUINT_FMT "%u"
+#endif
+
+static inline int fp_expval(mp_float_t x) {
+    mp_float_union_t fb = { x };
+    return (int)fb.p.exp - MP_FLOAT_EXP_OFFSET;
+}
 
-#define FLT_SIGN_MASK   0x80000000
+#if MICROPY_FLOAT_IMPL == MICROPY_FLOAT_IMPL_DOUBLE
 
-static inline int fp_signbit(float x) {
-    mp_float_union_t fb = {x};
-    return fb.i & FLT_SIGN_MASK;
+static inline int fp_isless1(mp_float_t x) {
+    return x < 1.0;
 }
-#define fp_isnan(x) isnan(x)
-#define fp_isinf(x) isinf(x)
-static inline int fp_iszero(float x) {
-    mp_float_union_t fb = {x};
-    return fb.i == 0;
+
+static inline int fp_iszero(mp_float_t x) {
+    return x == 0.0;
 }
-static inline int fp_isless1(float x) {
-    mp_float_union_t fb = {x};
+
+#if MICROPY_FLOAT_FORMAT_IMPL != MICROPY_FLOAT_FORMAT_IMPL_APPROX
+static inline int fp_equal(mp_float_t x, mp_float_t y) {
+    return x == y;
+}
+#else
+static inline mp_float_t fp_diff(mp_float_t x, mp_float_t y) {
+    return x - y;
+}
+#endif
+
+#elif MICROPY_FLOAT_IMPL == MICROPY_FLOAT_IMPL_FLOAT
+
+// The functions below are roughly equivalent to the ones above,
+// but they are optimized to reduce code footprint by skipping
+// handling for special values such as nan, inf, +/-0.0
+// for ports where FP support is done in software.
+//
+// They also take into account lost bits of REPR_C as needed.
+
+static inline int fp_isless1(mp_float_t x) {
+    mp_float_union_t fb = { x };
     return fb.i < 0x3f800000;
 }
 
-#elif MICROPY_FLOAT_IMPL == MICROPY_FLOAT_IMPL_DOUBLE
+static inline int fp_iszero(mp_float_t x) {
+    mp_float_union_t x_check = { x };
+    return !x_check.i; // this is valid for REPR_C as well
+}
 
-// CIRCUITPY-CHANGE: prevent warnings
-#pragma GCC diagnostic ignored "-Wfloat-equal"
-#define FPTYPE double
-#define FPCONST(x) x
-#define FPROUND_TO_ONE 0.999999999995
-#define FPDECEXP 256
-#define FPMIN_BUF_SIZE 7 // +9e+199
-#define fp_signbit(x) signbit(x)
-#define fp_isnan(x) isnan(x)
-#define fp_isinf(x) isinf(x)
-#define fp_iszero(x) (x == 0)
-#define fp_isless1(x) (x < 1.0)
+#if MICROPY_FLOAT_FORMAT_IMPL != MICROPY_FLOAT_FORMAT_IMPL_APPROX
+static inline int fp_equal(mp_float_t x, mp_float_t y) {
+    mp_float_union_t x_check = { x };
+    mp_float_union_t y_check = { y };
+    #if MICROPY_OBJ_REPR == MICROPY_OBJ_REPR_C
+    return (x_check.i & ~3) == (y_check.i & ~3);
+    #else
+    return x_check.i == y_check.i;
+    #endif
+}
+#else
+static inline mp_float_t fp_diff(mp_float_t x, mp_float_t y) {
+    #if MICROPY_OBJ_REPR == MICROPY_OBJ_REPR_C
+    mp_float_union_t x_check = { x };
+    mp_float_union_t y_check = { y };
+    x_check.i &= ~3;
+    y_check.i &= ~3;
+    return x_check.f - y_check.f;
+    #else
+    return x - y;
+    #endif
+}
+#endif
 
-#endif // MICROPY_FLOAT_IMPL == MICROPY_FLOAT_IMPL_FLOAT/DOUBLE
+#endif
 
-static inline int fp_expval(FPTYPE x) {
-    mp_float_union_t fb = {x};
-    return (int)((fb.i >> MP_FLOAT_FRAC_BITS) & (~(0xFFFFFFFF << MP_FLOAT_EXP_BITS))) - MP_FLOAT_EXP_OFFSET;
+#if MICROPY_FLOAT_IMPL == MICROPY_FLOAT_IMPL_FLOAT
+#define FPMIN_BUF_SIZE 6 // +9e+99
+#define MAX_MANTISSA_DIGITS  (9)
+#define SAFE_MANTISSA_DIGITS (6)
+#elif MICROPY_FLOAT_IMPL == MICROPY_FLOAT_IMPL_DOUBLE
+#define FPMIN_BUF_SIZE 7 // +9e+199
+#define MAX_MANTISSA_DIGITS  (19)
+#define SAFE_MANTISSA_DIGITS (16)
+#endif
+
+// Internal formatting flags
+#define FMT_MODE_E 0x01  // render using scientific notation (%e)
+#define FMT_MODE_G 0x02  // render using general format (%g)
+#define FMT_MODE_F 0x04  // render using using expanded fixed-point format (%f)
+#define FMT_E_CASE 0x20  // don't change this value (used for case conversion!)
+
+static char *mp_prepend_zeros(char *s, int cnt) {
+    *s++ = '0';
+    *s++ = '.';
+    while (cnt > 0) {
+        *s++ = '0';
+        cnt--;
+    }
+    return s;
 }
 
-int mp_format_float(FPTYPE f, char *buf, size_t buf_size, char fmt, int prec, char sign) {
+// Helper to convert a decimal mantissa (provided as an mp_large_float_uint_t) to string
+static int mp_format_mantissa(mp_large_float_uint_t mantissa, mp_large_float_uint_t mantissa_cap, char *buf, char *s,
+    int num_digits, int max_exp_zeros, int trailing_zeros, int dec, int e, int fmt_flags) {
 
-    char *s = buf;
+    DEBUG_PRINTF("mantissa=" MP_FFUINT_FMT " exp=%d (cap=" MP_FFUINT_FMT "):\n", mantissa, e, mantissa_cap);
 
-    if (buf_size <= FPMIN_BUF_SIZE) {
-        // FPMIN_BUF_SIZE is the minimum size needed to store any FP number.
-        // If the buffer does not have enough room for this (plus null terminator)
-        // then don't try to format the float.
+    if (mantissa) {
+        // If rounding/searching created an extra digit or removed too many, fix mantissa first
+        if (mantissa >= mantissa_cap) {
+            if (fmt_flags & FMT_MODE_F) {
+                assert(e >= 0);
+                num_digits++;
+                dec++;
+            } else {
+                mantissa /= 10;
+                e++;
+            }
+        }
+    }
 
-        if (buf_size >= 2) {
-            *s++ = '?';
+    // When 'g' format is used, replace small exponents by explicit zeros
+    if ((fmt_flags & FMT_MODE_G) && e != 0) {
+        if (e >= 0) {
+            // If 0 < e < max_exp_zeros, expand positive exponent into trailing zeros
+            if (e < max_exp_zeros) {
+                dec += e;
+                if (dec >= num_digits) {
+                    trailing_zeros = dec - (num_digits - 1);
+                }
+                e = 0;
+            }
+        } else {
+            // If -4 <= e < 0, expand negative exponent without losing significant digits
+            if (e >= -4) {
+                int cnt = 0;
+                while (e < 0 && !(mantissa % 10)) {
+                    mantissa /= 10;
+                    cnt++;
+                    e++;
+                }
+                num_digits -= cnt;
+                s = mp_prepend_zeros(s, cnt - e - 1);
+                dec = 255;
+                e = 0;
+            }
         }
-        if (buf_size >= 1) {
-            *s = '\0';
+    }
+
+    // Convert the integer mantissa to string
+    for (int digit = num_digits - 1; digit >= 0; digit--) {
+        int digit_ofs = (digit > dec ? digit + 1 : digit);
+        s[digit_ofs] = '0' + (int)(mantissa % 10);
+        mantissa /= 10;
+    }
+    int dot = (dec >= 255);
+    if (dec + 1 < num_digits) {
+        dot = 1;
+        s++;
+        s[dec] = '.';
+    }
+    s += num_digits;
+    #if DEBUG_FLOAT_FORMATTING
+    *s = 0;
+    DEBUG_PRINTF("  =      %s exp=%d num_digits=%d zeros=%d dec=%d\n", buf, e, num_digits, trailing_zeros, dec);
+    #endif
+
+    // Append or remove trailing zeros, as required by format
+    if (trailing_zeros) {
+        dec -= num_digits - 1;
+        while (trailing_zeros--) {
+            if (!dec--) {
+                *s++ = '.';
+                dot = 1;
+            }
+            *s++ = '0';
         }
-        return buf_size >= 2;
     }
-    if (fp_signbit(f) && !fp_isnan(f)) {
-        *s++ = '-';
-        f = -f;
-    } else {
-        if (sign) {
-            *s++ = sign;
+    if (fmt_flags & FMT_MODE_G) {
+        // 'g' format requires to remove trailing zeros after decimal point
+        if (dot) {
+            while (s[-1] == '0') {
+                s--;
+            }
+            if (s[-1] == '.') {
+                s--;
+            }
+        }
+    }
+
+    // Append the exponent if needed
+    if (((e != 0) || (fmt_flags & FMT_MODE_E)) && !(fmt_flags & FMT_MODE_F)) {
+        *s++ = 'E' | (fmt_flags & FMT_E_CASE);
+        if (e >= 0) {
+            *s++ = '+';
+        } else {
+            *s++ = '-';
+            e = -e;
         }
+        if (e >= 100) {
+            *s++ = '0' + (e / 100);
+        }
+        *s++ = '0' + ((e / 10) % 10);
+        *s++ = '0' + (e % 10);
     }
+    *s = '\0';
+    DEBUG_PRINTF("  ===>   %s\n", buf);
 
-    // buf_remaining contains bytes available for digits and exponent.
-    // It is buf_size minus room for the sign and null byte.
-    int buf_remaining = buf_size - 1 - (s - buf);
+    return s - buf;
+}
 
+// minimal value expected for buf_size, to avoid checking everywhere for overflow
+#define MIN_BUF_SIZE (MAX_MANTISSA_DIGITS + 10)
+
+int mp_format_float(mp_float_t f_entry, char *buf_entry, size_t buf_size, char fmt, int prec, char sign) {
+    assert(buf_size >= MIN_BUF_SIZE);
+
+    // Handle sign
+    mp_float_t f = f_entry;
+    char *buf = buf_entry;
+    if (signbit(f_entry) && !isnan(f_entry)) {
+        f = -f;
+        sign = '-';
+    }
+    if (sign) {
+        *buf++ = sign;
+        buf_size--;
+    }
+
+    // Handle inf/nan
+    char uc = fmt & 0x20;
     {
-        char uc = fmt & 0x20;
-        if (fp_isinf(f)) {
+        char *s = buf;
+        if (isinf(f)) {
             *s++ = 'I' ^ uc;
             *s++ = 'N' ^ uc;
             *s++ = 'F' ^ uc;
             goto ret;
-        } else if (fp_isnan(f)) {
+        } else if (isnan(f)) {
             *s++ = 'N' ^ uc;
             *s++ = 'A' ^ uc;
             *s++ = 'N' ^ uc;
         ret:
             *s = '\0';
-            return s - buf;
+            return s - buf_entry;
         }
     }
 
+    // Decode format character
+    int fmt_flags = (unsigned char)uc;  // setup FMT_E_CASE, clear all other bits
+    char lofmt = (char)(fmt | 0x20);  // fmt in lowercase
+    if (lofmt == 'f') {
+        fmt_flags |= FMT_MODE_F;
+    } else if (lofmt == 'g') {
+        fmt_flags |= FMT_MODE_G;
+    } else {
+        fmt_flags |= FMT_MODE_E;
+    }
+
+    // When precision is unspecified, default to 6
     if (prec < 0) {
         prec = 6;
     }
-    char e_char = 'E' | (fmt & 0x20);   // e_char will match case of fmt
-    fmt |= 0x20; // Force fmt to be lowercase
-    char org_fmt = fmt;
-    if (fmt == 'g' && prec == 0) {
-        prec = 1;
+    // Use high precision for `repr`, but switch to exponent mode
+    // after 16 digits in any case to match CPython behaviour
+    int max_exp_zeros = (prec < (int)buf_size - 3 ? prec : (int)buf_size - 3);
+    if (prec == MP_FLOAT_REPR_PREC) {
+        prec = MAX_MANTISSA_DIGITS;
+        max_exp_zeros = 16;
     }
-    int e;
-    int dec = 0;
-    char e_sign = '\0';
-    int num_digits = 0;
-    int signed_e = 0;
 
-    // Approximate power of 10 exponent from binary exponent.
-    // abs(e_guess) is lower bound on abs(power of 10 exponent).
-    int e_guess = (int)(fp_expval(f) * FPCONST(0.3010299956639812));  // 1/log2(10).
-    if (fp_iszero(f)) {
-        e = 0;
-        if (fmt == 'f') {
-            // Truncate precision to prevent buffer overflow
-            if (prec + 2 > buf_remaining) {
-                prec = buf_remaining - 2;
-            }
-            num_digits = prec + 1;
-        } else {
-            // Truncate precision to prevent buffer overflow
-            if (prec + 6 > buf_remaining) {
-                prec = buf_remaining - 6;
-            }
-            if (fmt == 'e') {
-                e_sign = '+';
-            }
+    // Precompute the exact decimal exponent of f, such that
+    // abs(e) is lower bound on abs(power of 10 exponent).
+    int e = 0;
+    if (!fp_iszero(f)) {
+        // Approximate power of 10 exponent from binary exponent.
+        e = (int)(fp_expval(f) * MICROPY_FLOAT_CONST(0.3010299956639812));  // 1/log2(10).
+        int positive_exp = !fp_isless1(f);
+        mp_float_t u_base = (mp_float_t)mp_decimal_exp((mp_large_float_t)1.0, e + positive_exp);
+        while ((f >= u_base) == positive_exp) {
+            e += (positive_exp ? 1 : -1);
+            u_base = (mp_float_t)mp_decimal_exp((mp_large_float_t)1.0, e + positive_exp);
         }
-    } else if (fp_isless1(f)) {
-        FPTYPE f_entry = f;  // Save f in case we go to 'f' format.
-        // Build negative exponent
-        e = -e_guess;
-        FPTYPE u_base = MICROPY_FLOAT_C_FUN(pow)(10, -e);
-        while (u_base > f) {
-            ++e;
-            u_base = MICROPY_FLOAT_C_FUN(pow)(10, -e);
-        }
-        // Normalize out the inferred unit.  Use divide because
-        // pow(10, e) * pow(10, -e) is slightly < 1 for some e in float32
-        // (e.g. print("%.12f" % ((1e13) * (1e-13))))
-        f /= u_base;
-
-        // If the user specified 'g' format, and e is <= 4, then we'll switch
-        // to the fixed format ('f')
-
-        if (fmt == 'f' || (fmt == 'g' && e <= 4)) {
-            fmt = 'f';
-            dec = 0;
+    }
 
-            if (org_fmt == 'g') {
-                prec += (e - 1);
-            }
+    // For 'e' format, prec is # digits after the decimal
+    // For 'f' format, prec is # digits after the decimal
+    // For 'g' format, prec is the max number of significant digits
+    //
+    // For 'e' & 'g' format, there will be a single digit before the decimal
+    // For 'f' format, zeros must be expanded instead of using an exponent.
+    // Make sure there is enough room in the buffer for them, or switch to format 'g'.
+    if ((fmt_flags & FMT_MODE_F) && e > 0) {
+        int req_size = e + prec + 2;
+        if (req_size > (int)buf_size) {
+            fmt_flags ^= FMT_MODE_F;
+            fmt_flags |= FMT_MODE_G;
+            prec++;
+        }
+    }
 
-            // truncate precision to prevent buffer overflow
-            if (prec + 2 > buf_remaining) {
-                prec = buf_remaining - 2;
+    // To work independently of the format, we precompute:
+    // - the max number of significant digits to produce
+    // - the number of leading zeros to prepend (mode f only)
+    // - the number of trailing zeros to append
+    int max_digits = prec;
+    int lead_zeros = 0;
+    int trail_zeros = 0;
+    if (fmt_flags & FMT_MODE_F) {
+        if (max_digits > (int)buf_size - 3) {
+            // cannot satisfy requested number of decimals given buf_size, sorry
+            max_digits = (int)buf_size - 3;
+        }
+        if (e < 0) {
+            if (max_digits > 2 && e < -2) {
+                // Insert explicit leading zeros
+                lead_zeros = (-e < max_digits ? -e : max_digits) - 2;
+                max_digits -= lead_zeros;
+            } else {
+                max_digits++;
             }
-
-            num_digits = prec;
-            signed_e = 0;
-            f = f_entry;
-            ++num_digits;
         } else {
-            // For e & g formats, we'll be printing the exponent, so set the
-            // sign.
-            e_sign = '-';
-            dec = 0;
-
-            if (prec > (buf_remaining - FPMIN_BUF_SIZE)) {
-                prec = buf_remaining - FPMIN_BUF_SIZE;
-                if (fmt == 'g') {
-                    prec++;
-                }
-            }
-            signed_e = -e;
+            max_digits += e + 1;
         }
     } else {
-        // Build positive exponent.
-        // We don't modify f at this point to avoid inaccuracies from
-        // scaling it.  Instead, we find the product of powers of 10
-        // that is not greater than it, and use that to start the
-        // mantissa.
-        e = e_guess;
-        FPTYPE next_u = MICROPY_FLOAT_C_FUN(pow)(10, e + 1);
-        while (f >= next_u) {
-            ++e;
-            next_u = MICROPY_FLOAT_C_FUN(pow)(10, e + 1);
+        if (!(fmt_flags & FMT_MODE_G) || max_digits == 0) {
+            max_digits++;
         }
+    }
+    if (max_digits > MAX_MANTISSA_DIGITS) {
+        // use trailing zeros to avoid overflowing the mantissa
+        trail_zeros = max_digits - MAX_MANTISSA_DIGITS;
+        max_digits = MAX_MANTISSA_DIGITS;
+    }
+    int overhead = (fmt_flags & FMT_MODE_F ? 3 : FPMIN_BUF_SIZE + 1);
+    if (trail_zeros > (int)buf_size - max_digits - overhead) {
+        // cannot satisfy requested number of decimals given buf_size, sorry
+        trail_zeros = (int)buf_size - max_digits - overhead;
+    }
 
-        // If the user specified fixed format (fmt == 'f') and e makes the
-        // number too big to fit into the available buffer, then we'll
-        // switch to the 'e' format.
-
-        if (fmt == 'f') {
-            if (e >= buf_remaining) {
-                fmt = 'e';
-            } else if ((e + prec + 2) > buf_remaining) {
-                prec = buf_remaining - e - 2;
-                if (prec < 0) {
-                    // This means no decimal point, so we can add one back
-                    // for the decimal.
-                    prec++;
-                }
-            }
-        }
-        if (fmt == 'e' && prec > (buf_remaining - FPMIN_BUF_SIZE)) {
-            prec = buf_remaining - FPMIN_BUF_SIZE;
-        }
-        if (fmt == 'g') {
-            // Truncate precision to prevent buffer overflow
-            if (prec + (FPMIN_BUF_SIZE - 1) > buf_remaining) {
-                prec = buf_remaining - (FPMIN_BUF_SIZE - 1);
-            }
-        }
-        // If the user specified 'g' format, and e is < prec, then we'll switch
-        // to the fixed format.
+    // When the caller asks for more precision than available for sure,
+    // Look for a shorter (rounded) representation first, and only dig
+    // into more digits if there is no short representation.
+    int num_digits = (SAFE_MANTISSA_DIGITS < max_digits ? SAFE_MANTISSA_DIGITS : max_digits);
+try_again:
+    ;
 
-        if (fmt == 'g' && e < prec) {
-            fmt = 'f';
-            prec -= (e + 1);
-        }
-        if (fmt == 'f') {
-            dec = e;
-            num_digits = prec + e + 1;
+    char *s = buf;
+    int extra_zeros = trail_zeros + (max_digits - num_digits);
+    int decexp;
+    int dec = 0;
+
+    if (fp_iszero(f)) {
+        // no need for scaling 0.0
+        decexp = 0;
+    } else if (fmt_flags & FMT_MODE_F) {
+        decexp = num_digits - 1;
+        if (e < 0) {
+            // Negative exponent: we keep a single leading zero in the mantissa,
+            // as using more would waste precious digits needed for accuracy.
+            if (lead_zeros > 0) {
+                // We are using leading zeros
+                s = mp_prepend_zeros(s, lead_zeros);
+                decexp += lead_zeros + 1;
+                dec = 255; // no decimal dot
+            } else {
+                // Small negative exponent, work directly on the mantissa
+                dec = 0;
+            }
         } else {
-            e_sign = '+';
+            // Positive exponent: we will add trailing zeros separately
+            decexp -= e;
+            dec = e;
         }
-        signed_e = e;
+    } else {
+        decexp = num_digits - e - 1;
     }
-    if (prec < 0) {
-        // This can happen when the prec is trimmed to prevent buffer overflow
-        prec = 0;
+    DEBUG_PRINTF("input=%.19g e=%d fmt=%c max_d=%d num_d=%d decexp=%d dec=%d l0=%d r0=%d\n",
+        (double)f, e, lofmt, max_digits, num_digits, decexp, dec, lead_zeros, extra_zeros);
+
+    // At this point,
+    // - buf points to beginning of output buffer for the unsigned representation
+    // - num_digits == the number of mantissa digits to add
+    // - (dec + 1) == the number of digits to print before adding a decimal point
+    // - decexp == the power of 10 exponent to apply to f to get the decimal mantissa
+    // - e == the power of 10 exponent to append ('e' or 'g' format)
+    mp_large_float_uint_t mantissa_cap = 10;
+    for (int n = 1; n < num_digits; n++) {
+        mantissa_cap *= 10;
     }
 
-    // At this point e contains the absolute value of the power of 10 exponent.
-    // (dec + 1) == the number of dgits before the decimal.
-
-    // For e, prec is # digits after the decimal
-    // For f, prec is # digits after the decimal
-    // For g, prec is the max number of significant digits
-    //
-    // For e & g there will be a single digit before the decimal
-    // for f there will be e digits before the decimal
-
-    if (fmt == 'e') {
-        num_digits = prec + 1;
-    } else if (fmt == 'g') {
-        if (prec == 0) {
-            prec = 1;
+    // Build the decimal mantissa into a large uint
+    mp_large_float_uint_t mantissa = 1;
+    if (sizeof(mp_large_float_t) == sizeof(mp_float_t) && num_digits > SAFE_MANTISSA_DIGITS && decexp > 1) {
+        // if we don't have large floats, use integer multiply to produce the last digits
+        if (num_digits > SAFE_MANTISSA_DIGITS + 1 && decexp > 2) {
+            mantissa = 100;
+            decexp -= 2;
+        } else {
+            mantissa = 10;
+            decexp -= 1;
         }
-        num_digits = prec;
     }
-
-    int d = 0;
-    for (int digit_index = signed_e; num_digits >= 0; --digit_index) {
-        FPTYPE u_base = FPCONST(1.0);
-        if (digit_index > 0) {
-            // Generate 10^digit_index for positive digit_index.
-            u_base = MICROPY_FLOAT_C_FUN(pow)(10, digit_index);
-        }
-        for (d = 0; d < 9; ++d) {
-            if (f < u_base) {
-                break;
-            }
-            f -= u_base;
-        }
-        // We calculate one more digit than we display, to use in rounding
-        // below.  So only emit the digit if it's one that we display.
-        if (num_digits > 0) {
-            // Emit this number (the leading digit).
-            *s++ = '0' + d;
-            if (dec == 0 && prec > 0) {
-                *s++ = '.';
-            }
-        }
-        --dec;
-        --num_digits;
-        if (digit_index <= 0) {
-            // Once we get below 1.0, we scale up f instead of calculating
-            // negative powers of 10 in u_base.  This provides better
-            // renditions of exact decimals like 1/16 etc.
-            f *= FPCONST(10.0);
+    mp_large_float_t mantissa_f = mp_decimal_exp((mp_large_float_t)f, decexp);
+    mantissa *= (mp_large_float_uint_t)(mantissa_f + (mp_large_float_t)0.5);
+    DEBUG_PRINTF("input=%.19g fmt=%c num_digits=%d dec=%d mantissa=" MP_FFUINT_FMT " r0=%d\n", (double)f, lofmt, num_digits, dec, mantissa, extra_zeros);
+
+    // Finally convert the decimal mantissa to a floating-point string, according to formatting rules
+    int reprlen = mp_format_mantissa(mantissa, mantissa_cap, buf, s, num_digits, max_exp_zeros, extra_zeros, dec, e, fmt_flags);
+    assert(reprlen + 1 <= (int)buf_size);
+
+    #if MICROPY_FLOAT_FORMAT_IMPL != MICROPY_FLOAT_FORMAT_IMPL_APPROX
+
+    if (num_digits < max_digits) {
+        // The initial precision might not be sufficient for an exact representation
+        // for all numbers. If the result is not exact, restart using next precision.
+        // parse the resulting number and compare against the original
+        mp_float_t check;
+        DEBUG_PRINTF("input=%.19g, compare to float('%s')\n", (double)f, buf);
+        mp_parse_float_internal(buf, reprlen, &check);
+        if (!fp_equal(check, f)) {
+            num_digits++;
+            DEBUG_PRINTF("Not perfect, retry using more digits (%d)\n", num_digits);
+            goto try_again;
         }
     }
-    // Rounding.  If the next digit to print is >= 5, round up.
-    if (d >= 5) {
-        char *rs = s;
-        rs--;
-        while (1) {
-            if (*rs == '.') {
-                rs--;
-                continue;
-            }
-            if (*rs < '0' || *rs > '9') {
-                // + or -
-                rs++; // So we sit on the digit to the right of the sign
-                break;
+
+    #else
+
+    // The initial decimal mantissa might not have been be completely accurate due
+    // to the previous loating point operations. The best way to verify this is to
+    // parse the resulting number and compare against the original
+    mp_float_t check;
+    DEBUG_PRINTF("input=%.19g, compare to float('%s')\n", (double)f, buf);
+    mp_parse_float_internal(buf, reprlen, &check);
+    mp_float_t diff = fp_diff(check, f);
+    mp_float_t best_diff = diff;
+    mp_large_float_uint_t best_mantissa = mantissa;
+
+    if (fp_iszero(diff)) {
+        // we have a perfect match
+        DEBUG_PRINTF(MP_FFUINT_FMT ": perfect match (direct)\n", mantissa);
+    } else {
+        // In order to get the best possible representation, we will perform a
+        // dichotomic search for a reversible representation.
+        // This will also provide optimal rounding on the fly.
+        unsigned err_range = 1;
+        if (num_digits > SAFE_MANTISSA_DIGITS) {
+            err_range <<= 3 * (num_digits - SAFE_MANTISSA_DIGITS);
+        }
+        int maxruns = 3 + 3 * (MAX_MANTISSA_DIGITS - SAFE_MANTISSA_DIGITS);
+        while (maxruns-- > 0) {
+            // update mantissa according to dichotomic search
+            if (signbit(diff)) {
+                mantissa += err_range;
+            } else {
+                // mantissa is expected to always have more significant digits than err_range
+                assert(mantissa >= err_range);
+                mantissa -= err_range;
             }
-            if (*rs < '9') {
-                (*rs)++;
+            // retry conversion
+            reprlen = mp_format_mantissa(mantissa, mantissa_cap, buf, s, num_digits, max_exp_zeros, extra_zeros, dec, e, fmt_flags);
+            assert(reprlen + 1 <= (int)buf_size);
+            DEBUG_PRINTF("input=%.19g, compare to float('%s')\n", (double)f, buf);
+            mp_parse_float_internal(buf, reprlen, &check);
+            DEBUG_PRINTF("check=%.19g num_digits=%d e=%d mantissa=" MP_FFUINT_FMT "\n", (double)check, num_digits, e, mantissa);
+            diff = fp_diff(check, f);
+            if (fp_iszero(diff)) {
+                // we have a perfect match
+                DEBUG_PRINTF(MP_FFUINT_FMT ": perfect match\n", mantissa);
                 break;
             }
-            *rs = '0';
-            if (rs == buf) {
-                break;
+            // keep track of our best estimate
+            mp_float_t delta = MICROPY_FLOAT_C_FUN(fabs)(diff) - MICROPY_FLOAT_C_FUN(fabs)(best_diff);
+            if (signbit(delta) || (fp_iszero(delta) && !(mantissa % 10u))) {
+                best_diff = diff;
+                best_mantissa = mantissa;
             }
-            rs--;
-        }
-        if (*rs == '0') {
-            // We need to insert a 1
-            if (rs[1] == '.' && fmt != 'f') {
-                // We're going to round 9.99 to 10.00
-                // Move the decimal point
-                rs[0] = '.';
-                rs[1] = '0';
-                if (e_sign == '-') {
-                    e--;
-                    if (e == 0) {
-                        e_sign = '+';
-                    }
-                } else {
-                    e++;
-                }
+            // string repr is not perfect: continue a dichotomic improvement
+            DEBUG_PRINTF(MP_FFUINT_FMT ": %.19g, err_range=%d\n", mantissa, (double)check, err_range);
+            if (err_range > 1) {
+                err_range >>= 1;
             } else {
-                // Need at extra digit at the end to make room for the leading '1'
-                // but if we're at the buffer size limit, just drop the final digit.
-                if ((size_t)(s + 1 - buf) < buf_size) {
-                    s++;
+                // We have tried all possible mantissa, without finding a reversible repr.
+                // Check if we have an alternate precision to try.
+                if (num_digits < max_digits) {
+                    num_digits++;
+                    DEBUG_PRINTF("Failed to find a perfect match, try with more digits (%d)\n", num_digits);
+                    goto try_again;
                 }
+                // Otherwise, keep the closest one, which is either the first one or the last one.
+                if (mantissa == best_mantissa) {
+                    // Last guess is the best one
+                    DEBUG_PRINTF(MP_FFUINT_FMT ": last guess was the best one\n", mantissa);
+                } else {
+                    // We had a better guess earlier
+                    DEBUG_PRINTF(MP_FFUINT_FMT ": use best guess\n", mantissa);
+                    reprlen = mp_format_mantissa(best_mantissa, mantissa_cap, buf, s, num_digits, max_exp_zeros, extra_zeros, dec, e, fmt_flags);
+                }
+                break;
             }
-            char *ss = s;
-            while (ss > rs) {
-                *ss = ss[-1];
-                ss--;
-            }
-            *rs = '1';
         }
     }
+    #endif
 
-    // verify that we did not overrun the input buffer so far
-    assert((size_t)(s + 1 - buf) <= buf_size);
-
-    if (org_fmt == 'g' && prec > 0) {
-        // Remove trailing zeros and a trailing decimal point
-        while (s[-1] == '0') {
-            s--;
-        }
-        if (s[-1] == '.') {
-            s--;
-        }
-    }
-    // Append the exponent
-    if (e_sign) {
-        *s++ = e_char;
-        *s++ = e_sign;
-        if (FPMIN_BUF_SIZE == 7 && e >= 100) {
-            *s++ = '0' + (e / 100);
-        }
-        *s++ = '0' + ((e / 10) % 10);
-        *s++ = '0' + (e % 10);
-    }
-    *s = '\0';
-
-    // verify that we did not overrun the input buffer
-    assert((size_t)(s + 1 - buf) <= buf_size);
-
-    return s - buf;
+    return buf + reprlen - buf_entry;
 }
 
 #endif // MICROPY_FLOAT_IMPL != MICROPY_FLOAT_IMPL_NONE
diff --git a/py/formatfloat.h b/py/formatfloat.h
index 9a1643b4ddff5..7b1414672b77b 100644
--- a/py/formatfloat.h
+++ b/py/formatfloat.h
@@ -29,6 +29,7 @@
 #include "py/mpconfig.h"
 
 #if MICROPY_PY_BUILTINS_FLOAT
+#define MP_FLOAT_REPR_PREC (99) // magic `prec` value for optimal `repr` behaviour
 int mp_format_float(mp_float_t f, char *buf, size_t bufSize, char fmt, int prec, char sign);
 #endif
 
diff --git a/py/gc.c b/py/gc.c
index fc7de6c4d3b4f..757c27e3de696 100644
--- a/py/gc.c
+++ b/py/gc.c
@@ -1447,7 +1447,7 @@ void gc_dump_alloc_table(const mp_print_t *print) {
                     }
                     if (bl2 - bl >= 2 * DUMP_BYTES_PER_LINE) {
                         // there are at least 2 lines containing only free blocks, so abbreviate their printing
-                        mp_printf(print, "\n       (%u lines all free)", (uint)(bl2 - bl) / DUMP_BYTES_PER_LINE);
+                        mp_printf(print, "\n       (%u lines all free)", (uint)((bl2 - bl) / DUMP_BYTES_PER_LINE));
                         bl = bl2 & (~(DUMP_BYTES_PER_LINE - 1));
                         if (bl >= area->gc_alloc_table_byte_len * BLOCKS_PER_ATB) {
                             // got to end of heap
@@ -1490,7 +1490,7 @@ void gc_dump_alloc_table(const mp_print_t *print) {
                     break;
                 }
                 */
-                /* this prints the uPy object type of the head block */
+                /* this prints the MicroPython object type of the head block */
                 case AT_HEAD: {
                     // CIRCUITPY-CHANGE: compiler warning avoidance
                     #pragma GCC diagnostic push
diff --git a/py/gc.h b/py/gc.h
index 0752478d1f286..f9028d637c5c6 100644
--- a/py/gc.h
+++ b/py/gc.h
@@ -71,6 +71,11 @@ bool gc_alloc_possible(void);
 // Use this function to sweep the whole heap and run all finalisers
 void gc_sweep_all(void);
 
+// These functions are used to manage weakrefs.
+void gc_weakref_mark(void *ptr);
+void gc_weakref_about_to_be_freed(void *ptr);
+void gc_weakref_sweep(void);
+
 enum {
     GC_ALLOC_FLAG_HAS_FINALISER = 1,
     // CIRCUITPY-CHANGE
diff --git a/py/make_root_pointers.py b/py/make_root_pointers.py
index efe398b8227ca..5da343c1270ec 100644
--- a/py/make_root_pointers.py
+++ b/py/make_root_pointers.py
@@ -6,8 +6,6 @@
 "struct _mp_state_vm_t" in py/mpstate.h
 """
 
-from __future__ import print_function
-
 import argparse
 import io
 import re
diff --git a/py/makecompresseddata.py b/py/makecompresseddata.py
index 1bce3e8e8374a..a6fa7db00b280 100644
--- a/py/makecompresseddata.py
+++ b/py/makecompresseddata.py
@@ -1,5 +1,3 @@
-from __future__ import print_function
-
 import collections
 import re
 import sys
diff --git a/py/makemoduledefs.py b/py/makemoduledefs.py
index 29162ab387c8b..c8fdc21f6fbe2 100644
--- a/py/makemoduledefs.py
+++ b/py/makemoduledefs.py
@@ -14,8 +14,6 @@
 the built-in version.
 """
 
-from __future__ import print_function
-
 import sys
 import re
 import io
@@ -87,19 +85,25 @@ def generate_module_table_header(modules):
             )
         )
 
+    # There should always be at least one module (__main__ in runtime.c)
+    assert mod_defs
+
     print("\n#define MICROPY_REGISTERED_MODULES \\")
 
     for mod_def in sorted(mod_defs):
         print("    {mod_def} \\".format(mod_def=mod_def))
-
     print("// MICROPY_REGISTERED_MODULES")
 
-    print("\n#define MICROPY_REGISTERED_EXTENSIBLE_MODULES \\")
+    # There are not necessarily any extensible modules (e.g., bare-arm or minimal x86)
+    print("\n#define MICROPY_HAVE_REGISTERED_EXTENSIBLE_MODULES ", len(extensible_mod_defs))
 
-    for mod_def in sorted(extensible_mod_defs):
-        print("    {mod_def} \\".format(mod_def=mod_def))
+    if extensible_mod_defs:
+        print("\n#define MICROPY_REGISTERED_EXTENSIBLE_MODULES \\")
+
+        for mod_def in sorted(extensible_mod_defs):
+            print("    {mod_def} \\".format(mod_def=mod_def))
 
-    print("// MICROPY_REGISTERED_EXTENSIBLE_MODULES")
+        print("// MICROPY_REGISTERED_EXTENSIBLE_MODULES")
 
 
 def generate_module_delegations(delegations):
diff --git a/py/makeqstrdata.py b/py/makeqstrdata.py
index 998328bf1d250..3fdb2d5476b8a 100644
--- a/py/makeqstrdata.py
+++ b/py/makeqstrdata.py
@@ -1,31 +1,13 @@
 """
 Process raw qstr file and output qstr data with length, hash and data bytes.
 
-This script works with Python 2.7, 3.3 and 3.4.
-
-CIRCUITPY-CHANGE:
-For documentation about the format of compressed translated strings, see
-supervisor/shared/translate/translate.h
+This script works with Python 3.3+.
 """
 
-from __future__ import print_function
-
-
 import re
 import sys
 
-# CIRCUITPY-CHANGE
-if hasattr(sys.stdout, "reconfigure"):
-    sys.stdout.reconfigure(encoding="utf-8")
-    sys.stderr.reconfigure(errors="backslashreplace")
-
-# Python 2/3 compatibility:
-#   - iterating through bytes is different
-#   - codepoint2name from html.entities is hard-coded
-if sys.version_info[0] == 2:
-    bytes_cons = lambda val, enc=None: bytearray(val)
-elif sys.version_info[0] == 3:  # Also handles MicroPython
-    bytes_cons = bytes
+bytes_cons = bytes
 
 # fmt: off
 codepoint2name = {
@@ -67,7 +49,6 @@
     253: "yacute", 165: "yen", 255: "yuml", 950: "zeta", 8205: "zwj", 8204: "zwnj"
 }
 # fmt: on
-# end compatibility code
 
 codepoint2name[ord("-")] = "hyphen"
 
diff --git a/py/makeqstrdefs.py b/py/makeqstrdefs.py
index a403985769489..8c07899baf843 100644
--- a/py/makeqstrdefs.py
+++ b/py/makeqstrdefs.py
@@ -2,11 +2,9 @@
 This script processes the output from the C preprocessor and extracts all
 qstr. Each qstr is transformed into a qstr definition of the form 'Q(...)'.
 
-This script works with Python 3.x (CIRCUITPY-CHANGE: not 2.x)
+This script works with Python 3.3+.
 """
 
-from __future__ import print_function
-
 import io
 import os
 import re
@@ -139,6 +137,7 @@ def qstr_unescape(qstr):
     return qstr
 
 
+# CIRCUITPY-CHANGE: output_filename as an arg
 def process_file(f, output_filename=None):
     # match gcc-like output (# n "file") and msvc-like output (#line n "file")
     re_line = re.compile(r"^#(?:line)?\s+\d+\s\"([^\"]+)\"")
@@ -292,6 +291,7 @@ class Args:
     args.input_filename = sys.argv[3]  # Unused for command=cat
     args.output_dir = sys.argv[4]
     args.output_file = None if len(sys.argv) == 5 else sys.argv[5]  # Unused for command=split
+    # CIRCUITPY-CHANGE
     if args.output_file == "_":
         args.output_file = None
 
@@ -306,6 +306,7 @@ class Args:
 
     if args.command == "split":
         with io.open(args.input_filename, encoding="utf-8") as infile:
+            # CIRCUITPY-CHANGE: pass output_file
             process_file(infile, args.output_file)
 
     if args.command == "cat":
diff --git a/py/makeversionhdr.py b/py/makeversionhdr.py
index 307bfac1e9adb..94321ef0bad4d 100644
--- a/py/makeversionhdr.py
+++ b/py/makeversionhdr.py
@@ -5,8 +5,6 @@
 This script works with Python 3.7 and newer
 """
 
-from __future__ import print_function
-
 import argparse
 import sys
 import os
diff --git a/py/malloc.c b/py/malloc.c
index fcf930ecfaa83..fc9795043a879 100644
--- a/py/malloc.c
+++ b/py/malloc.c
@@ -54,9 +54,11 @@
 // freely accessed - for interfacing with system and 3rd-party libs for
 // example. On the other hand, some (e.g. bare-metal) ports may use GC
 // heap as system heap, so, to avoid warnings, we do undef's first.
-// CIRCUITPY-CHANGE: Add selective collect support to malloc to optimize GC for large buffers
+#undef malloc
 #undef free
 #undef realloc
+#define malloc(b) gc_alloc((b), false)
+#define malloc_with_finaliser(b) gc_alloc((b), true)
 #define free gc_free
 #define realloc(ptr, n) gc_realloc(ptr, n, true)
 #define realloc_ext(ptr, n, mv) gc_realloc(ptr, n, mv)
@@ -68,6 +70,7 @@
 #error MICROPY_ENABLE_FINALISER requires MICROPY_ENABLE_GC
 #endif
 
+// CIRCUITPY-CHANGE: Add selective collect support to malloc to optimize GC for large buffers
 #if MICROPY_ENABLE_SELECTIVE_COLLECT
 #error MICROPY_ENABLE_SELECTIVE_COLLECT requires MICROPY_ENABLE_GC
 #endif
@@ -85,7 +88,7 @@ static void *realloc_ext(void *ptr, size_t n_bytes, bool allow_move) {
 
 #endif // MICROPY_ENABLE_GC
 
-// CIRCUITPY-CHANGE: Add malloc helper with flags instead of a list of bools.
+// CIRCUITPY-CHANGE: Add malloc helper to factor out flag handling and allow combinations.
 void *m_malloc_helper(size_t num_bytes, uint8_t flags) {
     void *ptr;
     #if MICROPY_ENABLE_GC
@@ -112,7 +115,6 @@ void *m_malloc_helper(size_t num_bytes, uint8_t flags) {
     MP_STATE_MEM(current_bytes_allocated) += num_bytes;
     UPDATE_PEAK();
     #endif
-    // CIRCUITPY-CHANGE
     // If this config is set then the GC clears all memory, so we don't need to.
     #if !MICROPY_GC_CONSERVATIVE_CLEAR
     if (flags & M_MALLOC_ENSURE_ZEROED) {
@@ -124,26 +126,37 @@ void *m_malloc_helper(size_t num_bytes, uint8_t flags) {
 }
 
 void *m_malloc(size_t num_bytes) {
-    // CIRCUITPY-CHANGE
+    // CIRCUITPY-CHANGE: use helper
     return m_malloc_helper(num_bytes, M_MALLOC_RAISE_ERROR | M_MALLOC_COLLECT);
 }
 
 void *m_malloc_maybe(size_t num_bytes) {
-    // CIRCUITPY-CHANGE
+    // CIRCUITPY-CHANGE: use helper
     return m_malloc_helper(num_bytes, M_MALLOC_COLLECT);
 }
 
+#if MICROPY_ENABLE_FINALISER
+void *m_malloc_with_finaliser(size_t num_bytes) {
+    // CIRCUITPY-CHANGE: use helper
+    return m_malloc_helper(num_bytes, M_MALLOC_COLLECT | M_MALLOC_WITH_FINALISER);
+}
+#endif
+
 void *m_malloc0(size_t num_bytes) {
-    return m_malloc_helper(num_bytes, M_MALLOC_ENSURE_ZEROED | M_MALLOC_RAISE_ERROR | M_MALLOC_COLLECT);
+    // CIRCUITPY-CHANGE: use helper
+    return m_malloc_helper(num_bytes,
+        (MICROPY_GC_CONSERVATIVE_CLEAR ? 0 : M_MALLOC_ENSURE_ZEROED)
+        | M_MALLOC_RAISE_ERROR | M_MALLOC_COLLECT);
 }
 
+// CIRCUITPY-CHANGE: add selective collect
 void *m_malloc_without_collect(size_t num_bytes) {
-    // CIRCUITPY-CHANGE
     return m_malloc_helper(num_bytes, M_MALLOC_RAISE_ERROR);
 }
 
+// CIRCUITPY-CHANGE: add selective collect
 void *m_malloc_maybe_without_collect(size_t num_bytes) {
-    // CIRCUITPY-CHANGE
+
     return m_malloc_helper(num_bytes, 0);
 }
 
@@ -224,6 +237,31 @@ void m_free(void *ptr)
 
 #if MICROPY_TRACKED_ALLOC
 
+#if MICROPY_PY_THREAD && !MICROPY_PY_THREAD_GIL
+// If there's no GIL, use the GC recursive mutex to protect the tracked node linked list
+// under m_tracked_head.
+//
+// (For ports with GIL, the expectation is to only call tracked alloc functions
+// while holding the GIL.)
+
+static inline void m_tracked_node_lock(void) {
+    mp_thread_recursive_mutex_lock(&MP_STATE_MEM(gc_mutex), 1);
+}
+
+static inline void m_tracked_node_unlock(void) {
+    mp_thread_recursive_mutex_unlock(&MP_STATE_MEM(gc_mutex));
+}
+
+#else
+
+static inline void m_tracked_node_lock(void) {
+}
+
+static inline void m_tracked_node_unlock(void) {
+}
+
+#endif
+
 #define MICROPY_TRACKED_ALLOC_STORE_SIZE (!MICROPY_ENABLE_GC)
 
 typedef struct _m_tracked_node_t {
@@ -237,6 +275,7 @@ typedef struct _m_tracked_node_t {
 
 #if MICROPY_DEBUG_VERBOSE
 static size_t m_tracked_count_links(size_t *nb) {
+    m_tracked_node_lock();
     m_tracked_node_t *node = MP_STATE_VM(m_tracked_head);
     size_t n = 0;
     *nb = 0;
@@ -249,6 +288,7 @@ static size_t m_tracked_count_links(size_t *nb) {
         #endif
         node = node->next;
     }
+    m_tracked_node_unlock();
     return n;
 }
 #endif
@@ -263,12 +303,14 @@ void *m_tracked_calloc(size_t nmemb, size_t size) {
     size_t n = m_tracked_count_links(&nb);
     DEBUG_printf("m_tracked_calloc(%u, %u) -> (%u;%u) %p\n", (int)nmemb, (int)size, (int)n, (int)nb, node);
     #endif
+    m_tracked_node_lock();
     if (MP_STATE_VM(m_tracked_head) != NULL) {
         MP_STATE_VM(m_tracked_head)->prev = node;
     }
     node->prev = NULL;
     node->next = MP_STATE_VM(m_tracked_head);
     MP_STATE_VM(m_tracked_head) = node;
+    m_tracked_node_unlock();
     #if MICROPY_TRACKED_ALLOC_STORE_SIZE
     node->size = nmemb * size;
     #endif
@@ -294,7 +336,8 @@ void m_tracked_free(void *ptr_in) {
     size_t nb;
     size_t n = m_tracked_count_links(&nb);
     DEBUG_printf("m_tracked_free(%p, [%p, %p], nbytes=%u, links=%u;%u)\n", node, node->prev, node->next, (int)data_bytes, (int)n, (int)nb);
-    #endif
+    #endif // MICROPY_DEBUG_VERBOSE
+    m_tracked_node_lock();
     if (node->next != NULL) {
         node->next->prev = node->prev;
     }
@@ -303,6 +346,7 @@ void m_tracked_free(void *ptr_in) {
     } else {
         MP_STATE_VM(m_tracked_head) = node->next;
     }
+    m_tracked_node_unlock();
     m_free(node
         #if MICROPY_MALLOC_USES_ALLOCATED_SIZE
         #if MICROPY_TRACKED_ALLOC_STORE_SIZE
diff --git a/py/misc.h b/py/misc.h
index 22f32147124fc..d5d7950574f90 100644
--- a/py/misc.h
+++ b/py/misc.h
@@ -26,6 +26,8 @@
 #ifndef MICROPY_INCLUDED_PY_MISC_H
 #define MICROPY_INCLUDED_PY_MISC_H
 
+#include "py/mpconfig.h"
+
 // a mini library of useful types and functions
 
 /** types *******************************************************/
@@ -33,13 +35,25 @@
 #include <stdbool.h>
 #include <stdint.h>
 #include <stddef.h>
-
-// CIRCUITPY-CHANGE: include directly instead of depending on previous includes
-#include "mpconfig.h"
+// CIRCUITPY-CHANGE: #ifdef instead of #if
+#ifdef __cplusplus // Required on at least one compiler to get ULLONG_MAX
+#include <climits>
+#else
+#include <limits.h>
+#endif
 
 typedef unsigned char byte;
 typedef unsigned int uint;
 
+#ifndef __has_builtin
+#define __has_builtin(x) (0)
+#endif
+#ifndef __has_feature
+// This macro is supported by Clang and gcc>=14
+#define __has_feature(x) (0)
+#endif
+
+
 /** generic ops *************************************************/
 
 #ifndef MIN
@@ -54,6 +68,7 @@ typedef unsigned int uint;
 #define MP_STRINGIFY(x) MP_STRINGIFY_HELPER(x)
 
 // Static assertion macro
+// CIRCUITPY-CHANGE: defined()
 #if defined(__cplusplus)
 #define MP_STATIC_ASSERT(cond) static_assert((cond), #cond)
 #elif __GNUC__ >= 5 || __STDC_VERSION__ >= 201112L
@@ -70,6 +85,7 @@ typedef unsigned int uint;
 #if defined(_MSC_VER) || defined(__cplusplus)
 #define MP_STATIC_ASSERT_NONCONSTEXPR(cond) ((void)1)
 #else
+// CIRCUITPY-CHANGE: defined()
 #if defined(__clang__)
 #pragma GCC diagnostic ignored "-Wgnu-folding-constant"
 #endif
@@ -98,9 +114,9 @@ typedef unsigned int uint;
 #define m_new0(type, num) ((type *)(m_malloc0(sizeof(type) * (num))))
 #define m_new_obj(type) (m_new(type, 1))
 #define m_new_obj_maybe(type) (m_new_maybe(type, 1))
-#define m_new_obj_var(obj_type, var_field, var_type, var_num) ((obj_type *)m_malloc_helper(offsetof(obj_type, var_field) + sizeof(var_type) * (var_num), M_MALLOC_RAISE_ERROR | M_MALLOC_COLLECT))
-#define m_new_obj_var0(obj_type, var_field, var_type, var_num) ((obj_type *)m_malloc_helper(offsetof(obj_type, var_field) + sizeof(var_type) * (var_num), M_MALLOC_ENSURE_ZEROED | M_MALLOC_RAISE_ERROR | M_MALLOC_COLLECT))
-#define m_new_obj_var_maybe(obj_type, var_field, var_type, var_num) ((obj_type *)m_malloc_helper(offsetof(obj_type, var_field) + sizeof(var_type) * (var_num), M_MALLOC_COLLECT))
+#define m_new_obj_var(obj_type, var_field, var_type, var_num) ((obj_type *)m_malloc(offsetof(obj_type, var_field) + sizeof(var_type) * (var_num)))
+#define m_new_obj_var0(obj_type, var_field, var_type, var_num) ((obj_type *)m_malloc0(offsetof(obj_type, var_field) + sizeof(var_type) * (var_num)))
+#define m_new_obj_var_maybe(obj_type, var_field, var_type, var_num) ((obj_type *)m_malloc_maybe(offsetof(obj_type, var_field) + sizeof(var_type) * (var_num)))
 #if MICROPY_MALLOC_USES_ALLOCATED_SIZE
 #define m_renew(type, ptr, old_num, new_num) ((type *)(m_realloc((ptr), sizeof(type) * (old_num), sizeof(type) * (new_num))))
 #define m_renew_maybe(type, ptr, old_num, new_num, allow_move) ((type *)(m_realloc_maybe((ptr), sizeof(type) * (old_num), sizeof(type) * (new_num), (allow_move))))
@@ -126,9 +142,13 @@ typedef unsigned int uint;
 void *m_malloc_helper(size_t num_bytes, uint8_t flags);
 void *m_malloc(size_t num_bytes);
 void *m_malloc_maybe(size_t num_bytes);
+void *m_malloc_with_finaliser(size_t num_bytes);
 void *m_malloc0(size_t num_bytes);
+
+// CIRCUITPY-CHANGE: _without_collect
 void *m_malloc_without_collect(size_t num_bytes);
 void *m_malloc_maybe_without_collect(size_t num_bytes);
+
 #if MICROPY_MALLOC_USES_ALLOCATED_SIZE
 void *m_realloc(void *ptr, size_t old_num_bytes, size_t new_num_bytes);
 void *m_realloc_maybe(void *ptr, size_t old_num_bytes, size_t new_num_bytes, bool allow_move);
@@ -138,7 +158,7 @@ void *m_realloc(void *ptr, size_t new_num_bytes);
 void *m_realloc_maybe(void *ptr, size_t new_num_bytes, bool allow_move);
 void m_free(void *ptr);
 #endif
-NORETURN void m_malloc_fail(size_t num_bytes);
+MP_NORETURN void m_malloc_fail(size_t num_bytes);
 
 #if MICROPY_TRACKED_ALLOC
 // These alloc/free functions track the pointers in a linked list so the GC does not reclaim
@@ -161,7 +181,7 @@ size_t m_get_peak_bytes_allocated(void);
 // align ptr to the nearest multiple of "alignment"
 #define MP_ALIGN(ptr, alignment) (void *)(((uintptr_t)(ptr) + ((alignment) - 1)) & ~((alignment) - 1))
 
-// CIRCUITPY-CHANGE
+// CIRCUITPY-CHANGE: addition
 #define sizeof_field(TYPE, MEMBER) sizeof((((TYPE *)0)->MEMBER))
 
 /** unichar / UTF-8 *********************************************/
@@ -308,6 +328,25 @@ typedef union _mp_float_union_t {
     mp_float_uint_t i;
 } mp_float_union_t;
 
+#if MICROPY_FLOAT_FORMAT_IMPL == MICROPY_FLOAT_FORMAT_IMPL_EXACT
+
+#if MICROPY_FLOAT_IMPL == MICROPY_FLOAT_IMPL_FLOAT
+// Exact float conversion requires using internally a bigger sort of floating point
+typedef double mp_large_float_t;
+#elif MICROPY_FLOAT_IMPL == MICROPY_FLOAT_IMPL_DOUBLE
+typedef long double mp_large_float_t;
+#endif
+// Always use a 64 bit mantissa for formatting and parsing
+typedef uint64_t mp_large_float_uint_t;
+
+#else // MICROPY_FLOAT_FORMAT_IMPL != MICROPY_FLOAT_FORMAT_IMPL_EXACT
+
+// No bigger floating points
+typedef mp_float_t mp_large_float_t;
+typedef mp_float_uint_t mp_large_float_uint_t;
+
+#endif
+
 #endif // MICROPY_PY_BUILTINS_FLOAT
 
 /** ROM string compression *************/
@@ -413,26 +452,28 @@ static inline bool mp_check(bool value) {
 static inline uint32_t mp_popcount(uint32_t x) {
     return __popcnt(x);
 }
-#else
+#else // _MSC_VER
 #define mp_clz(x) __builtin_clz(x)
 #define mp_clzl(x) __builtin_clzl(x)
 #define mp_clzll(x) __builtin_clzll(x)
 #define mp_ctz(x) __builtin_ctz(x)
 #define mp_check(x) (x)
-#if defined __has_builtin
 #if __has_builtin(__builtin_popcount)
 #define mp_popcount(x) __builtin_popcount(x)
-#endif
-#endif
-#if !defined(mp_popcount)
+#else
 static inline uint32_t mp_popcount(uint32_t x) {
     x = x - ((x >> 1) & 0x55555555);
     x = (x & 0x33333333) + ((x >> 2) & 0x33333333);
     x = (x + (x >> 4)) & 0x0F0F0F0F;
-    return x * 0x01010101;
+    return (x * 0x01010101) >> 24;
 }
-#endif
-#endif
+#endif // __has_builtin(__builtin_popcount)
+#endif // _MSC_VER
+
+#define MP_FIT_UNSIGNED(bits, value) (((value) & (~0U << (bits))) == 0)
+#define MP_FIT_SIGNED(bits, value) \
+    (MP_FIT_UNSIGNED(((bits) - 1), (value)) || \
+    (((value) & (~0U << ((bits) - 1))) == (~0U << ((bits) - 1))))
 
 // mp_int_t can be larger than long, i.e. Windows 64-bit, nan-box variants
 static inline uint32_t mp_clz_mpi(mp_int_t x) {
@@ -448,16 +489,107 @@ static inline uint32_t mp_clz_mpi(mp_int_t x) {
     }
     return zeroes;
     #else
-    MP_STATIC_ASSERT(sizeof(mp_int_t) == sizeof(long long)
-        || sizeof(mp_int_t) == sizeof(long));
+    #if MP_INT_MAX == INT_MAX
+    return mp_clz((unsigned)x);
+    #elif MP_INT_MAX == LONG_MAX
+    return mp_clzl((unsigned long)x);
+    #elif MP_INT_MAX == LLONG_MAX
+    return mp_clzll((unsigned long long)x);
+    #else
+    #error Unexpected MP_INT_MAX value
+    #endif
+    #endif
+}
 
-    // ugly, but should compile to single intrinsic unless O0 is set
-    if (mp_check(sizeof(mp_int_t) == sizeof(long))) {
-        return mp_clzl((unsigned long)x);
+// Overflow-checked operations
+
+// Integer overflow builtins were added to GCC 5, but __has_builtin only in GCC 10
+//
+// Note that the builtins has a defined result when overflow occurs, whereas the custom
+// functions below don't update the result if an overflow would occur (to avoid UB).
+#define MP_GCC_HAS_BUILTIN_OVERFLOW (__GNUC__ >= 5)
+
+#if MICROPY_USE_GCC_MUL_OVERFLOW_INTRINSIC
+
+#define mp_mul_ull_overflow __builtin_umulll_overflow
+#define mp_mul_ll_overflow __builtin_smulll_overflow
+static inline bool mp_mul_mp_int_t_overflow(mp_int_t x, mp_int_t y, mp_int_t *res) {
+    // __builtin_mul_overflow is a type-generic function, this inline ensures the argument
+    // types are checked to match mp_int_t.
+    return __builtin_mul_overflow(x, y, res);
+}
+
+#else
+
+bool mp_mul_ll_overflow(long long int x, long long int y, long long int *res);
+bool mp_mul_mp_int_t_overflow(mp_int_t x, mp_int_t y, mp_int_t *res);
+static inline bool mp_mul_ull_overflow(unsigned long long int x, unsigned long long int y, unsigned long long int *res) {
+    if (y > 0 && x > (ULLONG_MAX / y)) {
+        return true; // overflow
+    }
+    *res = x * y;
+    return false;
+}
+
+#endif
+
+#if __has_builtin(__builtin_saddll_overflow) || MP_GCC_HAS_BUILTIN_OVERFLOW
+#define mp_add_ll_overflow __builtin_saddll_overflow
+#else
+static inline bool mp_add_ll_overflow(long long int lhs, long long int rhs, long long int *res) {
+    bool overflow;
+
+    if (rhs > 0) {
+        overflow = (lhs > LLONG_MAX - rhs);
     } else {
-        return mp_clzll((unsigned long long)x);
+        overflow = (lhs < LLONG_MIN - rhs);
     }
-    #endif
+
+    if (!overflow) {
+        *res = lhs + rhs;
+    }
+
+    return overflow;
+}
+#endif
+
+#if __has_builtin(__builtin_ssubll_overflow) || MP_GCC_HAS_BUILTIN_OVERFLOW
+#define mp_sub_ll_overflow __builtin_ssubll_overflow
+#else
+static inline bool mp_sub_ll_overflow(long long int lhs, long long int rhs, long long int *res) {
+    bool overflow;
+
+    if (rhs > 0) {
+        overflow = (lhs < LLONG_MIN + rhs);
+    } else {
+        overflow = (lhs > LLONG_MAX + rhs);
+    }
+
+    if (!overflow) {
+        *res = lhs - rhs;
+    }
+
+    return overflow;
 }
+#endif
+
+
+// Helper macros for detecting if sanitizers are enabled
+//
+// Use sparingly, not for masking issues reported by sanitizers!
+//
+// Can be detected automatically in Clang and gcc>=14, need to be
+// set manually otherwise.
+#ifndef MP_UBSAN
+#define MP_UBSAN __has_feature(undefined_behavior_sanitizer)
+#endif
+
+#ifndef MP_ASAN
+#define MP_ASAN __has_feature(address_sanitizer)
+#endif
+
+#ifndef MP_SANITIZER_BUILD
+#define MP_SANITIZER_BUILD (MP_UBSAN || MP_ASAN)
+#endif
 
 #endif // MICROPY_INCLUDED_PY_MISC_H
diff --git a/py/mkrules.cmake b/py/mkrules.cmake
index 4374b8b4da3cb..e3d769cc59b5c 100644
--- a/py/mkrules.cmake
+++ b/py/mkrules.cmake
@@ -14,6 +14,9 @@ set(MICROPY_MODULEDEFS "${MICROPY_GENHDR_DIR}/moduledefs.h")
 set(MICROPY_ROOT_POINTERS_SPLIT "${MICROPY_GENHDR_DIR}/root_pointers.split")
 set(MICROPY_ROOT_POINTERS_COLLECTED "${MICROPY_GENHDR_DIR}/root_pointers.collected")
 set(MICROPY_ROOT_POINTERS "${MICROPY_GENHDR_DIR}/root_pointers.h")
+set(MICROPY_COMPRESSED_SPLIT "${MICROPY_GENHDR_DIR}/compressed.split")
+set(MICROPY_COMPRESSED_COLLECTED "${MICROPY_GENHDR_DIR}/compressed.collected")
+set(MICROPY_COMPRESSED_DATA "${MICROPY_GENHDR_DIR}/compressed.data.h")
 
 if(NOT MICROPY_PREVIEW_VERSION_2)
     set(MICROPY_PREVIEW_VERSION_2 0)
@@ -32,6 +35,13 @@ if(MICROPY_BOARD)
     )
 endif()
 
+# Need to do this before extracting MICROPY_CPP_DEF below.
+if(MICROPY_ROM_TEXT_COMPRESSION)
+    target_compile_definitions(${MICROPY_TARGET} PUBLIC
+        MICROPY_ROM_TEXT_COMPRESSION=\(1\)
+    )
+endif()
+
 # Need to do this before extracting MICROPY_CPP_DEF below. Rest of frozen
 # manifest handling is at the end of this file.
 if(MICROPY_FROZEN_MANIFEST)
@@ -84,6 +94,18 @@ target_sources(${MICROPY_TARGET} PRIVATE
     ${MICROPY_ROOT_POINTERS}
 )
 
+if(MICROPY_ROM_TEXT_COMPRESSION)
+    target_sources(${MICROPY_TARGET} PRIVATE
+        ${MICROPY_COMPRESSED_DATA}
+    )
+endif()
+
+# Ensure genhdr directory is removed on clean
+
+set_property(TARGET ${MICROPY_TARGET} APPEND PROPERTY ADDITIONAL_CLEAN_FILES
+    "${MICROPY_GENHDR_DIR}"
+)
+
 # Command to force the build of another command
 
 # Generate mpversion.h
@@ -197,11 +219,41 @@ add_custom_command(
     DEPENDS ${MICROPY_ROOT_POINTERS_COLLECTED} ${MICROPY_PY_DIR}/make_root_pointers.py
 )
 
+# Generate compressed.data.h
+
+add_custom_command(
+    OUTPUT ${MICROPY_COMPRESSED_SPLIT}
+    COMMAND ${Python3_EXECUTABLE} ${MICROPY_PY_DIR}/makeqstrdefs.py split compress ${MICROPY_QSTRDEFS_LAST} ${MICROPY_GENHDR_DIR}/compress _
+    COMMAND touch ${MICROPY_COMPRESSED_SPLIT}
+    DEPENDS ${MICROPY_QSTRDEFS_LAST}
+    VERBATIM
+    COMMAND_EXPAND_LISTS
+)
+
+add_custom_command(
+    OUTPUT ${MICROPY_COMPRESSED_COLLECTED}
+    COMMAND ${Python3_EXECUTABLE} ${MICROPY_PY_DIR}/makeqstrdefs.py cat compress _ ${MICROPY_GENHDR_DIR}/compress ${MICROPY_COMPRESSED_COLLECTED}
+    BYPRODUCTS "${MICROPY_COMPRESSED_COLLECTED}.hash"
+    DEPENDS ${MICROPY_COMPRESSED_SPLIT}
+    VERBATIM
+    COMMAND_EXPAND_LISTS
+)
+
+add_custom_command(
+    OUTPUT ${MICROPY_COMPRESSED_DATA}
+    COMMAND ${Python3_EXECUTABLE} ${MICROPY_PY_DIR}/makecompresseddata.py ${MICROPY_COMPRESSED_COLLECTED} > ${MICROPY_COMPRESSED_DATA}
+    DEPENDS ${MICROPY_COMPRESSED_COLLECTED} ${MICROPY_PY_DIR}/makecompresseddata.py
+)
+
 # Build frozen code if enabled
 
 if(MICROPY_FROZEN_MANIFEST)
     set(MICROPY_FROZEN_CONTENT "${CMAKE_BINARY_DIR}/frozen_content.c")
 
+    set_property(TARGET ${MICROPY_TARGET} APPEND PROPERTY ADDITIONAL_CLEAN_FILES
+        "${CMAKE_BINARY_DIR}/frozen_mpy"
+    )
+
     target_sources(${MICROPY_TARGET} PRIVATE
         ${MICROPY_FROZEN_CONTENT}
     )
diff --git a/py/mkrules.mk b/py/mkrules.mk
index f364297f0f209..03988996c71ce 100644
--- a/py/mkrules.mk
+++ b/py/mkrules.mk
@@ -11,6 +11,7 @@ ifeq ($(MICROPY_PREVIEW_VERSION_2),1)
 CFLAGS += -DMICROPY_PREVIEW_VERSION_2=1
 endif
 
+# CIRCUITPY-CHANGE: point to CircuitPython documentation
 HELP_BUILD_ERROR ?= "See \033[1;31mhttps://learn.adafruit.com/building-circuitpython; Adafruit Discord \#circuitpython-dev\033[0m"
 HELP_MPY_LIB_SUBMODULE ?= "\033[1;31mError: micropython-lib submodule is not initialized.\033[0m Run 'make submodules'"
 
@@ -112,6 +113,14 @@ $(BUILD)/%.pp: %.c
 	$(STEPECHO) "PreProcess $<"
 	$(Q)$(CPP) $(CFLAGS) -Wp,-C,-dD,-dI -o $@ $<
 
+.PHONY: $(BUILD)/%.sz
+$(BUILD)/%.sz: $(BUILD)/%.o
+	$(Q)$(SIZE) $<
+
+# Special case for compiling auto-generated source files.
+$(BUILD)/%.o: $(BUILD)/%.c
+	$(call compile_c)
+
 # The following rule uses | to create an order only prerequisite. Order only
 # prerequisites only get built if they don't exist. They don't cause timestamp
 # checking to be performed.
@@ -179,7 +188,7 @@ $(HEADER_BUILD)/compressed.collected: $(HEADER_BUILD)/compressed.split
 # will be created if they don't exist.
 OBJ_DIRS = $(sort $(dir $(OBJ)))
 $(OBJ): | $(OBJ_DIRS)
-// CIRCUITPY-CHANGE: use $(Q)
+# CIRCUITPY-CHANGE: use $(Q)
 $(OBJ_DIRS):
 	$(Q)$(MKDIR) -p $@
 
@@ -260,7 +269,7 @@ submodules:
 	$(ECHO) "Updating submodules: $(GIT_SUBMODULES)"
 ifneq ($(GIT_SUBMODULES),)
 	$(Q)cd $(TOP) && git submodule sync $(GIT_SUBMODULES)
-	$(Q)cd $(TOP) && git submodule update --init --filter=blob:none $(GIT_SUBMODULES) || \
+	$(Q)cd $(TOP) && git submodule update --init --filter=blob:none $(GIT_SUBMODULES) 2>/dev/null || \
 	  git submodule update --init $(GIT_SUBMODULES)
 endif
 .PHONY: submodules
diff --git a/py/modio.c b/py/modio.c
index d3e563dbcf447..9aeb42d30aa13 100644
--- a/py/modio.c
+++ b/py/modio.c
@@ -169,12 +169,13 @@ static mp_obj_t bufwriter_flush(mp_obj_t self_in) {
         int err;
         mp_uint_t out_sz = mp_stream_write_exactly(self->stream, self->buf, self->len, &err);
         (void)out_sz;
-        // TODO: try to recover from a case of non-blocking stream, e.g. move
-        // remaining chunk to the beginning of buffer.
-        assert(out_sz == self->len);
-        self->len = 0;
         if (err != 0) {
             mp_raise_OSError(err);
+        } else {
+            // TODO: try to recover from a case of non-blocking stream, e.g. move
+            // remaining chunk to the beginning of buffer.
+            assert(out_sz == self->len);
+            self->len = 0;
         }
     }
 
diff --git a/py/modmath.c b/py/modmath.c
index 2b41bbcd7d15e..2a9ed1b7f2291 100644
--- a/py/modmath.c
+++ b/py/modmath.c
@@ -37,7 +37,7 @@
 #define MP_PI_4 MICROPY_FLOAT_CONST(0.78539816339744830962)
 #define MP_3_PI_4 MICROPY_FLOAT_CONST(2.35619449019234492885)
 
-static NORETURN void math_error(void) {
+static MP_NORETURN void math_error(void) {
     mp_raise_ValueError(MP_ERROR_TEXT("math domain error"));
 }
 
@@ -99,12 +99,16 @@ mp_float_t MICROPY_FLOAT_C_FUN(log2)(mp_float_t x) {
 MATH_FUN_1(sqrt, sqrt)
 // pow(x, y): returns x to the power of y
 #if MICROPY_PY_MATH_POW_FIX_NAN
-mp_float_t pow_func(mp_float_t x, mp_float_t y) {
+mp_float_t MICROPY_FLOAT_C_FUN(pow_func)(mp_float_t x, mp_float_t y) {
     // pow(base, 0) returns 1 for any base, even when base is NaN
     // pow(+1, exponent) returns 1 for any exponent, even when exponent is NaN
     if (x == MICROPY_FLOAT_CONST(1.0) || y == MICROPY_FLOAT_CONST(0.0)) {
         return MICROPY_FLOAT_CONST(1.0);
     }
+    // pow(base, NaN) returns NaN for any other value of base
+    if (isnan(y)) {
+        return y;
+    }
     return MICROPY_FLOAT_C_FUN(pow)(x, y);
 }
 MATH_FUN_2(pow, pow_func)
@@ -161,6 +165,11 @@ MATH_FUN_2(atan2, atan2)
 MATH_FUN_1_TO_INT(ceil, ceil)
 // copysign(x, y)
 static mp_float_t MICROPY_FLOAT_C_FUN(copysign_func)(mp_float_t x, mp_float_t y) {
+    #if MICROPY_PY_MATH_COPYSIGN_FIX_NAN
+    if (isnan(y)) {
+        y = 0.0;
+    }
+    #endif
     return MICROPY_FLOAT_C_FUN(copysign)(x, y);
 }
 MATH_FUN_2(copysign, copysign_func)
diff --git a/py/modmicropython.c b/py/modmicropython.c
index ff25af8ff7eec..67bb32626c3fa 100644
--- a/py/modmicropython.c
+++ b/py/modmicropython.c
@@ -100,7 +100,7 @@ static mp_obj_t mp_micropython_qstr_info(size_t n_args, const mp_obj_t *args) {
     size_t n_pool, n_qstr, n_str_data_bytes, n_total_bytes;
     qstr_pool_info(&n_pool, &n_qstr, &n_str_data_bytes, &n_total_bytes);
     mp_printf(&mp_plat_print, "qstr pool: n_pool=%u, n_qstr=%u, n_str_data_bytes=%u, n_total_bytes=%u\n",
-        n_pool, n_qstr, n_str_data_bytes, n_total_bytes);
+        (uint)n_pool, (uint)n_qstr, (uint)n_str_data_bytes, (uint)n_total_bytes);
     if (n_args == 1) {
         // arg given means dump qstr data
         qstr_dump_data();
diff --git a/py/modsys.c b/py/modsys.c
index 2adbc0b7bd66f..bbae93d0c3f78 100644
--- a/py/modsys.c
+++ b/py/modsys.c
@@ -95,8 +95,16 @@ static const MP_DEFINE_STR_OBJ(mp_sys_implementation_machine_obj, MICROPY_BANNER
     MP_ROM_PTR(&mp_sys_implementation_machine_obj)
 
 #if MICROPY_PERSISTENT_CODE_LOAD
+// Note: Adding architecture flags to _mpy will break if the flags information
+//       takes up more bits than what is available in a small-int value.
+#if MICROPY_EMIT_RV32
+#include "py/asmrv32.h"
+#define MPY_FILE_ARCH_FLAGS (MICROPY_RV32_EXTENSIONS << 16)
+#else
+#define MPY_FILE_ARCH_FLAGS (0)
+#endif
 #define SYS_IMPLEMENTATION_ELEMS__MPY \
-    , MP_ROM_INT(MPY_FILE_HEADER_INT)
+    , MP_ROM_INT(MPY_FILE_HEADER_INT | MPY_FILE_ARCH_FLAGS)
 #else
 #define SYS_IMPLEMENTATION_ELEMS__MPY
 #endif
@@ -113,6 +121,18 @@ static const MP_DEFINE_STR_OBJ(mp_sys_implementation__build_obj, MICROPY_BOARD_B
 #define SYS_IMPLEMENTATION_ELEMS__BUILD
 #endif
 
+#if MICROPY_PY_THREAD
+#if MICROPY_PY_THREAD_GIL
+#define SYS_IMPLEMENTATION_ELEMS__THREAD \
+    , MP_ROM_QSTR(MP_QSTR_GIL)
+#else
+#define SYS_IMPLEMENTATION_ELEMS__THREAD \
+    , MP_ROM_QSTR(MP_QSTR_unsafe)
+#endif
+#else
+#define SYS_IMPLEMENTATION_ELEMS__THREAD
+#endif
+
 #if MICROPY_PREVIEW_VERSION_2
 #define SYS_IMPLEMENTATION_ELEMS__V2 \
     , MP_ROM_TRUE
@@ -130,6 +150,9 @@ static const qstr impl_fields[] = {
     #if defined(MICROPY_BOARD_BUILD_NAME)
     MP_QSTR__build,
     #endif
+    #if MICROPY_PY_THREAD
+    MP_QSTR__thread,
+    #endif
     #if MICROPY_PREVIEW_VERSION_2
     MP_QSTR__v2,
     #endif
@@ -137,20 +160,21 @@ static const qstr impl_fields[] = {
 static MP_DEFINE_ATTRTUPLE(
     mp_sys_implementation_obj,
     impl_fields,
-    3 + MICROPY_PERSISTENT_CODE_LOAD + MICROPY_BOARD_BUILD + MICROPY_PREVIEW_VERSION_2,
+    3 + MICROPY_PERSISTENT_CODE_LOAD + MICROPY_BOARD_BUILD + MICROPY_PY_THREAD + MICROPY_PREVIEW_VERSION_2,
     SYS_IMPLEMENTATION_ELEMS_BASE
     SYS_IMPLEMENTATION_ELEMS__MPY
     SYS_IMPLEMENTATION_ELEMS__BUILD
+    SYS_IMPLEMENTATION_ELEMS__THREAD
     SYS_IMPLEMENTATION_ELEMS__V2
     );
 #else
 static const mp_rom_obj_tuple_t mp_sys_implementation_obj = {
     {&mp_type_tuple},
     3 + MICROPY_PERSISTENT_CODE_LOAD,
-    // Do not include SYS_IMPLEMENTATION_ELEMS__BUILD or SYS_IMPLEMENTATION_ELEMS__V2
-    // because SYS_IMPLEMENTATION_ELEMS__MPY may be empty if
+    // Do not include SYS_IMPLEMENTATION_ELEMS__BUILD, SYS_IMPLEMENTATION_ELEMS__THREAD
+    // or SYS_IMPLEMENTATION_ELEMS__V2 because SYS_IMPLEMENTATION_ELEMS__MPY may be empty if
     // MICROPY_PERSISTENT_CODE_LOAD is disabled, which means they'll share
-    // the same index. Cannot query _build or _v2 if MICROPY_PY_ATTRTUPLE is
+    // the same index. Cannot query _build, _thread or _v2 if MICROPY_PY_ATTRTUPLE is
     // disabled.
     {
         SYS_IMPLEMENTATION_ELEMS_BASE
diff --git a/py/mpconfig.h b/py/mpconfig.h
index 5ff568e64b00a..69a338d746a2f 100644
--- a/py/mpconfig.h
+++ b/py/mpconfig.h
@@ -26,6 +26,14 @@
 #ifndef MICROPY_INCLUDED_PY_MPCONFIG_H
 #define MICROPY_INCLUDED_PY_MPCONFIG_H
 
+#include <stdint.h>
+
+#if defined(__cplusplus) // Required on at least one compiler to get ULLONG_MAX
+#include <climits>
+#else
+#include <limits.h>
+#endif
+
 // CIRCUITPY-CHANGE
 // Is this a CircuitPython build?
 #ifndef CIRCUITPY
@@ -40,7 +48,7 @@
 // as well as a fallback to generate MICROPY_GIT_TAG if the git repo or tags
 // are unavailable.
 #define MICROPY_VERSION_MAJOR 1
-#define MICROPY_VERSION_MINOR 25
+#define MICROPY_VERSION_MINOR 27
 #define MICROPY_VERSION_MICRO 0
 #define MICROPY_VERSION_PRERELEASE 0
 
@@ -173,6 +181,78 @@
 #define MICROPY_OBJ_IMMEDIATE_OBJS (MICROPY_OBJ_REPR != MICROPY_OBJ_REPR_D)
 #endif
 
+// Definition of the `mp_int_t` and `mp_uint_t` types and associated macros.
+// Normally, it suffices for the platform to do nothing: A type as wide
+// as a pointer is chosen, unless nanboxing (REPR_D) is selected, in
+// which case a 64-bit type is chosen to match the assumed size of
+// double-precision floats.
+//
+// In the case of exceptions, the port, board, or variant must define
+// MP_INT_TYPE as MP_INT_TYPE_OTHER and provide all the typedefs and
+// defines.
+#define MP_INT_TYPE_INTPTR (0)
+#define MP_INT_TYPE_INT64 (1)
+#define MP_INT_TYPE_OTHER (2)
+
+#if !defined(MP_INT_TYPE)
+#if MICROPY_OBJ_REPR == MICROPY_OBJ_REPR_D
+#define MP_INT_TYPE (MP_INT_TYPE_INT64)
+#else
+#define MP_INT_TYPE (MP_INT_TYPE_INTPTR)
+#endif
+#endif
+
+#if MP_INT_TYPE == MP_INT_TYPE_INTPTR
+typedef intptr_t mp_int_t;
+typedef uintptr_t mp_uint_t;
+#define MP_INT_MAX INTPTR_MAX
+#define MP_INT_MIN INTPTR_MIN
+#define MP_UINT_MAX INTPTR_UMAX
+#elif MP_INT_TYPE == MP_INT_TYPE_INT64
+typedef int64_t mp_int_t;
+typedef uint64_t mp_uint_t;
+#define MP_INT_MAX INT64_MAX
+#define MP_INT_MIN INT64_MIN
+#define MP_UINT_MAX INT64_UMAX
+#endif
+
+// mp_printf format support for mp_int_t. In the unusual case that MP_INT_MAX doesn't
+// match any of the standard C types (int/long/long long), provide all 3
+// macros. Otherwise, rely on these automatic definitions.
+#if !defined(INT_FMT)
+#if MP_INT_MAX == INT_MAX
+#define INT_FMT "%d"
+#define UINT_FMT "%u"
+#define HEX_FMT "%x"
+#elif MP_INT_MAX == LONG_MAX
+#define INT_FMT "%ld"
+#define UINT_FMT "%lu"
+#define HEX_FMT "%lx"
+#elif MP_INT_MAX == LLONG_MAX
+#define INT_FMT "%lld"
+#define UINT_FMT "%llu"
+#define HEX_FMT "%llx"
+#else
+#error Unexpected MP_INT_MAX value
+#endif
+#endif
+
+// mp_printf format support for size_t. In the unusual case that SIZE_MAX doesn't
+// match any of the standard C types (int/long/long long), provide a
+// macro. Otherwise, rely on these automatic definitions.
+#if !defined(SIZE_FMT)
+#if SIZE_MAX == UINT_MAX
+#define SIZE_FMT "%u"
+#elif SIZE_MAX == ULONG_MAX
+#define SIZE_FMT "%lu"
+#elif SIZE_MAX == ULLONG_MAX
+#define SIZE_FMT "%llu"
+#else
+#error Unexpected SIZE_MAX value
+#endif
+#endif
+
+
 /*****************************************************************************/
 /* Memory allocation policy                                                  */
 
@@ -418,6 +498,11 @@
 #define MICROPY_EMIT_INLINE_XTENSA (0)
 #endif
 
+// Whether to support uncommon Xtensa inline assembler opcodes
+#ifndef MICROPY_EMIT_INLINE_XTENSA_UNCOMMON_OPCODES
+#define MICROPY_EMIT_INLINE_XTENSA_UNCOMMON_OPCODES (0)
+#endif
+
 // Whether to emit Xtensa-Windowed native code
 #ifndef MICROPY_EMIT_XTENSAWIN
 #define MICROPY_EMIT_XTENSAWIN (0)
@@ -428,9 +513,9 @@
 #define MICROPY_EMIT_RV32 (0)
 #endif
 
-// CIRCUITPY-CHANGE: make sure MICROPY_EMIT_NATIVE_DEBUG is defined
-#ifndef MICROPY_EMIT_NATIVE_DEBUG
-#define MICROPY_EMIT_NATIVE_DEBUG (0)
+// Whether to emit RISC-V RV32 Zba opcodes in native code
+#ifndef MICROPY_EMIT_RV32_ZBA
+#define MICROPY_EMIT_RV32_ZBA (0)
 #endif
 
 // Whether to enable the RISC-V RV32 inline assembler
@@ -438,6 +523,11 @@
 #define MICROPY_EMIT_INLINE_RV32 (0)
 #endif
 
+// Whether to enable the human-readable native instructions emitter
+#ifndef MICROPY_EMIT_NATIVE_DEBUG
+#define MICROPY_EMIT_NATIVE_DEBUG (0)
+#endif
+
 // Convenience definition for whether any native emitter is enabled
 #define MICROPY_EMIT_NATIVE (MICROPY_EMIT_X64 || MICROPY_EMIT_X86 || MICROPY_EMIT_THUMB || MICROPY_EMIT_ARM || MICROPY_EMIT_XTENSA || MICROPY_EMIT_XTENSAWIN || MICROPY_EMIT_RV32 || MICROPY_EMIT_NATIVE_DEBUG)
 
@@ -497,6 +587,13 @@
 #define MICROPY_COMP_CONST (MICROPY_CONFIG_ROM_LEVEL_AT_LEAST_CORE_FEATURES)
 #endif
 
+// Whether to enable float constant folding like 1.2+3.4 (when MICROPY_COMP_CONST_FOLDING is also enabled)
+// and constant optimisation like id = const(1.2) (when MICROPY_COMP_CONST is also enabled)
+// and constant lookup like math.inf (when MICROPY_COMP_MODULE_CONST is also enabled)
+#ifndef MICROPY_COMP_CONST_FLOAT
+#define MICROPY_COMP_CONST_FLOAT (MICROPY_CONFIG_ROM_LEVEL_AT_LEAST_CORE_FEATURES)
+#endif
+
 // Whether to enable optimisation of: a, b = c, d
 // Costs 124 bytes (Thumb2)
 #ifndef MICROPY_COMP_DOUBLE_TUPLE_ASSIGN
@@ -727,6 +824,13 @@
 #define MICROPY_STACK_CHECK_MARGIN (0)
 #endif
 
+// The size of a separate stack used for hard IRQ handlers, which should be
+// checked instead of the main stack when running a hard callback. 0 implies
+// there is no separate ISR stack to check.
+#ifndef MICROPY_STACK_SIZE_HARD_IRQ
+#define MICROPY_STACK_SIZE_HARD_IRQ (0)
+#endif
+
 // Whether to have an emergency exception buffer
 #ifndef MICROPY_ENABLE_EMERGENCY_EXCEPTION_BUF
 #define MICROPY_ENABLE_EMERGENCY_EXCEPTION_BUF (0)
@@ -896,8 +1000,25 @@ typedef double mp_float_t;
 #define MICROPY_PY_BUILTINS_COMPLEX (MICROPY_PY_BUILTINS_FLOAT)
 #endif
 
-#ifndef MICROPY_PY_DOUBLE_TYPECODE
-#define MICROPY_PY_DOUBLE_TYPECODE (MICROPY_PY_BUILTINS_FLOAT)
+// Float to string conversion implementations
+//
+// Note that the EXACT method is only available if the compiler supports
+// floating points larger than mp_float_t:
+// - with MICROPY_FLOAT_IMPL_FLOAT, the compiler needs to support `double`
+// - with MICROPY_FLOAT_IMPL_DOUBLE, the compiler needs to support `long double`
+//
+#define MICROPY_FLOAT_FORMAT_IMPL_BASIC (0)  // smallest code, but inexact
+#define MICROPY_FLOAT_FORMAT_IMPL_APPROX (1) // slightly bigger, almost perfect
+#define MICROPY_FLOAT_FORMAT_IMPL_EXACT (2)  // bigger code, and 100% exact repr
+
+#ifndef MICROPY_FLOAT_FORMAT_IMPL
+#if MICROPY_FLOAT_IMPL == MICROPY_FLOAT_IMPL_FLOAT
+#define MICROPY_FLOAT_FORMAT_IMPL (MICROPY_FLOAT_FORMAT_IMPL_APPROX)
+#elif defined(__SIZEOF_LONG_DOUBLE__) && __SIZEOF_LONG_DOUBLE__ > __SIZEOF_DOUBLE__
+#define MICROPY_FLOAT_FORMAT_IMPL (MICROPY_FLOAT_FORMAT_IMPL_EXACT)
+#else
+#define MICROPY_FLOAT_FORMAT_IMPL (MICROPY_FLOAT_FORMAT_IMPL_APPROX)
+#endif
 #endif
 
 // Whether to use the native _Float16 for 16-bit float support
@@ -932,6 +1053,64 @@ typedef double mp_float_t;
 #define MICROPY_FULL_CHECKS (MICROPY_CONFIG_ROM_LEVEL_AT_LEAST_CORE_FEATURES)
 #endif
 
+// Ports can choose to use timestamps based on 2000-01-01 or 1970-01-01
+// Default is timestamps based on 2000-01-01
+#if !defined(MICROPY_EPOCH_IS_2000) && !defined(MICROPY_EPOCH_IS_1970)
+#define MICROPY_EPOCH_IS_2000 (1)
+#define MICROPY_EPOCH_IS_1970 (0)
+#elif !defined(MICROPY_EPOCH_IS_1970)
+#define MICROPY_EPOCH_IS_1970 (1 - (MICROPY_EPOCH_IS_2000))
+#elif !defined(MICROPY_EPOCH_IS_2000)
+#define MICROPY_EPOCH_IS_2000 (1 - (MICROPY_EPOCH_IS_1970))
+#endif
+
+// To maintain reasonable compatibility with CPython on embedded systems,
+// and avoid breaking anytime soon, time functions are defined to work
+// at least between 1970 and 2099 (included) on any machine.
+//
+// Specific ports can enable extended date support
+// - after 2099 using MICROPY_TIME_SUPPORT_Y2100_AND_BEYOND
+// - before 1970 using MICROPY_TIME_SUPPORT_Y1969_AND_BEFORE
+// The largest possible range is year 1600 to year 3000
+//
+// By default, extended date support is only enabled for machines using 64 bit pointers,
+// but it can be enabled by specific ports
+#ifndef MICROPY_TIME_SUPPORT_Y1969_AND_BEFORE
+#if MP_SSIZE_MAX > 2147483647
+#define MICROPY_TIME_SUPPORT_Y1969_AND_BEFORE (1)
+#else
+#define MICROPY_TIME_SUPPORT_Y1969_AND_BEFORE (0)
+#endif
+#endif
+
+// When support for dates <1970 is enabled, supporting >=2100 does not cost anything
+#ifndef MICROPY_TIME_SUPPORT_Y2100_AND_BEYOND
+#define MICROPY_TIME_SUPPORT_Y2100_AND_BEYOND (MICROPY_TIME_SUPPORT_Y1969_AND_BEFORE)
+#endif
+
+// The type to be used to represent platform-specific timestamps depends on the choices above
+#define MICROPY_TIMESTAMP_IMPL_LONG_LONG (0)
+#define MICROPY_TIMESTAMP_IMPL_UINT (1)
+#define MICROPY_TIMESTAMP_IMPL_TIME_T (2)
+
+#ifndef MICROPY_TIMESTAMP_IMPL
+#if MICROPY_TIME_SUPPORT_Y2100_AND_BEYOND || MICROPY_TIME_SUPPORT_Y1969_AND_BEFORE || MICROPY_EPOCH_IS_2000
+#define MICROPY_TIMESTAMP_IMPL (MICROPY_TIMESTAMP_IMPL_LONG_LONG)
+#else
+#define MICROPY_TIMESTAMP_IMPL (MICROPY_TIMESTAMP_IMPL_UINT)
+#endif
+#endif
+
+// `mp_timestamp_t` is the type that should be used by the port
+// to represent timestamps, and is referenced to the platform epoch
+#if MICROPY_TIMESTAMP_IMPL == MICROPY_TIMESTAMP_IMPL_LONG_LONG
+typedef long long mp_timestamp_t;
+#elif MICROPY_TIMESTAMP_IMPL == MICROPY_TIMESTAMP_IMPL_UINT
+typedef mp_uint_t mp_timestamp_t;
+#elif MICROPY_TIMESTAMP_IMPL == MICROPY_TIMESTAMP_IMPL_TIME_T
+typedef time_t mp_timestamp_t;
+#endif
+
 // Whether POSIX-semantics non-blocking streams are supported
 #ifndef MICROPY_STREAMS_NON_BLOCK
 #define MICROPY_STREAMS_NON_BLOCK (MICROPY_CONFIG_ROM_LEVEL_AT_LEAST_EXTRA_FEATURES)
@@ -943,6 +1122,16 @@ typedef double mp_float_t;
 #define MICROPY_STREAMS_POSIX_API (0)
 #endif
 
+// Whether to process __all__ when importing all public symbols from a module.
+#ifndef MICROPY_MODULE___ALL__
+#define MICROPY_MODULE___ALL__ (MICROPY_CONFIG_ROM_LEVEL_AT_LEAST_BASIC_FEATURES)
+#endif
+
+// Whether to set __file__ on imported modules.
+#ifndef MICROPY_MODULE___FILE__
+#define MICROPY_MODULE___FILE__ (MICROPY_CONFIG_ROM_LEVEL_AT_LEAST_CORE_FEATURES)
+#endif
+
 // Whether modules can use MP_REGISTER_MODULE_DELEGATION() to delegate failed
 // attribute lookups to a custom handler function.
 #ifndef MICROPY_MODULE_ATTR_DELEGATION
@@ -1030,6 +1219,16 @@ typedef double mp_float_t;
 #define MICROPY_ENABLE_VM_ABORT (0)
 #endif
 
+// Whether to handle abort behavior in pyexec code
+#ifndef MICROPY_PYEXEC_ENABLE_VM_ABORT
+#define MICROPY_PYEXEC_ENABLE_VM_ABORT (0)
+#endif
+
+// Whether to set exit codes according to the exit reason (keyboard interrupt, crash, normal exit, ...)
+#ifndef MICROPY_PYEXEC_ENABLE_EXIT_CODE_HANDLING
+#define MICROPY_PYEXEC_ENABLE_EXIT_CODE_HANDLING (0)
+#endif
+
 // Support for internal scheduler
 #ifndef MICROPY_ENABLE_SCHEDULER
 #define MICROPY_ENABLE_SCHEDULER (MICROPY_CONFIG_ROM_LEVEL_AT_LEAST_EXTRA_FEATURES)
@@ -1065,6 +1264,11 @@ typedef double mp_float_t;
 #define MICROPY_VFS_POSIX (0)
 #endif
 
+// Whether to include support for writable POSIX filesystems.
+#ifndef MICROPY_VFS_POSIX_WRITABLE
+#define MICROPY_VFS_POSIX_WRITABLE (1)
+#endif
+
 // Support for VFS FAT component, to mount a FAT filesystem within VFS
 #ifndef MICROPY_VFS_FAT
 #define MICROPY_VFS_FAT (0)
@@ -1105,7 +1309,15 @@ typedef double mp_float_t;
 #define MICROPY_PY_FUNCTION_ATTRS_CODE (MICROPY_CONFIG_ROM_LEVEL_AT_LEAST_FULL_FEATURES)
 #endif
 
-// Whether to support the descriptors __get__, __set__, __delete__
+// Whether bound_method can just use == (feature disabled), or requires a call to
+// mp_obj_equal (feature enabled), to test equality of the self and meth entities.
+// This is only needed if objects and functions can be identical without being the
+// same thing, eg when using an object proxy.
+#ifndef MICROPY_PY_BOUND_METHOD_FULL_EQUALITY_CHECK
+#define MICROPY_PY_BOUND_METHOD_FULL_EQUALITY_CHECK (0)
+#endif
+
+// Whether to support the descriptors __get__, __set__, __delete__, __set_name__
 // This costs some code size and makes load/store/delete of instance
 // attributes slower for the classes that use this feature
 #ifndef MICROPY_PY_DESCRIPTORS
@@ -1362,11 +1574,6 @@ typedef double mp_float_t;
 #define MICROPY_PY_BUILTINS_HELP_MODULES (MICROPY_CONFIG_ROM_LEVEL_AT_LEAST_EXTRA_FEATURES)
 #endif
 
-// Whether to set __file__ for imported modules
-#ifndef MICROPY_PY___FILE__
-#define MICROPY_PY___FILE__ (MICROPY_CONFIG_ROM_LEVEL_AT_LEAST_CORE_FEATURES)
-#endif
-
 // Whether to provide mem-info related functions in micropython module
 #ifndef MICROPY_PY_MICROPYTHON_MEM_INFO
 #define MICROPY_PY_MICROPYTHON_MEM_INFO (MICROPY_CONFIG_ROM_LEVEL_AT_LEAST_EXTRA_FEATURES)
@@ -1482,6 +1689,7 @@ typedef double mp_float_t;
 #endif
 
 // Whether to provide fix for pow(1, NaN) and pow(NaN, 0), which both should be 1 not NaN.
+// Also fixes pow(base, NaN) to return NaN for other values of base.
 #ifndef MICROPY_PY_MATH_POW_FIX_NAN
 #define MICROPY_PY_MATH_POW_FIX_NAN (0)
 #endif
@@ -1518,7 +1726,7 @@ typedef double mp_float_t;
 
 // Whether to provide "io.IOBase" class to support user streams
 #ifndef MICROPY_PY_IO_IOBASE
-#define MICROPY_PY_IO_IOBASE (MICROPY_CONFIG_ROM_LEVEL_AT_LEAST_EXTRA_FEATURES)
+#define MICROPY_PY_IO_IOBASE (MICROPY_CONFIG_ROM_LEVEL_AT_LEAST_CORE_FEATURES)
 #endif
 
 // Whether to provide "io.BytesIO" class
@@ -1536,15 +1744,16 @@ typedef double mp_float_t;
 #define MICROPY_PY_STRUCT (MICROPY_CONFIG_ROM_LEVEL_AT_LEAST_CORE_FEATURES)
 #endif
 
-// CIRCUITPY-CHANGE
-// Whether to provide non-standard typecodes in "struct" module
-#ifndef MICROPY_NONSTANDARD_TYPECODES
-#define MICROPY_NONSTANDARD_TYPECODES (1)
+// Whether struct module provides unsafe and non-standard typecodes O, P, S.
+// These typecodes are not in CPython and can cause crashes by accessing arbitrary
+// memory.
+#ifndef MICROPY_PY_STRUCT_UNSAFE_TYPECODES
+#define MICROPY_PY_STRUCT_UNSAFE_TYPECODES (1)
 #endif
 
 // Whether to provide "sys" module
 #ifndef MICROPY_PY_SYS
-#define MICROPY_PY_SYS (MICROPY_CONFIG_ROM_LEVEL_AT_LEAST_CORE_FEATURES)
+#define MICROPY_PY_SYS (1)
 #endif
 
 // Whether to initialise "sys.path" and "sys.argv" to their defaults in mp_init()
@@ -1800,11 +2009,11 @@ typedef double mp_float_t;
 #endif
 
 #ifndef MICROPY_PY_HASHLIB_MD5
-#define MICROPY_PY_HASHLIB_MD5 (0)
+#define MICROPY_PY_HASHLIB_MD5 (MICROPY_PY_SSL)
 #endif
 
 #ifndef MICROPY_PY_HASHLIB_SHA1
-#define MICROPY_PY_HASHLIB_SHA1  (0)
+#define MICROPY_PY_HASHLIB_SHA1  (MICROPY_PY_SSL)
 #endif
 
 #ifndef MICROPY_PY_HASHLIB_SHA256
@@ -1812,7 +2021,7 @@ typedef double mp_float_t;
 #endif
 
 #ifndef MICROPY_PY_CRYPTOLIB
-#define MICROPY_PY_CRYPTOLIB (0)
+#define MICROPY_PY_CRYPTOLIB (MICROPY_PY_SSL)
 #endif
 
 // Depends on MICROPY_PY_CRYPTOLIB
@@ -1935,6 +2144,11 @@ typedef double mp_float_t;
 #define MICROPY_PY_SSL_MBEDTLS_NEED_ACTIVE_CONTEXT (MICROPY_PY_SSL_ECDSA_SIGN_ALT)
 #endif
 
+// Whether to support DTLS protocol (non-CPython feature)
+#ifndef MICROPY_PY_SSL_DTLS
+#define MICROPY_PY_SSL_DTLS (MICROPY_SSL_MBEDTLS && MICROPY_CONFIG_ROM_LEVEL_AT_LEAST_EXTRA_FEATURES)
+#endif
+
 // Whether to provide the "vfs" module
 #ifndef MICROPY_PY_VFS
 #define MICROPY_PY_VFS (MICROPY_CONFIG_ROM_LEVEL_AT_LEAST_CORE_FEATURES && MICROPY_VFS)
@@ -2027,7 +2241,7 @@ typedef double mp_float_t;
 /*****************************************************************************/
 /* Miscellaneous settings                                                    */
 
-// All uPy objects in ROM must be aligned on at least a 4 byte boundary
+// All MicroPython objects in ROM must be aligned on at least a 4 byte boundary
 // so that the small-int/qstr/pointer distinction can be made.  For machines
 // that don't do this (eg 16-bit CPU), define the following macro to something
 // like __attribute__((aligned(4))).
@@ -2166,25 +2380,13 @@ typedef double mp_float_t;
 #define MP_SSIZE_MAX SSIZE_MAX
 #endif
 
-// printf format spec to use for mp_int_t and friends
-#ifndef INT_FMT
-#if defined(__LP64__)
-// Archs where mp_int_t == long, long != int
-#define UINT_FMT "%lu"
-#define INT_FMT "%ld"
-#elif defined(_WIN64)
-#define UINT_FMT "%llu"
-#define INT_FMT "%lld"
-#else
-// Archs where mp_int_t == int
-#define UINT_FMT "%u"
-#define INT_FMT "%d"
+// Modifier for function which doesn't return
+#ifndef MP_NORETURN
+#define MP_NORETURN __attribute__((noreturn))
 #endif
-#endif // INT_FMT
 
-// Modifier for function which doesn't return
-#ifndef NORETURN
-#define NORETURN __attribute__((noreturn))
+#if !MICROPY_PREVIEW_VERSION_2
+#define NORETURN MP_NORETURN
 #endif
 
 // Modifier for weak functions
@@ -2285,4 +2487,23 @@ typedef double mp_float_t;
 #define MP_WARN_CAT(x) (NULL)
 #endif
 
+// If true, use __builtin_mul_overflow (a gcc intrinsic supported by clang) for
+// overflow checking when multiplying two small ints. Otherwise, use a portable
+// algorithm.
+//
+// Most MCUs have a 32x32->64 bit multiply instruction, in which case the
+// intrinsic is likely to be faster and generate smaller code. The main exception is
+// cortex-m0 with __ARM_ARCH_ISA_THUMB == 1.
+//
+// The intrinsic is in GCC starting with version 5.
+#ifndef MICROPY_USE_GCC_MUL_OVERFLOW_INTRINSIC
+#if defined(__ARM_ARCH_ISA_THUMB) && (__GNUC__ >= 5)
+#define MICROPY_USE_GCC_MUL_OVERFLOW_INTRINSIC (__ARM_ARCH_ISA_THUMB >= 2)
+#elif (__GNUC__ >= 5)
+#define MICROPY_USE_GCC_MUL_OVERFLOW_INTRINSIC (1)
+#else
+#define MICROPY_USE_GCC_MUL_OVERFLOW_INTRINSIC (0)
+#endif
+#endif
+
 #endif // MICROPY_INCLUDED_PY_MPCONFIG_H
diff --git a/py/mphal.h b/py/mphal.h
index 95289ac856cb2..3907641be838a 100644
--- a/py/mphal.h
+++ b/py/mphal.h
@@ -27,6 +27,7 @@
 #define MICROPY_INCLUDED_PY_MPHAL_H
 
 #include <stdint.h>
+#include <stddef.h>
 #include "py/mpconfig.h"
 
 #ifdef MICROPY_MPHALPORT_H
diff --git a/py/mpprint.c b/py/mpprint.c
index e4e25f5a82e43..62e80d1e8e85c 100644
--- a/py/mpprint.c
+++ b/py/mpprint.c
@@ -40,8 +40,20 @@
 #include "py/formatfloat.h"
 #endif
 
-static const char pad_spaces[] = "                ";
-static const char pad_zeroes[] = "0000000000000000";
+static const char pad_spaces[16] = {' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' '};
+#define pad_spaces_size  (sizeof(pad_spaces))
+static const char pad_common[23] = {'0', '0', '0', '0', '0', '0', '0', '0', '0', '0', '0', '0', '0', '0', '0', '0', '_', '0', '0', '0', ',', '0', '0'};
+// The contents of pad_common is arranged to provide the following padding
+// strings with minimal flash size:
+//     0000000000000000 <- pad_zeroes
+//                 0000_000 <- pad_zeroes_underscore (offset: 12, size 5)
+//                      000,00 <- pad_zeroes_comma (offset: 17, size 4)
+#define pad_zeroes       (pad_common + 0)
+#define pad_zeroes_size  (16)
+#define pad_zeroes_underscore (pad_common + 12)
+#define pad_zeroes_underscore_size  (5)
+#define pad_zeroes_comma (pad_common + 17)
+#define pad_zeroes_comma_size  (4)
 
 static void plat_print_strn(void *env, const char *str, size_t len) {
     (void)env;
@@ -58,20 +70,37 @@ int mp_print_str(const mp_print_t *print, const char *str) {
     return len;
 }
 
-int mp_print_strn(const mp_print_t *print, const char *str, size_t len, int flags, char fill, int width) {
+int mp_print_strn(const mp_print_t *print, const char *str, size_t len, unsigned int flags, char fill, int width) {
     int left_pad = 0;
     int right_pad = 0;
     int pad = width - len;
     int pad_size;
     int total_chars_printed = 0;
     const char *pad_chars;
+    char grouping = flags >> PF_FLAG_SEP_POS;
 
     if (!fill || fill == ' ') {
         pad_chars = pad_spaces;
-        pad_size = sizeof(pad_spaces) - 1;
-    } else if (fill == '0') {
+        pad_size = pad_spaces_size;
+    } else if (fill == '0' && !grouping) {
         pad_chars = pad_zeroes;
-        pad_size = sizeof(pad_zeroes) - 1;
+        pad_size = pad_zeroes_size;
+    } else if (fill == '0') {
+        if (grouping == '_') {
+            pad_chars = pad_zeroes_underscore;
+            pad_size = pad_zeroes_underscore_size;
+        } else {
+            pad_chars = pad_zeroes_comma;
+            pad_size = pad_zeroes_comma_size;
+        }
+        // The result will never start with a grouping character. An extra leading zero is added.
+        // width is dead after this so we can use it in calculation
+        if (width % pad_size == 0) {
+            pad++;
+            width++;
+        }
+        // position the grouping character correctly within the pad repetition
+        pad_chars += pad_size - 1 - width % pad_size;
     } else {
         // Other pad characters are fairly unusual, so we'll take the hit
         // and output them 1 at a time.
@@ -201,7 +230,7 @@ static int mp_print_int(const mp_print_t *print, mp_uint_t x, int sgn, int base,
     return len;
 }
 
-int mp_print_mp_int(const mp_print_t *print, mp_obj_t x, int base, int base_char, int flags, char fill, int width, int prec) {
+int mp_print_mp_int(const mp_print_t *print, mp_obj_t x, unsigned int base, int base_char, int flags, char fill, int width, int prec) {
     // These are the only values for "base" that are required to be supported by this
     // function, since Python only allows the user to format integers in these bases.
     // If needed this function could be generalised to handle other values.
@@ -248,10 +277,7 @@ int mp_print_mp_int(const mp_print_t *print, mp_obj_t x, int base, int base_char
     int prefix_len = prefix - prefix_buf;
     prefix = prefix_buf;
 
-    char comma = '\0';
-    if (flags & PF_FLAG_SHOW_COMMA) {
-        comma = ',';
-    }
+    char comma = flags >> PF_FLAG_SEP_POS;
 
     // The size of this buffer is rather arbitrary. If it's not large
     // enough, a dynamic one will be allocated.
@@ -340,8 +366,8 @@ int mp_print_mp_int(const mp_print_t *print, mp_obj_t x, int base, int base_char
 }
 
 #if MICROPY_PY_BUILTINS_FLOAT
-int mp_print_float(const mp_print_t *print, mp_float_t f, char fmt, int flags, char fill, int width, int prec) {
-    char buf[32];
+int mp_print_float(const mp_print_t *print, mp_float_t f, char fmt, unsigned int flags, char fill, int width, int prec) {
+    char buf[36];
     char sign = '\0';
     int chrs = 0;
 
@@ -352,11 +378,17 @@ int mp_print_float(const mp_print_t *print, mp_float_t f, char fmt, int flags, c
         sign = ' ';
     }
 
-    int len = mp_format_float(f, buf, sizeof(buf), fmt, prec, sign);
+    int len = mp_format_float(f, buf, sizeof(buf) - 3, fmt, prec, sign);
 
     char *s = buf;
 
-    if ((flags & PF_FLAG_ADD_PERCENT) && (size_t)(len + 1) < sizeof(buf)) {
+    if ((flags & PF_FLAG_ALWAYS_DECIMAL) && strchr(buf, '.') == NULL && strchr(buf, 'e') == NULL && strchr(buf, 'n') == NULL) {
+        buf[len++] = '.';
+        buf[len++] = '0';
+        buf[len] = '\0';
+    }
+
+    if (flags & PF_FLAG_ADD_PERCENT) {
         buf[len++] = '%';
         buf[len] = '\0';
     }
@@ -376,14 +408,6 @@ int mp_print_float(const mp_print_t *print, mp_float_t f, char fmt, int flags, c
 }
 #endif
 
-// CIRCUITPY-CHANGE
-static int print_str_common(const mp_print_t *print, const char *str, int prec, size_t len, int flags, int fill, int width) {
-    if (prec >= 0 && (size_t)prec < len) {
-        len = prec;
-    }
-    return mp_print_strn(print, str, len, flags, fill, width);
-}
-
 int mp_printf(const mp_print_t *print, const char *fmt, ...) {
     va_list ap;
     va_start(ap, fmt);
@@ -424,8 +448,6 @@ int mp_vprintf(const mp_print_t *print, const char *fmt, va_list args) {
                 flags |= PF_FLAG_SHOW_SIGN;
             } else if (*fmt == ' ') {
                 flags |= PF_FLAG_SPACE_SIGN;
-            } else if (*fmt == '!') {
-                flags |= PF_FLAG_NO_TRAILZ;
             } else if (*fmt == '0') {
                 flags |= PF_FLAG_PAD_AFTER_SIGN;
                 fill = '0';
@@ -459,16 +481,36 @@ int mp_vprintf(const mp_print_t *print, const char *fmt, va_list args) {
             }
         }
 
-        // parse long specifiers (only for LP64 model where they make a difference)
-        #ifndef __LP64__
-        const
+        // parse long and long long specifiers (only where they make a difference)
+        #if (MP_INT_MAX > INT_MAX && MP_INT_MAX == LONG_MAX) || defined(MICROPY_UNIX_COVERAGE)
+        #define SUPPORT_L_FORMAT (1)
+        #else
+        #define SUPPORT_L_FORMAT (0)
         #endif
+        #if SUPPORT_L_FORMAT
         bool long_arg = false;
+        #endif
+
+        #if (MP_INT_MAX > LONG_MAX) || defined(MICROPY_UNIX_COVERAGE)
+        #define SUPPORT_LL_FORMAT (1)
+        #else
+        #define SUPPORT_LL_FORMAT (0)
+        #endif
+        #if SUPPORT_LL_FORMAT
+        bool long_long_arg = false;
+        #endif
+
         if (*fmt == 'l') {
             ++fmt;
-            #ifdef __LP64__
+            #if SUPPORT_L_FORMAT
             long_arg = true;
             #endif
+            #if SUPPORT_LL_FORMAT
+            if (*fmt == 'l') {
+                ++fmt;
+                long_long_arg = true;
+            }
+            #endif
         }
 
         if (*fmt == '\0') {
@@ -492,27 +534,19 @@ int mp_vprintf(const mp_print_t *print, const char *fmt, va_list args) {
                 qstr qst = va_arg(args, qstr);
                 size_t len;
                 const char *str = (const char *)qstr_data(qst, &len);
-                // CIRCUITPY-CHANGE
-                chrs += print_str_common(print, str, prec, len, flags, fill, width);
-                break;
-            }
-            // CIRCUITPY-CHANGE: new code to print compressed strings
-            case 'S': {
-                mp_rom_error_text_t arg = va_arg(args, mp_rom_error_text_t);
-                size_t len_with_nul = decompress_length(arg);
-                size_t len = len_with_nul - 1;
-                char str[len_with_nul];
-                decompress(arg, str);
-                chrs += print_str_common(print, str, prec, len, flags, fill, width);
+                if (prec >= 0 && (size_t)prec < len) {
+                    len = prec;
+                }
+                chrs += mp_print_strn(print, str, len, flags, fill, width);
                 break;
             }
             case 's': {
                 const char *str = va_arg(args, const char *);
                 #ifndef NDEBUG
                 // With debugging enabled, catch printing of null string pointers
-                if (str == NULL) {
-                    // CIRCUITPY-CHANGE
-                    str = "(null)";
+                if (prec != 0 && str == NULL) {
+                    chrs += mp_print_strn(print, "(null)", 6, flags, fill, width);
+                    break;
                 }
                 #endif
                 size_t len = strlen(str);
@@ -522,41 +556,58 @@ int mp_vprintf(const mp_print_t *print, const char *fmt, va_list args) {
                 chrs += mp_print_strn(print, str, len, flags, fill, width);
                 break;
             }
-            case 'd': {
-                mp_int_t val;
-                if (long_arg) {
-                    val = va_arg(args, long int);
-                } else {
-                    val = va_arg(args, int);
-                }
-                chrs += mp_print_int(print, val, 1, 10, 'a', flags, fill, width);
-                break;
-            }
+            case 'd':
+            case 'p':
+            case 'P':
             case 'u':
             case 'x':
             case 'X': {
-                int base = 16 - ((*fmt + 1) & 6); // maps char u/x/X to base 10/16/16
-                char fmt_c = (*fmt & 0xf0) - 'P' + 'A'; // maps char u/x/X to char a/a/A
+                char fmt_chr = *fmt;
                 mp_uint_t val;
-                if (long_arg) {
-                    val = va_arg(args, unsigned long int);
+                if (fmt_chr == 'p' || fmt_chr == 'P') {
+                    val = va_arg(args, uintptr_t);
+                }
+                #if SUPPORT_LL_FORMAT
+                else if (long_long_arg) {
+                    val = va_arg(args, unsigned long long);
+                }
+                #endif
+                #if SUPPORT_L_FORMAT
+                else if (long_arg) {
+                    if (sizeof(long) != sizeof(mp_uint_t) && fmt_chr == 'd') {
+                        val = va_arg(args, long);
+                    } else {
+                        val = va_arg(args, unsigned long);
+                    }
+                }
+                #endif
+                else {
+                    if (sizeof(int) != sizeof(mp_uint_t) && fmt_chr == 'd') {
+                        val = va_arg(args, int);
+                    } else {
+                        val = va_arg(args, unsigned);
+                    }
+                }
+                int base;
+                // Map format char x/p/X/P to a/a/A/A for hex letters.
+                // It doesn't matter what d/u map to.
+                char fmt_c = (fmt_chr & 0xf0) - 'P' + 'A';
+                if (fmt_chr == 'd' || fmt_chr == 'u') {
+                    base = 10;
                 } else {
-                    val = va_arg(args, unsigned int);
+                    base = 16;
+                }
+                // CIRCUITPY-CHANGE: include "0x" for 'p' and 'P'.
+                if (fmt_chr == 'p' || fmt_chr == 'P') {
+                    #if SUPPORT_INT_BASE_PREFIX
+                    chrs += mp_print_int(print, va_arg(args, unsigned long int), 0, 16, 'a', flags | PF_FLAG_SHOW_PREFIX, fill, width);
+                    #else
+                    chrs += mp_print_strn(print, "0x", 2, flags, fill, width);
+                    #endif
                 }
-                chrs += mp_print_int(print, val, 0, base, fmt_c, flags, fill, width);
+                chrs += mp_print_int(print, val, fmt_chr == 'd', base, fmt_c, flags, fill, width);
                 break;
             }
-            case 'p':
-            case 'P': // don't bother to handle upcase for 'P'
-                // Use unsigned long int to work on both ILP32 and LP64 systems
-                // CIRCUITPY-CHANGE: print 0x prefix
-                #if SUPPORT_INT_BASE_PREFIX
-                chrs += mp_print_int(print, va_arg(args, unsigned long int), 0, 16, 'a', flags | PF_FLAG_SHOW_PREFIX, fill, width);
-                #else
-                print->print_strn(print->data, "0x", 2);
-                chrs += mp_print_int(print, va_arg(args, unsigned long int), 0, 16, 'a', flags, fill, width) + 2;
-                #endif
-                break;
             #if MICROPY_PY_BUILTINS_FLOAT
             case 'e':
             case 'E':
@@ -573,18 +624,21 @@ int mp_vprintf(const mp_print_t *print, const char *fmt, va_list args) {
                 break;
             }
             #endif
-                // Because 'l' is eaten above, another 'l' means %ll.  We need to support
-                // this length specifier for OBJ_REPR_D (64-bit NaN boxing).
-                // TODO Either enable this unconditionally, or provide a specific config var.
-            #if (MICROPY_OBJ_REPR == MICROPY_OBJ_REPR_D) || defined(_WIN64)
-            case 'l': {
-                unsigned long long int arg_value = va_arg(args, unsigned long long int);
-                ++fmt;
-                assert(*fmt == 'u' || *fmt == 'd' || !"unsupported fmt char");
-                chrs += mp_print_int(print, arg_value, *fmt == 'd', 10, 'a', flags, fill, width);
+
+            // CIRCUITPY-CHANGE: new format code to print compressed strings
+            case 'S': {
+                mp_rom_error_text_t arg = va_arg(args, mp_rom_error_text_t);
+                size_t len_with_nul = decompress_length(arg);
+                size_t len = len_with_nul - 1;
+                char str[len_with_nul];
+                decompress(arg, str);
+                if (prec >= 0 && (size_t)prec < len) {
+                    len = prec;
+                }
+                chrs += mp_print_strn(print, str, len, flags, fill, width);
                 break;
             }
-            #endif
+
             default:
                 // if it's not %% then it's an unsupported format character
                 assert(*fmt == '%' || !"unsupported fmt char");
diff --git a/py/mpprint.h b/py/mpprint.h
index e883cc27047f1..614c61ea41537 100644
--- a/py/mpprint.h
+++ b/py/mpprint.h
@@ -31,13 +31,13 @@
 #define PF_FLAG_LEFT_ADJUST       (0x001)
 #define PF_FLAG_SHOW_SIGN         (0x002)
 #define PF_FLAG_SPACE_SIGN        (0x004)
-#define PF_FLAG_NO_TRAILZ         (0x008)
-#define PF_FLAG_SHOW_PREFIX       (0x010)
-#define PF_FLAG_SHOW_COMMA        (0x020)
-#define PF_FLAG_PAD_AFTER_SIGN    (0x040)
-#define PF_FLAG_CENTER_ADJUST     (0x080)
-#define PF_FLAG_ADD_PERCENT       (0x100)
-#define PF_FLAG_SHOW_OCTAL_LETTER (0x200)
+#define PF_FLAG_SHOW_PREFIX       (0x008)
+#define PF_FLAG_PAD_AFTER_SIGN    (0x010)
+#define PF_FLAG_CENTER_ADJUST     (0x020)
+#define PF_FLAG_ADD_PERCENT       (0x040)
+#define PF_FLAG_SHOW_OCTAL_LETTER (0x080)
+#define PF_FLAG_ALWAYS_DECIMAL    (0x100)
+#define PF_FLAG_SEP_POS           (9) // must be above all the above PF_FLAGs
 
 #if MICROPY_PY_IO && MICROPY_PY_SYS_STDFILES
 #define MP_PYTHON_PRINTER &mp_sys_stdout_print
@@ -69,9 +69,9 @@ extern const mp_print_t mp_sys_stdout_print;
 #endif
 
 int mp_print_str(const mp_print_t *print, const char *str);
-int mp_print_strn(const mp_print_t *print, const char *str, size_t len, int flags, char fill, int width);
+int mp_print_strn(const mp_print_t *print, const char *str, size_t len, unsigned int flags, char fill, int width);
 #if MICROPY_PY_BUILTINS_FLOAT
-int mp_print_float(const mp_print_t *print, mp_float_t f, char fmt, int flags, char fill, int width, int prec);
+int mp_print_float(const mp_print_t *print, mp_float_t f, char fmt, unsigned int flags, char fill, int width, int prec);
 #endif
 
 int mp_printf(const mp_print_t *print, const char *fmt, ...);
diff --git a/py/mpstate.h b/py/mpstate.h
index e5e5f8d9fa3d1..7934e843f0651 100644
--- a/py/mpstate.h
+++ b/py/mpstate.h
@@ -71,6 +71,12 @@ enum {
 // This structure contains dynamic configuration for the compiler.
 #if MICROPY_DYNAMIC_COMPILER
 typedef struct mp_dynamic_compiler_t {
+    // This is used to let mpy-cross pass options to the emitter chosen with
+    // `native_arch`.  The main use case for the time being is to give the
+    // RV32 emitter extended information about which extensions can be
+    // optionally used, in order to generate code that's better suited for the
+    // hardware platform the code will run on.
+    void *backend_options;
     uint8_t small_int_bits; // must be <= host small_int_bits
     uint8_t native_arch;
     uint8_t nlr_buf_num_regs;
diff --git a/py/mpz.c b/py/mpz.c
index 7d8bc03ca8610..74fd175463600 100644
--- a/py/mpz.c
+++ b/py/mpz.c
@@ -1541,7 +1541,8 @@ mp_int_t mpz_hash(const mpz_t *z) {
     mp_uint_t val = 0;
     mpz_dig_t *d = z->dig + z->len;
 
-    while (d-- > z->dig) {
+    while (d > z->dig) {
+        d--;
         val = (val << DIG_SIZE) | *d;
     }
 
@@ -1556,11 +1557,12 @@ bool mpz_as_int_checked(const mpz_t *i, mp_int_t *value) {
     mp_uint_t val = 0;
     mpz_dig_t *d = i->dig + i->len;
 
-    while (d-- > i->dig) {
+    while (d > i->dig) {
         if (val > (~(MP_OBJ_WORD_MSBIT_HIGH) >> DIG_SIZE)) {
             // will overflow
             return false;
         }
+        d--;
         val = (val << DIG_SIZE) | *d;
     }
 
@@ -1581,11 +1583,12 @@ bool mpz_as_uint_checked(const mpz_t *i, mp_uint_t *value) {
     mp_uint_t val = 0;
     mpz_dig_t *d = i->dig + i->len;
 
-    while (d-- > i->dig) {
+    while (d > i->dig) {
         if (val > (~(MP_OBJ_WORD_MSBIT_HIGH) >> (DIG_SIZE - 1))) {
             // will overflow
             return false;
         }
+        d--;
         val = (val << DIG_SIZE) | *d;
     }
 
@@ -1646,7 +1649,8 @@ mp_float_t mpz_as_float(const mpz_t *i) {
     mp_float_t val = 0;
     mpz_dig_t *d = i->dig + i->len;
 
-    while (d-- > i->dig) {
+    while (d > i->dig) {
+        d--;
         val = val * DIG_BASE + *d;
     }
 
@@ -1676,6 +1680,8 @@ size_t mpz_as_str_inpl(const mpz_t *i, unsigned int base, const char *prefix, ch
 
     size_t ilen = i->len;
 
+    int n_comma = (base == 10) ? 3 : 4;
+
     char *s = str;
     if (ilen == 0) {
         if (prefix) {
@@ -1721,7 +1727,7 @@ size_t mpz_as_str_inpl(const mpz_t *i, unsigned int base, const char *prefix, ch
                 break;
             }
         }
-        if (!done && comma && (s - last_comma) == 3) {
+        if (!done && comma && (s - last_comma) == n_comma) {
             *s++ = comma;
             last_comma = s;
         }
diff --git a/py/nativeglue.h b/py/nativeglue.h
index 00ed9f3f4fcb7..01825ac60edb4 100644
--- a/py/nativeglue.h
+++ b/py/nativeglue.h
@@ -143,7 +143,7 @@ typedef struct _mp_fun_table_t {
     int (*printf_)(const mp_print_t *print, const char *fmt, ...);
     int (*vprintf_)(const mp_print_t *print, const char *fmt, va_list args);
     #if defined(__GNUC__)
-    NORETURN // Only certain compilers support no-return attributes in function pointer declarations
+    MP_NORETURN // Only certain compilers support no-return attributes in function pointer declarations
     #endif
     // CIRCUITPY-CHANGE: raise_msg_str instead of raise_msg
     void (*raise_msg_str)(const mp_obj_type_t *exc_type, const char *msg);
diff --git a/py/nlr.c b/py/nlr.c
index 7ab0c0955a294..de2a38ceff3e9 100644
--- a/py/nlr.c
+++ b/py/nlr.c
@@ -81,7 +81,7 @@ void nlr_call_jump_callbacks(nlr_buf_t *nlr) {
 }
 
 #if MICROPY_ENABLE_VM_ABORT
-NORETURN void nlr_jump_abort(void) {
+MP_NORETURN void nlr_jump_abort(void) {
     MP_STATE_THREAD(nlr_top) = MP_STATE_VM(nlr_abort);
     nlr_jump(NULL);
 }
diff --git a/py/nlr.h b/py/nlr.h
index 340627b7aa1f0..446e78c7ebbf7 100644
--- a/py/nlr.h
+++ b/py/nlr.h
@@ -233,18 +233,18 @@ unsigned int nlr_push(nlr_buf_t *);
 
 unsigned int nlr_push_tail(nlr_buf_t *top);
 void nlr_pop(void);
-NORETURN void nlr_jump(void *val);
+MP_NORETURN void nlr_jump(void *val);
 
 #if MICROPY_ENABLE_VM_ABORT
 #define nlr_set_abort(buf) MP_STATE_VM(nlr_abort) = buf
 #define nlr_get_abort() MP_STATE_VM(nlr_abort)
-NORETURN void nlr_jump_abort(void);
+MP_NORETURN void nlr_jump_abort(void);
 #endif
 
 // This must be implemented by a port.  It's called by nlr_jump
 // if no nlr buf has been pushed.  It must not return, but rather
 // should bail out with a fatal error.
-NORETURN void nlr_jump_fail(void *val);
+MP_NORETURN void nlr_jump_fail(void *val);
 
 // use nlr_raise instead of nlr_jump so that debugging is easier
 #ifndef MICROPY_DEBUG_NLR
diff --git a/py/nlraarch64.c b/py/nlraarch64.c
index d6d87ebc50db8..3318004b5e037 100644
--- a/py/nlraarch64.c
+++ b/py/nlraarch64.c
@@ -56,7 +56,7 @@ __asm(
     #endif
     );
 
-NORETURN void nlr_jump(void *val) {
+MP_NORETURN void nlr_jump(void *val) {
     MP_NLR_JUMP_HEAD(val, top)
 
     MP_STATIC_ASSERT(offsetof(nlr_buf_t, regs) == 16); // asm assumes it
diff --git a/py/nlrmips.c b/py/nlrmips.c
index cba52b16a266a..5c55db7e268ec 100644
--- a/py/nlrmips.c
+++ b/py/nlrmips.c
@@ -57,7 +57,7 @@ __asm(
     ".end nlr_push            \n"
     );
 
-NORETURN void nlr_jump(void *val) {
+MP_NORETURN void nlr_jump(void *val) {
     MP_NLR_JUMP_HEAD(val, top)
     __asm(
         "move $4, %0    \n"
diff --git a/py/nlrpowerpc.c b/py/nlrpowerpc.c
index 8a69fe1eeca6b..cf140400e68f5 100644
--- a/py/nlrpowerpc.c
+++ b/py/nlrpowerpc.c
@@ -78,7 +78,7 @@ unsigned int nlr_push(nlr_buf_t *nlr) {
     return 0;
 }
 
-NORETURN void nlr_jump(void *val) {
+MP_NORETURN void nlr_jump(void *val) {
     MP_NLR_JUMP_HEAD(val, top)
 
     __asm__ volatile (
@@ -167,7 +167,7 @@ unsigned int nlr_push(nlr_buf_t *nlr) {
     return 0;
 }
 
-NORETURN void nlr_jump(void *val) {
+MP_NORETURN void nlr_jump(void *val) {
     MP_NLR_JUMP_HEAD(val, top)
 
     __asm__ volatile (
diff --git a/py/nlrrv32.c b/py/nlrrv32.c
index 9a12ede400daa..565a8629db5f0 100644
--- a/py/nlrrv32.c
+++ b/py/nlrrv32.c
@@ -50,7 +50,7 @@ __attribute__((naked)) unsigned int nlr_push(nlr_buf_t *nlr) {
         );
 }
 
-NORETURN void nlr_jump(void *val) {
+MP_NORETURN void nlr_jump(void *val) {
     MP_NLR_JUMP_HEAD(val, top)
     __asm volatile (
         "add  x10, x0, %0  \n" // Load nlr_buf address.
diff --git a/py/nlrrv64.c b/py/nlrrv64.c
index e7ba79797b857..b7d1467b8f6f6 100644
--- a/py/nlrrv64.c
+++ b/py/nlrrv64.c
@@ -50,7 +50,7 @@ __attribute__((naked)) unsigned int nlr_push(nlr_buf_t *nlr) {
         );
 }
 
-NORETURN void nlr_jump(void *val) {
+MP_NORETURN void nlr_jump(void *val) {
     MP_NLR_JUMP_HEAD(val, top)
     __asm volatile (
         "add  x10, x0, %0  \n" // Load nlr_buf address.
diff --git a/py/nlrthumb.c b/py/nlrthumb.c
index 265052568ffe4..1791d8b49294e 100644
--- a/py/nlrthumb.c
+++ b/py/nlrthumb.c
@@ -104,7 +104,7 @@ __attribute__((naked)) unsigned int nlr_push(nlr_buf_t *nlr) {
     #endif
 }
 
-NORETURN void nlr_jump(void *val) {
+MP_NORETURN void nlr_jump(void *val) {
     MP_NLR_JUMP_HEAD(val, top)
 
     __asm volatile (
diff --git a/py/nlrx64.c b/py/nlrx64.c
index d1ad91ff7d718..51224729fc90d 100644
--- a/py/nlrx64.c
+++ b/py/nlrx64.c
@@ -100,7 +100,7 @@ unsigned int nlr_push(nlr_buf_t *nlr) {
     #endif
 }
 
-NORETURN void nlr_jump(void *val) {
+MP_NORETURN void nlr_jump(void *val) {
     MP_NLR_JUMP_HEAD(val, top)
 
     __asm volatile (
diff --git a/py/nlrx86.c b/py/nlrx86.c
index 085e30d2034a1..26bf0dc6ccb85 100644
--- a/py/nlrx86.c
+++ b/py/nlrx86.c
@@ -78,7 +78,7 @@ unsigned int nlr_push(nlr_buf_t *nlr) {
     #endif
 }
 
-NORETURN void nlr_jump(void *val) {
+MP_NORETURN void nlr_jump(void *val) {
     MP_NLR_JUMP_HEAD(val, top)
 
     __asm volatile (
diff --git a/py/nlrxtensa.c b/py/nlrxtensa.c
index ff7af6edeef98..2d1bf35e381a3 100644
--- a/py/nlrxtensa.c
+++ b/py/nlrxtensa.c
@@ -55,7 +55,7 @@ unsigned int nlr_push(nlr_buf_t *nlr) {
     return 0; // needed to silence compiler warning
 }
 
-NORETURN void nlr_jump(void *val) {
+MP_NORETURN void nlr_jump(void *val) {
     MP_NLR_JUMP_HEAD(val, top)
 
     __asm volatile (
diff --git a/py/obj.c b/py/obj.c
index 29ae76557f8b5..ba3e6a9a9964d 100644
--- a/py/obj.c
+++ b/py/obj.c
@@ -157,7 +157,7 @@ void mp_obj_print_helper(const mp_print_t *print, mp_obj_t o_in, mp_print_kind_t
     if (MP_OBJ_TYPE_HAS_SLOT(type, print)) {
         MP_OBJ_TYPE_GET_SLOT(type, print)((mp_print_t *)print, o_in, kind);
     } else {
-        mp_printf(print, "<%q>", type->name);
+        mp_printf(print, "<%q>", (qstr)type->name);
     }
 }
 
@@ -417,6 +417,36 @@ mp_int_t mp_obj_get_int(mp_const_obj_t arg) {
     return val;
 }
 
+#if MICROPY_LONGINT_IMPL != MICROPY_LONGINT_IMPL_NONE
+mp_uint_t mp_obj_get_uint(mp_const_obj_t arg) {
+    if (!mp_obj_is_exact_type(arg, &mp_type_int)) {
+        mp_obj_t as_int = mp_unary_op(MP_UNARY_OP_INT_MAYBE, (mp_obj_t)arg);
+        if (as_int == MP_OBJ_NULL) {
+            mp_raise_TypeError_int_conversion(arg);
+        }
+        arg = as_int;
+    }
+    return mp_obj_int_get_uint_checked(arg);
+}
+
+long long mp_obj_get_ll(mp_const_obj_t arg) {
+    if (!mp_obj_is_exact_type(arg, &mp_type_int)) {
+        mp_obj_t as_int = mp_unary_op(MP_UNARY_OP_INT_MAYBE, (mp_obj_t)arg);
+        if (as_int == MP_OBJ_NULL) {
+            mp_raise_TypeError_int_conversion(arg);
+        }
+        arg = as_int;
+    }
+    if (mp_obj_is_small_int(arg)) {
+        return MP_OBJ_SMALL_INT_VALUE(arg);
+    } else {
+        long long res;
+        mp_obj_int_to_bytes_impl((mp_obj_t)arg, MP_ENDIANNESS_BIG, sizeof(res), (byte *)&res);
+        return res;
+    }
+}
+#endif
+
 mp_int_t mp_obj_get_int_truncated(mp_const_obj_t arg) {
     if (mp_obj_is_int(arg)) {
         return mp_obj_int_get_truncated(arg);
diff --git a/py/obj.h b/py/obj.h
index 38db17cba449b..eb7143bd43f62 100644
--- a/py/obj.h
+++ b/py/obj.h
@@ -184,13 +184,15 @@ static inline bool mp_obj_is_small_int(mp_const_obj_t o) {
 #define MP_OBJ_NEW_SMALL_INT(small_int) ((mp_obj_t)((((mp_uint_t)(small_int)) << 1) | 1))
 
 #if MICROPY_PY_BUILTINS_FLOAT
-#define MP_OBJ_NEW_CONST_FLOAT(f) MP_ROM_PTR((mp_obj_t)((((((uint64_t)f) & ~3) | 2) + 0x80800000) & 0xffffffff))
+#include <math.h>
+// note: MP_OBJ_NEW_CONST_FLOAT should be a MP_ROM_PTR but that macro isn't available yet
+#define MP_OBJ_NEW_CONST_FLOAT(f) ((mp_obj_t)((((((uint64_t)f) & ~3) | 2) + 0x80800000) & 0xffffffff))
 #define mp_const_float_e  MP_OBJ_NEW_CONST_FLOAT(0x402df854)
 #define mp_const_float_pi MP_OBJ_NEW_CONST_FLOAT(0x40490fdb)
+#define mp_const_float_nan MP_OBJ_NEW_CONST_FLOAT(0x7fc00000)
 #if MICROPY_PY_MATH_CONSTANTS
 #define mp_const_float_tau MP_OBJ_NEW_CONST_FLOAT(0x40c90fdb)
 #define mp_const_float_inf MP_OBJ_NEW_CONST_FLOAT(0x7f800000)
-#define mp_const_float_nan MP_OBJ_NEW_CONST_FLOAT(0xffc00000)
 #endif
 
 static inline bool mp_obj_is_float(mp_const_obj_t o) {
@@ -204,9 +206,17 @@ static inline mp_float_t mp_obj_float_get(mp_const_obj_t o) {
         mp_float_t f;
         mp_uint_t u;
     } num = {.u = ((mp_uint_t)o - 0x80800000u) & ~3u};
+    // Rather than always truncating toward zero, which creates a strong
+    // bias, copy the two previous bits to fill in the two missing bits.
+    // This appears to be a pretty good heuristic.
+    num.u |= (num.u >> 2) & 3u;
     return num.f;
 }
 static inline mp_obj_t mp_obj_new_float(mp_float_t f) {
+    if (isnan(f)) {
+        // prevent creation of bad nanboxed pointers via array.array or struct
+        return mp_const_float_nan;
+    }
     union {
         mp_float_t f;
         mp_uint_t u;
@@ -257,8 +267,10 @@ static inline bool mp_obj_is_immediate_obj(mp_const_obj_t o) {
 #error MICROPY_OBJ_REPR_D requires MICROPY_FLOAT_IMPL_DOUBLE
 #endif
 
+#include <math.h>
 #define mp_const_float_e {((mp_obj_t)((uint64_t)0x4005bf0a8b145769 + 0x8004000000000000))}
 #define mp_const_float_pi {((mp_obj_t)((uint64_t)0x400921fb54442d18 + 0x8004000000000000))}
+#define mp_const_float_nan {((mp_obj_t)((uint64_t)0x7ff8000000000000 + 0x8004000000000000))}
 #if MICROPY_PY_MATH_CONSTANTS
 #define mp_const_float_tau {((mp_obj_t)((uint64_t)0x401921fb54442d18 + 0x8004000000000000))}
 #define mp_const_float_inf {((mp_obj_t)((uint64_t)0x7ff0000000000000 + 0x8004000000000000))}
@@ -276,6 +288,13 @@ static inline mp_float_t mp_obj_float_get(mp_const_obj_t o) {
     return num.f;
 }
 static inline mp_obj_t mp_obj_new_float(mp_float_t f) {
+    if (isnan(f)) {
+        // prevent creation of bad nanboxed pointers via array.array or struct
+        struct {
+            uint64_t r;
+        } num = mp_const_float_nan;
+        return num.r;
+    }
     union {
         mp_float_t f;
         uint64_t r;
@@ -371,25 +390,25 @@ typedef struct _mp_rom_obj_t { mp_const_obj_t o; } mp_rom_obj_t;
 
 #define MP_DEFINE_CONST_FUN_OBJ_0(obj_name, fun_name) \
     const mp_obj_fun_builtin_fixed_t obj_name = \
-    {{&mp_type_fun_builtin_0}, .fun._0 = fun_name}
+    {.base = {.type = &mp_type_fun_builtin_0}, .fun = {._0 = fun_name}}
 #define MP_DEFINE_CONST_FUN_OBJ_1(obj_name, fun_name) \
     const mp_obj_fun_builtin_fixed_t obj_name = \
-    {{&mp_type_fun_builtin_1}, .fun._1 = fun_name}
+    {.base = {.type = &mp_type_fun_builtin_1}, .fun = {._1 = fun_name}}
 #define MP_DEFINE_CONST_FUN_OBJ_2(obj_name, fun_name) \
     const mp_obj_fun_builtin_fixed_t obj_name = \
-    {{&mp_type_fun_builtin_2}, .fun._2 = fun_name}
+    {.base = {.type = &mp_type_fun_builtin_2}, .fun = {._2 = fun_name}}
 #define MP_DEFINE_CONST_FUN_OBJ_3(obj_name, fun_name) \
     const mp_obj_fun_builtin_fixed_t obj_name = \
-    {{&mp_type_fun_builtin_3}, .fun._3 = fun_name}
+    {.base = {.type = &mp_type_fun_builtin_3}, .fun = {._3 = fun_name}}
 #define MP_DEFINE_CONST_FUN_OBJ_VAR(obj_name, n_args_min, fun_name) \
     const mp_obj_fun_builtin_var_t obj_name = \
-    {{&mp_type_fun_builtin_var}, MP_OBJ_FUN_MAKE_SIG(n_args_min, MP_OBJ_FUN_ARGS_MAX, false), .fun.var = fun_name}
+    {.base = {.type = &mp_type_fun_builtin_var}, .sig = MP_OBJ_FUN_MAKE_SIG(n_args_min, MP_OBJ_FUN_ARGS_MAX, false), .fun = {.var = fun_name}}
 #define MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(obj_name, n_args_min, n_args_max, fun_name) \
     const mp_obj_fun_builtin_var_t obj_name = \
-    {{&mp_type_fun_builtin_var}, MP_OBJ_FUN_MAKE_SIG(n_args_min, n_args_max, false), .fun.var = fun_name}
+    {.base = {.type = &mp_type_fun_builtin_var}, .sig = MP_OBJ_FUN_MAKE_SIG(n_args_min, n_args_max, false), .fun = {.var = fun_name}}
 #define MP_DEFINE_CONST_FUN_OBJ_KW(obj_name, n_args_min, fun_name) \
     const mp_obj_fun_builtin_var_t obj_name = \
-    {{&mp_type_fun_builtin_var}, MP_OBJ_FUN_MAKE_SIG(n_args_min, MP_OBJ_FUN_ARGS_MAX, true), .fun.kw = fun_name}
+    {.base = {.type = &mp_type_fun_builtin_var}, .sig = MP_OBJ_FUN_MAKE_SIG(n_args_min, MP_OBJ_FUN_ARGS_MAX, true), .fun = {.kw = fun_name}}
 
 // CIRCUITPY-CHANGE
 #define MP_DEFINE_CONST_PROP_GET(obj_name, fun_name) \
@@ -516,9 +535,7 @@ static inline bool mp_map_slot_is_filled(const mp_map_t *map, size_t pos) {
 
 void mp_map_init(mp_map_t *map, size_t n);
 void mp_map_init_fixed_table(mp_map_t *map, size_t n, const mp_obj_t *table);
-mp_map_t *mp_map_new(size_t n);
 void mp_map_deinit(mp_map_t *map);
-void mp_map_free(mp_map_t *map);
 mp_map_elem_t *mp_map_lookup(mp_map_t *map, mp_obj_t index, mp_map_lookup_kind_t lookup_kind);
 void mp_map_clear(mp_map_t *map);
 void mp_map_dump(mp_map_t *map);
@@ -555,6 +572,10 @@ typedef mp_obj_t (*mp_fun_var_t)(size_t n, const mp_obj_t *);
 typedef mp_obj_t (*mp_fun_kw_t)(size_t n, const mp_obj_t *, mp_map_t *);
 
 // Flags for type behaviour (mp_obj_type_t.flags)
+// If MP_TYPE_FLAG_IS_SUBCLASSED is set, then subclasses of this class have been created.
+//   Mutations to this class that would require updating all subclasses must be rejected.
+// If MP_TYPE_FLAG_HAS_SPECIAL_ACCESSORS is set, then attribute lookups involving this
+//   class need to additionally check for special accessor methods, such as from descriptors.
 // If MP_TYPE_FLAG_EQ_NOT_REFLEXIVE is clear then __eq__ is reflexive (A==A returns True).
 // If MP_TYPE_FLAG_EQ_CHECKS_OTHER_TYPE is clear then the type can't be equal to an
 //   instance of any different class that also clears this flag.  If this flag is set
@@ -572,6 +593,8 @@ typedef mp_obj_t (*mp_fun_kw_t)(size_t n, const mp_obj_t *, mp_map_t *);
 // If MP_TYPE_FLAG_ITER_IS_STREAM is set then the type implicitly gets a "return self"
 //   getiter, and mp_stream_unbuffered_iter for iternext.
 // If MP_TYPE_FLAG_INSTANCE_TYPE is set then this is an instance type (i.e. defined in Python).
+// If MP_TYPE_FLAG_SUBSCR_ALLOWS_STACK_SLICE is set then the "subscr" slot allows a stack
+//   allocated slice to be passed in (no references to it will be retained after the call).
 #define MP_TYPE_FLAG_NONE (0x0000)
 #define MP_TYPE_FLAG_IS_SUBCLASSED (0x0001)
 #define MP_TYPE_FLAG_HAS_SPECIAL_ACCESSORS (0x0002)
@@ -585,8 +608,9 @@ typedef mp_obj_t (*mp_fun_kw_t)(size_t n, const mp_obj_t *, mp_map_t *);
 #define MP_TYPE_FLAG_ITER_IS_CUSTOM (0x0100)
 #define MP_TYPE_FLAG_ITER_IS_STREAM (MP_TYPE_FLAG_ITER_IS_ITERNEXT | MP_TYPE_FLAG_ITER_IS_CUSTOM)
 #define MP_TYPE_FLAG_INSTANCE_TYPE (0x0200)
+#define MP_TYPE_FLAG_SUBSCR_ALLOWS_STACK_SLICE (0x0400)
 // CIRCUITPY-CHANGE: check for valid types in json dumps
-#define MP_TYPE_FLAG_PRINT_JSON (0x0400)
+#define MP_TYPE_FLAG_PRINT_JSON (0x0800)
 
 typedef enum {
     PRINT_STR = 0,
@@ -827,7 +851,7 @@ typedef struct _mp_obj_full_type_t {
 #define MP_DEFINE_CONST_OBJ_TYPE_NARGS(_1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18, _19, _20, _21, _22, _23, _24, _25, _26, _27, _28, N, ...) MP_DEFINE_CONST_OBJ_TYPE_NARGS_##N
 
 // This macros is used to define a object type in ROM.
-// Invoke as MP_DEFINE_CONST_OBJ_TYPE(_typename, _name, _flags, _make_new [, slot, func]*)
+// Invoke as MP_DEFINE_CONST_OBJ_TYPE(_typename, _name, _flags, [, slot, func]*)
 // It uses the number of arguments to select which MP_DEFINE_CONST_OBJ_TYPE_*
 // macro to use based on the number of arguments. It works by shifting the
 // numeric values 12, 11, ... 0 by the number of arguments, such that the
@@ -847,7 +871,7 @@ extern const mp_obj_type_t mp_type_bytearray;
 extern const mp_obj_type_t mp_type_memoryview;
 extern const mp_obj_type_t mp_type_float;
 extern const mp_obj_type_t mp_type_complex;
-// CIRCUITPY-CHANGE
+// CIRCUITPY-CHANGE: add traceback support
 extern const mp_obj_type_t mp_type_traceback;
 extern const mp_obj_type_t mp_type_tuple;
 extern const mp_obj_type_t mp_type_list;
@@ -909,7 +933,7 @@ extern const mp_obj_type_t mp_type_ImportError;
 extern const mp_obj_type_t mp_type_IndentationError;
 extern const mp_obj_type_t mp_type_IndexError;
 extern const mp_obj_type_t mp_type_KeyboardInterrupt;
-// CIRCUITPY-CHANGE
+// CIRCUITPY-CHANGE: add ReloadException
 extern const mp_obj_type_t mp_type_ReloadException;
 extern const mp_obj_type_t mp_type_KeyError;
 extern const mp_obj_type_t mp_type_LookupError;
@@ -917,9 +941,9 @@ extern const mp_obj_type_t mp_type_MemoryError;
 extern const mp_obj_type_t mp_type_NameError;
 extern const mp_obj_type_t mp_type_NotImplementedError;
 extern const mp_obj_type_t mp_type_OSError;
-// CIRCUITPY-CHANGE
+// CIRCUITPY-CHANGE: add ConnectionError
 extern const mp_obj_type_t mp_type_ConnectionError;
-// CIRCUITPY-CHANGE
+// CIRCUITPY-CHANGE: add BrokenPipeError
 extern const mp_obj_type_t mp_type_BrokenPipeError;
 extern const mp_obj_type_t mp_type_OverflowError;
 extern const mp_obj_type_t mp_type_RuntimeError;
@@ -927,6 +951,7 @@ extern const mp_obj_type_t mp_type_StopAsyncIteration;
 extern const mp_obj_type_t mp_type_StopIteration;
 extern const mp_obj_type_t mp_type_SyntaxError;
 extern const mp_obj_type_t mp_type_SystemExit;
+// CIRCUITPY-CHANGE: add TimeoutError
 extern const mp_obj_type_t mp_type_TimeoutError;
 extern const mp_obj_type_t mp_type_TypeError;
 extern const mp_obj_type_t mp_type_UnicodeError;
@@ -991,11 +1016,11 @@ void *mp_obj_malloc_helper(size_t num_bytes, const mp_obj_type_t *type);
 // Object allocation macros for allocating objects that have a finaliser.
 #if MICROPY_ENABLE_FINALISER
 #define mp_obj_malloc_with_finaliser(struct_type, obj_type) ((struct_type *)mp_obj_malloc_with_finaliser_helper(sizeof(struct_type), obj_type))
-#define mp_obj_malloc_var_with_finaliser(struct_type, var_type, var_num, obj_type) ((struct_type *)mp_obj_malloc_with_finaliser_helper(sizeof(struct_type) + sizeof(var_type) * (var_num), obj_type))
+#define mp_obj_malloc_var_with_finaliser(struct_type, var_field, var_type, var_num, obj_type) ((struct_type *)mp_obj_malloc_with_finaliser_helper(offsetof(struct_type, var_field) + sizeof(var_type) * (var_num), obj_type))
 void *mp_obj_malloc_with_finaliser_helper(size_t num_bytes, const mp_obj_type_t *type);
 #else
 #define mp_obj_malloc_with_finaliser(struct_type, obj_type) mp_obj_malloc(struct_type, obj_type)
-#define mp_obj_malloc_var_with_finaliser(struct_type, var_type, var_num, obj_type) mp_obj_malloc_var(struct_type, var_type, var_num, obj_type)
+#define mp_obj_malloc_var_with_finaliser(struct_type, var_field, var_type, var_num, obj_type) mp_obj_malloc_var(struct_type, var_field, var_type, var_num, obj_type)
 #endif
 
 // These macros are derived from more primitive ones and are used to
@@ -1032,7 +1057,6 @@ bool mp_obj_is_dict_or_ordereddict(mp_obj_t o);
 // type check is done on iter method to allow tuple, namedtuple, attrtuple
 #define mp_obj_is_tuple_compatible(o) (MP_OBJ_TYPE_GET_SLOT_OR_NULL(mp_obj_get_type(o), iter) == mp_obj_tuple_getiter)
 
-mp_obj_t mp_obj_new_type(qstr name, mp_obj_t bases_tuple, mp_obj_t locals_dict);
 static inline mp_obj_t mp_obj_new_bool(mp_int_t x) {
     return x ? mp_const_true : mp_const_false;
 }
@@ -1053,10 +1077,10 @@ mp_obj_t mp_obj_new_str_from_utf8_vstr(vstr_t *vstr); // input data must be vali
 #endif
 mp_obj_t mp_obj_new_bytes_from_vstr(vstr_t *vstr);
 mp_obj_t mp_obj_new_bytes(const byte *data, size_t len);
-// CIRCUITPY-CHANGE
+// CIRCUITPY-CHANGE: new routine
 mp_obj_t mp_obj_new_bytes_of_zeros(size_t len);
 mp_obj_t mp_obj_new_bytearray(size_t n, const void *items);
-// CIRCUITPY-CHANGE
+// CIRCUITPY-CHANGE: new routine
 mp_obj_t mp_obj_new_bytearray_of_zeros(size_t n);
 mp_obj_t mp_obj_new_bytearray_by_ref(size_t n, void *items);
 #if MICROPY_PY_BUILTINS_FLOAT
@@ -1092,7 +1116,7 @@ mp_obj_t mp_obj_new_memoryview(byte typecode, size_t nitems, void *items);
 
 const mp_obj_type_t *mp_obj_get_type(mp_const_obj_t o_in);
 const char *mp_obj_get_type_str(mp_const_obj_t o_in);
-// CIRCUITPY-CHANGE
+// CIRCUITPY-CHANGE: new routine
 #define mp_obj_get_type_qstr(o_in) (mp_obj_get_type((o_in))->name)
 bool mp_obj_is_subclass_fast(mp_const_obj_t object, mp_const_obj_t classinfo); // arguments should be type objects
 mp_obj_t mp_obj_cast_to_native_base(mp_obj_t self_in, mp_const_obj_t native_type);
@@ -1100,7 +1124,7 @@ mp_obj_t mp_obj_cast_to_native_base(mp_obj_t self_in, mp_const_obj_t native_type
 void mp_obj_print_helper(const mp_print_t *print, mp_obj_t o_in, mp_print_kind_t kind);
 void mp_obj_print(mp_obj_t o, mp_print_kind_t kind);
 void mp_obj_print_exception(const mp_print_t *print, mp_obj_t exc);
-// CIRCUITPY-CHANGE
+// CIRCUITPY-CHANGE: new routine
 void mp_obj_print_exception_with_limit(const mp_print_t *print, mp_obj_t exc, mp_int_t limit);
 
 bool mp_obj_is_true(mp_obj_t arg);
@@ -1114,6 +1138,8 @@ static inline bool mp_obj_is_integer(mp_const_obj_t o) {
 }
 
 mp_int_t mp_obj_get_int(mp_const_obj_t arg);
+mp_uint_t mp_obj_get_uint(mp_const_obj_t arg);
+long long mp_obj_get_ll(mp_const_obj_t arg);
 mp_int_t mp_obj_get_int_truncated(mp_const_obj_t arg);
 bool mp_obj_get_int_maybe(mp_const_obj_t arg, mp_int_t *value);
 #if MICROPY_PY_BUILTINS_FLOAT
@@ -1163,7 +1189,7 @@ bool mp_obj_exception_match(mp_obj_t exc, mp_const_obj_t exc_type);
 void mp_obj_exception_clear_traceback(mp_obj_t self_in);
 void mp_obj_exception_add_traceback(mp_obj_t self_in, qstr file, size_t line, qstr block);
 void mp_obj_exception_get_traceback(mp_obj_t self_in, size_t *n, size_t **values);
-// CIRCUITPY-CHANGE
+// CIRCUITPY-CHANGE: new routine
 mp_obj_t mp_obj_exception_get_traceback_obj(mp_obj_t self_in);
 mp_obj_t mp_obj_exception_get_value(mp_obj_t self_in);
 mp_obj_t mp_obj_exception_make_new(const mp_obj_type_t *type_in, size_t n_args, size_t n_kw, const mp_obj_t *args);
@@ -1240,7 +1266,7 @@ void mp_obj_tuple_del(mp_obj_t self_in);
 mp_int_t mp_obj_tuple_hash(mp_obj_t self_in);
 
 // list
-// CIRCUITPY-CHANGE
+// CIRCUITPY-CHANGE: public routine
 mp_obj_t mp_obj_list_clear(mp_obj_t self_in);
 mp_obj_t mp_obj_list_append(mp_obj_t self_in, mp_obj_t arg);
 mp_obj_t mp_obj_list_remove(mp_obj_t self_in, mp_obj_t value);
@@ -1336,7 +1362,7 @@ typedef struct _mp_rom_obj_static_class_method_t {
 } mp_rom_obj_static_class_method_t;
 
 // property
-// CIRCUITPY-CHANGE
+// CIRCUITPY-CHANGE: extra args
 const mp_obj_t *mp_obj_property_get(mp_obj_t self_in, size_t *n_proxy);
 
 // sequence helpers
diff --git a/py/objarray.c b/py/objarray.c
index 0be1947167d6e..1e259a20ac8cb 100644
--- a/py/objarray.c
+++ b/py/objarray.c
@@ -126,6 +126,19 @@ static mp_obj_array_t *array_new(char typecode, size_t n) {
 #endif
 
 #if MICROPY_PY_BUILTINS_BYTEARRAY || MICROPY_PY_ARRAY
+static void array_extend_impl(mp_obj_array_t *array, mp_obj_t arg, char typecode, size_t len) {
+    mp_obj_t iterable = mp_getiter(arg, NULL);
+    mp_obj_t item;
+    size_t i = 0;
+    while ((item = mp_iternext(iterable)) != MP_OBJ_STOP_ITERATION) {
+        if (len == 0) {
+            array_append(MP_OBJ_FROM_PTR(array), item);
+        } else {
+            mp_binary_set_val_array(typecode, array->items, i++, item);
+        }
+    }
+}
+
 static mp_obj_t array_construct(char typecode, mp_obj_t initializer) {
     // bytearrays can be raw-initialised from anything with the buffer protocol
     // other arrays can only be raw-initialised from bytes and bytearray objects
@@ -158,18 +171,7 @@ static mp_obj_t array_construct(char typecode, mp_obj_t initializer) {
     }
 
     mp_obj_array_t *array = array_new(typecode, len);
-
-    mp_obj_t iterable = mp_getiter(initializer, NULL);
-    mp_obj_t item;
-    size_t i = 0;
-    while ((item = mp_iternext(iterable)) != MP_OBJ_STOP_ITERATION) {
-        if (len == 0) {
-            array_append(MP_OBJ_FROM_PTR(array), item);
-        } else {
-            mp_binary_set_val_array(typecode, array->items, i++, item);
-        }
-    }
-
+    array_extend_impl(array, initializer, typecode, len);
     return MP_OBJ_FROM_PTR(array);
 }
 #endif
@@ -298,7 +300,7 @@ static void memoryview_attr(mp_obj_t self_in, qstr attr, mp_obj_t *dest) {
         mp_obj_array_t *self = MP_OBJ_TO_PTR(self_in);
         dest[0] = MP_OBJ_NEW_SMALL_INT(mp_binary_get_size('@', self->typecode & TYPECODE_MASK, NULL));
     }
-    // CIRCUITPY-CHANGE: prevent warning
+    // CIRCUITPY-CHANGE: add MICROPY_CPYTHON_COMPAT
     #if MICROPY_PY_BUILTINS_BYTES_HEX || MICROPY_CPYTHON_COMPAT
     else {
         // Need to forward to locals dict.
@@ -493,39 +495,42 @@ static mp_obj_t array_extend(mp_obj_t self_in, mp_obj_t arg_in) {
 
     // allow to extend by anything that has the buffer protocol (extension to CPython)
     mp_buffer_info_t arg_bufinfo;
-    // CIRCUITPY-CHANGE: allow appending an iterable
-    if (mp_get_buffer(arg_in, &arg_bufinfo, MP_BUFFER_READ)) {
-        size_t sz = mp_binary_get_size('@', self->typecode, NULL);
-
-        // convert byte count to element count
-        size_t len = arg_bufinfo.len / sz;
-
-        // make sure we have enough room to extend
-        // TODO: alloc policy; at the moment we go conservative
-        if (self->free < len) {
-            self->items = m_renew(byte, self->items, (self->len + self->free) * sz, (self->len + len) * sz);
-            self->free = 0;
-        } else {
-            self->free -= len;
-        }
+    if (!mp_get_buffer(arg_in, &arg_bufinfo, MP_BUFFER_READ)) {
+        array_extend_impl(self, arg_in, 0, 0);
+        return mp_const_none;
+    }
 
-        // extend
-        mp_seq_copy((byte *)self->items + self->len * sz, arg_bufinfo.buf, len * sz, byte);
-        self->len += len;
-    } else {
-        // Otherwise argument must be an iterable of items to append
-        mp_obj_t iterable = mp_getiter(arg_in, NULL);
-        mp_obj_t item;
-        while ((item = mp_iternext(iterable)) != MP_OBJ_STOP_ITERATION) {
-            array_append(self_in, item);
+    size_t sz = mp_binary_get_size('@', self->typecode, NULL);
+
+    // convert byte count to element count
+    size_t len = arg_bufinfo.len / sz;
+
+    // make sure we have enough room to extend
+    // TODO: alloc policy; at the moment we go conservative
+    if (self->free < len) {
+        self->items = m_renew(byte, self->items, (self->len + self->free) * sz, (self->len + len) * sz);
+        self->free = 0;
+
+        if (self_in == arg_in) {
+            // Get arg_bufinfo again in case self->items has moved
+            //
+            // (Note not possible to handle case that arg_in is a memoryview into self)
+            mp_get_buffer_raise(arg_in, &arg_bufinfo, MP_BUFFER_READ);
         }
+    } else {
+        self->free -= len;
     }
+
+    // extend
+    mp_seq_copy((byte *)self->items + self->len * sz, arg_bufinfo.buf, len * sz, byte);
+    self->len += len;
+
     return mp_const_none;
 }
 MP_DEFINE_CONST_FUN_OBJ_2(mp_obj_array_extend_obj, array_extend);
 #endif
 
-// CIRCUITPY-CHANGE: buffer_finder used belo
+// CIRCUITPY-CHANGE: buffer_finder used below
 #if MICROPY_PY_BUILTINS_BYTEARRAY && MICROPY_CPYTHON_COMPAT
 static mp_obj_t buffer_finder(size_t n_args, const mp_obj_t *args, int direction, bool is_index) {
     mp_check_self(mp_obj_is_type(args[0], &mp_type_bytearray));
@@ -564,7 +569,6 @@ static mp_obj_t buffer_finder(size_t n_args, const mp_obj_t *args, int direction
     }
     return MP_OBJ_NEW_SMALL_INT(p - (const byte *)haystack_bufinfo.buf);
 }
-
 // CIRCUITPY-CHANGE: provides find, rfind, index
 static mp_obj_t buffer_find(size_t n_args, const mp_obj_t *args) {
     return buffer_finder(n_args, args, 1, false);
@@ -667,7 +671,7 @@ static mp_obj_t array_subscr(mp_obj_t self_in, mp_obj_t index_in, mp_obj_t value
                     mp_seq_replace_slice_no_grow(dest_items, o->len,
                         slice.start, slice.stop, src_items + src_offs, src_len, item_sz);
                     // CIRCUITPY-CHANGE
-                    #if MICROPY_NONSTANDARD_TYPECODES
+                    #if MICROPY_PY_STRUCT_UNSAFE_TYPECODES
                     // Clear "freed" elements at the end of list
                     // TODO: This is actually only needed for typecode=='O'
                     mp_seq_clear(dest_items, o->len + len_adj, o->len, item_sz);
@@ -803,7 +807,7 @@ MP_DEFINE_CONST_OBJ_TYPE(
 MP_DEFINE_CONST_OBJ_TYPE(
     mp_type_bytearray,
     MP_QSTR_bytearray,
-    MP_TYPE_FLAG_EQ_CHECKS_OTHER_TYPE | MP_TYPE_FLAG_ITER_IS_GETITER,
+    MP_TYPE_FLAG_EQ_CHECKS_OTHER_TYPE | MP_TYPE_FLAG_ITER_IS_GETITER | MP_TYPE_FLAG_SUBSCR_ALLOWS_STACK_SLICE,
     make_new, bytearray_make_new,
     print, array_print,
     iter, array_iterator_new,
@@ -842,7 +846,7 @@ MP_DEFINE_CONST_DICT(memoryview_locals_dict, memoryview_locals_dict_table);
 MP_DEFINE_CONST_OBJ_TYPE(
     mp_type_memoryview,
     MP_QSTR_memoryview,
-    MP_TYPE_FLAG_EQ_CHECKS_OTHER_TYPE | MP_TYPE_FLAG_ITER_IS_GETITER,
+    MP_TYPE_FLAG_EQ_CHECKS_OTHER_TYPE | MP_TYPE_FLAG_ITER_IS_GETITER | MP_TYPE_FLAG_SUBSCR_ALLOWS_STACK_SLICE,
     make_new, memoryview_make_new,
     iter, array_iterator_new,
     unary_op, array_unary_op,
diff --git a/py/objboundmeth.c b/py/objboundmeth.c
index e3503ff154a65..6df67f7bf9e0c 100644
--- a/py/objboundmeth.c
+++ b/py/objboundmeth.c
@@ -102,7 +102,11 @@ static mp_obj_t bound_meth_binary_op(mp_binary_op_t op, mp_obj_t lhs_in, mp_obj_
     }
     mp_obj_bound_meth_t *lhs = MP_OBJ_TO_PTR(lhs_in);
     mp_obj_bound_meth_t *rhs = MP_OBJ_TO_PTR(rhs_in);
+    #if MICROPY_PY_BOUND_METHOD_FULL_EQUALITY_CHECK
+    return mp_obj_new_bool(mp_obj_equal(lhs->self, rhs->self) && mp_obj_equal(lhs->meth, rhs->meth));
+    #else
     return mp_obj_new_bool(lhs->self == rhs->self && lhs->meth == rhs->meth);
+    #endif
 }
 
 #if MICROPY_PY_FUNCTION_ATTRS
diff --git a/py/objcell.c b/py/objcell.c
index 95966c7917cb7..5c030c7405a80 100644
--- a/py/objcell.c
+++ b/py/objcell.c
@@ -30,7 +30,7 @@
 static void cell_print(const mp_print_t *print, mp_obj_t o_in, mp_print_kind_t kind) {
     (void)kind;
     mp_obj_cell_t *o = MP_OBJ_TO_PTR(o_in);
-    mp_printf(print, "<cell %p ", o->obj);
+    mp_printf(print, "<cell " HEX_FMT " ", (mp_uint_t)o->obj);
     if (o->obj == MP_OBJ_NULL) {
         mp_print_str(print, "(nil)");
     } else {
diff --git a/py/objcode.c b/py/objcode.c
index 9b98a696798d4..09904f10f3683 100644
--- a/py/objcode.c
+++ b/py/objcode.c
@@ -69,6 +69,7 @@ static mp_obj_tuple_t *code_consts(const mp_module_context_t *context, const mp_
     return consts;
 }
 
+#if !MICROPY_PREVIEW_VERSION_2
 static mp_obj_t raw_code_lnotab(const mp_raw_code_t *rc) {
     // const mp_bytecode_prelude_t *prelude = &rc->prelude;
     uint start = 0;
@@ -106,6 +107,68 @@ static mp_obj_t raw_code_lnotab(const mp_raw_code_t *rc) {
     m_del(byte, buffer, buffer_size);
     return o;
 }
+#endif
+
+static mp_obj_t code_colines_iter(mp_obj_t);
+static mp_obj_t code_colines_next(mp_obj_t);
+typedef struct _mp_obj_colines_iter_t {
+    mp_obj_base_t base;
+    mp_fun_1_t iternext;
+    const mp_raw_code_t *rc;
+    mp_uint_t bc;
+    mp_uint_t source_line;
+    const byte *ci;
+} mp_obj_colines_iter_t;
+
+static mp_obj_t code_colines_iter(mp_obj_t self_in) {
+    mp_obj_code_t *self = MP_OBJ_TO_PTR(self_in);
+    mp_obj_colines_iter_t *iter = mp_obj_malloc(mp_obj_colines_iter_t, &mp_type_polymorph_iter);
+    iter->iternext = code_colines_next;
+    iter->rc = self->rc;
+    iter->bc = 0;
+    iter->source_line = 1;
+    iter->ci = self->rc->prelude.line_info;
+    return MP_OBJ_FROM_PTR(iter);
+}
+static MP_DEFINE_CONST_FUN_OBJ_1(code_colines_obj, code_colines_iter);
+
+static mp_obj_t code_colines_next(mp_obj_t iter_in) {
+    mp_obj_colines_iter_t *iter = MP_OBJ_TO_PTR(iter_in);
+    const byte *ci_end = iter->rc->prelude.line_info_top;
+
+    mp_uint_t start = iter->bc;
+    mp_uint_t line_no = iter->source_line;
+    bool another = true;
+
+    while (another && iter->ci < ci_end) {
+        another = false;
+        mp_code_lineinfo_t decoded = mp_bytecode_decode_lineinfo(&iter->ci);
+        iter->bc += decoded.bc_increment;
+        iter->source_line += decoded.line_increment;
+
+        if (decoded.bc_increment == 0) {
+            line_no = iter->source_line;
+            another = true;
+        } else if (decoded.line_increment == 0) {
+            another = true;
+        }
+    }
+
+    if (another) {
+        mp_uint_t prelude_size = (iter->rc->prelude.opcodes - (const byte *)iter->rc->fun_data);
+        mp_uint_t bc_end = iter->rc->fun_data_len - prelude_size;
+        if (iter->bc >= bc_end) {
+            return MP_OBJ_STOP_ITERATION;
+        } else {
+            iter->bc = bc_end;
+        }
+    }
+
+    mp_uint_t end = iter->bc;
+    mp_obj_t next[3] = {MP_OBJ_NEW_SMALL_INT(start), MP_OBJ_NEW_SMALL_INT(end), MP_OBJ_NEW_SMALL_INT(line_no)};
+
+    return mp_obj_new_tuple(MP_ARRAY_SIZE(next), next);
+}
 
 static void code_attr(mp_obj_t self_in, qstr attr, mp_obj_t *dest) {
     if (dest[0] != MP_OBJ_NULL) {
@@ -137,12 +200,18 @@ static void code_attr(mp_obj_t self_in, qstr attr, mp_obj_t *dest) {
         case MP_QSTR_co_names:
             dest[0] = MP_OBJ_FROM_PTR(o->dict_locals);
             break;
+        #if !MICROPY_PREVIEW_VERSION_2
         case MP_QSTR_co_lnotab:
             if (!o->lnotab) {
                 o->lnotab = raw_code_lnotab(rc);
             }
             dest[0] = o->lnotab;
             break;
+        #endif
+        case MP_QSTR_co_lines:
+            dest[0] = MP_OBJ_FROM_PTR(&code_colines_obj);
+            dest[1] = self_in;
+            break;
     }
 }
 
@@ -168,7 +237,9 @@ mp_obj_t mp_obj_new_code(const mp_module_context_t *context, const mp_raw_code_t
     o->context = context;
     o->rc = rc;
     o->dict_locals = mp_locals_get(); // this is a wrong! how to do this properly?
+    #if !MICROPY_PREVIEW_VERSION_2
     o->lnotab = MP_OBJ_NULL;
+    #endif
     return MP_OBJ_FROM_PTR(o);
 }
 
diff --git a/py/objcode.h b/py/objcode.h
index 8db9a34b6e1c9..7be15e23f5271 100644
--- a/py/objcode.h
+++ b/py/objcode.h
@@ -72,15 +72,16 @@ static inline const void *mp_code_get_proto_fun(mp_obj_code_t *self) {
 
 #include "py/emitglue.h"
 
-#define MP_CODE_QSTR_MAP(context, idx) (context->constants.qstr_table[idx])
+#define MP_CODE_QSTR_MAP(context, idx) ((qstr)(context->constants.qstr_table[idx]))
 
 typedef struct _mp_obj_code_t {
-    // TODO this was 4 words
     mp_obj_base_t base;
     const mp_module_context_t *context;
     const mp_raw_code_t *rc;
     mp_obj_dict_t *dict_locals;
+    #if !MICROPY_PREVIEW_VERSION_2
     mp_obj_t lnotab;
+    #endif
 } mp_obj_code_t;
 
 mp_obj_t mp_obj_new_code(const mp_module_context_t *context, const mp_raw_code_t *rc, bool result_required);
diff --git a/py/objcomplex.c b/py/objcomplex.c
index d7287efdc13dd..88f4444f09e4d 100644
--- a/py/objcomplex.c
+++ b/py/objcomplex.c
@@ -49,29 +49,18 @@ typedef struct _mp_obj_complex_t {
 static void complex_print(const mp_print_t *print, mp_obj_t o_in, mp_print_kind_t kind) {
     (void)kind;
     mp_obj_complex_t *o = MP_OBJ_TO_PTR(o_in);
-    #if MICROPY_FLOAT_IMPL == MICROPY_FLOAT_IMPL_FLOAT
-    char buf[16];
-    #if MICROPY_OBJ_REPR == MICROPY_OBJ_REPR_C
-    const int precision = 6;
-    #else
-    const int precision = 7;
-    #endif
-    #else
-    char buf[32];
-    const int precision = 16;
-    #endif
-    if (o->real == 0) {
-        mp_format_float(o->imag, buf, sizeof(buf), 'g', precision, '\0');
-        mp_printf(print, "%sj", buf);
+    const char *suffix;
+    int flags = 0;
+    if (o->real != 0) {
+        mp_print_str(print, "(");
+        mp_print_float(print, o->real, 'g', 0, '\0', -1, MP_FLOAT_REPR_PREC);
+        flags = PF_FLAG_SHOW_SIGN;
+        suffix = "j)";
     } else {
-        mp_format_float(o->real, buf, sizeof(buf), 'g', precision, '\0');
-        mp_printf(print, "(%s", buf);
-        if (o->imag >= 0 || isnan(o->imag)) {
-            mp_print_str(print, "+");
-        }
-        mp_format_float(o->imag, buf, sizeof(buf), 'g', precision, '\0');
-        mp_printf(print, "%sj)", buf);
+        suffix = "j";
     }
+    mp_print_float(print, o->imag, 'g', flags, '\0', -1, MP_FLOAT_REPR_PREC);
+    mp_print_str(print, suffix);
 }
 
 static mp_obj_t complex_make_new(const mp_obj_type_t *type_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
diff --git a/py/objdict.c b/py/objdict.c
index 79a606f09707b..d459d1ae48647 100644
--- a/py/objdict.c
+++ b/py/objdict.c
@@ -101,7 +101,7 @@ static void dict_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_
         #endif
     }
     if (MICROPY_PY_COLLECTIONS_ORDEREDDICT && self->base.type != &mp_type_dict && kind != PRINT_JSON) {
-        mp_printf(print, "%q(", self->base.type->name);
+        mp_printf(print, "%q(", (qstr)self->base.type->name);
     }
     mp_print_str(print, "{");
     size_t cur = 0;
@@ -616,7 +616,8 @@ static mp_obj_t dict_view_unary_op(mp_unary_op_t op, mp_obj_t o_in) {
     if (op == MP_UNARY_OP_HASH && o->kind == MP_DICT_VIEW_VALUES) {
         return MP_OBJ_NEW_SMALL_INT((mp_uint_t)o_in);
     }
-    return MP_OBJ_NULL;
+    // delegate all other ops to dict unary op handler
+    return dict_unary_op(op, o->dict);
 }
 
 static mp_obj_t dict_view_binary_op(mp_binary_op_t op, mp_obj_t lhs_in, mp_obj_t rhs_in) {
diff --git a/py/objfloat.c b/py/objfloat.c
index 3610c2b85862d..ecc0f61a6abc9 100644
--- a/py/objfloat.c
+++ b/py/objfloat.c
@@ -34,6 +34,11 @@
 
 #if MICROPY_PY_BUILTINS_FLOAT
 
+// Workaround a bug in Windows SDK version 10.0.26100.0, where NAN is no longer constant.
+#if defined(_MSC_VER) && !defined(_UCRT_NOISY_NAN)
+#define _UCRT_NOISY_NAN
+#endif
+
 #include <math.h>
 #include "py/formatfloat.h"
 
@@ -51,13 +56,6 @@
 #define M_PI (3.14159265358979323846)
 #endif
 
-// Workaround a bug in recent MSVC where NAN is no longer constant.
-// (By redefining back to the previous MSVC definition of NAN)
-#if defined(_MSC_VER) && _MSC_VER >= 1942
-#undef NAN
-#define NAN (-(float)(((float)(1e+300 * 1e+300)) * 0.0F))
-#endif
-
 typedef struct _mp_obj_float_t {
     mp_obj_base_t base;
     mp_float_t value;
@@ -116,23 +114,7 @@ mp_int_t mp_float_hash(mp_float_t src) {
 static void float_print(const mp_print_t *print, mp_obj_t o_in, mp_print_kind_t kind) {
     (void)kind;
     mp_float_t o_val = mp_obj_float_get(o_in);
-    #if MICROPY_FLOAT_IMPL == MICROPY_FLOAT_IMPL_FLOAT
-    char buf[16];
-    #if MICROPY_OBJ_REPR == MICROPY_OBJ_REPR_C
-    const int precision = 6;
-    #else
-    const int precision = 7;
-    #endif
-    #else
-    char buf[32];
-    const int precision = 16;
-    #endif
-    mp_format_float(o_val, buf, sizeof(buf), 'g', precision, '\0');
-    mp_print_str(print, buf);
-    if (strchr(buf, '.') == NULL && strchr(buf, 'e') == NULL && strchr(buf, 'n') == NULL) {
-        // Python floats always have decimal point (unless inf or nan)
-        mp_print_str(print, ".0");
-    }
+    mp_print_float(print, o_val, 'g', PF_FLAG_ALWAYS_DECIMAL, '\0', -1, MP_FLOAT_REPR_PREC);
 }
 
 static mp_obj_t float_make_new(const mp_obj_type_t *type_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
@@ -324,6 +306,10 @@ mp_obj_t mp_obj_float_binary_op(mp_binary_op_t op, mp_float_t lhs_val, mp_obj_t
                 lhs_val = MICROPY_FLOAT_CONST(1.0);
                 break;
             }
+            if (isnan(rhs_val)) {
+                lhs_val = rhs_val;
+                break;
+            }
             #endif
             lhs_val = MICROPY_FLOAT_C_FUN(pow)(lhs_val, rhs_val);
             break;
diff --git a/py/objfun.c b/py/objfun.c
index e6a923d59e886..34565cf633632 100644
--- a/py/objfun.c
+++ b/py/objfun.c
@@ -184,7 +184,8 @@ static mp_obj_t fun_bc_make_new(const mp_obj_type_t *type, size_t n_args, size_t
 static void fun_bc_print(const mp_print_t *print, mp_obj_t o_in, mp_print_kind_t kind) {
     (void)kind;
     mp_obj_fun_bc_t *o = MP_OBJ_TO_PTR(o_in);
-    mp_printf(print, "<function %q at 0x%p>", mp_obj_fun_get_name(o_in), o);
+    // CIRCUITPY-CHANGE: %p already prints "0x", so don't include it explicitly.
+    mp_printf(print, "<function %q at %p>", mp_obj_fun_get_name(o_in), o);
 }
 #endif
 
diff --git a/py/objint.c b/py/objint.c
index b12f09c9d38a7..cabbd7b8f0e12 100644
--- a/py/objint.c
+++ b/py/objint.c
@@ -117,9 +117,15 @@ static mp_fp_as_int_class_t mp_classify_fp_as_int(mp_float_t val) {
     }
     // 8 * sizeof(uintptr_t) counts the number of bits for a small int
     // TODO provide a way to configure this properly
+    #if MICROPY_OBJ_REPR == MICROPY_OBJ_REPR_B
+    if (e <= ((8 * sizeof(uintptr_t) + MP_FLOAT_EXP_BIAS - 4) << MP_FLOAT_EXP_SHIFT_I32)) {
+        return MP_FP_CLASS_FIT_SMALLINT;
+    }
+    #else
     if (e <= ((8 * sizeof(uintptr_t) + MP_FLOAT_EXP_BIAS - 3) << MP_FLOAT_EXP_SHIFT_I32)) {
         return MP_FP_CLASS_FIT_SMALLINT;
     }
+    #endif
     #if MICROPY_LONGINT_IMPL == MICROPY_LONGINT_IMPL_LONGLONG
     if (e <= (((sizeof(long long) * MP_BITS_PER_BYTE) + MP_FLOAT_EXP_BIAS - 2) << MP_FLOAT_EXP_SHIFT_I32)) {
         return MP_FP_CLASS_FIT_LONGINT;
@@ -211,7 +217,7 @@ static const uint8_t log_base2_floor[] = {
 size_t mp_int_format_size(size_t num_bits, int base, const char *prefix, char comma) {
     assert(2 <= base && base <= 16);
     size_t num_digits = num_bits / log_base2_floor[base - 1] + 1;
-    size_t num_commas = comma ? num_digits / 3 : 0;
+    size_t num_commas = comma ? (base == 10 ? num_digits / 3 : num_digits / 4): 0;
     size_t prefix_len = prefix ? strlen(prefix) : 0;
     return num_digits + num_commas + prefix_len + 2; // +1 for sign, +1 for null byte
 }
@@ -249,10 +255,11 @@ char *mp_obj_int_formatted(char **buf, size_t *buf_size, size_t *fmt_size, mp_co
 
     char sign = '\0';
     if (num < 0) {
-        num = -num;
+        num = -(fmt_uint_t)num;
         sign = '-';
     }
 
+    int n_comma = (base == 10) ? 3 : 4;
     size_t needed_size = mp_int_format_size(sizeof(fmt_int_t) * 8, base, prefix, comma);
     if (needed_size > *buf_size) {
         *buf = m_new(char, needed_size);
@@ -277,7 +284,7 @@ char *mp_obj_int_formatted(char **buf, size_t *buf_size, size_t *fmt_size, mp_co
                 c += '0';
             }
             *(--b) = c;
-            if (comma && num != 0 && b > str && (last_comma - b) == 3) {
+            if (comma && num != 0 && b > str && (last_comma - b) == n_comma) {
                 *(--b) = comma;
                 last_comma = b;
             }
diff --git a/py/objint_longlong.c b/py/objint_longlong.c
index 0fad693c7adcd..f24aa0cc18664 100644
--- a/py/objint_longlong.c
+++ b/py/objint_longlong.c
@@ -43,6 +43,10 @@
 const mp_obj_int_t mp_sys_maxsize_obj = {{&mp_type_int}, MP_SSIZE_MAX};
 #endif
 
+static void raise_long_long_overflow(void) {
+    mp_raise_msg(&mp_type_OverflowError, MP_ERROR_TEXT("result overflows long long storage"));
+}
+
 // CIRCUITPY-CHANGE: bit_length
 mp_obj_t mp_obj_int_bit_length_impl(mp_obj_t self_in) {
     assert(mp_obj_is_type(self_in, &mp_type_int));
@@ -132,7 +136,6 @@ mp_obj_t mp_obj_int_unary_op(mp_unary_op_t op, mp_obj_t o_in) {
         // small int if the value fits without truncation
         case MP_UNARY_OP_HASH:
             return MP_OBJ_NEW_SMALL_INT((mp_int_t)o->val);
-
         case MP_UNARY_OP_POSITIVE:
             return o_in;
         case MP_UNARY_OP_NEGATIVE:
@@ -159,6 +162,8 @@ mp_obj_t mp_obj_int_unary_op(mp_unary_op_t op, mp_obj_t o_in) {
 mp_obj_t mp_obj_int_binary_op(mp_binary_op_t op, mp_obj_t lhs_in, mp_obj_t rhs_in) {
     long long lhs_val;
     long long rhs_val;
+    bool overflow = false;
+    long long result;
 
     if (mp_obj_is_small_int(lhs_in)) {
         lhs_val = MP_OBJ_SMALL_INT_VALUE(lhs_in);
@@ -171,21 +176,41 @@ mp_obj_t mp_obj_int_binary_op(mp_binary_op_t op, mp_obj_t lhs_in, mp_obj_t rhs_i
         rhs_val = MP_OBJ_SMALL_INT_VALUE(rhs_in);
     } else if (mp_obj_is_exact_type(rhs_in, &mp_type_int)) {
         rhs_val = ((mp_obj_int_t *)rhs_in)->val;
+    #if MICROPY_PY_BUILTINS_FLOAT
+    } else if (mp_obj_is_float(rhs_in)) {
+        return mp_obj_float_binary_op(op, (mp_float_t)lhs_val, rhs_in);
+    #endif
+    #if MICROPY_PY_BUILTINS_COMPLEX
+    } else if (mp_obj_is_type(rhs_in, &mp_type_complex)) {
+        return mp_obj_complex_binary_op(op, (mp_float_t)lhs_val, 0, rhs_in);
+    #endif
     } else {
         // delegate to generic function to check for extra cases
         return mp_obj_int_binary_op_extra_cases(op, lhs_in, rhs_in);
     }
 
+    #if MICROPY_PY_BUILTINS_FLOAT
+    if (op == MP_BINARY_OP_TRUE_DIVIDE || op == MP_BINARY_OP_INPLACE_TRUE_DIVIDE) {
+        if (rhs_val == 0) {
+            goto zero_division;
+        }
+        return mp_obj_new_float((mp_float_t)lhs_val / (mp_float_t)rhs_val);
+    }
+    #endif
+
     switch (op) {
         case MP_BINARY_OP_ADD:
         case MP_BINARY_OP_INPLACE_ADD:
-            return mp_obj_new_int_from_ll(lhs_val + rhs_val);
+            overflow = mp_add_ll_overflow(lhs_val, rhs_val, &result);
+            break;
         case MP_BINARY_OP_SUBTRACT:
         case MP_BINARY_OP_INPLACE_SUBTRACT:
-            return mp_obj_new_int_from_ll(lhs_val - rhs_val);
+            overflow = mp_sub_ll_overflow(lhs_val, rhs_val, &result);
+            break;
         case MP_BINARY_OP_MULTIPLY:
         case MP_BINARY_OP_INPLACE_MULTIPLY:
-            return mp_obj_new_int_from_ll(lhs_val * rhs_val);
+            overflow = mp_mul_ll_overflow(lhs_val, rhs_val, &result);
+            break;
         case MP_BINARY_OP_FLOOR_DIVIDE:
         case MP_BINARY_OP_INPLACE_FLOOR_DIVIDE:
             if (rhs_val == 0) {
@@ -211,9 +236,21 @@ mp_obj_t mp_obj_int_binary_op(mp_binary_op_t op, mp_obj_t lhs_in, mp_obj_t rhs_i
 
         case MP_BINARY_OP_LSHIFT:
         case MP_BINARY_OP_INPLACE_LSHIFT:
-            return mp_obj_new_int_from_ll(lhs_val << (int)rhs_val);
+            if (rhs_val < 0) {
+                // negative shift not allowed
+                mp_raise_ValueError(MP_ERROR_TEXT("negative shift count"));
+            }
+            overflow = rhs_val >= (sizeof(long long) * MP_BITS_PER_BYTE)
+                || lhs_val > (LLONG_MAX >> rhs_val)
+                || lhs_val < (LLONG_MIN >> rhs_val);
+            result = (unsigned long long)lhs_val << rhs_val;
+            break;
         case MP_BINARY_OP_RSHIFT:
         case MP_BINARY_OP_INPLACE_RSHIFT:
+            if ((int)rhs_val < 0) {
+                // negative shift not allowed
+                mp_raise_ValueError(MP_ERROR_TEXT("negative shift count"));
+            }
             return mp_obj_new_int_from_ll(lhs_val >> (int)rhs_val);
 
         case MP_BINARY_OP_POWER:
@@ -225,18 +262,18 @@ mp_obj_t mp_obj_int_binary_op(mp_binary_op_t op, mp_obj_t lhs_in, mp_obj_t rhs_i
                 mp_raise_ValueError(MP_ERROR_TEXT("negative power with no float support"));
                 #endif
             }
-            long long ans = 1;
-            while (rhs_val > 0) {
+            result = 1;
+            while (rhs_val > 0 && !overflow) {
                 if (rhs_val & 1) {
-                    ans *= lhs_val;
+                    overflow = mp_mul_ll_overflow(result, lhs_val, &result);
                 }
-                if (rhs_val == 1) {
+                if (rhs_val == 1 || overflow) {
                     break;
                 }
                 rhs_val /= 2;
-                lhs_val *= lhs_val;
+                overflow = mp_mul_ll_overflow(lhs_val, lhs_val, &lhs_val);
             }
-            return mp_obj_new_int_from_ll(ans);
+            break;
         }
 
         case MP_BINARY_OP_LESS:
@@ -254,8 +291,14 @@ mp_obj_t mp_obj_int_binary_op(mp_binary_op_t op, mp_obj_t lhs_in, mp_obj_t rhs_i
             return MP_OBJ_NULL; // op not supported
     }
 
+    if (overflow) {
+        raise_long_long_overflow();
+    }
+
+    return mp_obj_new_int_from_ll(result);
+
 zero_division:
-    mp_raise_ZeroDivisionError();
+    mp_raise_msg(&mp_type_ZeroDivisionError, MP_ERROR_TEXT("divide by zero"));
 }
 
 mp_obj_t mp_obj_new_int(mp_int_t value) {
@@ -277,22 +320,12 @@ mp_obj_t mp_obj_new_int_from_ll(long long val) {
 }
 
 mp_obj_t mp_obj_new_int_from_ull(unsigned long long val) {
-    // TODO raise an exception if the unsigned long long won't fit
     if (val >> (sizeof(unsigned long long) * 8 - 1) != 0) {
-        mp_raise_msg(&mp_type_OverflowError, MP_ERROR_TEXT("ulonglong too large"));
+        raise_long_long_overflow();
     }
     return mp_obj_new_int_from_ll(val);
 }
 
-mp_obj_t mp_obj_new_int_from_str_len(const char **str, size_t len, bool neg, unsigned int base) {
-    // TODO this does not honor the given length of the string, but it all cases it should anyway be null terminated
-    // TODO check overflow
-    char *endptr;
-    mp_obj_t result = mp_obj_new_int_from_ll(strtoll(*str, &endptr, base));
-    *str = endptr;
-    return result;
-}
-
 mp_int_t mp_obj_int_get_truncated(mp_const_obj_t self_in) {
     if (mp_obj_is_small_int(self_in)) {
         return MP_OBJ_SMALL_INT_VALUE(self_in);
@@ -303,8 +336,33 @@ mp_int_t mp_obj_int_get_truncated(mp_const_obj_t self_in) {
 }
 
 mp_int_t mp_obj_int_get_checked(mp_const_obj_t self_in) {
-    // TODO: Check overflow
-    return mp_obj_int_get_truncated(self_in);
+    if (mp_obj_is_small_int(self_in)) {
+        return MP_OBJ_SMALL_INT_VALUE(self_in);
+    } else {
+        const mp_obj_int_t *self = self_in;
+        long long value = self->val;
+        mp_int_t truncated = (mp_int_t)value;
+        if ((long long)truncated == value) {
+            return truncated;
+        }
+    }
+    mp_raise_msg(&mp_type_OverflowError, MP_ERROR_TEXT("overflow converting long int to machine word"));
+}
+
+mp_uint_t mp_obj_int_get_uint_checked(mp_const_obj_t self_in) {
+    if (mp_obj_is_small_int(self_in)) {
+        if (MP_OBJ_SMALL_INT_VALUE(self_in) >= 0) {
+            return MP_OBJ_SMALL_INT_VALUE(self_in);
+        }
+    } else {
+        const mp_obj_int_t *self = self_in;
+        long long value = self->val;
+        mp_uint_t truncated = (mp_uint_t)value;
+        if (value >= 0 && (long long)truncated == value) {
+            return truncated;
+        }
+    }
+    mp_raise_msg(&mp_type_OverflowError, MP_ERROR_TEXT("overflow converting long int to machine word"));
 }
 
 #if MICROPY_PY_BUILTINS_FLOAT
diff --git a/py/objint_mpz.c b/py/objint_mpz.c
index 111f53009fb1f..1bede811a4aaa 100644
--- a/py/objint_mpz.c
+++ b/py/objint_mpz.c
@@ -364,9 +364,10 @@ static mpz_t *mp_mpz_for_int(mp_obj_t arg, mpz_t *temp) {
 mp_obj_t mp_obj_int_pow3(mp_obj_t base, mp_obj_t exponent,  mp_obj_t modulus) {
     if (!mp_obj_is_int(base) || !mp_obj_is_int(exponent) || !mp_obj_is_int(modulus)) {
         mp_raise_TypeError(MP_ERROR_TEXT("pow() with 3 arguments requires integers"));
+    } else if (modulus == MP_OBJ_NEW_SMALL_INT(0)) {
+        mp_raise_ValueError(MP_ERROR_TEXT("divide by zero"));
     } else {
-        mp_obj_t result = mp_obj_new_int_from_ull(0); // Use the _from_ull version as this forces an mpz int
-        mp_obj_int_t *res_p = (mp_obj_int_t *)MP_OBJ_TO_PTR(result);
+        mp_obj_int_t *res_p = mp_obj_int_new_mpz();
 
         mpz_t l_temp, r_temp, m_temp;
         mpz_t *lhs = mp_mpz_for_int(base,     &l_temp);
@@ -389,7 +390,7 @@ mp_obj_t mp_obj_int_pow3(mp_obj_t base, mp_obj_t exponent,  mp_obj_t modulus) {
         if (mod == &m_temp) {
             mpz_deinit(mod);
         }
-        return result;
+        return MP_OBJ_FROM_PTR(res_p);
     }
 }
 #endif
diff --git a/py/objlist.c b/py/objlist.c
index 3137e9fa53483..a29fc51b10472 100644
--- a/py/objlist.c
+++ b/py/objlist.c
@@ -118,7 +118,7 @@ static mp_obj_t list_unary_op(mp_unary_op_t op, mp_obj_t self_in) {
 }
 
 static mp_obj_t list_binary_op(mp_binary_op_t op, mp_obj_t lhs, mp_obj_t rhs) {
-    // CIRCUITPY-CHANGE
+    // CIRCUITPY-CHANGE: allow subclassing
     mp_obj_list_t *o = native_list(lhs);
     switch (op) {
         case MP_BINARY_OP_ADD: {
@@ -142,7 +142,7 @@ static mp_obj_t list_binary_op(mp_binary_op_t op, mp_obj_t lhs, mp_obj_t rhs) {
             if (n < 0) {
                 n = 0;
             }
-            // CIRCUITPY-CHANGE
+            // CIRCUITPY-CHANGE: overflow check (PR#1279)
             size_t new_len = mp_seq_multiply_len(o->len, n);
             mp_obj_list_t *s = list_new(new_len);
             mp_seq_multiply(o->items, sizeof(*o->items), o->len, n, s->items);
@@ -171,76 +171,66 @@ static mp_obj_t list_binary_op(mp_binary_op_t op, mp_obj_t lhs, mp_obj_t rhs) {
 }
 
 static mp_obj_t list_subscr(mp_obj_t self_in, mp_obj_t index, mp_obj_t value) {
-    // CIRCUITPY-CHANGE
-    mp_obj_list_t *self = native_list(self_in);
-    if (value == MP_OBJ_NULL) {
-        // delete
-        #if MICROPY_PY_BUILTINS_SLICE
-        if (mp_obj_is_type(index, &mp_type_slice)) {
-            mp_bound_slice_t slice;
-            if (!mp_seq_get_fast_slice_indexes(self->len, index, &slice)) {
-                mp_raise_NotImplementedError(NULL);
+    #if MICROPY_PY_BUILTINS_SLICE
+    if (mp_obj_is_type(index, &mp_type_slice)) {
+        // CIRCUITPY-CHANGE: handle subclassing
+        mp_obj_list_t *self = native_list(self_in);
+        mp_bound_slice_t slice;
+        bool fast = mp_seq_get_fast_slice_indexes(self->len, index, &slice);
+        if (value == MP_OBJ_SENTINEL) {
+            // load
+            if (!fast) {
+                return mp_seq_extract_slice(self->items, &slice);
             }
-
-            mp_int_t len_adj = slice.start - slice.stop;
-            assert(len_adj <= 0);
-            mp_seq_replace_slice_no_grow(self->items, self->len, slice.start, slice.stop, self->items /*NULL*/, 0, sizeof(*self->items));
+            mp_obj_list_t *res = list_new(slice.stop - slice.start);
+            mp_seq_copy(res->items, self->items + slice.start, res->len, mp_obj_t);
+            return MP_OBJ_FROM_PTR(res);
+        }
+        // assign/delete
+        if (value == MP_OBJ_NULL) {
+            // delete is equivalent to slice assignment of an empty sequence
+            value = mp_const_empty_tuple;
+        }
+        if (!fast) {
+            mp_raise_NotImplementedError(NULL);
+        }
+        size_t value_len;
+        mp_obj_t *value_items;
+        mp_obj_get_array(value, &value_len, &value_items);
+        mp_int_t len_adj = value_len - (slice.stop - slice.start);
+        if (len_adj > 0) {
+            if (self->len + len_adj > self->alloc) {
+                // TODO: Might optimize memory copies here by checking if block can
+                // be grown inplace or not
+                self->items = m_renew(mp_obj_t, self->items, self->alloc, self->len + len_adj);
+                self->alloc = self->len + len_adj;
+            }
+            mp_seq_replace_slice_grow_inplace(self->items, self->len,
+                slice.start, slice.stop, value_items, value_len, len_adj, sizeof(*self->items));
+        } else {
+            mp_seq_replace_slice_no_grow(self->items, self->len,
+                slice.start, slice.stop, value_items, value_len, sizeof(*self->items));
             // Clear "freed" elements at the end of list
             mp_seq_clear(self->items, self->len + len_adj, self->len, sizeof(*self->items));
-            self->len += len_adj;
-            return mp_const_none;
+            // TODO: apply allocation policy re: alloc_size
         }
-        #endif
-        // CIRCUITPY-CHANGE
-        mp_obj_t args[2] = {MP_OBJ_FROM_PTR(self), index};
+        self->len += len_adj;
+        return mp_const_none;
+    }
+    #endif
+    if (value == MP_OBJ_NULL) {
+        // delete
+        // CIRCUITPY-CHANGE: handle subclassing
+        mp_obj_t args[2] = {MP_OBJ_FROM_PTR(self_in), index};
         list_pop(2, args);
         return mp_const_none;
     } else if (value == MP_OBJ_SENTINEL) {
         // load
-        #if MICROPY_PY_BUILTINS_SLICE
-        if (mp_obj_is_type(index, &mp_type_slice)) {
-            mp_bound_slice_t slice;
-            if (!mp_seq_get_fast_slice_indexes(self->len, index, &slice)) {
-                return mp_seq_extract_slice(self->items, &slice);
-            }
-            mp_obj_list_t *res = list_new(slice.stop - slice.start);
-            mp_seq_copy(res->items, self->items + slice.start, res->len, mp_obj_t);
-            return MP_OBJ_FROM_PTR(res);
-        }
-        #endif
+        // CIRCUITPY-CHANGE: handle subclassing
+        mp_obj_list_t *self = native_list(self_in);
         size_t index_val = mp_get_index(self->base.type, self->len, index, false);
         return self->items[index_val];
     } else {
-        #if MICROPY_PY_BUILTINS_SLICE
-        if (mp_obj_is_type(index, &mp_type_slice)) {
-            size_t value_len;
-            mp_obj_t *value_items;
-            mp_obj_get_array(value, &value_len, &value_items);
-            mp_bound_slice_t slice_out;
-            if (!mp_seq_get_fast_slice_indexes(self->len, index, &slice_out)) {
-                mp_raise_NotImplementedError(NULL);
-            }
-            mp_int_t len_adj = value_len - (slice_out.stop - slice_out.start);
-            if (len_adj > 0) {
-                if (self->len + len_adj > self->alloc) {
-                    // TODO: Might optimize memory copies here by checking if block can
-                    // be grown inplace or not
-                    self->items = m_renew(mp_obj_t, self->items, self->alloc, self->len + len_adj);
-                    self->alloc = self->len + len_adj;
-                }
-                mp_seq_replace_slice_grow_inplace(self->items, self->len,
-                    slice_out.start, slice_out.stop, value_items, value_len, len_adj, sizeof(*self->items));
-            } else {
-                mp_seq_replace_slice_no_grow(self->items, self->len,
-                    slice_out.start, slice_out.stop, value_items, value_len, sizeof(*self->items));
-                // Clear "freed" elements at the end of list
-                mp_seq_clear(self->items, self->len + len_adj, self->len, sizeof(*self->items));
-                // TODO: apply allocation policy re: alloc_size
-            }
-            self->len += len_adj;
-            return mp_const_none;
-        }
-        #endif
         mp_obj_list_store(self_in, index, value);
         return mp_const_none;
     }
@@ -252,7 +242,7 @@ static mp_obj_t list_getiter(mp_obj_t o_in, mp_obj_iter_buf_t *iter_buf) {
 
 mp_obj_t mp_obj_list_append(mp_obj_t self_in, mp_obj_t arg) {
     mp_check_self(mp_obj_is_type(self_in, &mp_type_list));
-    // CIRCUITPY-CHANGE
+    // CIRCUITPY-CHANGE: handle subclassing
     mp_obj_list_t *self = native_list(self_in);
     if (self->len >= self->alloc) {
         self->items = m_renew(mp_obj_t, self->items, self->alloc, self->alloc * 2);
@@ -266,7 +256,7 @@ mp_obj_t mp_obj_list_append(mp_obj_t self_in, mp_obj_t arg) {
 static mp_obj_t list_extend(mp_obj_t self_in, mp_obj_t arg_in) {
     mp_check_self(mp_obj_is_type(self_in, &mp_type_list));
     if (mp_obj_is_type(arg_in, &mp_type_list)) {
-        // CIRCUITPY-CHANGE
+        // CIRCUITPY-CHANGE: handle subclassing
         mp_obj_list_t *self = native_list(self_in);
         mp_obj_list_t *arg = native_list(arg_in);
 
@@ -285,7 +275,7 @@ static mp_obj_t list_extend(mp_obj_t self_in, mp_obj_t arg_in) {
     return mp_const_none; // return None, as per CPython
 }
 
-// CIRCUITPY-CHANGE: used elsewhere so not static; impl is different
+// CIRCUITPY-CHANGE: provide version for C use outside this file
 inline mp_obj_t mp_obj_list_pop(mp_obj_list_t *self, size_t index) {
     if (self->len == 0) {
         // CIRCUITPY-CHANGE: more specific mp_raise
@@ -303,18 +293,28 @@ inline mp_obj_t mp_obj_list_pop(mp_obj_list_t *self, size_t index) {
     return ret;
 }
 
-// CIRCUITPY-CHANGE
 static mp_obj_t list_pop(size_t n_args, const mp_obj_t *args) {
     mp_check_self(mp_obj_is_type(args[0], &mp_type_list));
     mp_obj_list_t *self = native_list(args[0]);
     size_t index = mp_get_index(self->base.type, self->len, n_args == 1 ? MP_OBJ_NEW_SMALL_INT(-1) : args[1], false);
+    // CIRCUITPY-CHANGE: use factored-out pop code
     return mp_obj_list_pop(self, index);
 }
 
+// "head" is actually the *exclusive lower bound* of the range to sort. That is,
+// the first element to be sorted is `head[1]`, not `head[0]`. Similarly `tail`
+// is an *inclusive upper bound* of the range to sort. That is, the final
+// element to sort is `tail[0]`, not `tail[-1]`.
+//
+// The pivot element is always chosen as `tail[0]`.
+//
+// These unusual choices allows structuring the partitioning
+// process as a do/while loop, which generates smaller code than the equivalent
+// code with usual C bounds & a while or for loop.
 static void mp_quicksort(mp_obj_t *head, mp_obj_t *tail, mp_obj_t key_fn, mp_obj_t binop_less_result) {
     mp_cstack_check();
-    while (head < tail) {
-        mp_obj_t *h = head - 1;
+    while (tail - head > 1) { // So long as at least 2 elements remain
+        mp_obj_t *h = head;
         mp_obj_t *t = tail;
         mp_obj_t v = key_fn == MP_OBJ_NULL ? tail[0] : mp_call_function_1(key_fn, tail[0]); // get pivot using key_fn
         for (;;) {
@@ -325,19 +325,21 @@ static void mp_quicksort(mp_obj_t *head, mp_obj_t *tail, mp_obj_t key_fn, mp_obj
             if (h >= t) {
                 break;
             }
+            // A pair of objects must be swapped to the other side of the partition
             mp_obj_t x = h[0];
             h[0] = t[0];
             t[0] = x;
         }
+        // Place the pivot element in the proper position
         mp_obj_t x = h[0];
         h[0] = tail[0];
         tail[0] = x;
         // do the smaller recursive call first, to keep stack within O(log(N))
-        if (t - head < tail - h - 1) {
+        if (t - head < tail - h) {
             mp_quicksort(head, t, key_fn, binop_less_result);
-            head = h + 1;
+            head = h;
         } else {
-            mp_quicksort(h + 1, tail, key_fn, binop_less_result);
+            mp_quicksort(h, tail, key_fn, binop_less_result);
             tail = t;
         }
     }
@@ -362,7 +364,7 @@ mp_obj_t mp_obj_list_sort(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_
     mp_obj_list_t *self = native_list(pos_args[0]);
 
     if (self->len > 1) {
-        mp_quicksort(self->items, self->items + self->len - 1,
+        mp_quicksort(self->items - 1, self->items + self->len - 1,
             args.key.u_obj == mp_const_none ? MP_OBJ_NULL : args.key.u_obj,
             args.reverse.u_bool ? mp_const_false : mp_const_true);
     }
@@ -370,10 +372,10 @@ mp_obj_t mp_obj_list_sort(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_
     return mp_const_none;
 }
 
-// CIRCUITPY-CHANGE: used elsewhere so not static
+// CIRCUITPY-CHANGE: rename and make not static for use elsewhere
 mp_obj_t mp_obj_list_clear(mp_obj_t self_in) {
     mp_check_self(mp_obj_is_type(self_in, &mp_type_list));
-    // CIRCUITPY-CHANGE
+    // CIRCUITPY-CHANGE: handle subclassing
     mp_obj_list_t *self = native_list(self_in);
     self->len = 0;
     self->items = m_renew(mp_obj_t, self->items, self->alloc, LIST_MIN_ALLOC);
@@ -384,27 +386,28 @@ mp_obj_t mp_obj_list_clear(mp_obj_t self_in) {
 
 static mp_obj_t list_copy(mp_obj_t self_in) {
     mp_check_self(mp_obj_is_type(self_in, &mp_type_list));
-    // CIRCUITPY-CHANGE
+    // CIRCUITPY-CHANGE: handle subclassing
     mp_obj_list_t *self = native_list(self_in);
     return mp_obj_new_list(self->len, self->items);
 }
 
 static mp_obj_t list_count(mp_obj_t self_in, mp_obj_t value) {
     mp_check_self(mp_obj_is_type(self_in, &mp_type_list));
-    // CIRCUITPY-CHANGE
+    // CIRCUITPY-CHANGE: handle subclassing
     mp_obj_list_t *self = native_list(self_in);
     return mp_seq_count_obj(self->items, self->len, value);
 }
 
 static mp_obj_t list_index(size_t n_args, const mp_obj_t *args) {
     mp_check_self(mp_obj_is_type(args[0], &mp_type_list));
-    // CIRCUITPY-CHANGE
+    // CIRCUITPY-CHANGE: handle subclassing
     mp_obj_list_t *self = native_list(args[0]);
     return mp_seq_index_obj(self->items, self->len, n_args, args);
 }
 
-// CIRCUITPY-CHANGE: used elsewhere so not static
-inline void mp_obj_list_insert(mp_obj_list_t *self, size_t index, mp_obj_t obj) {
+// CIRCUITPY-CHANGE: factor out for C use elsewhere; not meant to emulate Python API
+inline void mp_obj_list_insert(mp_obj_list_t *self_in, size_t index, mp_obj_t obj) {
+    mp_obj_list_t *self = native_list(self_in);
     mp_obj_list_append(MP_OBJ_FROM_PTR(self), mp_const_none);
 
     for (size_t i = self->len - 1; i > index; --i) {
@@ -428,7 +431,7 @@ static mp_obj_t list_insert(mp_obj_t self_in, mp_obj_t idx, mp_obj_t obj) {
     if ((size_t)index > self->len) {
         index = self->len;
     }
-    // CIRCUITPY-CHANGE
+    // CIRCUITPY-CHANGE: use factored-out insert code
     mp_obj_list_insert(self, index, obj);
     return mp_const_none;
 }
diff --git a/py/objmodule.c b/py/objmodule.c
index a5c1dee968ea8..84b6a10f9abd4 100644
--- a/py/objmodule.c
+++ b/py/objmodule.c
@@ -34,11 +34,6 @@
 #include "py/runtime.h"
 #include "py/builtin.h"
 
-// CIRCUITPY-CHANGE
-#if CIRCUITPY_WARNINGS
-#include "shared-module/warnings/__init__.h"
-#endif
-
 static void module_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
     (void)kind;
     mp_obj_module_t *self = MP_OBJ_TO_PTR(self_in);
@@ -49,7 +44,7 @@ static void module_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kin
         module_name = mp_obj_str_get_str(elem->value);
     }
 
-    #if MICROPY_PY___FILE__
+    #if MICROPY_MODULE___FILE__
     // If we store __file__ to imported modules then try to lookup this
     // symbol to give more information about the module.
     elem = mp_map_lookup(&self->globals->map, MP_OBJ_NEW_QSTR(MP_QSTR___file__), MP_MAP_LOOKUP);
@@ -157,11 +152,13 @@ static const mp_rom_map_elem_t mp_builtin_module_table[] = {
 };
 MP_DEFINE_CONST_MAP(mp_builtin_module_map, mp_builtin_module_table);
 
+#if MICROPY_HAVE_REGISTERED_EXTENSIBLE_MODULES
 static const mp_rom_map_elem_t mp_builtin_extensible_module_table[] = {
     // built-in modules declared with MP_REGISTER_EXTENSIBLE_MODULE()
     MICROPY_REGISTERED_EXTENSIBLE_MODULES
 };
 MP_DEFINE_CONST_MAP(mp_builtin_extensible_module_map, mp_builtin_extensible_module_table);
+#endif
 
 #if MICROPY_MODULE_ATTR_DELEGATION && defined(MICROPY_MODULE_DELEGATIONS)
 typedef struct _mp_module_delegation_entry_t {
@@ -178,13 +175,13 @@ static const mp_module_delegation_entry_t mp_builtin_module_delegation_table[] =
 // Attempts to find (and initialise) a built-in, otherwise returns
 // MP_OBJ_NULL.
 mp_obj_t mp_module_get_builtin(qstr module_name, bool extensible) {
-    // CIRCUITPY-CHANGE
-    #if CIRCUITPY_PARALLELDISPLAYBUS && CIRCUITPY_WARNINGS
-    if (module_name == MP_QSTR_paralleldisplay) {
-        warnings_warn(&mp_type_FutureWarning, MP_ERROR_TEXT("%q renamed %q"), MP_QSTR_paralleldisplay, MP_QSTR_paralleldisplaybus);
-    }
+    #if MICROPY_HAVE_REGISTERED_EXTENSIBLE_MODULES
+    const mp_map_t *map = extensible ? &mp_builtin_extensible_module_map : &mp_builtin_module_map;
+    #else
+    const mp_map_t *map = &mp_builtin_module_map;
     #endif
-    mp_map_elem_t *elem = mp_map_lookup((mp_map_t *)(extensible ? &mp_builtin_extensible_module_map : &mp_builtin_module_map), MP_OBJ_NEW_QSTR(module_name), MP_MAP_LOOKUP);
+    mp_map_elem_t *elem = mp_map_lookup((mp_map_t *)map, MP_OBJ_NEW_QSTR(module_name), MP_MAP_LOOKUP);
+
     if (!elem) {
         #if MICROPY_PY_SYS
         // Special case for sys, which isn't extensible but can always be
@@ -194,6 +191,7 @@ mp_obj_t mp_module_get_builtin(qstr module_name, bool extensible) {
         }
         #endif
 
+        #if MICROPY_HAVE_REGISTERED_EXTENSIBLE_MODULES
         if (extensible) {
             // At this point we've already tried non-extensible built-ins, the
             // filesystem, and now extensible built-ins. No match, so fail
@@ -210,6 +208,7 @@ mp_obj_t mp_module_get_builtin(qstr module_name, bool extensible) {
         // the old behaviour of the u-prefix being used to force a built-in
         // import.
         // CIRCUITPY-CHANGE: Don't look for `ufoo`.
+        #endif
         return MP_OBJ_NULL;
     }
 
diff --git a/py/objmodule.h b/py/objmodule.h
index 8b14cd9fc3d30..221392ccce431 100644
--- a/py/objmodule.h
+++ b/py/objmodule.h
@@ -32,10 +32,16 @@
 // Only include module definitions when not doing qstr extraction, because the
 // qstr extraction stage also generates this module definition header file.
 #include "genhdr/moduledefs.h"
+// CIRCUITPY-CHANGE: avoid undef warning
+#else
+#define MICROPY_HAVE_REGISTERED_EXTENSIBLE_MODULES (0)
 #endif
 
 extern const mp_map_t mp_builtin_module_map;
+
+#if MICROPY_HAVE_REGISTERED_EXTENSIBLE_MODULES
 extern const mp_map_t mp_builtin_extensible_module_map;
+#endif
 
 mp_obj_t mp_module_get_builtin(qstr module_name, bool extensible);
 
diff --git a/py/objnamedtuple.c b/py/objnamedtuple.c
index b6bbe6e05d8b2..d687dbfda59d6 100644
--- a/py/objnamedtuple.c
+++ b/py/objnamedtuple.c
@@ -73,7 +73,7 @@ MP_DEFINE_CONST_FUN_OBJ_1(namedtuple_asdict_obj, namedtuple_asdict);
 void namedtuple_print(const mp_print_t *print, mp_obj_t o_in, mp_print_kind_t kind) {
     (void)kind;
     mp_obj_namedtuple_t *o = MP_OBJ_TO_PTR(o_in);
-    mp_printf(print, "%q", o->tuple.base.type->name);
+    mp_printf(print, "%q", (qstr)o->tuple.base.type->name);
     const qstr *fields = ((mp_obj_namedtuple_type_t *)o->tuple.base.type)->fields;
     mp_obj_attrtuple_print_helper(print, fields, &o->tuple);
 }
diff --git a/py/objrange.c b/py/objrange.c
index bde2ebaabb4ed..dea9fe5f2963a 100644
--- a/py/objrange.c
+++ b/py/objrange.c
@@ -41,9 +41,9 @@ typedef struct _mp_obj_range_it_t {
 static mp_obj_t range_it_iternext(mp_obj_t o_in) {
     mp_obj_range_it_t *o = MP_OBJ_TO_PTR(o_in);
     if ((o->step > 0 && o->cur < o->stop) || (o->step < 0 && o->cur > o->stop)) {
-        mp_obj_t o_out = MP_OBJ_NEW_SMALL_INT(o->cur);
+        mp_int_t cur = o->cur;
         o->cur += o->step;
-        return o_out;
+        return mp_obj_new_int(cur);
     } else {
         return MP_OBJ_STOP_ITERATION;
     }
@@ -133,7 +133,7 @@ static mp_obj_t range_unary_op(mp_unary_op_t op, mp_obj_t self_in) {
         case MP_UNARY_OP_BOOL:
             return mp_obj_new_bool(len > 0);
         case MP_UNARY_OP_LEN:
-            return MP_OBJ_NEW_SMALL_INT(len);
+            return mp_obj_new_int(len);
         default:
             return MP_OBJ_NULL;      // op not supported
     }
@@ -165,20 +165,16 @@ static mp_obj_t range_subscr(mp_obj_t self_in, mp_obj_t index, mp_obj_t value) {
         #if MICROPY_PY_BUILTINS_SLICE
         if (mp_obj_is_type(index, &mp_type_slice)) {
             mp_bound_slice_t slice;
-            mp_seq_get_fast_slice_indexes(len, index, &slice);
+            mp_obj_slice_indices(index, len, &slice);
             mp_obj_range_t *o = mp_obj_malloc(mp_obj_range_t, &mp_type_range);
             o->start = self->start + slice.start * self->step;
             o->stop = self->start + slice.stop * self->step;
             o->step = slice.step * self->step;
-            if (slice.step < 0) {
-                // Negative slice steps have inclusive stop, so adjust for exclusive
-                o->stop -= self->step;
-            }
             return MP_OBJ_FROM_PTR(o);
         }
         #endif
         size_t index_val = mp_get_index(self->base.type, len, index, false);
-        return MP_OBJ_NEW_SMALL_INT(self->start + index_val * self->step);
+        return mp_obj_new_int(self->start + index_val * self->step);
     } else {
         return MP_OBJ_NULL; // op not supported
     }
diff --git a/py/objringio.c b/py/objringio.c
index ba1ec25307ea4..0025b26be3b07 100644
--- a/py/objringio.c
+++ b/py/objringio.c
@@ -39,22 +39,19 @@ typedef struct _micropython_ringio_obj_t {
 
 static mp_obj_t micropython_ringio_make_new(const mp_obj_type_t *type, size_t n_args, size_t n_kw, const mp_obj_t *args) {
     mp_arg_check_num(n_args, n_kw, 1, 1, false);
-    mp_int_t buff_size = -1;
     mp_buffer_info_t bufinfo = {NULL, 0, 0};
 
     if (!mp_get_buffer(args[0], &bufinfo, MP_BUFFER_RW)) {
-        buff_size = mp_obj_get_int(args[0]);
+        bufinfo.len = mp_obj_get_int(args[0]) + 1;
+        bufinfo.buf = m_new(uint8_t, bufinfo.len);
     }
-    micropython_ringio_obj_t *self = mp_obj_malloc(micropython_ringio_obj_t, type);
-    if (bufinfo.buf != NULL) {
-        // buffer passed in, use it directly for ringbuffer.
-        self->ringbuffer.buf = bufinfo.buf;
-        self->ringbuffer.size = bufinfo.len;
-        self->ringbuffer.iget = self->ringbuffer.iput = 0;
-    } else {
-        // Allocate new buffer, add one extra to buff_size as ringbuf consumes one byte for tracking.
-        ringbuf_alloc(&(self->ringbuffer), buff_size + 1);
+    if (bufinfo.len < 2 || bufinfo.len > UINT16_MAX) {
+        mp_raise_ValueError(NULL);
     }
+    micropython_ringio_obj_t *self = mp_obj_malloc(micropython_ringio_obj_t, type);
+    self->ringbuffer.buf = bufinfo.buf;
+    self->ringbuffer.size = bufinfo.len;
+    self->ringbuffer.iget = self->ringbuffer.iput = 0;
     return MP_OBJ_FROM_PTR(self);
 }
 
diff --git a/py/objstr.c b/py/objstr.c
index 1874cdb01d03d..bd650bbe18ad6 100644
--- a/py/objstr.c
+++ b/py/objstr.c
@@ -33,6 +33,7 @@
 #include "py/objlist.h"
 #include "py/runtime.h"
 #include "py/cstack.h"
+#include "py/objtuple.h"
 
 // CIRCUITPY-CHANGE
 const char nibble_to_hex_upper[16] = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
@@ -46,7 +47,7 @@ static mp_obj_t str_modulo_format(mp_obj_t pattern, size_t n_args, const mp_obj_
 #endif
 
 static mp_obj_t mp_obj_new_bytes_iterator(mp_obj_t str, mp_obj_iter_buf_t *iter_buf);
-static NORETURN void bad_implicit_conversion(mp_obj_t self_in);
+static MP_NORETURN void bad_implicit_conversion(mp_obj_t self_in);
 
 static mp_obj_t mp_obj_new_str_type_from_vstr(const mp_obj_type_t *type, vstr_t *vstr);
 
@@ -372,8 +373,7 @@ mp_obj_t mp_obj_str_binary_op(mp_binary_op_t op, mp_obj_t lhs_in, mp_obj_t rhs_i
         mp_obj_t *args = &rhs_in;
         size_t n_args = 1;
         mp_obj_t dict = MP_OBJ_NULL;
-        if (mp_obj_is_type(rhs_in, &mp_type_tuple)) {
-            // TODO: Support tuple subclasses?
+        if (mp_obj_is_tuple_compatible(rhs_in)) {
             mp_obj_tuple_get(rhs_in, &n_args, &args);
         } else if (mp_obj_is_type(rhs_in, &mp_type_dict)) {
             dict = rhs_in;
@@ -1018,7 +1018,7 @@ static mp_obj_t arg_as_int(mp_obj_t arg) {
 #endif
 
 #if MICROPY_ERROR_REPORTING <= MICROPY_ERROR_REPORTING_TERSE
-static NORETURN void terse_str_format_value_error(void) {
+static MP_NORETURN void terse_str_format_value_error(void) {
     mp_raise_ValueError(MP_ERROR_TEXT("bad format string"));
 }
 #else
@@ -1205,7 +1205,7 @@ static vstr_t mp_obj_str_format_helper(const char *str, const char *top, int *ar
         int width = -1;
         int precision = -1;
         char type = '\0';
-        int flags = 0;
+        unsigned int flags = 0;
 
         if (format_spec) {
             // The format specifier (from http://docs.python.org/2/library/string.html#formatspec)
@@ -1250,8 +1250,9 @@ static vstr_t mp_obj_str_format_helper(const char *str, const char *top, int *ar
                 }
             }
             s = str_to_int(s, stop, &width);
-            if (*s == ',') {
-                flags |= PF_FLAG_SHOW_COMMA;
+            if (*s == ',' || *s == '_') {
+                MP_STATIC_ASSERT((unsigned)'_' << PF_FLAG_SEP_POS >> PF_FLAG_SEP_POS == '_');
+                flags |= (unsigned)*s << PF_FLAG_SEP_POS;
                 s++;
             }
             if (*s == '.') {
@@ -1324,7 +1325,7 @@ static vstr_t mp_obj_str_format_helper(const char *str, const char *top, int *ar
                 }
 
                 case '\0':  // No explicit format type implies 'd'
-                case 'n':   // I don't think we support locales in uPy so use 'd'
+                case 'n':   // I don't think we support locales in MicroPython so use 'd'
                 case 'd':
                     mp_print_mp_int(&print, arg, 10, 'a', flags, fill, width, 0);
                     continue;
@@ -2395,7 +2396,7 @@ bool mp_obj_str_equal(mp_obj_t s1, mp_obj_t s2) {
     }
 }
 
-static NORETURN void bad_implicit_conversion(mp_obj_t self_in) {
+static MP_NORETURN void bad_implicit_conversion(mp_obj_t self_in) {
     #if MICROPY_ERROR_REPORTING <= MICROPY_ERROR_REPORTING_TERSE
     mp_raise_TypeError(MP_ERROR_TEXT("can't convert to str implicitly"));
     #else
diff --git a/py/objtuple.c b/py/objtuple.c
index e0b31edaf2376..b2ccbbb299082 100644
--- a/py/objtuple.c
+++ b/py/objtuple.c
@@ -31,9 +31,6 @@
 #include "py/objtuple.h"
 #include "py/runtime.h"
 
-// type check is done on getiter method to allow tuple, namedtuple, attrtuple
-#define mp_obj_is_tuple_compatible(o) (MP_OBJ_TYPE_GET_SLOT_OR_NULL(mp_obj_get_type(o), iter) == mp_obj_tuple_getiter)
-
 /******************************************************************************/
 /* tuple                                                                      */
 
diff --git a/py/objtuple.h b/py/objtuple.h
index e2d010e6c5a3d..783522a6222b5 100644
--- a/py/objtuple.h
+++ b/py/objtuple.h
@@ -57,7 +57,7 @@ extern const mp_obj_type_t mp_type_attrtuple;
 
 #define MP_DEFINE_ATTRTUPLE(tuple_obj_name, fields, nitems, ...) \
     const mp_rom_obj_tuple_t tuple_obj_name = { \
-        .base = {&mp_type_attrtuple}, \
+        .base = {.type = &mp_type_attrtuple}, \
         .len = nitems, \
         .items = { __VA_ARGS__, MP_ROM_PTR((void *)fields) } \
     }
@@ -68,4 +68,7 @@ void mp_obj_attrtuple_print_helper(const mp_print_t *print, const qstr *fields,
 
 mp_obj_t mp_obj_new_attrtuple(const qstr *fields, size_t n, const mp_obj_t *items);
 
+// type check is done on getiter method to allow tuple, namedtuple, attrtuple
+#define mp_obj_is_tuple_compatible(o) (MP_OBJ_TYPE_GET_SLOT_OR_NULL(mp_obj_get_type(o), iter) == mp_obj_tuple_getiter)
+
 #endif // MICROPY_INCLUDED_PY_OBJTUPLE_H
diff --git a/py/objtype.c b/py/objtype.c
index 074d6f39293db..b1a984b50e057 100644
--- a/py/objtype.c
+++ b/py/objtype.c
@@ -44,6 +44,7 @@
 #define ENABLE_SPECIAL_ACCESSORS \
     (MICROPY_PY_DESCRIPTORS || MICROPY_PY_DELATTR_SETATTR || MICROPY_PY_BUILTINS_PROPERTY)
 
+static mp_obj_t mp_obj_new_type(qstr name, mp_obj_t bases_tuple, mp_obj_t locals_dict);
 static mp_obj_t mp_obj_is_subclass(mp_obj_t object, mp_obj_t classinfo);
 static mp_obj_t static_class_method_make_new(const mp_obj_type_t *self_in, size_t n_args, size_t n_kw, const mp_obj_t *args);
 
@@ -690,8 +691,8 @@ static void mp_obj_instance_load_attr(mp_obj_t self_in, qstr attr, mp_obj_t *des
     // try __getattr__
     if (attr != MP_QSTR___getattr__) {
         #if MICROPY_PY_DESCRIPTORS
-        // With descriptors enabled, don't delegate lookups of __get__/__set__/__delete__.
-        if (attr == MP_QSTR___get__ || attr == MP_QSTR___set__ || attr == MP_QSTR___delete__) {
+        // With descriptors enabled, don't delegate lookups of __get__/__set__/__delete__/__set_name__.
+        if (attr == MP_QSTR___get__ || attr == MP_QSTR___set__ || attr == MP_QSTR___delete__ || attr == MP_QSTR___set_name__) {
             return;
         }
         #endif
@@ -996,7 +997,7 @@ static bool check_for_special_accessors(mp_obj_t key, mp_obj_t value) {
     #endif
     #if MICROPY_PY_DESCRIPTORS
     static const uint8_t to_check[] = {
-        MP_QSTR___get__, MP_QSTR___set__, MP_QSTR___delete__,
+        MP_QSTR___get__, MP_QSTR___set__, MP_QSTR___delete__, // not needed for MP_QSTR___set_name__ though
     };
     for (size_t i = 0; i < MP_ARRAY_SIZE(to_check); ++i) {
         mp_obj_t dest_temp[2];
@@ -1010,10 +1011,52 @@ static bool check_for_special_accessors(mp_obj_t key, mp_obj_t value) {
 }
 #endif
 
+#if MICROPY_PY_DESCRIPTORS
+// Shared data layout for the __set_name__ call and a linked list of calls to be made.
+typedef union _setname_list_t setname_list_t;
+union _setname_list_t {
+    mp_obj_t call[4];
+    struct {
+        mp_obj_t _meth;
+        mp_obj_t _self;
+        setname_list_t *next; // can use the "owner" argument position temporarily for the linked list
+        mp_obj_t _name;
+    };
+};
+
+// Append any `__set_name__` method on `value` to the setname list, with its per-attr args
+static setname_list_t *setname_maybe_bind_append(setname_list_t *tail, mp_obj_t name, mp_obj_t value) {
+    // make certain our type-punning is safe:
+    MP_STATIC_ASSERT_NONCONSTEXPR(offsetof(setname_list_t, next) == offsetof(setname_list_t, call[2]));
+
+    // tail is a blank list entry
+    mp_load_method_maybe(value, MP_QSTR___set_name__, tail->call);
+    if (tail->call[1] != MP_OBJ_NULL) {
+        // Each time a __set_name__ is found, leave it in-place in the former tail and allocate a new tail
+        tail->next = m_new_obj(setname_list_t);
+        tail->next->next = NULL;
+        tail->call[3] = name;
+        return tail->next;
+    } else {
+        return tail;
+    }
+}
+
+// Execute the captured `__set_name__` calls, destroying the setname list in the process.
+static inline void setname_consume_call_all(setname_list_t *head, mp_obj_t owner) {
+    setname_list_t *next;
+    while ((next = head->next) != NULL) {
+        head->call[2] = owner;
+        mp_call_method_n_kw(2, 0, head->call);
+        head = next;
+    }
+}
+#endif
+
 static void type_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
     (void)kind;
     mp_obj_type_t *self = MP_OBJ_TO_PTR(self_in);
-    mp_printf(print, "<class '%q'>", self->name);
+    mp_printf(print, "<class '%q'>", (qstr)self->name);
 }
 
 static mp_obj_t type_make_new(const mp_obj_type_t *type_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
@@ -1043,7 +1086,7 @@ static mp_obj_t type_call(mp_obj_t self_in, size_t n_args, size_t n_kw, const mp
 
     if (!MP_OBJ_TYPE_HAS_SLOT(self, make_new)) {
         #if MICROPY_ERROR_REPORTING <= MICROPY_ERROR_REPORTING_TERSE
-        mp_raise_TypeError(MP_ERROR_TEXT("cannot create instance"));
+        mp_raise_TypeError(MP_ERROR_TEXT("can't create instance"));
         #else
         // CIRCUITPY-CHANGE: more specific mp_raise
         mp_raise_TypeError_varg(MP_ERROR_TEXT("can't create '%q' instances"), self->name);
@@ -1159,7 +1202,7 @@ MP_DEFINE_CONST_OBJ_TYPE(
     attr, type_attr
     );
 
-mp_obj_t mp_obj_new_type(qstr name, mp_obj_t bases_tuple, mp_obj_t locals_dict) {
+static mp_obj_t mp_obj_new_type(qstr name, mp_obj_t bases_tuple, mp_obj_t locals_dict) {
     // Verify input objects have expected type
     if (!mp_obj_is_type(bases_tuple, &mp_type_tuple)) {
         mp_raise_TypeError(NULL);
@@ -1252,20 +1295,38 @@ mp_obj_t mp_obj_new_type(qstr name, mp_obj_t bases_tuple, mp_obj_t locals_dict)
         }
     }
 
+    #if MICROPY_PY_DESCRIPTORS
+    // To avoid any dynamic allocations when no __set_name__ exists,
+    // the head of this list is kept on the stack (marked blank with `next = NULL`).
+    setname_list_t setname_list = { .next = NULL };
+    setname_list_t *setname_tail = &setname_list;
+    #endif
+
     #if ENABLE_SPECIAL_ACCESSORS
-    // Check if the class has any special accessor methods
-    if (!(o->flags & MP_TYPE_FLAG_HAS_SPECIAL_ACCESSORS)) {
-        for (size_t i = 0; i < locals_ptr->map.alloc; i++) {
-            if (mp_map_slot_is_filled(&locals_ptr->map, i)) {
-                const mp_map_elem_t *elem = &locals_ptr->map.table[i];
-                if (check_for_special_accessors(elem->key, elem->value)) {
-                    o->flags |= MP_TYPE_FLAG_HAS_SPECIAL_ACCESSORS;
-                    break;
-                }
+    // Check if the class has any special accessor methods,
+    // and accumulate bound __set_name__ methods that need to be called
+    for (size_t i = 0; i < locals_ptr->map.alloc; i++) {
+        #if !MICROPY_PY_DESCRIPTORS
+        // __set_name__ needs to scan the entire locals map, can't early-terminate
+        if (o->flags & MP_TYPE_FLAG_HAS_SPECIAL_ACCESSORS) {
+            break;
+        }
+        #endif
+
+        if (mp_map_slot_is_filled(&locals_ptr->map, i)) {
+            const mp_map_elem_t *elem = &locals_ptr->map.table[i];
+
+            if (!(o->flags & MP_TYPE_FLAG_HAS_SPECIAL_ACCESSORS) // elidable when the early-termination check is enabled
+                && check_for_special_accessors(elem->key, elem->value)) {
+                o->flags |= MP_TYPE_FLAG_HAS_SPECIAL_ACCESSORS;
             }
+
+            #if MICROPY_PY_DESCRIPTORS
+            setname_tail = setname_maybe_bind_append(setname_tail, elem->key, elem->value);
+            #endif
         }
     }
-    #endif
+    #endif // ENABLE_SPECIAL_ACCESSORS
 
     const mp_obj_type_t *native_base;
     size_t num_native_bases = instance_count_native_bases(o, &native_base);
@@ -1273,8 +1334,7 @@ mp_obj_t mp_obj_new_type(qstr name, mp_obj_t bases_tuple, mp_obj_t locals_dict)
         mp_raise_TypeError(MP_ERROR_TEXT("multiple bases have instance lay-out conflict"));
     }
 
-    mp_map_t *locals_map = &MP_OBJ_TYPE_GET_SLOT(o, locals_dict)->map;
-    mp_map_elem_t *elem = mp_map_lookup(locals_map, MP_OBJ_NEW_QSTR(MP_QSTR___new__), MP_MAP_LOOKUP);
+    mp_map_elem_t *elem = mp_map_lookup(&locals_ptr->map, MP_OBJ_NEW_QSTR(MP_QSTR___new__), MP_MAP_LOOKUP);
     if (elem != NULL) {
         // __new__ slot exists; check if it is a function
         if (mp_obj_is_fun(elem->value)) {
@@ -1283,6 +1343,10 @@ mp_obj_t mp_obj_new_type(qstr name, mp_obj_t bases_tuple, mp_obj_t locals_dict)
         }
     }
 
+    #if MICROPY_PY_DESCRIPTORS
+    setname_consume_call_all(&setname_list, MP_OBJ_FROM_PTR(o));
+    #endif
+
     return MP_OBJ_FROM_PTR(o);
 }
 
diff --git a/py/parse.c b/py/parse.c
index a393b0ee8c153..36150ef468bdf 100644
--- a/py/parse.c
+++ b/py/parse.c
@@ -341,18 +341,34 @@ static uint8_t peek_rule(parser_t *parser, size_t n) {
 }
 #endif
 
-bool mp_parse_node_get_int_maybe(mp_parse_node_t pn, mp_obj_t *o) {
+#if MICROPY_COMP_CONST_FOLDING || MICROPY_EMIT_INLINE_ASM
+static bool mp_parse_node_get_number_maybe(mp_parse_node_t pn, mp_obj_t *o) {
     if (MP_PARSE_NODE_IS_SMALL_INT(pn)) {
         *o = MP_OBJ_NEW_SMALL_INT(MP_PARSE_NODE_LEAF_SMALL_INT(pn));
         return true;
     } else if (MP_PARSE_NODE_IS_STRUCT_KIND(pn, RULE_const_object)) {
         mp_parse_node_struct_t *pns = (mp_parse_node_struct_t *)pn;
         *o = mp_parse_node_extract_const_object(pns);
-        return mp_obj_is_int(*o);
+        return mp_obj_is_int(*o)
+               #if MICROPY_COMP_CONST_FLOAT
+               || mp_obj_is_float(*o)
+               #endif
+        ;
     } else {
         return false;
     }
 }
+#endif
+
+#if MICROPY_EMIT_INLINE_ASM
+bool mp_parse_node_get_int_maybe(mp_parse_node_t pn, mp_obj_t *o) {
+    return mp_parse_node_get_number_maybe(pn, o)
+           #if MICROPY_COMP_CONST_FLOAT
+           && mp_obj_is_int(*o)
+           #endif
+    ;
+}
+#endif
 
 #if MICROPY_COMP_CONST_TUPLE || MICROPY_COMP_CONST
 static bool mp_parse_node_is_const(mp_parse_node_t pn) {
@@ -647,12 +663,32 @@ static const mp_rom_map_elem_t mp_constants_table[] = {
     #if MICROPY_PY_UCTYPES
     { MP_ROM_QSTR(MP_QSTR_uctypes), MP_ROM_PTR(&mp_module_uctypes) },
     #endif
+    #if MICROPY_PY_BUILTINS_FLOAT && MICROPY_PY_MATH && MICROPY_COMP_CONST_FLOAT
+    { MP_ROM_QSTR(MP_QSTR_math), MP_ROM_PTR(&mp_module_math) },
+    #endif
     // Extra constants as defined by a port
     MICROPY_PORT_CONSTANTS
 };
 static MP_DEFINE_CONST_MAP(mp_constants_map, mp_constants_table);
 #endif
 
+static bool binary_op_maybe(mp_binary_op_t op, mp_obj_t lhs, mp_obj_t rhs, mp_obj_t *res) {
+    nlr_buf_t nlr;
+    if (nlr_push(&nlr) == 0) {
+        mp_obj_t tmp = mp_binary_op(op, lhs, rhs);
+        nlr_pop();
+        #if MICROPY_PY_BUILTINS_COMPLEX
+        if (mp_obj_is_type(tmp, &mp_type_complex)) {
+            return false;
+        }
+        #endif
+        *res = tmp;
+        return true;
+    } else {
+        return false;
+    }
+}
+
 static bool fold_logical_constants(parser_t *parser, uint8_t rule_id, size_t *num_args) {
     if (rule_id == RULE_or_test
         || rule_id == RULE_and_test) {
@@ -711,7 +747,7 @@ static bool fold_logical_constants(parser_t *parser, uint8_t rule_id, size_t *nu
 }
 
 static bool fold_constants(parser_t *parser, uint8_t rule_id, size_t num_args) {
-    // this code does folding of arbitrary integer expressions, eg 1 + 2 * 3 + 4
+    // this code does folding of arbitrary numeric expressions, eg 1 + 2 * 3 + 4
     // it does not do partial folding, eg 1 + 2 + x -> 3 + x
 
     mp_obj_t arg0;
@@ -721,7 +757,7 @@ static bool fold_constants(parser_t *parser, uint8_t rule_id, size_t num_args) {
         || rule_id == RULE_power) {
         // folding for binary ops: | ^ & **
         mp_parse_node_t pn = peek_result(parser, num_args - 1);
-        if (!mp_parse_node_get_int_maybe(pn, &arg0)) {
+        if (!mp_parse_node_get_number_maybe(pn, &arg0)) {
             return false;
         }
         mp_binary_op_t op;
@@ -737,58 +773,45 @@ static bool fold_constants(parser_t *parser, uint8_t rule_id, size_t num_args) {
         for (ssize_t i = num_args - 2; i >= 0; --i) {
             pn = peek_result(parser, i);
             mp_obj_t arg1;
-            if (!mp_parse_node_get_int_maybe(pn, &arg1)) {
+            if (!mp_parse_node_get_number_maybe(pn, &arg1)) {
                 return false;
             }
-            if (op == MP_BINARY_OP_POWER && mp_obj_int_sign(arg1) < 0) {
-                // ** can't have negative rhs
+            if (!binary_op_maybe(op, arg0, arg1, &arg0)) {
                 return false;
             }
-            arg0 = mp_binary_op(op, arg0, arg1);
         }
     } else if (rule_id == RULE_shift_expr
                || rule_id == RULE_arith_expr
                || rule_id == RULE_term) {
         // folding for binary ops: << >> + - * @ / % //
         mp_parse_node_t pn = peek_result(parser, num_args - 1);
-        if (!mp_parse_node_get_int_maybe(pn, &arg0)) {
+        if (!mp_parse_node_get_number_maybe(pn, &arg0)) {
             return false;
         }
         for (ssize_t i = num_args - 2; i >= 1; i -= 2) {
             pn = peek_result(parser, i - 1);
             mp_obj_t arg1;
-            if (!mp_parse_node_get_int_maybe(pn, &arg1)) {
+            if (!mp_parse_node_get_number_maybe(pn, &arg1)) {
                 return false;
             }
             mp_token_kind_t tok = MP_PARSE_NODE_LEAF_ARG(peek_result(parser, i));
-            if (tok == MP_TOKEN_OP_AT || tok == MP_TOKEN_OP_SLASH) {
-                // Can't fold @ or /
-                return false;
-            }
             mp_binary_op_t op = MP_BINARY_OP_LSHIFT + (tok - MP_TOKEN_OP_DBL_LESS);
-            int rhs_sign = mp_obj_int_sign(arg1);
-            if (op <= MP_BINARY_OP_RSHIFT) {
-                // << and >> can't have negative rhs
-                if (rhs_sign < 0) {
-                    return false;
-                }
-            } else if (op >= MP_BINARY_OP_FLOOR_DIVIDE) {
-                // % and // can't have zero rhs
-                if (rhs_sign == 0) {
-                    return false;
-                }
+            if (!binary_op_maybe(op, arg0, arg1, &arg0)) {
+                return false;
             }
-            arg0 = mp_binary_op(op, arg0, arg1);
         }
     } else if (rule_id == RULE_factor_2) {
         // folding for unary ops: + - ~
         mp_parse_node_t pn = peek_result(parser, 0);
-        if (!mp_parse_node_get_int_maybe(pn, &arg0)) {
+        if (!mp_parse_node_get_number_maybe(pn, &arg0)) {
             return false;
         }
         mp_token_kind_t tok = MP_PARSE_NODE_LEAF_ARG(peek_result(parser, 1));
         mp_unary_op_t op;
         if (tok == MP_TOKEN_OP_TILDE) {
+            if (!mp_obj_is_int(arg0)) {
+                return false;
+            }
             op = MP_UNARY_OP_INVERT;
         } else {
             assert(tok == MP_TOKEN_OP_PLUS || tok == MP_TOKEN_OP_MINUS); // should be
@@ -860,7 +883,7 @@ static bool fold_constants(parser_t *parser, uint8_t rule_id, size_t num_args) {
             return false;
         }
         // id1.id2
-        // look it up in constant table, see if it can be replaced with an integer
+        // look it up in constant table, see if it can be replaced with an integer or a float
         mp_parse_node_struct_t *pns1 = (mp_parse_node_struct_t *)pn1;
         assert(MP_PARSE_NODE_IS_ID(pns1->nodes[0]));
         qstr q_base = MP_PARSE_NODE_LEAF_ARG(pn0);
@@ -871,7 +894,7 @@ static bool fold_constants(parser_t *parser, uint8_t rule_id, size_t num_args) {
         }
         mp_obj_t dest[2];
         mp_load_method_maybe(elem->value, q_attr, dest);
-        if (!(dest[0] != MP_OBJ_NULL && mp_obj_is_int(dest[0]) && dest[1] == MP_OBJ_NULL)) {
+        if (!(dest[0] != MP_OBJ_NULL && (mp_obj_is_int(dest[0]) || mp_obj_is_float(dest[0])) && dest[1] == MP_OBJ_NULL)) {
             return false;
         }
         arg0 = dest[0];
diff --git a/py/parsenum.c b/py/parsenum.c
index 874216f08d005..c52f040e1a210 100644
--- a/py/parsenum.c
+++ b/py/parsenum.c
@@ -28,6 +28,7 @@
 #include <stdlib.h>
 
 #include "py/runtime.h"
+#include "py/misc.h"
 #include "py/parsenumbase.h"
 #include "py/parsenum.h"
 #include "py/smallint.h"
@@ -36,7 +37,7 @@
 #include <math.h>
 #endif
 
-static NORETURN void raise_exc(mp_obj_t exc, mp_lexer_t *lex) {
+static MP_NORETURN void raise_exc(mp_obj_t exc, mp_lexer_t *lex) {
     // if lex!=NULL then the parser called us and we need to convert the
     // exception's type from ValueError to SyntaxError and add traceback info
     if (lex != NULL) {
@@ -46,6 +47,27 @@ static NORETURN void raise_exc(mp_obj_t exc, mp_lexer_t *lex) {
     nlr_raise(exc);
 }
 
+#if MICROPY_LONGINT_IMPL != MICROPY_LONGINT_IMPL_LONGLONG
+// For the common small integer parsing case, we parse directly to mp_int_t and
+// check that the value doesn't overflow a smallint (in which case we fail over
+// to bigint parsing if supported)
+typedef mp_int_t parsed_int_t;
+
+#define PARSED_INT_MUL_OVERFLOW mp_mul_mp_int_t_overflow
+#define PARSED_INT_FITS MP_SMALL_INT_FITS
+#else
+// In the special case where bigint support is long long, we save code size by
+// parsing directly to long long and then return either a bigint or smallint
+// from the same result.
+//
+// To avoid pulling in (slow) signed 64-bit math routines we do the initial
+// parsing to an unsigned long long and only convert to signed at the end.
+typedef unsigned long long parsed_int_t;
+
+#define PARSED_INT_MUL_OVERFLOW mp_mul_ull_overflow
+#define PARSED_INT_FITS(I) ((I) <= (unsigned long long)LLONG_MAX + 1)
+#endif
+
 mp_obj_t mp_parse_num_integer(const char *restrict str_, size_t len, int base, mp_lexer_t *lex) {
     const byte *restrict str = (const byte *)str_;
     const byte *restrict top = str + len;
@@ -77,7 +99,7 @@ mp_obj_t mp_parse_num_integer(const char *restrict str_, size_t len, int base, m
     str += mp_parse_num_base((const char *)str, top - str, &base);
 
     // string should be an integer number
-    mp_int_t int_val = 0;
+    parsed_int_t parsed_val = 0;
     const byte *restrict str_val_start = str;
     for (; str < top; str++) {
         // get next digit as a value
@@ -99,25 +121,32 @@ mp_obj_t mp_parse_num_integer(const char *restrict str_, size_t len, int base, m
             break;
         }
 
-        // add next digi and check for overflow
-        if (mp_small_int_mul_overflow(int_val, base)) {
+        // add next digit and check for overflow
+        if (PARSED_INT_MUL_OVERFLOW(parsed_val, base, &parsed_val)) {
             goto overflow;
         }
-        int_val = int_val * base + dig;
-        if (!MP_SMALL_INT_FITS(int_val)) {
+        parsed_val += dig;
+        if (!PARSED_INT_FITS(parsed_val)) {
             goto overflow;
         }
     }
 
-    // negate value if needed
-    if (neg) {
-        int_val = -int_val;
+    #if MICROPY_LONGINT_IMPL != MICROPY_LONGINT_IMPL_LONGLONG
+    // The PARSED_INT_FITS check above ensures parsed_val fits in small int representation
+    ret_val = MP_OBJ_NEW_SMALL_INT(neg ? (-parsed_val) : parsed_val);
+have_ret_val:
+    #else
+    // The PARSED_INT_FITS check above ensures parsed_val won't overflow signed long long
+    long long signed_val = -parsed_val;
+    if (!neg) {
+        if (signed_val == LLONG_MIN) {
+            goto overflow;
+        }
+        signed_val = -signed_val;
     }
+    ret_val = mp_obj_new_int_from_ll(signed_val); // Could be large or small int
+    #endif
 
-    // create the small int
-    ret_val = MP_OBJ_NEW_SMALL_INT(int_val);
-
-have_ret_val:
     // check we parsed something
     if (str == str_val_start) {
         goto value_error;
@@ -136,6 +165,7 @@ mp_obj_t mp_parse_num_integer(const char *restrict str_, size_t len, int base, m
     return ret_val;
 
 overflow:
+    #if MICROPY_LONGINT_IMPL != MICROPY_LONGINT_IMPL_LONGLONG
     // reparse using long int
     {
         const char *s2 = (const char *)str_val_start;
@@ -143,6 +173,9 @@ mp_obj_t mp_parse_num_integer(const char *restrict str_, size_t len, int base, m
         str = (const byte *)s2;
         goto have_ret_val;
     }
+    #else
+    mp_raise_msg(&mp_type_OverflowError, MP_ERROR_TEXT("result overflows long long storage"));
+    #endif
 
 value_error:
     {
@@ -167,6 +200,8 @@ mp_obj_t mp_parse_num_integer(const char *restrict str_, size_t len, int base, m
     }
 }
 
+#if MICROPY_PY_BUILTINS_FLOAT
+
 enum {
     REAL_IMAG_STATE_START = 0,
     REAL_IMAG_STATE_HAVE_REAL = 1,
@@ -179,27 +214,81 @@ typedef enum {
     PARSE_DEC_IN_EXP,
 } parse_dec_in_t;
 
-#if MICROPY_PY_BUILTINS_FLOAT
 // MANTISSA_MAX is used to retain precision while not overflowing mantissa
-// SMALL_NORMAL_VAL is the smallest power of 10 that is still a normal float
-// EXACT_POWER_OF_10 is the largest value of x so that 10^x can be stored exactly in a float
-//   Note: EXACT_POWER_OF_10 is at least floor(log_5(2^mantissa_length)). Indeed, 10^n = 2^n * 5^n
-//   so we only have to store the 5^n part in the mantissa (the 2^n part will go into the float's
-//   exponent).
+#define MANTISSA_MAX (sizeof(mp_large_float_uint_t) == 8 ? 0x1999999999999998ULL : 0x19999998U)
+
+// MAX_EXACT_POWER_OF_5 is the largest value of x so that 5^x can be stored exactly in a float
 #if MICROPY_FLOAT_IMPL == MICROPY_FLOAT_IMPL_FLOAT
-#define MANTISSA_MAX 0x19999998U
-#define SMALL_NORMAL_VAL (1e-37F)
-#define SMALL_NORMAL_EXP (-37)
-#define EXACT_POWER_OF_10 (9)
+#define MAX_EXACT_POWER_OF_5 (10)
 #elif MICROPY_FLOAT_IMPL == MICROPY_FLOAT_IMPL_DOUBLE
-#define MANTISSA_MAX 0x1999999999999998ULL
-#define SMALL_NORMAL_VAL (1e-307)
-#define SMALL_NORMAL_EXP (-307)
-#define EXACT_POWER_OF_10 (22)
+#define MAX_EXACT_POWER_OF_5 (22)
 #endif
 
+// Helper to compute `num * (10.0 ** dec_exp)`
+mp_large_float_t mp_decimal_exp(mp_large_float_t num, int dec_exp) {
+    // CIRCUITPY-CHANGE: ignore float equal warning
+    #pragma GCC diagnostic push
+    #pragma GCC diagnostic ignored "-Wfloat-equal"
+    if (dec_exp == 0 || num == (mp_large_float_t)(0.0)) {
+        return num;
+    }
+    #pragma GCC diagnostic pop
+
+    #if MICROPY_FLOAT_FORMAT_IMPL == MICROPY_FLOAT_FORMAT_IMPL_EXACT
+
+    // If the assert below fails, it means you have chosen MICROPY_FLOAT_FORMAT_IMPL_EXACT
+    // manually on a platform where `larger floats` are not supported, which would
+    // result in inexact conversions. To fix this issue, change your `mpconfigport.h`
+    // and select MICROPY_FLOAT_FORMAT_IMPL_APPROX instead
+    assert(sizeof(mp_large_float_t) > sizeof(mp_float_t));
+
+    // Perform power using simple multiplications, to avoid
+    // dependency to higher-precision pow() function
+    int neg_exp = (dec_exp < 0);
+    if (neg_exp) {
+        dec_exp = -dec_exp;
+    }
+    mp_large_float_t res = num;
+    mp_large_float_t expo = (mp_large_float_t)10.0;
+    while (dec_exp) {
+        if (dec_exp & 1) {
+            if (neg_exp) {
+                res /= expo;
+            } else {
+                res *= expo;
+            }
+        }
+        dec_exp >>= 1;
+        if (dec_exp) {
+            expo *= expo;
+        }
+    }
+    return res;
+
+    #else
+    // MICROPY_FLOAT_FORMAT_IMPL != MICROPY_FLOAT_FORMAT_IMPL_EXACT
+
+    mp_float_union_t res = {num};
+    // Multiply first by (2.0 ** dec_exp) via the exponent
+    // - this will ensure that the result of `pow()` is always in mp_float_t range
+    //   when the result is expected to be in mp_float_t range (e.g. during format)
+    // - we don't need to care about p.exp overflow, as (5.0 ** dec_exp) will anyway
+    //   force the final result toward the proper edge if needed (0.0 or inf)
+    res.p.exp += dec_exp;
+    // Use positive exponents when they are more precise then negative
+    if (dec_exp < 0 && dec_exp >= -MAX_EXACT_POWER_OF_5) {
+        res.f /= MICROPY_FLOAT_C_FUN(pow)(5, -dec_exp);
+    } else {
+        res.f *= MICROPY_FLOAT_C_FUN(pow)(5, dec_exp);
+    }
+    return (mp_large_float_t)res.f;
+
+    #endif
+}
+
+
 // Break out inner digit accumulation routine to ease trailing zero deferral.
-static mp_float_uint_t accept_digit(mp_float_uint_t p_mantissa, unsigned int dig, int *p_exp_extra, int in) {
+static mp_large_float_uint_t accept_digit(mp_large_float_uint_t p_mantissa, unsigned int dig, int *p_exp_extra, int in) {
     // Core routine to ingest an additional digit.
     if (p_mantissa < MANTISSA_MAX) {
         // dec_val won't overflow so keep accumulating
@@ -216,6 +305,85 @@ static mp_float_uint_t accept_digit(mp_float_uint_t p_mantissa, unsigned int dig
         return p_mantissa;
     }
 }
+
+// Helper to parse an unsigned decimal number into a mp_float_t
+const char *mp_parse_float_internal(const char *str, size_t len, mp_float_t *res) {
+    const char *top = str + len;
+
+    parse_dec_in_t in = PARSE_DEC_IN_INTG;
+    bool exp_neg = false;
+    mp_large_float_uint_t mantissa = 0;
+    int exp_val = 0;
+    int exp_extra = 0;
+    int trailing_zeros_intg = 0, trailing_zeros_frac = 0;
+    while (str < top) {
+        unsigned int dig = *str++;
+        if ('0' <= dig && dig <= '9') {
+            dig -= '0';
+            if (in == PARSE_DEC_IN_EXP) {
+                // don't overflow exp_val when adding next digit, instead just truncate
+                // it and the resulting float will still be correct, either inf or 0.0
+                // (use INT_MAX/2 to allow adding exp_extra at the end without overflow)
+                if (exp_val < (INT_MAX / 2 - 9) / 10) {
+                    exp_val = 10 * exp_val + dig;
+                }
+            } else {
+                if (dig == 0 || mantissa >= MANTISSA_MAX) {
+                    // Defer treatment of zeros in fractional part.  If nothing comes afterwards, ignore them.
+                    // Also, once we reach MANTISSA_MAX, treat every additional digit as a trailing zero.
+                    if (in == PARSE_DEC_IN_INTG) {
+                        ++trailing_zeros_intg;
+                    } else {
+                        ++trailing_zeros_frac;
+                    }
+                } else {
+                    // Time to un-defer any trailing zeros.  Intg zeros first.
+                    while (trailing_zeros_intg) {
+                        mantissa = accept_digit(mantissa, 0, &exp_extra, PARSE_DEC_IN_INTG);
+                        --trailing_zeros_intg;
+                    }
+                    while (trailing_zeros_frac) {
+                        mantissa = accept_digit(mantissa, 0, &exp_extra, PARSE_DEC_IN_FRAC);
+                        --trailing_zeros_frac;
+                    }
+                    mantissa = accept_digit(mantissa, dig, &exp_extra, in);
+                }
+            }
+        } else if (in == PARSE_DEC_IN_INTG && dig == '.') {
+            in = PARSE_DEC_IN_FRAC;
+        } else if (in != PARSE_DEC_IN_EXP && ((dig | 0x20) == 'e')) {
+            in = PARSE_DEC_IN_EXP;
+            if (str < top) {
+                if (str[0] == '+') {
+                    str++;
+                } else if (str[0] == '-') {
+                    str++;
+                    exp_neg = true;
+                }
+            }
+            if (str == top) {
+                return NULL;
+            }
+        } else if (dig == '_') {
+            continue;
+        } else {
+            // unknown character
+            str--;
+            break;
+        }
+    }
+
+    // work out the exponent
+    if (exp_neg) {
+        exp_val = -exp_val;
+    }
+    exp_val += exp_extra + trailing_zeros_intg;
+
+    // At this point, we just need to multiply the mantissa by its base 10 exponent.
+    *res = (mp_float_t)mp_decimal_exp(mantissa, exp_val);
+
+    return str;
+}
 #endif // MICROPY_PY_BUILTINS_FLOAT
 
 #if MICROPY_PY_BUILTINS_COMPLEX
@@ -253,111 +421,23 @@ parse_start:;
     const char *str_val_start = str;
 
     // determine what the string is
-    if (str < top && (str[0] | 0x20) == 'i') {
-        // string starts with 'i', should be 'inf' or 'infinity' (case insensitive)
-        if (str + 2 < top && (str[1] | 0x20) == 'n' && (str[2] | 0x20) == 'f') {
-            // inf
-            str += 3;
-            dec_val = (mp_float_t)INFINITY;
-            if (str + 4 < top && (str[0] | 0x20) == 'i' && (str[1] | 0x20) == 'n' && (str[2] | 0x20) == 'i' && (str[3] | 0x20) == 't' && (str[4] | 0x20) == 'y') {
-                // infinity
-                str += 5;
-            }
-        }
-    } else if (str < top && (str[0] | 0x20) == 'n') {
-        // string starts with 'n', should be 'nan' (case insensitive)
-        if (str + 2 < top && (str[1] | 0x20) == 'a' && (str[2] | 0x20) == 'n') {
-            // NaN
-            str += 3;
-            dec_val = MICROPY_FLOAT_C_FUN(nan)("");
+    if (str + 2 < top && (str[0] | 0x20) == 'i' && (str[1] | 0x20) == 'n' && (str[2] | 0x20) == 'f') {
+        // 'inf' or 'infinity' (case insensitive)
+        str += 3;
+        dec_val = (mp_float_t)INFINITY;
+        if (str + 4 < top && (str[0] | 0x20) == 'i' && (str[1] | 0x20) == 'n' && (str[2] | 0x20) == 'i' && (str[3] | 0x20) == 't' && (str[4] | 0x20) == 'y') {
+            // infinity
+            str += 5;
         }
+    } else if (str + 2 < top && (str[0] | 0x20) == 'n' && (str[1] | 0x20) == 'a' && (str[2] | 0x20) == 'n') {
+        // 'nan' (case insensitive)
+        str += 3;
+        dec_val = MICROPY_FLOAT_C_FUN(nan)("");
     } else {
         // string should be a decimal number
-        parse_dec_in_t in = PARSE_DEC_IN_INTG;
-        bool exp_neg = false;
-        mp_float_uint_t mantissa = 0;
-        int exp_val = 0;
-        int exp_extra = 0;
-        int trailing_zeros_intg = 0, trailing_zeros_frac = 0;
-        while (str < top) {
-            unsigned int dig = *str++;
-            if ('0' <= dig && dig <= '9') {
-                dig -= '0';
-                if (in == PARSE_DEC_IN_EXP) {
-                    // don't overflow exp_val when adding next digit, instead just truncate
-                    // it and the resulting float will still be correct, either inf or 0.0
-                    // (use INT_MAX/2 to allow adding exp_extra at the end without overflow)
-                    if (exp_val < (INT_MAX / 2 - 9) / 10) {
-                        exp_val = 10 * exp_val + dig;
-                    }
-                } else {
-                    if (dig == 0 || mantissa >= MANTISSA_MAX) {
-                        // Defer treatment of zeros in fractional part.  If nothing comes afterwards, ignore them.
-                        // Also, once we reach MANTISSA_MAX, treat every additional digit as a trailing zero.
-                        if (in == PARSE_DEC_IN_INTG) {
-                            ++trailing_zeros_intg;
-                        } else {
-                            ++trailing_zeros_frac;
-                        }
-                    } else {
-                        // Time to un-defer any trailing zeros.  Intg zeros first.
-                        while (trailing_zeros_intg) {
-                            mantissa = accept_digit(mantissa, 0, &exp_extra, PARSE_DEC_IN_INTG);
-                            --trailing_zeros_intg;
-                        }
-                        while (trailing_zeros_frac) {
-                            mantissa = accept_digit(mantissa, 0, &exp_extra, PARSE_DEC_IN_FRAC);
-                            --trailing_zeros_frac;
-                        }
-                        mantissa = accept_digit(mantissa, dig, &exp_extra, in);
-                    }
-                }
-            } else if (in == PARSE_DEC_IN_INTG && dig == '.') {
-                in = PARSE_DEC_IN_FRAC;
-            } else if (in != PARSE_DEC_IN_EXP && ((dig | 0x20) == 'e')) {
-                in = PARSE_DEC_IN_EXP;
-                if (str < top) {
-                    if (str[0] == '+') {
-                        str++;
-                    } else if (str[0] == '-') {
-                        str++;
-                        exp_neg = true;
-                    }
-                }
-                if (str == top) {
-                    goto value_error;
-                }
-            } else if (dig == '_') {
-                continue;
-            } else {
-                // unknown character
-                str--;
-                break;
-            }
-        }
-
-        // work out the exponent
-        if (exp_neg) {
-            exp_val = -exp_val;
-        }
-
-        // apply the exponent, making sure it's not a subnormal value
-        exp_val += exp_extra + trailing_zeros_intg;
-        dec_val = (mp_float_t)mantissa;
-        if (exp_val < SMALL_NORMAL_EXP) {
-            exp_val -= SMALL_NORMAL_EXP;
-            dec_val *= SMALL_NORMAL_VAL;
-        }
-
-        // At this point, we need to multiply the mantissa by its base 10 exponent. If possible,
-        // we would rather manipulate numbers that have an exact representation in IEEE754. It
-        // turns out small positive powers of 10 do, whereas small negative powers of 10 don't.
-        // So in that case, we'll yield a division of exact values rather than a multiplication
-        // of slightly erroneous values.
-        if (exp_val < 0 && exp_val >= -EXACT_POWER_OF_10) {
-            dec_val /= MICROPY_FLOAT_C_FUN(pow)(10, -exp_val);
-        } else {
-            dec_val *= MICROPY_FLOAT_C_FUN(pow)(10, exp_val);
+        str = mp_parse_float_internal(str, top - str, &dec_val);
+        if (!str) {
+            goto value_error;
         }
     }
 
diff --git a/py/parsenum.h b/py/parsenum.h
index f444632d23021..d532cb194a5d8 100644
--- a/py/parsenum.h
+++ b/py/parsenum.h
@@ -34,6 +34,11 @@
 
 mp_obj_t mp_parse_num_integer(const char *restrict str, size_t len, int base, mp_lexer_t *lex);
 
+#if MICROPY_PY_BUILTINS_FLOAT
+mp_large_float_t mp_decimal_exp(mp_large_float_t num, int dec_exp);
+const char *mp_parse_float_internal(const char *str, size_t len, mp_float_t *res);
+#endif
+
 #if MICROPY_PY_BUILTINS_COMPLEX
 mp_obj_t mp_parse_num_decimal(const char *str, size_t len, bool allow_imag, bool force_complex, mp_lexer_t *lex);
 
diff --git a/py/persistentcode.c b/py/persistentcode.c
index 93f4c33deb4e2..5c3de3174bcd0 100644
--- a/py/persistentcode.c
+++ b/py/persistentcode.c
@@ -63,6 +63,10 @@ typedef struct _bytecode_prelude_t {
     uint code_info_size;
 } bytecode_prelude_t;
 
+#if MICROPY_EMIT_RV32
+#include "py/asmrv32.h"
+#endif
+
 #endif // MICROPY_PERSISTENT_CODE_LOAD || MICROPY_PERSISTENT_CODE_SAVE
 
 #if MICROPY_PERSISTENT_CODE_LOAD
@@ -72,6 +76,8 @@ typedef struct _bytecode_prelude_t {
 static int read_byte(mp_reader_t *reader);
 static size_t read_uint(mp_reader_t *reader);
 
+#if MICROPY_EMIT_MACHINE_CODE
+
 #if MICROPY_PERSISTENT_CODE_TRACK_FUN_DATA || MICROPY_PERSISTENT_CODE_TRACK_BSS_RODATA
 
 // An mp_obj_list_t that tracks native text/BSS/rodata to prevent the GC from reclaiming them.
@@ -86,8 +92,6 @@ static void track_root_pointer(void *ptr) {
 
 #endif
 
-#if MICROPY_EMIT_MACHINE_CODE
-
 typedef struct _reloc_info_t {
     mp_reader_t *reader;
     mp_module_context_t *context;
@@ -422,15 +426,17 @@ static mp_raw_code_t *load_raw_code(mp_reader_t *reader, mp_module_context_t *co
 
         // Relocate and commit code to executable address space
         reloc_info_t ri = {reader, context, rodata, bss};
+        #if MICROPY_PERSISTENT_CODE_TRACK_FUN_DATA
+        if (native_scope_flags & MP_SCOPE_FLAG_VIPERRELOC) {
+            // Track the function data memory so it's not reclaimed by the GC.
+            track_root_pointer(fun_data);
+        }
+        #endif
         #if defined(MP_PLAT_COMMIT_EXEC)
         void *opt_ri = (native_scope_flags & MP_SCOPE_FLAG_VIPERRELOC) ? &ri : NULL;
         fun_data = MP_PLAT_COMMIT_EXEC(fun_data, fun_data_len, opt_ri);
         #else
         if (native_scope_flags & MP_SCOPE_FLAG_VIPERRELOC) {
-            #if MICROPY_PERSISTENT_CODE_TRACK_FUN_DATA
-            // Track the function data memory so it's not reclaimed by the GC.
-            track_root_pointer(fun_data);
-            #endif
             // Do the relocations.
             mp_native_relocate(&ri, fun_data, (uintptr_t)fun_data);
         }
@@ -480,7 +486,7 @@ void mp_raw_code_load(mp_reader_t *reader, mp_compiled_module_t *cm) {
         || header[3] > MP_SMALL_INT_BITS) {
         mp_raise_ValueError(MP_ERROR_TEXT("incompatible .mpy file"));
     }
-    if (MPY_FEATURE_DECODE_ARCH(header[2]) != MP_NATIVE_ARCH_NONE) {
+    if (arch != MP_NATIVE_ARCH_NONE) {
         if (!MPY_FEATURE_ARCH_TEST(arch)) {
             if (MPY_FEATURE_ARCH_TEST(MP_NATIVE_ARCH_NONE)) {
                 // On supported ports this can be resolved by enabling feature, eg
@@ -492,6 +498,23 @@ void mp_raw_code_load(mp_reader_t *reader, mp_compiled_module_t *cm) {
         }
     }
 
+    size_t arch_flags = 0;
+    if (MPY_FEATURE_ARCH_FLAGS_TEST(header[2])) {
+        #if MICROPY_EMIT_RV32
+        arch_flags = read_uint(reader);
+
+        if (MPY_FEATURE_ARCH_TEST(MP_NATIVE_ARCH_RV32IMC)) {
+            if ((arch_flags & (size_t)asm_rv32_allowed_extensions()) != arch_flags) {
+                mp_raise_ValueError(MP_ERROR_TEXT("incompatible .mpy file"));
+            }
+        } else
+        #endif
+        {
+            (void)arch_flags;
+            mp_raise_ValueError(MP_ERROR_TEXT("incompatible .mpy file"));
+        }
+    }
+
     size_t n_qstr = read_uint(reader);
     size_t n_obj = read_uint(reader);
     mp_module_context_alloc_tables(cm->context, n_qstr, n_obj);
@@ -513,6 +536,7 @@ void mp_raw_code_load(mp_reader_t *reader, mp_compiled_module_t *cm) {
     cm->has_native = MPY_FEATURE_DECODE_ARCH(header[2]) != MP_NATIVE_ARCH_NONE;
     cm->n_qstr = n_qstr;
     cm->n_obj = n_obj;
+    cm->arch_flags = arch_flags;
     #endif
 
     // Deregister exception handler and close the reader.
@@ -682,7 +706,7 @@ void mp_raw_code_save(mp_compiled_module_t *cm, mp_print_t *print) {
     byte header[4] = {
         'C',
         MPY_VERSION,
-        cm->has_native ? MPY_FEATURE_ENCODE_SUB_VERSION(MPY_SUB_VERSION) | MPY_FEATURE_ENCODE_ARCH(MPY_FEATURE_ARCH_DYNAMIC) : 0,
+        (cm->arch_flags != 0 ? MPY_FEATURE_ARCH_FLAGS : 0) | (cm->has_native ? MPY_FEATURE_ENCODE_SUB_VERSION(MPY_SUB_VERSION) | MPY_FEATURE_ENCODE_ARCH(MPY_FEATURE_ARCH_DYNAMIC) : 0),
         #if MICROPY_DYNAMIC_COMPILER
         mp_dynamic_compiler.small_int_bits,
         #else
@@ -691,6 +715,10 @@ void mp_raw_code_save(mp_compiled_module_t *cm, mp_print_t *print) {
     };
     mp_print_bytes(print, header, sizeof(header));
 
+    if (cm->arch_flags) {
+        mp_print_uint(print, cm->arch_flags);
+    }
+
     // Number of entries in constant table.
     mp_print_uint(print, cm->n_qstr);
     mp_print_uint(print, cm->n_obj);
@@ -769,7 +797,7 @@ static void bit_vector_clear(bit_vector_t *self) {
 static bool bit_vector_is_set(bit_vector_t *self, size_t index) {
     const size_t bits_size = sizeof(*self->bits) * MP_BITS_PER_BYTE;
     return index / bits_size < self->alloc
-           && (self->bits[index / bits_size] & (1 << (index % bits_size))) != 0;
+           && (self->bits[index / bits_size] & ((uintptr_t)1 << (index % bits_size))) != 0;
 }
 
 static void bit_vector_set(bit_vector_t *self, size_t index) {
@@ -780,7 +808,7 @@ static void bit_vector_set(bit_vector_t *self, size_t index) {
         self->bits = m_renew(uintptr_t, self->bits, self->alloc, new_alloc);
         self->alloc = new_alloc;
     }
-    self->bits[index / bits_size] |= 1 << (index % bits_size);
+    self->bits[index / bits_size] |= (uintptr_t)1 << (index % bits_size);
 }
 
 typedef struct _mp_opcode_t {
diff --git a/py/persistentcode.h b/py/persistentcode.h
index 46b474e57f707..85668e608c85b 100644
--- a/py/persistentcode.h
+++ b/py/persistentcode.h
@@ -50,7 +50,7 @@
 
 // Macros to encode/decode native architecture to/from the feature byte
 #define MPY_FEATURE_ENCODE_ARCH(arch) ((arch) << 2)
-#define MPY_FEATURE_DECODE_ARCH(feat) ((feat) >> 2)
+#define MPY_FEATURE_DECODE_ARCH(feat) (((feat) >> 2) & 0x2F)
 
 // Define the host architecture
 #if MICROPY_EMIT_X86
@@ -90,6 +90,10 @@
 #define MPY_FILE_HEADER_INT (MPY_VERSION \
     | (MPY_FEATURE_ENCODE_SUB_VERSION(MPY_SUB_VERSION) | MPY_FEATURE_ENCODE_ARCH(MPY_FEATURE_ARCH)) << 8)
 
+// Architecture-specific flags are present in the .mpy file
+#define MPY_FEATURE_ARCH_FLAGS (0x40)
+#define MPY_FEATURE_ARCH_FLAGS_TEST(x) (((x) & MPY_FEATURE_ARCH_FLAGS) == MPY_FEATURE_ARCH_FLAGS)
+
 enum {
     MP_NATIVE_ARCH_NONE = 0,
     MP_NATIVE_ARCH_X86,
@@ -103,6 +107,7 @@ enum {
     MP_NATIVE_ARCH_XTENSA,
     MP_NATIVE_ARCH_XTENSAWIN,
     MP_NATIVE_ARCH_RV32IMC,
+    MP_NATIVE_ARCH_RV64IMC,
     MP_NATIVE_ARCH_DEBUG, // this entry should always be last
 };
 
diff --git a/py/profile.c b/py/profile.c
index 397d0291f9fad..b5a0c54728c97 100644
--- a/py/profile.c
+++ b/py/profile.c
@@ -80,7 +80,7 @@ static void frame_print(const mp_print_t *print, mp_obj_t o_in, mp_print_kind_t
         "<frame at 0x%p, file '%q', line %d, code %q>",
         frame,
         MP_CODE_QSTR_MAP(code->context, 0),
-        frame->lineno,
+        (int)frame->lineno,
         MP_CODE_QSTR_MAP(code->context, prelude->qstr_block_name_idx)
         );
 }
diff --git a/py/py.cmake b/py/py.cmake
index 6c180ae53e6f2..b99d2d24b5db3 100644
--- a/py/py.cmake
+++ b/py/py.cmake
@@ -58,6 +58,7 @@ set(MICROPY_SOURCE_PY
     ${MICROPY_PY_DIR}/mpz.c
     ${MICROPY_PY_DIR}/nativeglue.c
     ${MICROPY_PY_DIR}/nlr.c
+    ${MICROPY_PY_DIR}/nlraarch64.c
     ${MICROPY_PY_DIR}/nlrmips.c
     ${MICROPY_PY_DIR}/nlrpowerpc.c
     ${MICROPY_PY_DIR}/nlrrv32.c
diff --git a/py/py.mk b/py/py.mk
index c05327bf81d55..21be07c794fb1 100644
--- a/py/py.mk
+++ b/py/py.mk
@@ -191,6 +191,7 @@ PY_CORE_O_BASENAME = $(addprefix py/,\
 	objnamedtuple.o \
 	objrange.o \
 	objreversed.o \
+	objringio.o \
 	objset.o \
 	objsingleton.o \
 	objslice.o \
@@ -289,7 +290,7 @@ $(HEADER_BUILD)/compressed_translations.generated.h: $(PY_SRC)/maketranslationda
 PY_CORE_O += $(PY_BUILD)/translations-$(TRANSLATION).o
 
 # build a list of registered modules for py/objmodule.c.
-$(HEADER_BUILD)/moduledefs.h: $(HEADER_BUILD)/moduledefs.collected
+$(HEADER_BUILD)/moduledefs.h: $(HEADER_BUILD)/moduledefs.collected $(PY_SRC)/makemoduledefs.py
 	@$(ECHO) "GEN $@"
 	$(Q)$(PYTHON) $(PY_SRC)/makemoduledefs.py $< > $@
 
diff --git a/py/repl.c b/py/repl.c
index c9a20305c79ff..bbfdd2ea6a6e2 100644
--- a/py/repl.c
+++ b/py/repl.c
@@ -181,8 +181,11 @@ static bool test_qstr(mp_obj_t obj, qstr name) {
         return dest[0] != MP_OBJ_NULL;
     } else {
         // try builtin module
-        return mp_map_lookup((mp_map_t *)&mp_builtin_module_map, MP_OBJ_NEW_QSTR(name), MP_MAP_LOOKUP) ||
-               mp_map_lookup((mp_map_t *)&mp_builtin_extensible_module_map, MP_OBJ_NEW_QSTR(name), MP_MAP_LOOKUP);
+        return mp_map_lookup((mp_map_t *)&mp_builtin_module_map, MP_OBJ_NEW_QSTR(name), MP_MAP_LOOKUP)
+               #if MICROPY_HAVE_REGISTERED_EXTENSIBLE_MODULES
+               || mp_map_lookup((mp_map_t *)&mp_builtin_extensible_module_map, MP_OBJ_NEW_QSTR(name), MP_MAP_LOOKUP)
+               #endif
+        ;
     }
 }
 
@@ -237,6 +240,10 @@ static void print_completions(const mp_print_t *print,
     for (qstr q = q_first; q <= q_last; ++q) {
         size_t d_len;
         const char *d_str = (const char *)qstr_data(q, &d_len);
+        // filter out words that begin with underscore unless there's already a partial match
+        if (s_len == 0 && d_str[0] == '_') {
+            continue;
+        }
         if (s_len <= d_len && strncmp(s_start, d_str, s_len) == 0) {
             if (test_qstr(obj, q)) {
                 int gap = (line_len + WORD_SLOT_LEN - 1) / WORD_SLOT_LEN * WORD_SLOT_LEN - line_len;
diff --git a/py/runtime.c b/py/runtime.c
index 9def98380fa45..81abc3de87570 100644
--- a/py/runtime.c
+++ b/py/runtime.c
@@ -134,7 +134,7 @@ void mp_init(void) {
     MP_STATE_VM(mp_module_builtins_override_dict) = NULL;
     #endif
 
-    #if MICROPY_PERSISTENT_CODE_TRACK_FUN_DATA || MICROPY_PERSISTENT_CODE_TRACK_BSS_RODATA
+    #if MICROPY_EMIT_MACHINE_CODE && (MICROPY_PERSISTENT_CODE_TRACK_FUN_DATA || MICROPY_PERSISTENT_CODE_TRACK_BSS_RODATA)
     MP_STATE_VM(persistent_code_root_pointers) = MP_OBJ_NULL;
     #endif
 
@@ -446,7 +446,7 @@ mp_obj_t MICROPY_WRAP_MP_BINARY_OP(mp_binary_op)(mp_binary_op_t op, mp_obj_t lhs
             // Operations that can overflow:
             //      +       result always fits in mp_int_t, then handled by SMALL_INT check
             //      -       result always fits in mp_int_t, then handled by SMALL_INT check
-            //      *       checked explicitly
+            //      *       checked explicitly for fit in mp_int_t, then handled by SMALL_INT check
             //      /       if lhs=MIN and rhs=-1; result always fits in mp_int_t, then handled by SMALL_INT check
             //      %       if lhs=MIN and rhs=-1; result always fits in mp_int_t, then handled by SMALL_INT check
             //      <<      checked explicitly
@@ -505,30 +505,16 @@ mp_obj_t MICROPY_WRAP_MP_BINARY_OP(mp_binary_op)(mp_binary_op_t op, mp_obj_t lhs
                     break;
                 case MP_BINARY_OP_MULTIPLY:
                 case MP_BINARY_OP_INPLACE_MULTIPLY: {
-
-                    // If long long type exists and is larger than mp_int_t, then
-                    // we can use the following code to perform overflow-checked multiplication.
-                    // Otherwise (eg in x64 case) we must use mp_small_int_mul_overflow.
-                    #if 0
-                    // compute result using long long precision
-                    long long res = (long long)lhs_val * (long long)rhs_val;
-                    if (res > MP_SMALL_INT_MAX || res < MP_SMALL_INT_MIN) {
-                        // result overflowed SMALL_INT, so return higher precision integer
-                        return mp_obj_new_int_from_ll(res);
-                    } else {
-                        // use standard precision
-                        lhs_val = (mp_int_t)res;
-                    }
-                    #endif
-
-                    if (mp_small_int_mul_overflow(lhs_val, rhs_val)) {
+                    mp_int_t int_res;
+                    if (mp_mul_mp_int_t_overflow(lhs_val, rhs_val, &int_res)) {
                         // use higher precision
                         lhs = mp_obj_new_int_from_ll(lhs_val);
                         goto generic_binary_op;
                     } else {
                         // use standard precision
-                        return MP_OBJ_NEW_SMALL_INT(lhs_val * rhs_val);
+                        lhs_val = int_res;
                     }
+                    break;
                 }
                 case MP_BINARY_OP_FLOOR_DIVIDE:
                 case MP_BINARY_OP_INPLACE_FLOOR_DIVIDE:
@@ -568,19 +554,19 @@ mp_obj_t MICROPY_WRAP_MP_BINARY_OP(mp_binary_op)(mp_binary_op_t op, mp_obj_t lhs
                         mp_int_t ans = 1;
                         while (rhs_val > 0) {
                             if (rhs_val & 1) {
-                                if (mp_small_int_mul_overflow(ans, lhs_val)) {
+                                if (mp_mul_mp_int_t_overflow(ans, lhs_val, &ans)) {
                                     goto power_overflow;
                                 }
-                                ans *= lhs_val;
                             }
                             if (rhs_val == 1) {
                                 break;
                             }
                             rhs_val /= 2;
-                            if (mp_small_int_mul_overflow(lhs_val, lhs_val)) {
+                            mp_int_t int_res;
+                            if (mp_mul_mp_int_t_overflow(lhs_val, lhs_val, &int_res)) {
                                 goto power_overflow;
                             }
-                            lhs_val *= lhs_val;
+                            lhs_val = int_res;
                         }
                         lhs_val = ans;
                     }
@@ -976,7 +962,7 @@ mp_obj_t mp_call_method_n_kw_var(bool have_self, size_t n_args_n_kw, const mp_ob
 
 // unpacked items are stored in reverse order into the array pointed to by items
 // CIRCUITPY-CHANGE: noline
-void __attribute__((noinline, )) mp_unpack_sequence(mp_obj_t seq_in, size_t num, mp_obj_t *items) {
+MP_NOINLINE void mp_unpack_sequence(mp_obj_t seq_in, size_t num, mp_obj_t *items) {
     size_t seq_len;
     if (mp_obj_is_type(seq_in, &mp_type_tuple) || mp_obj_is_type(seq_in, &mp_type_list)) {
         mp_obj_t *seq_items;
@@ -1301,6 +1287,19 @@ void mp_load_method(mp_obj_t base, qstr attr, mp_obj_t *dest) {
             mp_raise_msg_varg(&mp_type_AttributeError,
                 MP_ERROR_TEXT("type object '%q' has no attribute '%q'"),
                 ((mp_obj_type_t *)MP_OBJ_TO_PTR(base))->name, attr);
+        #if MICROPY_MODULE___ALL__ && MICROPY_ERROR_REPORTING >= MICROPY_ERROR_REPORTING_DETAILED
+        } else if (mp_obj_is_type(base, &mp_type_module)) {
+            // report errors in __all__ as done by CPython
+            mp_obj_t dest_name[2];
+            qstr module_name = MP_QSTR_;
+            mp_load_method_maybe(base, MP_QSTR___name__, dest_name);
+            if (mp_obj_is_qstr(dest_name[0])) {
+                module_name = mp_obj_str_get_qstr(dest_name[0]);
+            }
+            mp_raise_msg_varg(&mp_type_AttributeError,
+                MP_ERROR_TEXT("module '%q' has no attribute '%q'"),
+                module_name, attr);
+        #endif
         } else {
             mp_raise_msg_varg(&mp_type_AttributeError,
                 MP_ERROR_TEXT("'%s' object has no attribute '%q'"),
@@ -1619,7 +1618,7 @@ mp_obj_t mp_import_name(qstr name, mp_obj_t fromlist, mp_obj_t level) {
     // build args array
     mp_obj_t args[5];
     args[0] = MP_OBJ_NEW_QSTR(name);
-    args[1] = mp_const_none; // TODO should be globals
+    args[1] = MP_OBJ_FROM_PTR(mp_globals_get()); // globals of the current context
     args[2] = mp_const_none; // TODO should be locals
     args[3] = fromlist;
     args[4] = level;
@@ -1639,20 +1638,17 @@ mp_obj_t mp_import_name(qstr name, mp_obj_t fromlist, mp_obj_t level) {
 }
 
 // CIRCUITPY-CHANGE: noinline
-mp_obj_t __attribute__((noinline, )) mp_import_from(mp_obj_t module, qstr name) {
+MP_NOINLINE mp_obj_t mp_import_from(mp_obj_t module, qstr name) {
     DEBUG_printf("import from %p %s\n", module, qstr_str(name));
 
     mp_obj_t dest[2];
 
     mp_load_method_maybe(module, name, dest);
-
     if (dest[1] != MP_OBJ_NULL) {
-        // Hopefully we can't import bound method from an object
-    import_error:
-        mp_raise_msg_varg(&mp_type_ImportError, MP_ERROR_TEXT("can't import name %q"), name);
-    }
-
-    if (dest[0] != MP_OBJ_NULL) {
+        // Importing a bound method from a class instance.
+        return mp_obj_new_bound_meth(dest[0], dest[1]);
+    } else if (dest[0] != MP_OBJ_NULL) {
+        // Importing a function or attribute.
         return dest[0];
     }
 
@@ -1685,13 +1681,36 @@ mp_obj_t __attribute__((noinline, )) mp_import_from(mp_obj_t module, qstr name)
     goto import_error;
 
     #endif
+
+import_error:
+    mp_raise_msg_varg(&mp_type_ImportError, MP_ERROR_TEXT("can't import name %q"), name);
 }
 
 void mp_import_all(mp_obj_t module) {
     DEBUG_printf("import all %p\n", module);
 
-    // TODO: Support __all__
     mp_map_t *map = &mp_obj_module_get_globals(module)->map;
+
+    #if MICROPY_MODULE___ALL__
+    mp_map_elem_t *elem = mp_map_lookup(map, MP_OBJ_NEW_QSTR(MP_QSTR___all__), MP_MAP_LOOKUP);
+    if (elem != NULL) {
+        // When __all__ is defined, we must explicitly load all specified
+        // symbols, possibly invoking the module __getattr__ function
+        size_t len;
+        mp_obj_t *items;
+        mp_obj_get_array(elem->value, &len, &items);
+        for (size_t i = 0; i < len; i++) {
+            qstr qname = mp_obj_str_get_qstr(items[i]);
+            mp_obj_t dest[2];
+            mp_load_method(module, qname, dest);
+            mp_store_name(qname, dest[0]);
+        }
+        return;
+    }
+    #endif
+
+    // By default, the set of public names includes all names found in the module's
+    // namespace which do not begin with an underscore character ('_')
     for (size_t i = 0; i < map->alloc; i++) {
         if (mp_map_slot_is_filled(map, i)) {
             // Entry in module global scope may be generated programmatically
@@ -1747,7 +1766,7 @@ mp_obj_t mp_parse_compile_execute(mp_lexer_t *lex, mp_parse_input_kind_t parse_i
 #endif // MICROPY_ENABLE_COMPILER
 
 // CIRCUITPY-CHANGE: MP_COLD
-NORETURN MP_COLD void m_malloc_fail(size_t num_bytes) {
+MP_COLD MP_NORETURN void m_malloc_fail(size_t num_bytes) {
     DEBUG_printf("memory allocation failed, allocating %u bytes\n", (uint)num_bytes);
     #if MICROPY_ENABLE_GC
     if (gc_is_locked()) {
@@ -1761,29 +1780,29 @@ NORETURN MP_COLD void m_malloc_fail(size_t num_bytes) {
 #if MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_NONE
 
 // CIRCUITPY-CHANGE: MP_COLD
-NORETURN MP_COLD void mp_raise_type(const mp_obj_type_t *exc_type) {
+MP_COLD MP_NORETURN void mp_raise_type(const mp_obj_type_t *exc_type) {
     nlr_raise(mp_obj_new_exception(exc_type));
 }
 
 // CIRCUITPY-CHANGE: MP_COLD
-NORETURN MP_COLD void mp_raise_ValueError_no_msg(void) {
+MP_COLD MP_NORETURN void mp_raise_ValueError_no_msg(void) {
     mp_raise_type(&mp_type_ValueError);
 }
 
 // CIRCUITPY-CHANGE: MP_COLD
-NORETURN MP_COLD void mp_raise_TypeError_no_msg(void) {
+MP_COLD MP_NORETURN void mp_raise_TypeError_no_msg(void) {
     mp_raise_type(&mp_type_TypeError);
 }
 
 // CIRCUITPY-CHANGE: MP_COLD
-NORETURN MP_COLD void mp_raise_NotImplementedError_no_msg(void) {
+MP_COLD MP_NORETURN void mp_raise_NotImplementedError_no_msg(void) {
     mp_raise_type(&mp_type_NotImplementedError);
 }
 
 #else
 
 // CIRCUITPY-CHANGE: MP_COLD
-NORETURN MP_COLD void mp_raise_msg(const mp_obj_type_t *exc_type, mp_rom_error_text_t msg) {
+MP_COLD MP_NORETURN void mp_raise_msg(const mp_obj_type_t *exc_type, mp_rom_error_text_t msg) {
     if (msg == NULL) {
         nlr_raise(mp_obj_new_exception(exc_type));
     } else {
@@ -1792,24 +1811,24 @@ NORETURN MP_COLD void mp_raise_msg(const mp_obj_type_t *exc_type, mp_rom_error_t
 }
 
 // CIRCUITPY-CHANGE: new function for use below.
-NORETURN MP_COLD void mp_raise_msg_vlist(const mp_obj_type_t *exc_type, mp_rom_error_text_t fmt, va_list argptr) {
+MP_COLD MP_NORETURN void mp_raise_msg_vlist(const mp_obj_type_t *exc_type, mp_rom_error_text_t fmt, va_list argptr) {
     mp_obj_t exception = mp_obj_new_exception_msg_vlist(exc_type, fmt, argptr);
     nlr_raise(exception);
 }
 
 // CIRCUITPY-CHANGE: MP_COLD and use mp_raise_msg_vlist()
-NORETURN MP_COLD void mp_raise_msg_varg(const mp_obj_type_t *exc_type, mp_rom_error_text_t fmt, ...) {
+MP_COLD MP_NORETURN void mp_raise_msg_varg(const mp_obj_type_t *exc_type, mp_rom_error_text_t fmt, ...) {
     va_list argptr;
     va_start(argptr, fmt);
     mp_raise_msg_vlist(exc_type, fmt, argptr);
     va_end(argptr);
 }
 
-NORETURN MP_COLD void mp_raise_ValueError(mp_rom_error_text_t msg) {
+MP_COLD MP_NORETURN void mp_raise_ValueError(mp_rom_error_text_t msg) {
     mp_raise_msg(&mp_type_ValueError, msg);
 }
 
-NORETURN MP_COLD void mp_raise_msg_str(const mp_obj_type_t *exc_type, const char *msg) {
+MP_COLD MP_NORETURN void mp_raise_msg_str(const mp_obj_type_t *exc_type, const char *msg) {
     if (msg == NULL) {
         nlr_raise(mp_obj_new_exception(exc_type));
     } else {
@@ -1818,17 +1837,17 @@ NORETURN MP_COLD void mp_raise_msg_str(const mp_obj_type_t *exc_type, const char
 }
 
 // CIRCUITPY-CHANGE: added
-NORETURN MP_COLD void mp_raise_AttributeError(mp_rom_error_text_t msg) {
+MP_COLD MP_NORETURN void mp_raise_AttributeError(mp_rom_error_text_t msg) {
     mp_raise_msg(&mp_type_AttributeError, msg);
 }
 
 // CIRCUITPY-CHANGE: added
-NORETURN MP_COLD void mp_raise_RuntimeError(mp_rom_error_text_t msg) {
+MP_COLD MP_NORETURN void mp_raise_RuntimeError(mp_rom_error_text_t msg) {
     mp_raise_msg(&mp_type_RuntimeError, msg);
 }
 
 // CIRCUITPY-CHANGE: added
-NORETURN MP_COLD void mp_raise_RuntimeError_varg(mp_rom_error_text_t fmt, ...) {
+MP_COLD MP_NORETURN void mp_raise_RuntimeError_varg(mp_rom_error_text_t fmt, ...) {
     va_list argptr;
     va_start(argptr, fmt);
     mp_raise_msg_vlist(&mp_type_RuntimeError, fmt, argptr);
@@ -1836,17 +1855,17 @@ NORETURN MP_COLD void mp_raise_RuntimeError_varg(mp_rom_error_text_t fmt, ...) {
 }
 
 // CIRCUITPY-CHANGE: added
-NORETURN MP_COLD void mp_raise_ImportError(mp_rom_error_text_t msg) {
+MP_COLD MP_NORETURN void mp_raise_ImportError(mp_rom_error_text_t msg) {
     mp_raise_msg(&mp_type_ImportError, msg);
 }
 
 // CIRCUITPY-CHANGE: added
-NORETURN MP_COLD void mp_raise_IndexError(mp_rom_error_text_t msg) {
+MP_COLD MP_NORETURN void mp_raise_IndexError(mp_rom_error_text_t msg) {
     mp_raise_msg(&mp_type_IndexError, msg);
 }
 
 // CIRCUITPY-CHANGE: added
-NORETURN MP_COLD void mp_raise_IndexError_varg(mp_rom_error_text_t fmt, ...) {
+MP_COLD MP_NORETURN void mp_raise_IndexError_varg(mp_rom_error_text_t fmt, ...) {
     va_list argptr;
     va_start(argptr, fmt);
     mp_raise_msg_vlist(&mp_type_IndexError, fmt, argptr);
@@ -1854,7 +1873,7 @@ NORETURN MP_COLD void mp_raise_IndexError_varg(mp_rom_error_text_t fmt, ...) {
 }
 
 // CIRCUITPY-CHANGE: added
-NORETURN MP_COLD void mp_raise_ValueError_varg(mp_rom_error_text_t fmt, ...) {
+MP_COLD MP_NORETURN void mp_raise_ValueError_varg(mp_rom_error_text_t fmt, ...) {
     va_list argptr;
     va_start(argptr, fmt);
     mp_raise_msg_vlist(&mp_type_ValueError, fmt, argptr);
@@ -1862,12 +1881,12 @@ NORETURN MP_COLD void mp_raise_ValueError_varg(mp_rom_error_text_t fmt, ...) {
 }
 
 // CIRCUITPY-CHANGE: MP_COLD
-NORETURN MP_COLD void mp_raise_TypeError(mp_rom_error_text_t msg) {
+MP_COLD MP_NORETURN void mp_raise_TypeError(mp_rom_error_text_t msg) {
     mp_raise_msg(&mp_type_TypeError, msg);
 }
 
 // CIRCUITPY-CHANGE: added
-NORETURN MP_COLD void mp_raise_TypeError_varg(mp_rom_error_text_t fmt, ...) {
+MP_COLD MP_NORETURN void mp_raise_TypeError_varg(mp_rom_error_text_t fmt, ...) {
     va_list argptr;
     va_start(argptr, fmt);
     mp_raise_msg_vlist(&mp_type_TypeError, fmt, argptr);
@@ -1875,12 +1894,12 @@ NORETURN MP_COLD void mp_raise_TypeError_varg(mp_rom_error_text_t fmt, ...) {
 }
 
 // CIRCUITPY-CHANGE: added
-NORETURN MP_COLD void mp_raise_OSError_msg(mp_rom_error_text_t msg) {
+MP_COLD MP_NORETURN void mp_raise_OSError_msg(mp_rom_error_text_t msg) {
     mp_raise_msg(&mp_type_OSError, msg);
 }
 
 // CIRCUITPY-CHANGE: added
-NORETURN MP_COLD void mp_raise_OSError_errno_str(int errno_, mp_obj_t str) {
+MP_COLD MP_NORETURN void mp_raise_OSError_errno_str(int errno_, mp_obj_t str) {
     mp_obj_t args[2] = {
         MP_OBJ_NEW_SMALL_INT(errno_),
         str,
@@ -1889,7 +1908,7 @@ NORETURN MP_COLD void mp_raise_OSError_errno_str(int errno_, mp_obj_t str) {
 }
 
 // CIRCUITPY-CHANGE: added
-NORETURN MP_COLD void mp_raise_OSError_msg_varg(mp_rom_error_text_t fmt, ...) {
+MP_COLD MP_NORETURN void mp_raise_OSError_msg_varg(mp_rom_error_text_t fmt, ...) {
     va_list argptr;
     va_start(argptr, fmt);
     mp_raise_msg_vlist(&mp_type_OSError, fmt, argptr);
@@ -1897,21 +1916,23 @@ NORETURN MP_COLD void mp_raise_OSError_msg_varg(mp_rom_error_text_t fmt, ...) {
 }
 
 // CIRCUITPY-CHANGE: added
-NORETURN MP_COLD void mp_raise_ConnectionError(mp_rom_error_text_t msg) {
+MP_COLD MP_NORETURN void mp_raise_ConnectionError(mp_rom_error_text_t msg) {
     mp_raise_msg(&mp_type_ConnectionError, msg);
 }
 
 // CIRCUITPY-CHANGE: added
-NORETURN MP_COLD void mp_raise_BrokenPipeError(void) {
+MP_COLD MP_NORETURN void mp_raise_BrokenPipeError(void) {
     mp_raise_type_arg(&mp_type_BrokenPipeError, MP_OBJ_NEW_SMALL_INT(MP_EPIPE));
 }
 
-NORETURN MP_COLD void mp_raise_NotImplementedError(mp_rom_error_text_t msg) {
+MP_COLD MP_NORETURN void mp_raise_NotImplementedError(mp_rom_error_text_t msg) {
     mp_raise_msg(&mp_type_NotImplementedError, msg);
 }
 
+#endif
+
 // CIRCUITPY-CHANGE: added
-NORETURN MP_COLD void mp_raise_NotImplementedError_varg(mp_rom_error_text_t fmt, ...) {
+MP_COLD MP_NORETURN void mp_raise_NotImplementedError_varg(mp_rom_error_text_t fmt, ...) {
     va_list argptr;
     va_start(argptr, fmt);
     mp_raise_msg_vlist(&mp_type_NotImplementedError, fmt, argptr);
@@ -1919,7 +1940,7 @@ NORETURN MP_COLD void mp_raise_NotImplementedError_varg(mp_rom_error_text_t fmt,
 }
 
 // CIRCUITPY-CHANGE: added
-NORETURN MP_COLD void mp_raise_OverflowError_varg(mp_rom_error_text_t fmt, ...) {
+MP_COLD MP_NORETURN void mp_raise_OverflowError_varg(mp_rom_error_text_t fmt, ...) {
     va_list argptr;
     va_start(argptr, fmt);
     mp_raise_msg_vlist(&mp_type_OverflowError, fmt, argptr);
@@ -1927,11 +1948,11 @@ NORETURN MP_COLD void mp_raise_OverflowError_varg(mp_rom_error_text_t fmt, ...)
 }
 
 // CIRCUITPY-CHANGE: MP_COLD
-NORETURN MP_COLD void mp_raise_type_arg(const mp_obj_type_t *exc_type, mp_obj_t arg) {
+MP_COLD MP_NORETURN void mp_raise_type_arg(const mp_obj_type_t *exc_type, mp_obj_t arg) {
     nlr_raise(mp_obj_new_exception_arg1(exc_type, arg));
 }
 
-NORETURN void mp_raise_StopIteration(mp_obj_t arg) {
+MP_NORETURN void mp_raise_StopIteration(mp_obj_t arg) {
     if (arg == MP_OBJ_NULL) {
         mp_raise_type(&mp_type_StopIteration);
     } else {
@@ -1939,7 +1960,7 @@ NORETURN void mp_raise_StopIteration(mp_obj_t arg) {
     }
 }
 
-NORETURN void mp_raise_TypeError_int_conversion(mp_const_obj_t arg) {
+MP_NORETURN void mp_raise_TypeError_int_conversion(mp_const_obj_t arg) {
     #if MICROPY_ERROR_REPORTING <= MICROPY_ERROR_REPORTING_TERSE
     (void)arg;
     mp_raise_TypeError(MP_ERROR_TEXT("can't convert to int"));
@@ -1950,12 +1971,12 @@ NORETURN void mp_raise_TypeError_int_conversion(mp_const_obj_t arg) {
 }
 
 // CIRCUITPY-CHANGE: MP_COLD
-NORETURN MP_COLD void mp_raise_OSError(int errno_) {
+MP_COLD MP_NORETURN void mp_raise_OSError(int errno_) {
     mp_raise_type_arg(&mp_type_OSError, MP_OBJ_NEW_SMALL_INT(errno_));
 }
 
 // CIRCUITPY-CHANGE: MP_COLD
-NORETURN MP_COLD void mp_raise_OSError_with_filename(int errno_, const char *filename) {
+MP_COLD MP_NORETURN void mp_raise_OSError_with_filename(int errno_, const char *filename) {
     vstr_t vstr;
     vstr_init(&vstr, 32);
     vstr_printf(&vstr, "can't open %s", filename);
@@ -1965,13 +1986,12 @@ NORETURN MP_COLD void mp_raise_OSError_with_filename(int errno_, const char *fil
 }
 
 // CIRCUITPY-CHANGE: added
-NORETURN MP_COLD void mp_raise_ZeroDivisionError(void) {
+MP_COLD MP_NORETURN void mp_raise_ZeroDivisionError(void) {
     mp_raise_msg(&mp_type_ZeroDivisionError, MP_ERROR_TEXT("division by zero"));
 }
 #if MICROPY_STACK_CHECK || MICROPY_ENABLE_PYSTACK
 // CIRCUITPY-CHANGE: MP_COLD
-NORETURN MP_COLD void mp_raise_recursion_depth(void) {
+MP_COLD MP_NORETURN void mp_raise_recursion_depth(void) {
     mp_raise_RuntimeError(MP_ERROR_TEXT("maximum recursion depth exceeded"));
 }
 #endif
-#endif
diff --git a/py/runtime.h b/py/runtime.h
index a2d69638ffc38..22ed9c3eaf9b8 100644
--- a/py/runtime.h
+++ b/py/runtime.h
@@ -37,11 +37,12 @@
 #include "supervisor/shared/translate/translate.h"
 
 // For use with mp_call_function_1_from_nlr_jump_callback.
+// Initialize an nlr_jump_callback_node_call_function_1_t struct for use with
+// nlr_push_jump_callback(&ctx.callback, mp_call_function_1_from_nlr_jump_callback);
 #define MP_DEFINE_NLR_JUMP_CALLBACK_FUNCTION_1(ctx, f, a) \
-    nlr_jump_callback_node_call_function_1_t ctx = { \
-        .func = (void (*)(void *))(f), \
-        .arg = (a), \
-    }
+    nlr_jump_callback_node_call_function_1_t ctx; \
+    ctx.func = (void (*)(void *))(f); \
+    ctx.arg = (a)
 
 typedef enum {
     MP_VM_RETURN_NORMAL,
@@ -58,6 +59,12 @@ typedef enum {
     MP_ARG_KW_ONLY   = 0x200,
 } mp_arg_flag_t;
 
+typedef enum {
+    MP_HANDLE_PENDING_CALLBACKS_ONLY,
+    MP_HANDLE_PENDING_CALLBACKS_AND_EXCEPTIONS,
+    MP_HANDLE_PENDING_CALLBACKS_AND_CLEAR_EXCEPTIONS,
+} mp_handle_pending_behaviour_t;
+
 typedef union _mp_arg_val_t {
     bool u_bool;
     mp_int_t u_int;
@@ -106,7 +113,14 @@ void mp_sched_keyboard_interrupt(void);
 #if MICROPY_ENABLE_VM_ABORT
 void mp_sched_vm_abort(void);
 #endif
-void mp_handle_pending(bool raise_exc);
+
+void mp_handle_pending_internal(mp_handle_pending_behaviour_t behavior);
+
+static inline void mp_handle_pending(bool raise_exc) {
+    mp_handle_pending_internal(raise_exc ?
+        MP_HANDLE_PENDING_CALLBACKS_AND_EXCEPTIONS :
+        MP_HANDLE_PENDING_CALLBACKS_AND_CLEAR_EXCEPTIONS);
+}
 
 #if MICROPY_ENABLE_SCHEDULER
 void mp_sched_lock(void);
@@ -134,7 +148,7 @@ void mp_event_wait_indefinite(void);
 void mp_event_wait_ms(mp_uint_t timeout_ms);
 
 // extra printing method specifically for mp_obj_t's which are integral type
-int mp_print_mp_int(const mp_print_t *print, mp_obj_t x, int base, int base_char, int flags, char fill, int width, int prec);
+int mp_print_mp_int(const mp_print_t *print, mp_obj_t x, unsigned base, int base_char, int flags, char fill, int width, int prec);
 
 void mp_arg_check_num_sig(size_t n_args, size_t n_kw, uint32_t sig);
 static inline void mp_arg_check_num(size_t n_args, size_t n_kw, size_t n_args_min, size_t n_args_max, bool takes_kw) {
@@ -142,11 +156,11 @@ static inline void mp_arg_check_num(size_t n_args, size_t n_kw, size_t n_args_mi
 }
 void mp_arg_parse_all(size_t n_pos, const mp_obj_t *pos, mp_map_t *kws, size_t n_allowed, const mp_arg_t *allowed, mp_arg_val_t *out_vals);
 void mp_arg_parse_all_kw_array(size_t n_pos, size_t n_kw, const mp_obj_t *args, size_t n_allowed, const mp_arg_t *allowed, mp_arg_val_t *out_vals);
-NORETURN void mp_arg_error_terse_mismatch(void);
-NORETURN void mp_arg_error_unimpl_kw(void);
+MP_NORETURN void mp_arg_error_terse_mismatch(void);
+MP_NORETURN void mp_arg_error_unimpl_kw(void);
 
 // CIRCUITPY-CHANGE: arg validation routines
-NORETURN void mp_arg_error_invalid(qstr arg_name);
+MP_NORETURN void mp_arg_error_invalid(qstr arg_name);
 mp_int_t mp_arg_validate_int(mp_int_t i, mp_int_t required_i, qstr arg_name);
 mp_int_t mp_arg_validate_int_min(mp_int_t i, mp_int_t min, qstr arg_name);
 mp_int_t mp_arg_validate_int_max(mp_int_t i, mp_int_t j, qstr arg_name);
@@ -194,9 +208,16 @@ static inline void mp_thread_init_state(mp_state_thread_t *ts, size_t stack_size
     ts->gc_lock_depth = 0;
 
     // There are no pending jump callbacks or exceptions yet
+    ts->nlr_top = NULL;
     ts->nlr_jump_callback_top = NULL;
     ts->mp_pending_exception = MP_OBJ_NULL;
 
+    #if MICROPY_PY_SYS_SETTRACE
+    ts->prof_trace_callback = MP_OBJ_NULL;
+    ts->prof_callback_is_executing = false;
+    ts->current_code_state = NULL;
+    #endif
+
     // If locals/globals are not given, inherit from main thread
     if (locals == NULL) {
         locals = mp_state_ctx.thread.dict_locals;
@@ -274,10 +295,10 @@ mp_obj_t mp_import_from(mp_obj_t module, qstr name);
 void mp_import_all(mp_obj_t module);
 
 #if MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_NONE
-NORETURN void mp_raise_type(const mp_obj_type_t *exc_type);
-NORETURN void mp_raise_ValueError_no_msg(void);
-NORETURN void mp_raise_TypeError_no_msg(void);
-NORETURN void mp_raise_NotImplementedError_no_msg(void);
+MP_NORETURN void mp_raise_type(const mp_obj_type_t *exc_type);
+MP_NORETURN void mp_raise_ValueError_no_msg(void);
+MP_NORETURN void mp_raise_TypeError_no_msg(void);
+MP_NORETURN void mp_raise_NotImplementedError_no_msg(void);
 #define mp_raise_msg(exc_type, msg) mp_raise_type(exc_type)
 #define mp_raise_msg_varg(exc_type, ...) mp_raise_type(exc_type)
 #define mp_raise_ValueError(msg) mp_raise_ValueError_no_msg()
@@ -285,46 +306,46 @@ NORETURN void mp_raise_NotImplementedError_no_msg(void);
 #define mp_raise_NotImplementedError(msg) mp_raise_NotImplementedError_no_msg()
 #else
 #define mp_raise_type(exc_type) mp_raise_msg(exc_type, NULL)
-NORETURN void mp_raise_msg(const mp_obj_type_t *exc_type, mp_rom_error_text_t msg);
-NORETURN void mp_raise_msg_varg(const mp_obj_type_t *exc_type, mp_rom_error_text_t fmt, ...);
-NORETURN void mp_raise_ValueError(mp_rom_error_text_t msg);
-NORETURN void mp_raise_TypeError(mp_rom_error_text_t msg);
-NORETURN void mp_raise_NotImplementedError(mp_rom_error_text_t msg);
+MP_NORETURN void mp_raise_msg(const mp_obj_type_t *exc_type, mp_rom_error_text_t msg);
+MP_NORETURN void mp_raise_msg_varg(const mp_obj_type_t *exc_type, mp_rom_error_text_t fmt, ...);
+MP_NORETURN void mp_raise_ValueError(mp_rom_error_text_t msg);
+MP_NORETURN void mp_raise_TypeError(mp_rom_error_text_t msg);
+MP_NORETURN void mp_raise_NotImplementedError(mp_rom_error_text_t msg);
 #endif
 
 // CIRCUITPY-CHANGE: new mp_raise routines
-NORETURN void mp_raise_type_arg(const mp_obj_type_t *exc_type, mp_obj_t arg);
-NORETURN void mp_raise_msg(const mp_obj_type_t *exc_type, mp_rom_error_text_t msg);
-NORETURN void mp_raise_msg_varg(const mp_obj_type_t *exc_type, mp_rom_error_text_t fmt
+MP_NORETURN void mp_raise_type_arg(const mp_obj_type_t *exc_type, mp_obj_t arg);
+MP_NORETURN void mp_raise_msg(const mp_obj_type_t *exc_type, mp_rom_error_text_t msg);
+MP_NORETURN void mp_raise_msg_varg(const mp_obj_type_t *exc_type, mp_rom_error_text_t fmt
     , ...);
-NORETURN void mp_raise_msg_vlist(const mp_obj_type_t *exc_type, mp_rom_error_text_t fmt, va_list argptr);
+MP_NORETURN void mp_raise_msg_vlist(const mp_obj_type_t *exc_type, mp_rom_error_text_t fmt, va_list argptr);
 // Only use this string version in native mpy files. Otherwise, use the compressed string version.
-NORETURN void mp_raise_msg_str(const mp_obj_type_t *exc_type, const char *msg);
-
-NORETURN void mp_raise_AttributeError(mp_rom_error_text_t msg);
-NORETURN void mp_raise_BrokenPipeError(void);
-NORETURN void mp_raise_ConnectionError(mp_rom_error_text_t msg);
-NORETURN void mp_raise_ImportError(mp_rom_error_text_t msg);
-NORETURN void mp_raise_IndexError(mp_rom_error_text_t msg);
-NORETURN void mp_raise_IndexError_varg(mp_rom_error_text_t msg, ...);
-NORETURN void mp_raise_NotImplementedError(mp_rom_error_text_t msg);
-NORETURN void mp_raise_NotImplementedError_varg(mp_rom_error_text_t fmt, ...);
-NORETURN void mp_raise_OSError_errno_str(int errno_, mp_obj_t str);
-NORETURN void mp_raise_OSError(int errno_);
-NORETURN void mp_raise_OSError_msg(mp_rom_error_text_t msg);
-NORETURN void mp_raise_OSError_msg_varg(mp_rom_error_text_t fmt, ...);
-NORETURN void mp_raise_OSError_with_filename(int errno_, const char *filename);
-NORETURN void mp_raise_OverflowError_varg(mp_rom_error_text_t fmt, ...);
-NORETURN void mp_raise_recursion_depth(void);
-NORETURN void mp_raise_RuntimeError(mp_rom_error_text_t msg);
-NORETURN void mp_raise_RuntimeError_varg(mp_rom_error_text_t fmt, ...);
-NORETURN void mp_raise_StopIteration(mp_obj_t arg);
-NORETURN void mp_raise_TypeError(mp_rom_error_text_t msg);
-NORETURN void mp_raise_TypeError_varg(mp_rom_error_text_t fmt, ...);
-NORETURN void mp_raise_TypeError_int_conversion(mp_const_obj_t arg);
-NORETURN void mp_raise_ValueError(mp_rom_error_text_t msg);
-NORETURN void mp_raise_ValueError_varg(mp_rom_error_text_t fmt, ...);
-NORETURN void mp_raise_ZeroDivisionError(void);
+MP_NORETURN void mp_raise_msg_str(const mp_obj_type_t *exc_type, const char *msg);
+
+MP_NORETURN void mp_raise_AttributeError(mp_rom_error_text_t msg);
+MP_NORETURN void mp_raise_BrokenPipeError(void);
+MP_NORETURN void mp_raise_ConnectionError(mp_rom_error_text_t msg);
+MP_NORETURN void mp_raise_ImportError(mp_rom_error_text_t msg);
+MP_NORETURN void mp_raise_IndexError(mp_rom_error_text_t msg);
+MP_NORETURN void mp_raise_IndexError_varg(mp_rom_error_text_t msg, ...);
+MP_NORETURN void mp_raise_NotImplementedError(mp_rom_error_text_t msg);
+MP_NORETURN void mp_raise_NotImplementedError_varg(mp_rom_error_text_t fmt, ...);
+MP_NORETURN void mp_raise_OSError_errno_str(int errno_, mp_obj_t str);
+MP_NORETURN void mp_raise_OSError(int errno_);
+MP_NORETURN void mp_raise_OSError_msg(mp_rom_error_text_t msg);
+MP_NORETURN void mp_raise_OSError_msg_varg(mp_rom_error_text_t fmt, ...);
+MP_NORETURN void mp_raise_OSError_with_filename(int errno_, const char *filename);
+MP_NORETURN void mp_raise_OverflowError_varg(mp_rom_error_text_t fmt, ...);
+MP_NORETURN void mp_raise_recursion_depth(void);
+MP_NORETURN void mp_raise_RuntimeError(mp_rom_error_text_t msg);
+MP_NORETURN void mp_raise_RuntimeError_varg(mp_rom_error_text_t fmt, ...);
+MP_NORETURN void mp_raise_StopIteration(mp_obj_t arg);
+MP_NORETURN void mp_raise_TypeError(mp_rom_error_text_t msg);
+MP_NORETURN void mp_raise_TypeError_varg(mp_rom_error_text_t fmt, ...);
+MP_NORETURN void mp_raise_TypeError_int_conversion(mp_const_obj_t arg);
+MP_NORETURN void mp_raise_ValueError(mp_rom_error_text_t msg);
+MP_NORETURN void mp_raise_ValueError_varg(mp_rom_error_text_t fmt, ...);
+MP_NORETURN void mp_raise_ZeroDivisionError(void);
 
 #if MICROPY_BUILTIN_METHOD_CHECK_SELF_ARG
 #undef mp_check_self
diff --git a/py/runtime_utils.c b/py/runtime_utils.c
index 98252c3122048..33da558e30f08 100644
--- a/py/runtime_utils.c
+++ b/py/runtime_utils.c
@@ -53,3 +53,59 @@ mp_obj_t mp_call_function_2_protected(mp_obj_t fun, mp_obj_t arg1, mp_obj_t arg2
         return MP_OBJ_NULL;
     }
 }
+
+#if !MICROPY_USE_GCC_MUL_OVERFLOW_INTRINSIC
+bool mp_mul_ll_overflow(long long int x, long long int y, long long int *res) {
+    bool overflow;
+
+    // Check for multiply overflow; see CERT INT32-C
+    if (x > 0) { // x is positive
+        if (y > 0) { // x and y are positive
+            overflow = (x > (LLONG_MAX / y));
+        } else { // x positive, y nonpositive
+            overflow = (y < (LLONG_MIN / x));
+        } // x positive, y nonpositive
+    } else { // x is nonpositive
+        if (y > 0) { // x is nonpositive, y is positive
+            overflow = (x < (LLONG_MIN / y));
+        } else { // x and y are nonpositive
+            overflow = (x != 0 && y < (LLONG_MAX / x));
+        } // End if x and y are nonpositive
+    } // End if x is nonpositive
+
+    if (!overflow) {
+        *res = x * y;
+    }
+
+    return overflow;
+}
+
+bool mp_mul_mp_int_t_overflow(mp_int_t x, mp_int_t y, mp_int_t *res) {
+    // Check for multiply overflow; see CERT INT32-C
+    if (x > 0) { // x is positive
+        if (y > 0) { // x and y are positive
+            if (x > (MP_INT_MAX / y)) {
+                return true;
+            }
+        } else { // x positive, y nonpositive
+            if (y < (MP_INT_MIN / x)) {
+                return true;
+            }
+        } // x positive, y nonpositive
+    } else { // x is nonpositive
+        if (y > 0) { // x is nonpositive, y is positive
+            if (x < (MP_INT_MIN / y)) {
+                return true;
+            }
+        } else { // x and y are nonpositive
+            if (x != 0 && y < (MP_INT_MAX / x)) {
+                return true;
+            }
+        } // End if x and y are nonpositive
+    } // End if x is nonpositive
+
+    // Result doesn't overflow
+    *res = x * y;
+    return false;
+}
+#endif
diff --git a/py/scheduler.c b/py/scheduler.c
index 92e5af6b31b20..ee9cd96b331a6 100644
--- a/py/scheduler.c
+++ b/py/scheduler.c
@@ -97,17 +97,21 @@ static inline void mp_sched_run_pending(void) {
 
     #if MICROPY_SCHEDULER_STATIC_NODES
     // Run all pending C callbacks.
-    while (MP_STATE_VM(sched_head) != NULL) {
-        mp_sched_node_t *node = MP_STATE_VM(sched_head);
-        MP_STATE_VM(sched_head) = node->next;
-        if (MP_STATE_VM(sched_head) == NULL) {
-            MP_STATE_VM(sched_tail) = NULL;
-        }
-        mp_sched_callback_t callback = node->callback;
-        node->callback = NULL;
-        MICROPY_END_ATOMIC_SECTION(atomic_state);
-        callback(node);
-        atomic_state = MICROPY_BEGIN_ATOMIC_SECTION();
+    mp_sched_node_t *original_tail = MP_STATE_VM(sched_tail);
+    if (original_tail != NULL) {
+        mp_sched_node_t *node;
+        do {
+            node = MP_STATE_VM(sched_head);
+            MP_STATE_VM(sched_head) = node->next;
+            if (MP_STATE_VM(sched_head) == NULL) {
+                MP_STATE_VM(sched_tail) = NULL;
+            }
+            mp_sched_callback_t callback = node->callback;
+            node->callback = NULL;
+            MICROPY_END_ATOMIC_SECTION(atomic_state);
+            callback(node);
+            atomic_state = MICROPY_BEGIN_ATOMIC_SECTION();
+        } while (node != original_tail); // Don't execute any callbacks scheduled during this run
     }
     #endif
 
@@ -218,24 +222,27 @@ MP_REGISTER_ROOT_POINTER(mp_sched_item_t sched_queue[MICROPY_SCHEDULER_DEPTH]);
 
 // Called periodically from the VM or from "waiting" code (e.g. sleep) to
 // process background tasks and pending exceptions (e.g. KeyboardInterrupt).
-void mp_handle_pending(bool raise_exc) {
+void mp_handle_pending_internal(mp_handle_pending_behaviour_t behavior) {
+    bool handle_exceptions = (behavior != MP_HANDLE_PENDING_CALLBACKS_ONLY);
+    bool raise_exceptions = (behavior == MP_HANDLE_PENDING_CALLBACKS_AND_EXCEPTIONS);
+
     // Handle pending VM abort.
     #if MICROPY_ENABLE_VM_ABORT
-    if (MP_STATE_VM(vm_abort) && mp_thread_is_main_thread()) {
+    if (handle_exceptions && MP_STATE_VM(vm_abort) && mp_thread_is_main_thread()) {
         MP_STATE_VM(vm_abort) = false;
-        if (raise_exc && nlr_get_abort() != NULL) {
+        if (raise_exceptions && nlr_get_abort() != NULL) {
             nlr_jump_abort();
         }
     }
     #endif
 
     // Handle any pending exception.
-    if (MP_STATE_THREAD(mp_pending_exception) != MP_OBJ_NULL) {
+    if (handle_exceptions && MP_STATE_THREAD(mp_pending_exception) != MP_OBJ_NULL) {
         mp_uint_t atomic_state = MICROPY_BEGIN_ATOMIC_SECTION();
         mp_obj_t obj = MP_STATE_THREAD(mp_pending_exception);
         if (obj != MP_OBJ_NULL) {
             MP_STATE_THREAD(mp_pending_exception) = MP_OBJ_NULL;
-            if (raise_exc) {
+            if (raise_exceptions) {
                 MICROPY_END_ATOMIC_SECTION(atomic_state);
                 nlr_raise(obj);
             }
diff --git a/py/sequence.c b/py/sequence.c
index ac7ad5368b91e..6bbc62f0f7fb1 100644
--- a/py/sequence.c
+++ b/py/sequence.c
@@ -34,18 +34,13 @@
 #define SWAP(type, var1, var2) { type t = var2; var2 = var1; var1 = t; }
 
 // CIRCUITPY-CHANGE: detect sequence overflow
-#if __GNUC__ < 5
-// n.b. does not actually detect overflow!
-#define __builtin_mul_overflow(a, b, x) (*(x) = (a) * (b), false)
-#endif
-
 // Detect when a multiply causes an overflow.
 size_t mp_seq_multiply_len(size_t item_sz, size_t len) {
-    size_t new_len;
-    if (__builtin_mul_overflow(item_sz, len, &new_len)) {
+    mp_int_t new_len;
+    if (mp_mul_mp_int_t_overflow(item_sz, len, &new_len)) {
         mp_raise_msg(&mp_type_OverflowError, MP_ERROR_TEXT("small int overflow"));
     }
-    return new_len;
+    return (size_t)new_len;
 }
 
 // Implements backend of sequence * integer operation. Assumes elements are
diff --git a/py/showbc.c b/py/showbc.c
index 6913d18c1ca82..792fccd013383 100644
--- a/py/showbc.c
+++ b/py/showbc.c
@@ -144,17 +144,9 @@ void mp_bytecode_print(const mp_print_t *print, const mp_raw_code_t *rc, size_t
         mp_uint_t source_line = 1;
         mp_printf(print, "  bc=" INT_FMT " line=" UINT_FMT "\n", bc, source_line);
         for (const byte *ci = code_info; ci < line_info_top;) {
-            if ((ci[0] & 0x80) == 0) {
-                // 0b0LLBBBBB encoding
-                bc += ci[0] & 0x1f;
-                source_line += ci[0] >> 5;
-                ci += 1;
-            } else {
-                // 0b1LLLBBBB 0bLLLLLLLL encoding (l's LSB in second byte)
-                bc += ci[0] & 0xf;
-                source_line += ((ci[0] << 4) & 0x700) | ci[1];
-                ci += 2;
-            }
+            mp_code_lineinfo_t decoded = mp_bytecode_decode_lineinfo(&ci);
+            bc += decoded.bc_increment;
+            source_line += decoded.line_increment;
             mp_printf(print, "  bc=" INT_FMT " line=" UINT_FMT "\n", bc, source_line);
         }
     }
diff --git a/py/smallint.c b/py/smallint.c
index aa542ca7bf29a..eb99b58667a07 100644
--- a/py/smallint.c
+++ b/py/smallint.c
@@ -26,32 +26,6 @@
 
 #include "py/smallint.h"
 
-bool mp_small_int_mul_overflow(mp_int_t x, mp_int_t y) {
-    // Check for multiply overflow; see CERT INT32-C
-    if (x > 0) { // x is positive
-        if (y > 0) { // x and y are positive
-            if (x > (MP_SMALL_INT_MAX / y)) {
-                return true;
-            }
-        } else { // x positive, y nonpositive
-            if (y < (MP_SMALL_INT_MIN / x)) {
-                return true;
-            }
-        } // x positive, y nonpositive
-    } else { // x is nonpositive
-        if (y > 0) { // x is nonpositive, y is positive
-            if (x < (MP_SMALL_INT_MIN / y)) {
-                return true;
-            }
-        } else { // x and y are nonpositive
-            if (x != 0 && y < (MP_SMALL_INT_MAX / x)) {
-                return true;
-            }
-        } // End if x and y are nonpositive
-    } // End if x is nonpositive
-    return false;
-}
-
 mp_int_t mp_small_int_modulo(mp_int_t dividend, mp_int_t divisor) {
     // Python specs require that mod has same sign as second operand
     dividend %= divisor;
diff --git a/py/smallint.h b/py/smallint.h
index 584e0018d1ba3..ec5b0af3b2867 100644
--- a/py/smallint.h
+++ b/py/smallint.h
@@ -68,7 +68,6 @@
 // The number of bits in a MP_SMALL_INT including the sign bit.
 #define MP_SMALL_INT_BITS (MP_IMAX_BITS(MP_SMALL_INT_MAX) + 1)
 
-bool mp_small_int_mul_overflow(mp_int_t x, mp_int_t y);
 mp_int_t mp_small_int_modulo(mp_int_t dividend, mp_int_t divisor);
 mp_int_t mp_small_int_floor_divide(mp_int_t num, mp_int_t denom);
 
diff --git a/py/stream.c b/py/stream.c
index fbf7fd878a133..520422cc92fcf 100644
--- a/py/stream.c
+++ b/py/stream.c
@@ -260,9 +260,14 @@ void mp_stream_write_adaptor(void *self, const char *buf, size_t len) {
     mp_stream_write(MP_OBJ_FROM_PTR(self), buf, len, MP_STREAM_RW_WRITE);
 }
 
-static mp_obj_t stream_write_method(size_t n_args, const mp_obj_t *args) {
+static mp_obj_t stream_readinto_write_generic(size_t n_args, const mp_obj_t *args, byte flags) {
     mp_buffer_info_t bufinfo;
-    mp_get_buffer_raise(args[1], &bufinfo, MP_BUFFER_READ);
+    mp_get_buffer_raise(args[1], &bufinfo, (flags & MP_STREAM_RW_WRITE) ? MP_BUFFER_READ : MP_BUFFER_WRITE);
+
+    // CPython extension, allow optional maximum length and offset:
+    // - stream.operation(buf, max_len)
+    // - stream.operation(buf, off, max_len)
+    // Similar to https://docs.python.org/3/library/socket.html#socket.socket.recv_into
     size_t max_len = (size_t)-1;
     size_t off = 0;
     if (n_args == 3) {
@@ -275,45 +280,31 @@ static mp_obj_t stream_write_method(size_t n_args, const mp_obj_t *args) {
         }
     }
     bufinfo.len -= off;
-    return mp_stream_write(args[0], (byte *)bufinfo.buf + off, MIN(bufinfo.len, max_len), MP_STREAM_RW_WRITE);
+
+    // Perform the readinto or write operation.
+    return mp_stream_write(args[0], (byte *)bufinfo.buf + off, MIN(bufinfo.len, max_len), flags);
+}
+
+static mp_obj_t stream_write_method(size_t n_args, const mp_obj_t *args) {
+    return stream_readinto_write_generic(n_args, args, MP_STREAM_RW_WRITE);
 }
 MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mp_stream_write_obj, 2, 4, stream_write_method);
 
-static mp_obj_t stream_write1_method(mp_obj_t self_in, mp_obj_t arg) {
-    mp_buffer_info_t bufinfo;
-    mp_get_buffer_raise(arg, &bufinfo, MP_BUFFER_READ);
-    return mp_stream_write(self_in, bufinfo.buf, bufinfo.len, MP_STREAM_RW_WRITE | MP_STREAM_RW_ONCE);
+static mp_obj_t stream_write1_method(size_t n_args, const mp_obj_t *args) {
+    return stream_readinto_write_generic(n_args, args, MP_STREAM_RW_WRITE | MP_STREAM_RW_ONCE);
 }
-MP_DEFINE_CONST_FUN_OBJ_2(mp_stream_write1_obj, stream_write1_method);
+MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mp_stream_write1_obj, 2, 4, stream_write1_method);
 
 static mp_obj_t stream_readinto(size_t n_args, const mp_obj_t *args) {
-    mp_buffer_info_t bufinfo;
-    mp_get_buffer_raise(args[1], &bufinfo, MP_BUFFER_WRITE);
-
-    // CPython extension: if 2nd arg is provided, that's max len to read,
-    // instead of full buffer. Similar to
-    // https://docs.python.org/3/library/socket.html#socket.socket.recv_into
-    mp_uint_t len = bufinfo.len;
-    if (n_args > 2) {
-        len = mp_obj_get_int(args[2]);
-        if (len > bufinfo.len) {
-            len = bufinfo.len;
-        }
-    }
-
-    int error;
-    mp_uint_t out_sz = mp_stream_read_exactly(args[0], bufinfo.buf, len, &error);
-    if (error != 0) {
-        if (mp_is_nonblocking_error(error)) {
-            return mp_const_none;
-        }
-        mp_raise_OSError(error);
-    } else {
-        return MP_OBJ_NEW_SMALL_INT(out_sz);
-    }
+    return stream_readinto_write_generic(n_args, args, MP_STREAM_RW_READ);
 }
 MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mp_stream_readinto_obj, 2, 3, stream_readinto);
 
+static mp_obj_t stream_readinto1(size_t n_args, const mp_obj_t *args) {
+    return stream_readinto_write_generic(n_args, args, MP_STREAM_RW_READ | MP_STREAM_RW_ONCE);
+}
+MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mp_stream_readinto1_obj, 2, 3, stream_readinto1);
+
 static mp_obj_t stream_readall(mp_obj_t self_in) {
     const mp_stream_p_t *stream_p = mp_get_stream(self_in);
 
diff --git a/py/stream.h b/py/stream.h
index 5e1cd5d441302..6e60e849b5f48 100644
--- a/py/stream.h
+++ b/py/stream.h
@@ -87,10 +87,11 @@ typedef struct _mp_stream_p_t {
 MP_DECLARE_CONST_FUN_OBJ_VAR_BETWEEN(mp_stream_read_obj);
 MP_DECLARE_CONST_FUN_OBJ_VAR_BETWEEN(mp_stream_read1_obj);
 MP_DECLARE_CONST_FUN_OBJ_VAR_BETWEEN(mp_stream_readinto_obj);
+MP_DECLARE_CONST_FUN_OBJ_VAR_BETWEEN(mp_stream_readinto1_obj);
 MP_DECLARE_CONST_FUN_OBJ_VAR_BETWEEN(mp_stream_unbuffered_readline_obj);
 MP_DECLARE_CONST_FUN_OBJ_1(mp_stream_unbuffered_readlines_obj);
 MP_DECLARE_CONST_FUN_OBJ_VAR_BETWEEN(mp_stream_write_obj);
-MP_DECLARE_CONST_FUN_OBJ_2(mp_stream_write1_obj);
+MP_DECLARE_CONST_FUN_OBJ_VAR_BETWEEN(mp_stream_write1_obj);
 MP_DECLARE_CONST_FUN_OBJ_1(mp_stream_close_obj);
 MP_DECLARE_CONST_FUN_OBJ_VAR_BETWEEN(mp_stream___exit___obj);
 MP_DECLARE_CONST_FUN_OBJ_VAR_BETWEEN(mp_stream_seek_obj);
diff --git a/py/vm.c b/py/vm.c
index 6fd1778261971..860aa36e39792 100644
--- a/py/vm.c
+++ b/py/vm.c
@@ -205,6 +205,22 @@ static mp_obj_t get_active_exception(mp_exc_stack_t *exc_sp, mp_exc_stack_t *exc
     return MP_OBJ_NULL;
 }
 
+#if MICROPY_PY_BUILTINS_SLICE
+// This function is marked "no inline" so it doesn't increase the C stack usage of the main VM function.
+MP_NOINLINE static mp_obj_t *build_slice_stack_allocated(byte op, mp_obj_t *sp, mp_obj_t step) {
+    mp_obj_t stop = sp[2];
+    mp_obj_t start = sp[1];
+    mp_obj_slice_t slice = { .base = { .type = &mp_type_slice }, .start = start, .stop = stop, .step = step };
+    if (op == MP_BC_LOAD_SUBSCR) {
+        SET_TOP(mp_obj_subscr(TOP(), MP_OBJ_FROM_PTR(&slice), MP_OBJ_SENTINEL));
+    } else { // MP_BC_STORE_SUBSCR
+        mp_obj_subscr(TOP(), MP_OBJ_FROM_PTR(&slice), sp[-1]);
+        sp -= 2;
+    }
+    return sp;
+}
+#endif
+
 // fastn has items in reverse order (fastn[0] is local[0], fastn[-1] is local[1], etc)
 // sp points to bottom of stack which grows up
 // returns:
@@ -871,9 +887,20 @@ unwind_jump:;
                         // 3-argument slice includes step
                         step = POP();
                     }
-                    mp_obj_t stop = POP();
-                    mp_obj_t start = TOP();
-                    SET_TOP(mp_obj_new_slice(start, stop, step));
+                    if ((*ip == MP_BC_LOAD_SUBSCR || *ip == MP_BC_STORE_SUBSCR)
+                        && (mp_obj_get_type(sp[-2])->flags & MP_TYPE_FLAG_SUBSCR_ALLOWS_STACK_SLICE)) {
+                        // Fast path optimisation for when the BUILD_SLICE is immediately followed
+                        // by a LOAD/STORE_SUBSCR for an accepting type, to avoid needing to allocate
+                        // the slice on the heap.  In some cases (e.g. a[1:3] = x) this can result
+                        // in no allocations at all.  We can't do this for instance types because
+                        // the get/set/delattr implementation may keep a reference to the slice.
+                        byte op = *ip++;
+                        sp = build_slice_stack_allocated(op, sp - 2, step);
+                    } else {
+                        mp_obj_t stop = POP();
+                        mp_obj_t start = TOP();
+                        SET_TOP(mp_obj_new_slice(start, stop, step));
+                    }
                     DISPATCH();
                 }
                 #endif
diff --git a/py/vstr.c b/py/vstr.c
index 00972edf89796..522509d0d05cf 100644
--- a/py/vstr.c
+++ b/py/vstr.c
@@ -51,7 +51,7 @@ void vstr_init(vstr_t *vstr, size_t alloc) {
 // Init the vstr so it allocs exactly enough ram to hold a null-terminated
 // string of the given length, and set the length.
 void vstr_init_len(vstr_t *vstr, size_t len) {
-    // CIRCUITPY-CHANGE
+    // CIRCUITPY-CHANGE: check for invalid length
     if (len == SIZE_MAX) {
         m_malloc_fail(len);
     }
diff --git a/pyproject.toml b/pyproject.toml
index 7003a6af9aeae..5f84ca104ac47 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,35 +1,26 @@
-# SPDX-FileCopyrightText: 2024 Scott Shawcroft for Adafruit Industries
-#
-# SPDX-License-Identifier: MIT
-
-[tool.setuptools_scm]
 # can be empty if no extra settings are needed, presence enables setuptools-scm
-
-# Codespell settings copied from MicroPython
-
 [tool.ruff]
-target-version = "py37"
-
+target-version = "py312"
 line-length = 99
-# Exclude third-party code from linting and formatting. Ruff doesn't know how to ignore submodules.
-# Exclude the following tests:
-#   repl_: not real python files
-#   viper_args: uses f(*)
+# Include Python source files that don't end with .py
+extend-include = [ "tools/cc1" ]
+# Exclude third-party code from linting and formatting
 extend-exclude = [
+  # CIRCUITPY-CHANGES
   "extmod/ulab",
   "frozen",
   "lib",
   "ports/analog/msdk",
   "ports/atmel-samd/asf4",
   "ports/broadcom/peripherals",
+  "ports/espress/tools",
   "ports/espressif/esp-idf",
   "ports/espressif/esp-protocols",
   "ports/raspberrypi/sdk",
   "ports/silabs/gecko_sdk",
   "ports/silabs/tools/slc_cli_linux",
   "ports/stm/st_driver",
-  "tests/*/repl_*.py",
-  "tests/micropython/viper_args.py",
+  "tests/cpydiff/syntax_assign_expr.py", # intentionally incorrect CPython code
   "tools/adabot",
   "tools/bitmap_font",
   "tools/cc1",
@@ -40,9 +31,32 @@ extend-exclude = [
 ]
 # Exclude third-party code, and exclude the following tests:
 #   basics: needs careful attention before applying automatic formatting
-format.exclude = [ "tests/basics/*.py" ]
+#   repl_: not real python files
+#   viper_args: uses f(*)
+format.exclude = [
+  "tests/*/repl_*.py",
+  "tests/basics/*.py",
+  "tests/cmdline/cmd_compile_only_error.py",
+  "tests/micropython/test_normalize_newlines.py",
+  "tests/micropython/viper_args.py",
+]
 lint.extend-select = [ "C9", "PLC" ]
-lint.ignore = [
+lint.exclude = [
+  # Ruff finds Python SyntaxError in these files
+  "tests/cmdline/cmd_compile_only_error.py",
+  "tests/cmdline/repl_autocomplete.py",
+  "tests/cmdline/repl_autocomplete_underscore.py",
+  "tests/cmdline/repl_autoindent.py",
+  "tests/cmdline/repl_basic.py",
+  "tests/cmdline/repl_cont.py",
+  "tests/cmdline/repl_emacs_keys.py",
+  "tests/cmdline/repl_paste.py",
+  "tests/cmdline/repl_words_move.py",
+  "tests/feature_check/repl_emacs_check.py",
+  "tests/feature_check/repl_words_move_check.py",
+  "tests/micropython/viper_args.py",
+]
+lint.extend-ignore = [
   "E401",
   "E402",
   "E722",
@@ -51,35 +65,27 @@ lint.ignore = [
   "F401",
   "F403",
   "F405",
-  "PLC1901",
+  "PLC0206",
+  "PLC0415", # conditional imports are common in MicroPython
 ]
 # manifest.py files are evaluated with some global names pre-defined
 lint.per-file-ignores."**/manifest.py" = [ "F821" ]
 lint.per-file-ignores."ports/**/boards/**/manifest_*.py" = [ "F821" ]
-# Exclude all tests from linting (does not apply to formatting).
+lint.per-file-ignores."ports/cc3200/tools/uniflash.py" = [ "E711" ]
+# Exclude all tests from linting.
 lint.per-file-ignores."tests/**/*.py" = [ "ALL" ]
+# Uses assignment expressions.
+lint.per-file-ignores."tests/cpydiff/syntax_assign_expr.py" = [ "F821" ]
 lint.mccabe.max-complexity = 40
 
 [tool.codespell]
 count = ""
-ignore-regex = '\b[A-Z]{3}\b'
-ignore-words-list = "ans,asend,aranges,deques,dout,emac,extint,hsi,iput,mis,notin,numer,ser,shft,synopsys,technic,ure,curren"
+ignore-regex = "\\b[A-Z]{3}\\b"
+# CIRCUITPY-CHANGE: aranges
+ignore-words-list = "ans,aranges,asend,deques,dout,emac,extint,hsi,iput,mis,notin,numer,ser,shft,synopsys,technic,ure,curren"
 quiet-level = 3
-skip = """
-*/build*,\
-./.git,\
-./drivers/cc3100,\
-./lib,\
-./ports/cc3200/FreeRTOS,\
-./ports/cc3200/bootmgr/sl,\
-./ports/cc3200/hal,\
-./ports/cc3200/simplelink,\
-./ports/cc3200/telnet,\
-./ports/esp32/managed_components,\
-./ports/nrf/drivers/bluetooth/s1*,\
-./ports/stm32/usbhost,\
-./tests,\
-ACKNOWLEDGEMENTS,\
-"""
-
-# Ruff settings copied from MicroPython
+skip = """\
+  */build*,./.git,./drivers/cc3100,./lib,./ports/cc3200/FreeRTOS,./ports/cc3200/bootmgr/sl,./ports/cc3200/hal,./ports/c\
+  c3200/simplelink,./ports/cc3200/telnet,./ports/esp32/managed_components,./ports/nrf/drivers/bluetooth/s1*,./ports/stm\
+  32/usbhost,./tests,ACKNOWLEDGEMENTS,\
+  """
diff --git a/shared-bindings/_bleio/__init__.c b/shared-bindings/_bleio/__init__.c
index 3bf8c1a2c9c56..1ec9fd96e766b 100644
--- a/shared-bindings/_bleio/__init__.c
+++ b/shared-bindings/_bleio/__init__.c
@@ -56,7 +56,7 @@
 //|
 //|
 MP_DEFINE_BLEIO_EXCEPTION(BluetoothError, Exception)
-NORETURN void mp_raise_bleio_BluetoothError(mp_rom_error_text_t fmt, ...) {
+MP_NORETURN void mp_raise_bleio_BluetoothError(mp_rom_error_text_t fmt, ...) {
     va_list argptr;
     va_start(argptr, fmt);
     mp_obj_t exception = mp_obj_new_exception_msg_vlist(&mp_type_bleio_BluetoothError, fmt, argptr);
@@ -72,7 +72,7 @@ NORETURN void mp_raise_bleio_BluetoothError(mp_rom_error_text_t fmt, ...) {
 //|
 //|
 MP_DEFINE_BLEIO_EXCEPTION(RoleError, bleio_BluetoothError)
-NORETURN void mp_raise_bleio_RoleError(mp_rom_error_text_t msg) {
+MP_NORETURN void mp_raise_bleio_RoleError(mp_rom_error_text_t msg) {
     mp_raise_msg(&mp_type_bleio_RoleError, msg);
 }
 
@@ -83,7 +83,7 @@ NORETURN void mp_raise_bleio_RoleError(mp_rom_error_text_t msg) {
 //|
 //|
 MP_DEFINE_BLEIO_EXCEPTION(SecurityError, bleio_BluetoothError)
-NORETURN void mp_raise_bleio_SecurityError(mp_rom_error_text_t fmt, ...) {
+MP_NORETURN void mp_raise_bleio_SecurityError(mp_rom_error_text_t fmt, ...) {
     va_list argptr;
     va_start(argptr, fmt);
     mp_obj_t exception = mp_obj_new_exception_msg_vlist(&mp_type_bleio_SecurityError, fmt, argptr);
diff --git a/shared-bindings/_bleio/__init__.h b/shared-bindings/_bleio/__init__.h
index f7428d2fb2138..0c5a5fec06b29 100644
--- a/shared-bindings/_bleio/__init__.h
+++ b/shared-bindings/_bleio/__init__.h
@@ -45,9 +45,9 @@ void common_hal_bleio_init(void);
 
 extern mp_obj_t bleio_set_adapter(mp_obj_t adapter_obj);
 
-NORETURN void mp_raise_bleio_BluetoothError(mp_rom_error_text_t msg, ...);
-NORETURN void mp_raise_bleio_RoleError(mp_rom_error_text_t msg);
-NORETURN void mp_raise_bleio_SecurityError(mp_rom_error_text_t msg, ...);
+MP_NORETURN void mp_raise_bleio_BluetoothError(mp_rom_error_text_t msg, ...);
+MP_NORETURN void mp_raise_bleio_RoleError(mp_rom_error_text_t msg);
+MP_NORETURN void mp_raise_bleio_SecurityError(mp_rom_error_text_t msg, ...);
 
 bleio_adapter_obj_t *common_hal_bleio_allocate_adapter_or_raise(void);
 void common_hal_bleio_device_discover_remote_services(mp_obj_t device, mp_obj_t service_uuids_whitelist);
diff --git a/shared-bindings/adafruit_pixelbuf/PixelBuf.c b/shared-bindings/adafruit_pixelbuf/PixelBuf.c
index cdffbfa627aa1..4144f086b98d6 100644
--- a/shared-bindings/adafruit_pixelbuf/PixelBuf.c
+++ b/shared-bindings/adafruit_pixelbuf/PixelBuf.c
@@ -24,7 +24,7 @@
 #include "extmod/ulab/code/ndarray.h"
 #endif
 
-static NORETURN void invalid_byteorder(void) {
+static MP_NORETURN void invalid_byteorder(void) {
     mp_arg_error_invalid(MP_QSTR_byteorder);
 }
 
diff --git a/shared-bindings/alarm/__init__.h b/shared-bindings/alarm/__init__.h
index af92b381137c8..37bfd9c51b7cd 100644
--- a/shared-bindings/alarm/__init__.h
+++ b/shared-bindings/alarm/__init__.h
@@ -24,7 +24,7 @@ extern mp_obj_t common_hal_alarm_light_sleep_until_alarms(size_t n_alarms, const
 // it will exit idle as if deep sleep was exited
 extern void common_hal_alarm_set_deep_sleep_alarms(size_t n_alarms, const mp_obj_t *alarms, size_t n_dios, digitalio_digitalinout_obj_t **preserve_dios);
 
-extern NORETURN void common_hal_alarm_enter_deep_sleep(void);
+extern MP_NORETURN void common_hal_alarm_enter_deep_sleep(void);
 
 // May be used to re-initialize peripherals like GPIO, if the VM reset returned
 // them to a default state
diff --git a/shared-bindings/math/__init__.c b/shared-bindings/math/__init__.c
index 54fe53280ca8e..49ca2958d8c96 100644
--- a/shared-bindings/math/__init__.c
+++ b/shared-bindings/math/__init__.c
@@ -26,7 +26,7 @@
 //| """
 //|
 
-static NORETURN void math_error(void) {
+static MP_NORETURN void math_error(void) {
     mp_raise_ValueError(MP_ERROR_TEXT("math domain error"));
 }
 
diff --git a/shared-bindings/memorymonitor/__init__.c b/shared-bindings/memorymonitor/__init__.c
index 64d0140ff7930..e364344b363bd 100644
--- a/shared-bindings/memorymonitor/__init__.c
+++ b/shared-bindings/memorymonitor/__init__.c
@@ -25,7 +25,7 @@
 //|
 MP_DEFINE_MEMORYMONITOR_EXCEPTION(AllocationError, Exception)
 
-NORETURN void mp_raise_memorymonitor_AllocationError(mp_rom_error_text_t fmt, ...) {
+MP_NORETURN void mp_raise_memorymonitor_AllocationError(mp_rom_error_text_t fmt, ...) {
     va_list argptr;
     va_start(argptr, fmt);
     mp_obj_t exception = mp_obj_new_exception_msg_vlist(&mp_type_memorymonitor_AllocationError, fmt, argptr);
diff --git a/shared-bindings/memorymonitor/__init__.h b/shared-bindings/memorymonitor/__init__.h
index 28480bea7b52b..5f141b924d09d 100644
--- a/shared-bindings/memorymonitor/__init__.h
+++ b/shared-bindings/memorymonitor/__init__.h
@@ -23,4 +23,4 @@ void memorymonitor_exception_print(const mp_print_t *print, mp_obj_t o_in, mp_pr
 
 extern const mp_obj_type_t mp_type_memorymonitor_AllocationError;
 
-NORETURN void mp_raise_memorymonitor_AllocationError(mp_rom_error_text_t msg, ...);
+MP_NORETURN void mp_raise_memorymonitor_AllocationError(mp_rom_error_text_t msg, ...);
diff --git a/shared-bindings/microcontroller/Pin.c b/shared-bindings/microcontroller/Pin.c
index e74d54b0770a7..1fcde50e060b6 100644
--- a/shared-bindings/microcontroller/Pin.c
+++ b/shared-bindings/microcontroller/Pin.c
@@ -175,14 +175,14 @@ void validate_pins(qstr what, uint8_t *pin_nos, mp_int_t max_pins, mp_obj_t seq,
     }
 }
 
-NORETURN void raise_ValueError_invalid_pin(void) {
+MP_NORETURN void raise_ValueError_invalid_pin(void) {
     mp_arg_error_invalid(MP_QSTR_pin);
 }
 
-NORETURN void raise_ValueError_invalid_pins(void) {
+MP_NORETURN void raise_ValueError_invalid_pins(void) {
     mp_arg_error_invalid(MP_QSTR_pins);
 }
 
-NORETURN void raise_ValueError_invalid_pin_name(qstr pin_name) {
+MP_NORETURN void raise_ValueError_invalid_pin_name(qstr pin_name) {
     mp_raise_ValueError_varg(MP_ERROR_TEXT("Invalid %q pin"), pin_name);
 }
diff --git a/shared-bindings/microcontroller/Pin.h b/shared-bindings/microcontroller/Pin.h
index 1245b5f23e4a7..8ddca71bfbbe3 100644
--- a/shared-bindings/microcontroller/Pin.h
+++ b/shared-bindings/microcontroller/Pin.h
@@ -21,9 +21,9 @@ void validate_no_duplicate_pins(mp_obj_t seq, qstr arg_name);
 void validate_no_duplicate_pins_2(mp_obj_t seq1, mp_obj_t seq2, qstr arg_name1, qstr arg_name2);
 void validate_list_is_free_pins(qstr what, const mcu_pin_obj_t **pins_out, mp_int_t max_pins, mp_obj_t seq, uint8_t *count_out);
 void validate_pins(qstr what, uint8_t *pin_nos, mp_int_t max_pins, mp_obj_t seq, uint8_t *count_out);
-NORETURN void raise_ValueError_invalid_pin(void);
-NORETURN void raise_ValueError_invalid_pins(void);
-NORETURN void raise_ValueError_invalid_pin_name(qstr pin_name);
+MP_NORETURN void raise_ValueError_invalid_pin(void);
+MP_NORETURN void raise_ValueError_invalid_pins(void);
+MP_NORETURN void raise_ValueError_invalid_pin_name(qstr pin_name);
 
 void assert_pin_free(const mcu_pin_obj_t *pin);
 
diff --git a/shared-bindings/microcontroller/__init__.h b/shared-bindings/microcontroller/__init__.h
index 2a4a973278162..5c5902ff965f5 100644
--- a/shared-bindings/microcontroller/__init__.h
+++ b/shared-bindings/microcontroller/__init__.h
@@ -20,7 +20,7 @@ extern void common_hal_mcu_disable_interrupts(void);
 extern void common_hal_mcu_enable_interrupts(void);
 
 extern void common_hal_mcu_on_next_reset(mcu_runmode_t runmode);
-NORETURN extern void common_hal_mcu_reset(void);
+MP_NORETURN extern void common_hal_mcu_reset(void);
 
 extern const mp_obj_dict_t mcu_pin_globals;
 
diff --git a/shared-bindings/paralleldisplaybus/__init__.c b/shared-bindings/paralleldisplaybus/__init__.c
index 24d968c9e3111..19a381570bada 100644
--- a/shared-bindings/paralleldisplaybus/__init__.c
+++ b/shared-bindings/paralleldisplaybus/__init__.c
@@ -29,6 +29,3 @@ const mp_obj_module_t paralleldisplaybus_module = {
 };
 
 MP_REGISTER_MODULE(MP_QSTR_paralleldisplaybus, paralleldisplaybus_module);
-
-// Remove in CircuitPython 10
-MP_REGISTER_MODULE(MP_QSTR_paralleldisplay, paralleldisplaybus_module);
diff --git a/shared-bindings/socketpool/SocketPool.c b/shared-bindings/socketpool/SocketPool.c
index 7ae7003d0c364..1fc9e2c3335ca 100644
--- a/shared-bindings/socketpool/SocketPool.c
+++ b/shared-bindings/socketpool/SocketPool.c
@@ -189,7 +189,7 @@ MP_DEFINE_CONST_OBJ_TYPE(
     locals_dict, &socketpool_socketpool_locals_dict
     );
 
-MP_WEAK NORETURN
+MP_WEAK MP_NORETURN
 void common_hal_socketpool_socketpool_raise_gaierror_noname(void) {
     vstr_t vstr;
     mp_print_t print;
diff --git a/shared-bindings/socketpool/SocketPool.h b/shared-bindings/socketpool/SocketPool.h
index 36035ed00e11a..60d58372b9131 100644
--- a/shared-bindings/socketpool/SocketPool.h
+++ b/shared-bindings/socketpool/SocketPool.h
@@ -25,6 +25,6 @@ bool socketpool_socket(socketpool_socketpool_obj_t *self,
     socketpool_socketpool_addressfamily_t family, socketpool_socketpool_sock_t type,
     int proto, socketpool_socket_obj_t *sock);
 
-NORETURN void common_hal_socketpool_socketpool_raise_gaierror_noname(void);
+MP_NORETURN void common_hal_socketpool_socketpool_raise_gaierror_noname(void);
 
 mp_obj_t common_hal_socketpool_getaddrinfo_raise(socketpool_socketpool_obj_t *self, const char *host, int port, int family, int type, int proto, int flags);
diff --git a/shared-bindings/storage/__init__.h b/shared-bindings/storage/__init__.h
index ed3e8d44e4aed..6df604262956a 100644
--- a/shared-bindings/storage/__init__.h
+++ b/shared-bindings/storage/__init__.h
@@ -16,7 +16,7 @@ void common_hal_storage_umount_path(const char *path);
 void common_hal_storage_umount_object(mp_obj_t vfs_obj);
 void common_hal_storage_remount(const char *path, bool readonly, bool disable_concurrent_write_protection);
 mp_obj_t common_hal_storage_getmount(const char *path);
-NORETURN void common_hal_storage_erase_filesystem(bool extended);
+MP_NORETURN void common_hal_storage_erase_filesystem(bool extended);
 
 bool common_hal_storage_disable_usb_drive(void);
 bool common_hal_storage_enable_usb_drive(void);
diff --git a/shared-bindings/usb/core/__init__.c b/shared-bindings/usb/core/__init__.c
index 3907effb8ff25..29dab285084ef 100644
--- a/shared-bindings/usb/core/__init__.c
+++ b/shared-bindings/usb/core/__init__.c
@@ -30,7 +30,7 @@
 //|
 //|
 MP_DEFINE_USB_CORE_EXCEPTION(USBError, OSError)
-NORETURN void mp_raise_usb_core_USBError(mp_rom_error_text_t fmt, ...) {
+MP_NORETURN void mp_raise_usb_core_USBError(mp_rom_error_text_t fmt, ...) {
     mp_obj_t exception;
     if (fmt == NULL) {
         exception = mp_obj_new_exception(&mp_type_usb_core_USBError);
@@ -50,7 +50,7 @@ NORETURN void mp_raise_usb_core_USBError(mp_rom_error_text_t fmt, ...) {
 //|
 //|
 MP_DEFINE_USB_CORE_EXCEPTION(USBTimeoutError, usb_core_USBError)
-NORETURN void mp_raise_usb_core_USBTimeoutError(void) {
+MP_NORETURN void mp_raise_usb_core_USBTimeoutError(void) {
     mp_raise_type(&mp_type_usb_core_USBTimeoutError);
 }
 
diff --git a/shared-bindings/usb/core/__init__.h b/shared-bindings/usb/core/__init__.h
index 0dc08fae53257..adb8430a6c382 100644
--- a/shared-bindings/usb/core/__init__.h
+++ b/shared-bindings/usb/core/__init__.h
@@ -25,8 +25,8 @@ void usb_core_exception_print(const mp_print_t *print, mp_obj_t o_in, mp_print_k
 extern const mp_obj_type_t mp_type_usb_core_USBError;
 extern const mp_obj_type_t mp_type_usb_core_USBTimeoutError;
 
-NORETURN void mp_raise_usb_core_USBError(mp_rom_error_text_t fmt, ...);
-NORETURN void mp_raise_usb_core_USBTimeoutError(void);
+MP_NORETURN void mp_raise_usb_core_USBError(mp_rom_error_text_t fmt, ...);
+MP_NORETURN void mp_raise_usb_core_USBTimeoutError(void);
 
 // Find is all Python object oriented so we don't need a separate common-hal API
 // for it. It uses the device common-hal instead.
diff --git a/shared-bindings/util.h b/shared-bindings/util.h
index d53e5c6e8da13..11f0a00db71ea 100644
--- a/shared-bindings/util.h
+++ b/shared-bindings/util.h
@@ -9,7 +9,7 @@
 #include "py/mpprint.h"
 #include "py/runtime.h"
 
-NORETURN void raise_deinited_error(void);
+MP_NORETURN void raise_deinited_error(void);
 void properties_print_helper(const mp_print_t *print, mp_obj_t self_in, const mp_arg_t *properties, size_t n_properties);
 void properties_construct_helper(mp_obj_t self_in, const mp_arg_t *args, const mp_arg_val_t *vals, size_t n_properties);
 bool path_exists(const char *path);
diff --git a/shared-module/ssl/SSLSocket.c b/shared-module/ssl/SSLSocket.c
index 8911fa2f454d8..fa1de8bb484aa 100644
--- a/shared-module/ssl/SSLSocket.c
+++ b/shared-module/ssl/SSLSocket.c
@@ -44,7 +44,7 @@ static void mbedtls_debug(void *ctx, int level, const char *file, int line, cons
 #define DEBUG_PRINT(...) do {} while (0)
 #endif
 
-static NORETURN void mbedtls_raise_error(int err) {
+static MP_NORETURN void mbedtls_raise_error(int err) {
     // _mbedtls_ssl_send and _mbedtls_ssl_recv (below) turn positive error codes from the
     // underlying socket into negative codes to pass them through mbedtls. Here we turn them
     // positive again so they get interpreted as the OSError they really are. The
diff --git a/shared-module/struct/__init__.c b/shared-module/struct/__init__.c
index 715b504302115..4b6b2b589efc8 100644
--- a/shared-module/struct/__init__.c
+++ b/shared-module/struct/__init__.c
@@ -14,7 +14,8 @@
 #include "shared-bindings/struct/__init__.h"
 
 static void struct_validate_format(char fmt) {
-    #if MICROPY_NONSTANDARD_TYPECODES
+    #if MICROPY_PY_STRUCT_UNSAFE_TYPECODES
+
     if (fmt == 'S' || fmt == 'O') {
         mp_raise_RuntimeError(MP_ERROR_TEXT("'S' and 'O' are not supported format types"));
     }
diff --git a/shared/libc/abort_.c b/shared/libc/abort_.c
index 3051eae81e0ce..54eab67d3fb49 100644
--- a/shared/libc/abort_.c
+++ b/shared/libc/abort_.c
@@ -1,7 +1,7 @@
 #include <py/runtime.h>
 
-NORETURN void abort_(void);
+MP_NORETURN void abort_(void);
 
-NORETURN void abort_(void) {
+MP_NORETURN void abort_(void) {
     mp_raise_msg(&mp_type_RuntimeError, MP_ERROR_TEXT("abort() called"));
 }
diff --git a/shared/memzip/make-memzip.py b/shared/memzip/make-memzip.py
index 92a5d6168bb1d..e406c55a43ca7 100755
--- a/shared/memzip/make-memzip.py
+++ b/shared/memzip/make-memzip.py
@@ -7,8 +7,6 @@
 # This is somewhat like frozen modules in python, but allows arbitrary files
 # to be used.
 
-from __future__ import print_function
-
 import argparse
 import os
 import subprocess
diff --git a/shared/netutils/trace.c b/shared/netutils/trace.c
index a6dfb42c28f00..24af4d5ca315f 100644
--- a/shared/netutils/trace.c
+++ b/shared/netutils/trace.c
@@ -56,7 +56,7 @@ static const char *ethertype_str(uint16_t type) {
 }
 
 void netutils_ethernet_trace(const mp_print_t *print, size_t len, const uint8_t *buf, unsigned int flags) {
-    mp_printf(print, "[% 8d] ETH%cX len=%u", mp_hal_ticks_ms(), flags & NETUTILS_TRACE_IS_TX ? 'T' : 'R', len);
+    mp_printf(print, "[% 8u] ETH%cX len=%u", (unsigned)mp_hal_ticks_ms(), flags & NETUTILS_TRACE_IS_TX ? 'T' : 'R', len);
     mp_printf(print, " dst=%02x:%02x:%02x:%02x:%02x:%02x", buf[0], buf[1], buf[2], buf[3], buf[4], buf[5]);
     mp_printf(print, " src=%02x:%02x:%02x:%02x:%02x:%02x", buf[6], buf[7], buf[8], buf[9], buf[10], buf[11]);
 
diff --git a/shared/runtime/gchelper_generic.c b/shared/runtime/gchelper_generic.c
index 464aeaa9981de..230a24440050f 100644
--- a/shared/runtime/gchelper_generic.c
+++ b/shared/runtime/gchelper_generic.c
@@ -42,6 +42,7 @@
 // stack already by the caller.
 #if defined(__x86_64__)
 
+// CIRCUITPY-CHANGE: use __asm__ instead of asm
 static void gc_helper_get_regs(gc_helper_regs_t arr) {
     register long rbx __asm__ ("rbx");
     register long rbp __asm__ ("rbp");
diff --git a/shared/runtime/interrupt_char.c b/shared/runtime/interrupt_char.c
index 5cec1988f41b3..1f2702017190f 100644
--- a/shared/runtime/interrupt_char.c
+++ b/shared/runtime/interrupt_char.c
@@ -31,6 +31,7 @@
 
 #if MICROPY_KBD_EXCEPTION
 
+// CIRCUITPY-CHANGE
 #ifdef __ZEPHYR__
 #include <zephyr/kernel.h>
 
diff --git a/shared/runtime/interrupt_char.h b/shared/runtime/interrupt_char.h
index c4a465456a8d1..44fd4b45a6121 100644
--- a/shared/runtime/interrupt_char.h
+++ b/shared/runtime/interrupt_char.h
@@ -29,6 +29,7 @@
 // CIRCUITPY-CHANGE
 #include <stdbool.h>
 
+// CIRCUITPY-CHANGE
 #ifdef __ZEPHYR__
 #include <zephyr/kernel.h>
 
diff --git a/shared/runtime/mpirq.c b/shared/runtime/mpirq.c
deleted file mode 100644
index 6111b9b10cfe4..0000000000000
--- a/shared/runtime/mpirq.c
+++ /dev/null
@@ -1,136 +0,0 @@
-/*
- * This file is part of the MicroPython project, http://micropython.org/
- *
- * The MIT License (MIT)
- *
- * Copyright (c) 2015 Daniel Campora
- *               2018 Tobias Badertscher
- *
- * Permission is hereby granted, free of charge, to any person obtaining a copy
- * of this software and associated documentation files (the "Software"), to deal
- * in the Software without restriction, including without limitation the rights
- * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
- * copies of the Software, and to permit persons to whom the Software is
- * furnished to do so, subject to the following conditions:
- *
- * The above copyright notice and this permission notice shall be included in
- * all copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
- * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
- * THE SOFTWARE.
- */
-
-#include <stdio.h>
-
-#include "py/runtime.h"
-#include "py/gc.h"
-#include "shared/runtime/mpirq.h"
-
-#if MICROPY_ENABLE_SCHEDULER
-
-/******************************************************************************
- DECLARE PUBLIC DATA
- ******************************************************************************/
-
-const mp_arg_t mp_irq_init_args[] = {
-    { MP_QSTR_handler, MP_ARG_OBJ, {.u_rom_obj = MP_ROM_NONE} },
-    { MP_QSTR_trigger, MP_ARG_INT, {.u_int = 0} },
-    { MP_QSTR_hard, MP_ARG_BOOL, {.u_bool = false} },
-};
-
-/******************************************************************************
- DECLARE PRIVATE DATA
- ******************************************************************************/
-
-/******************************************************************************
- DEFINE PUBLIC FUNCTIONS
- ******************************************************************************/
-
-mp_irq_obj_t *mp_irq_new(const mp_irq_methods_t *methods, mp_obj_t parent) {
-    mp_irq_obj_t *self = m_new0(mp_irq_obj_t, 1);
-    mp_irq_init(self, methods, parent);
-    return self;
-}
-
-void mp_irq_init(mp_irq_obj_t *self, const mp_irq_methods_t *methods, mp_obj_t parent) {
-    self->base.type = &mp_irq_type;
-    self->methods = (mp_irq_methods_t *)methods;
-    self->parent = parent;
-    self->handler = mp_const_none;
-    self->ishard = false;
-}
-
-void mp_irq_handler(mp_irq_obj_t *self) {
-    if (self->handler != mp_const_none) {
-        if (self->ishard) {
-            // When executing code within a handler we must lock the scheduler to
-            // prevent any scheduled callbacks from running, and lock the GC to
-            // prevent any memory allocations.
-            mp_sched_lock();
-            gc_lock();
-            nlr_buf_t nlr;
-            if (nlr_push(&nlr) == 0) {
-                mp_call_function_1(self->handler, self->parent);
-                nlr_pop();
-            } else {
-                // Uncaught exception; disable the callback so that it doesn't run again
-                self->methods->trigger(self->parent, 0);
-                self->handler = mp_const_none;
-                mp_printf(MICROPY_ERROR_PRINTER, "Uncaught exception in IRQ callback handler\n");
-                mp_obj_print_exception(MICROPY_ERROR_PRINTER, MP_OBJ_FROM_PTR(nlr.ret_val));
-            }
-            gc_unlock();
-            mp_sched_unlock();
-        } else {
-            // Schedule call to user function
-            mp_sched_schedule(self->handler, self->parent);
-        }
-    }
-}
-
-/******************************************************************************/
-// MicroPython bindings
-
-static mp_obj_t mp_irq_flags(mp_obj_t self_in) {
-    mp_irq_obj_t *self = MP_OBJ_TO_PTR(self_in);
-    return mp_obj_new_int(self->methods->info(self->parent, MP_IRQ_INFO_FLAGS));
-}
-static MP_DEFINE_CONST_FUN_OBJ_1(mp_irq_flags_obj, mp_irq_flags);
-
-static mp_obj_t mp_irq_trigger(size_t n_args, const mp_obj_t *args) {
-    mp_irq_obj_t *self = MP_OBJ_TO_PTR(args[0]);
-    mp_obj_t ret_obj = mp_obj_new_int(self->methods->info(self->parent, MP_IRQ_INFO_TRIGGERS));
-    if (n_args == 2) {
-        // Set trigger
-        self->methods->trigger(self->parent, mp_obj_get_int(args[1]));
-    }
-    return ret_obj;
-}
-static MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mp_irq_trigger_obj, 1, 2, mp_irq_trigger);
-
-static mp_obj_t mp_irq_call(mp_obj_t self_in, size_t n_args, size_t n_kw, const mp_obj_t *args) {
-    mp_arg_check_num(n_args, n_kw, 0, 0, false);
-    mp_irq_handler(MP_OBJ_TO_PTR(self_in));
-    return mp_const_none;
-}
-
-static const mp_rom_map_elem_t mp_irq_locals_dict_table[] = {
-    { MP_ROM_QSTR(MP_QSTR_flags),               MP_ROM_PTR(&mp_irq_flags_obj) },
-    { MP_ROM_QSTR(MP_QSTR_trigger),             MP_ROM_PTR(&mp_irq_trigger_obj) },
-};
-static MP_DEFINE_CONST_DICT(mp_irq_locals_dict, mp_irq_locals_dict_table);
-
-MP_DEFINE_CONST_OBJ_TYPE(
-    mp_irq_type,
-    MP_QSTR_irq,
-    MP_TYPE_FLAG_NONE,
-    call, mp_irq_call,
-    locals_dict, &mp_irq_locals_dict
-    );
-
-#endif // MICROPY_ENABLE_SCHEDULER
diff --git a/shared/runtime/mpirq.h b/shared/runtime/mpirq.h
deleted file mode 100644
index dd423c0101137..0000000000000
--- a/shared/runtime/mpirq.h
+++ /dev/null
@@ -1,82 +0,0 @@
-/*
- * This file is part of the MicroPython project, http://micropython.org/
- *
- * The MIT License (MIT)
- *
- * Copyright (c) 2015 Daniel Campora
- *
- * Permission is hereby granted, free of charge, to any person obtaining a copy
- * of this software and associated documentation files (the "Software"), to deal
- * in the Software without restriction, including without limitation the rights
- * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
- * copies of the Software, and to permit persons to whom the Software is
- * furnished to do so, subject to the following conditions:
- *
- * The above copyright notice and this permission notice shall be included in
- * all copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
- * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
- * THE SOFTWARE.
- */
-#ifndef MICROPY_INCLUDED_LIB_UTILS_MPIRQ_H
-#define MICROPY_INCLUDED_LIB_UTILS_MPIRQ_H
-
-#include "py/runtime.h"
-
-/******************************************************************************
- DEFINE CONSTANTS
- ******************************************************************************/
-
-enum {
-    MP_IRQ_ARG_INIT_handler = 0,
-    MP_IRQ_ARG_INIT_trigger,
-    MP_IRQ_ARG_INIT_hard,
-    MP_IRQ_ARG_INIT_NUM_ARGS,
-};
-
-/******************************************************************************
- DEFINE TYPES
- ******************************************************************************/
-
-typedef mp_uint_t (*mp_irq_trigger_fun_t)(mp_obj_t self, mp_uint_t trigger);
-typedef mp_uint_t (*mp_irq_info_fun_t)(mp_obj_t self, mp_uint_t info_type);
-
-enum {
-    MP_IRQ_INFO_FLAGS,
-    MP_IRQ_INFO_TRIGGERS,
-};
-
-typedef struct _mp_irq_methods_t {
-    mp_irq_trigger_fun_t trigger;
-    mp_irq_info_fun_t info;
-} mp_irq_methods_t;
-
-typedef struct _mp_irq_obj_t {
-    mp_obj_base_t base;
-    mp_irq_methods_t *methods;
-    mp_obj_t parent;
-    mp_obj_t handler;
-    bool ishard;
-} mp_irq_obj_t;
-
-/******************************************************************************
- DECLARE EXPORTED DATA
- ******************************************************************************/
-
-extern const mp_arg_t mp_irq_init_args[];
-extern const mp_obj_type_t mp_irq_type;
-
-/******************************************************************************
- DECLARE PUBLIC FUNCTIONS
- ******************************************************************************/
-
-mp_irq_obj_t *mp_irq_new(const mp_irq_methods_t *methods, mp_obj_t parent);
-void mp_irq_init(mp_irq_obj_t *self, const mp_irq_methods_t *methods, mp_obj_t parent);
-void mp_irq_handler(mp_irq_obj_t *self);
-
-#endif // MICROPY_INCLUDED_LIB_UTILS_MPIRQ_H
diff --git a/shared/runtime/pyexec.c b/shared/runtime/pyexec.c
index 06680ff2dd125..bc5f89bdc81ad 100644
--- a/shared/runtime/pyexec.c
+++ b/shared/runtime/pyexec.c
@@ -38,15 +38,12 @@
 #include "py/gc.h"
 #include "py/frozenmod.h"
 #include "py/mphal.h"
-#if MICROPY_HW_ENABLE_USB
-#include "irq.h"
-#include "usb.h"
-#endif
 #include "shared/readline/readline.h"
 #include "shared/runtime/pyexec.h"
+#include "extmod/modplatform.h"
 #include "genhdr/mpversion.h"
 
-// CIRCUITPY-CHANGE: atexit support
+// CIRCUITPY-CHANGE: add atexit support
 #if CIRCUITPY_ATEXIT
 #include "shared-module/atexit/__init__.h"
 #endif
@@ -87,57 +84,71 @@ static int parse_compile_execute(const void *source, mp_parse_input_kind_t input
     nlr_buf_t nlr;
     nlr.ret_val = NULL;
     if (nlr_push(&nlr) == 0) {
-        // CIRCUITPY-CHANGE
-        mp_obj_t module_fun = mp_const_none;
-        // CIRCUITPY-CHANGE
+        #if MICROPY_PYEXEC_ENABLE_VM_ABORT
+        nlr_set_abort(&nlr);
+        #endif
+
+        // CIRCUITPY-CHANGE: move declaration for easier handling of atexit #if.
+        // Also make it possible to determine if module_fun was set.
+        mp_obj_t module_fun = NULL;
+
+        // CIRCUITPY-CHANGE: add atexit support
         #if CIRCUITPY_ATEXIT
-        if (!(exec_flags & EXEC_FLAG_SOURCE_IS_ATEXIT))
+        if (exec_flags & EXEC_FLAG_SOURCE_IS_ATEXIT) {
+            atexit_callback_t *callback = (atexit_callback_t *)source;
+            mp_call_function_n_kw(callback->func, callback->n_pos, callback->n_kw, callback->args);
+        } else
         #endif
-        // CIRCUITPY-CHANGE: multiple code changes
-        {
-            #if MICROPY_MODULE_FROZEN_MPY
-            if (exec_flags & EXEC_FLAG_SOURCE_IS_RAW_CODE) {
-                // source is a raw_code object, create the function
-                const mp_frozen_module_t *frozen = source;
-                mp_module_context_t *ctx = m_new_obj(mp_module_context_t);
-                ctx->module.globals = mp_globals_get();
-                ctx->constants = frozen->constants;
-                module_fun = mp_make_function_from_proto_fun(frozen->proto_fun, ctx, NULL);
-            } else
-            #endif
-            {
-                #if MICROPY_ENABLE_COMPILER
-                mp_lexer_t *lex;
-                if (exec_flags & EXEC_FLAG_SOURCE_IS_VSTR) {
-                    const vstr_t *vstr = source;
-                    lex = mp_lexer_new_from_str_len(MP_QSTR__lt_stdin_gt_, vstr->buf, vstr->len, 0);
-                } else if (exec_flags & EXEC_FLAG_SOURCE_IS_READER) {
-                    lex = mp_lexer_new(MP_QSTR__lt_stdin_gt_, *(mp_reader_t *)source);
-                } else if (exec_flags & EXEC_FLAG_SOURCE_IS_FILENAME) {
-                    lex = mp_lexer_new_from_file(qstr_from_str(source));
-                } else {
-                    lex = (mp_lexer_t *)source;
-                }
-                // source is a lexer, parse and compile the script
-                qstr source_name = lex->source_name;
-                // CIRCUITPY-CHANGE
-                #if MICROPY_PY___FILE__
-                if (input_kind == MP_PARSE_FILE_INPUT) {
-                    mp_store_global(MP_QSTR___file__, MP_OBJ_NEW_QSTR(source_name));
-                }
-                #endif
 
-                mp_parse_tree_t parse_tree = mp_parse(lex, input_kind);
-                module_fun = mp_compile(&parse_tree, source_name, exec_flags & EXEC_FLAG_IS_REPL);
-                #else
-                mp_raise_msg(&mp_type_RuntimeError, MP_ERROR_TEXT("script compilation not supported"));
-                #endif
+        #if MICROPY_MODULE_FROZEN_MPY
+        if (exec_flags & EXEC_FLAG_SOURCE_IS_RAW_CODE) {
+            // source is a raw_code object, create the function
+            const mp_frozen_module_t *frozen = source;
+            mp_module_context_t *ctx = m_new_obj(mp_module_context_t);
+            ctx->module.globals = mp_globals_get();
+            ctx->constants = frozen->constants;
+            module_fun = mp_make_function_from_proto_fun(frozen->proto_fun, ctx, NULL);
+        } else
+        #endif
+        {
+            #if MICROPY_ENABLE_COMPILER
+            mp_lexer_t *lex;
+            if (exec_flags & EXEC_FLAG_SOURCE_IS_VSTR) {
+                const vstr_t *vstr = source;
+                lex = mp_lexer_new_from_str_len(MP_QSTR__lt_stdin_gt_, vstr->buf, vstr->len, 0);
+            } else if (exec_flags & EXEC_FLAG_SOURCE_IS_READER) {
+                lex = mp_lexer_new(MP_QSTR__lt_stdin_gt_, *(mp_reader_t *)source);
+            } else if (exec_flags & EXEC_FLAG_SOURCE_IS_FILENAME) {
+                lex = mp_lexer_new_from_file(qstr_from_str(source));
+            } else {
+                lex = (mp_lexer_t *)source;
             }
-
-            // If the code was loaded from a file, collect any garbage before running.
+            // source is a lexer, parse and compile the script
+            qstr source_name = lex->source_name;
+            #if MICROPY_MODULE___FILE__
             if (input_kind == MP_PARSE_FILE_INPUT) {
-                gc_collect();
+                mp_store_global(MP_QSTR___file__, MP_OBJ_NEW_QSTR(source_name));
             }
+            #endif
+            mp_parse_tree_t parse_tree = mp_parse(lex, input_kind);
+            #if defined(MICROPY_UNIX_COVERAGE)
+            // allow to print the parse tree in the coverage build
+            if (mp_verbose_flag >= 3) {
+                printf("----------------\n");
+                mp_parse_node_print(&mp_plat_print, parse_tree.root, 0);
+                printf("----------------\n");
+            }
+            #endif
+            module_fun = mp_compile(&parse_tree, source_name, exec_flags & EXEC_FLAG_IS_REPL);
+            #else
+            mp_raise_msg(&mp_type_RuntimeError, MP_ERROR_TEXT("script compilation not supported"));
+            #endif
+        }
+
+        // CIRCUITPY-CHANGE: garbage collect after loading
+        // If the code was loaded from a file, collect any garbage before running.
+        if (input_kind == MP_PARSE_FILE_INPUT) {
+            gc_collect();
         }
 
         // execute code
@@ -147,22 +158,19 @@ static int parse_compile_execute(const void *source, mp_parse_input_kind_t input
         #if MICROPY_REPL_INFO
         start = mp_hal_ticks_ms();
         #endif
-        // CIRCUITPY-CHANGE
-        #if CIRCUITPY_ATEXIT
-        if (exec_flags & EXEC_FLAG_SOURCE_IS_ATEXIT) {
-            atexit_callback_t *callback = (atexit_callback_t *)source;
-            mp_call_function_n_kw(callback->func, callback->n_pos, callback->n_kw, callback->args);
-        } else
+        #if MICROPY_PYEXEC_COMPILE_ONLY
+        if (!mp_compile_only)
         #endif
-        // CIRCUITPY-CHANGE
-        if (module_fun != mp_const_none) {
-            mp_call_function_0(module_fun);
+        {
+            // CIRCUITPY-CHANGE: if atexit function was called, there is nothing to call.
+            if (module_fun != NULL) {
+                mp_call_function_0(module_fun);
+            }
         }
         mp_hal_set_interrupt_char(-1); // disable interrupt
         mp_handle_pending(true); // handle any pending exceptions (and any callbacks)
         nlr_pop();
-        // CIRCUITPY-CHANGE
-        ret = 0;
+        ret = PYEXEC_NORMAL_EXIT;
         if (exec_flags & EXEC_FLAG_PRINT_EOF) {
             mp_hal_stdout_tx_strn("\x04", 1);
         }
@@ -181,36 +189,65 @@ static int parse_compile_execute(const void *source, mp_parse_input_kind_t input
             mp_hal_stdout_tx_strn("\x04", 1);
         }
 
-        // check for SystemExit
-
-        // CIRCUITPY-CHANGE
+        // CIRCUITPY-CHANGE: Name and use some values.
         // nlr.ret_val is an exception object.
         mp_obj_t exception_obj = (mp_obj_t)nlr.ret_val;
+        const mp_obj_type_t *exception_obj_type = mp_obj_get_type(exception_obj);
 
-        if (mp_obj_is_subclass_fast(MP_OBJ_FROM_PTR(mp_obj_get_type(exception_obj)), MP_OBJ_FROM_PTR(&mp_type_SystemExit))) {
-            // at the moment, the value of SystemExit is unused
+        #if MICROPY_PYEXEC_ENABLE_VM_ABORT
+        if (nlr.ret_val == NULL) { // abort
+            ret = PYEXEC_ABORT;
+        } else
+        #endif
+
+        if (mp_obj_is_subclass_fast(MP_OBJ_FROM_PTR(exception_obj_type), MP_OBJ_FROM_PTR(&mp_type_SystemExit))) { // system exit
+            #if MICROPY_PYEXEC_ENABLE_EXIT_CODE_HANDLING
+            // None is an exit value of 0; an int is its value; anything else is 1
+            mp_obj_t val = mp_obj_exception_get_value(MP_OBJ_FROM_PTR(nlr.ret_val));
+            if (val != mp_const_none) {
+                if (mp_obj_is_int(val)) {
+                    ret = (int)mp_obj_int_get_truncated(val);
+                } else {
+                    mp_obj_print_helper(MICROPY_ERROR_PRINTER, val, PRINT_STR);
+                    mp_print_str(MICROPY_ERROR_PRINTER, "\n");
+                    ret = PYEXEC_UNHANDLED_EXCEPTION;
+                }
+            } else {
+                ret = PYEXEC_NORMAL_EXIT;
+            }
+            // Set PYEXEC_FORCED_EXIT flag so REPL knows to exit
+            ret |= PYEXEC_FORCED_EXIT;
+            #else
             ret = PYEXEC_FORCED_EXIT;
-            // CIRCUITPY-CHANGE
+            #endif
+            // CIRCUITPY-CHANGE: support DeepSleepRequest
         #if CIRCUITPY_ALARM
-        } else if (mp_obj_is_subclass_fast(MP_OBJ_FROM_PTR(mp_obj_get_type(exception_obj)), MP_OBJ_FROM_PTR(&mp_type_DeepSleepRequest))) {
+        } else if (mp_obj_is_subclass_fast(MP_OBJ_FROM_PTR(exception_obj_type), MP_OBJ_FROM_PTR(&mp_type_DeepSleepRequest))) {
             ret = PYEXEC_DEEP_SLEEP;
         #endif
+            // CIRCUITPY-CHANGE: support ReloadException
         } else if (exception_obj == MP_OBJ_FROM_PTR(&MP_STATE_VM(mp_reload_exception))) {
             ret = PYEXEC_RELOAD;
-        } else {
-            mp_obj_print_exception(&mp_plat_print, exception_obj);
-            ret = PYEXEC_EXCEPTION;
+        } else { // other exception
+            mp_obj_print_exception(&mp_plat_print, MP_OBJ_FROM_PTR(nlr.ret_val));
+            ret = PYEXEC_UNHANDLED_EXCEPTION;
+            #if MICROPY_PYEXEC_ENABLE_EXIT_CODE_HANDLING
+            if (mp_obj_is_subclass_fast(MP_OBJ_FROM_PTR(((mp_obj_base_t *)nlr.ret_val)->type), MP_OBJ_FROM_PTR(&mp_type_KeyboardInterrupt))) { // keyboard interrupt
+                ret = PYEXEC_KEYBOARD_INTERRUPT;
+            }
+            #endif
         }
-
     }
+
+    // CIRCUITPY_CHANGE: Fill in result out argument.
     if (result != NULL) {
         result->return_code = ret;
-        #if CIRCUITPY_ALARM
         // Don't set the exception object if we exited for deep sleep.
-        if (ret != 0 && ret != PYEXEC_DEEP_SLEEP) {
-        #else
-        if (ret != 0) {
+        if (ret != 0
+            #if CIRCUITPY_ALARM
+            && ret != PYEXEC_DEEP_SLEEP
             #endif
+            ) {
             mp_obj_t return_value = (mp_obj_t)nlr.ret_val;
             result->exception = return_value;
             result->exception_line = -1;
@@ -227,6 +264,10 @@ static int parse_compile_execute(const void *source, mp_parse_input_kind_t input
         }
     }
 
+    #if MICROPY_PYEXEC_ENABLE_VM_ABORT
+    nlr_set_abort(NULL);
+    #endif
+
     #if MICROPY_REPL_INFO
     // display debugging info if wanted
     if ((exec_flags & EXEC_FLAG_ALLOW_DEBUGGING) && repl_display_debugging_info) {
@@ -484,7 +525,10 @@ static int pyexec_friendly_repl_process_char(int c) {
             // CIRCUITPY-CHANGE: print CircuitPython-style banner.
             mp_hal_stdout_tx_str(MICROPY_FULL_VERSION_INFO);
             mp_hal_stdout_tx_str("\r\n");
+            #if MICROPY_PY_BUILTINS_HELP
+            // CIRCUITPY-CHANGE: don't print help info
             // mp_hal_stdout_tx_str("Type \"help()\" for more information.\r\n");
+            #endif
             goto input_restart;
         } else if (ret == CHAR_CTRL_C) {
             // break
@@ -570,10 +614,21 @@ MP_REGISTER_ROOT_POINTER(vstr_t * repl_line);
 
 #else // MICROPY_REPL_EVENT_DRIVEN
 
+// CIRCUITPY-CHANGE: avoid warnings
+#if !defined(MICROPY_HAL_HAS_STDIO_MODE_SWITCH) || !MICROPY_HAL_HAS_STDIO_MODE_SWITCH
+// If the port doesn't need any stdio mode switching calls then provide trivial ones.
+static inline void mp_hal_stdio_mode_raw(void) {
+}
+static inline void mp_hal_stdio_mode_orig(void) {
+}
+#endif
+
 int pyexec_raw_repl(void) {
     vstr_t line;
     vstr_init(&line, 32);
 
+    mp_hal_stdio_mode_raw();
+
 raw_repl_reset:
     mp_hal_stdout_tx_str("raw REPL; CTRL-B to exit\r\n");
 
@@ -587,6 +642,7 @@ int pyexec_raw_repl(void) {
                 if (vstr_len(&line) == 2 && vstr_str(&line)[0] == CHAR_CTRL_E) {
                     int ret = do_reader_stdin(vstr_str(&line)[1]);
                     if (ret & PYEXEC_FORCED_EXIT) {
+                        mp_hal_stdio_mode_orig();
                         return ret;
                     }
                     vstr_reset(&line);
@@ -599,6 +655,7 @@ int pyexec_raw_repl(void) {
                 mp_hal_stdout_tx_str("\r\n");
                 vstr_clear(&line);
                 pyexec_mode_kind = PYEXEC_MODE_FRIENDLY_REPL;
+                mp_hal_stdio_mode_orig();
                 return 0;
             } else if (c == CHAR_CTRL_C) {
                 // clear line
@@ -619,14 +676,18 @@ int pyexec_raw_repl(void) {
             // exit for a soft reset
             mp_hal_stdout_tx_str("\r\n");
             vstr_clear(&line);
+            mp_hal_stdio_mode_orig();
             return PYEXEC_FORCED_EXIT;
         }
 
+        // Switch to original terminal mode to execute code, eg to support keyboard interrupt (SIGINT).
+        mp_hal_stdio_mode_orig();
         // CIRCUITPY-CHANGE: add last arg, handle reload
         int ret = parse_compile_execute(&line, MP_PARSE_FILE_INPUT, EXEC_FLAG_PRINT_EOF | EXEC_FLAG_SOURCE_IS_VSTR, NULL);
         if (ret & (PYEXEC_FORCED_EXIT | PYEXEC_RELOAD)) {
             return ret;
         }
+        mp_hal_stdio_mode_raw();
     }
 }
 
@@ -634,6 +695,8 @@ int pyexec_friendly_repl(void) {
     vstr_t line;
     vstr_init(&line, 32);
 
+    mp_hal_stdio_mode_raw();
+
 friendly_repl_reset:
     // CIRCUITPY-CHANGE: CircuitPython-style banner.
     mp_hal_stdout_tx_str("\r\n");
@@ -661,20 +724,6 @@ int pyexec_friendly_repl(void) {
 
     for (;;) {
     input_restart:
-
-        #if MICROPY_HW_ENABLE_USB
-        if (usb_vcp_is_enabled()) {
-            // If the user gets to here and interrupts are disabled then
-            // they'll never see the prompt, traceback etc. The USB REPL needs
-            // interrupts to be enabled or no transfers occur. So we try to
-            // do the user a favor and re-enable interrupts.
-            if (query_irq() == IRQ_STATE_DISABLED) {
-                enable_irq(IRQ_STATE_ENABLED);
-                mp_hal_stdout_tx_str("MPY: enabling IRQs\r\n");
-            }
-        }
-        #endif
-
         // If the GC is locked at this point there is no way out except a reset,
         // so force the GC to be unlocked to help the user debug what went wrong.
         if (MP_STATE_THREAD(gc_lock_depth) != 0) {
@@ -705,6 +754,7 @@ int pyexec_friendly_repl(void) {
             mp_hal_stdout_tx_str("\r\n");
             vstr_clear(&line);
             pyexec_mode_kind = PYEXEC_MODE_RAW_REPL;
+            mp_hal_stdio_mode_orig();
             return 0;
         } else if (ret == CHAR_CTRL_B) {
             // reset friendly REPL
@@ -718,6 +768,7 @@ int pyexec_friendly_repl(void) {
             // exit for a soft reset
             mp_hal_stdout_tx_str("\r\n");
             vstr_clear(&line);
+            mp_hal_stdio_mode_orig();
             return PYEXEC_FORCED_EXIT;
         } else if (ret == CHAR_CTRL_E) {
             // paste mode
@@ -762,11 +813,14 @@ int pyexec_friendly_repl(void) {
             }
         }
 
+        // Switch to original terminal mode to execute code, eg to support keyboard interrupt (SIGINT).
+        mp_hal_stdio_mode_orig();
         // CIRCUITPY-CHANGE: add last arg
         ret = parse_compile_execute(&line, parse_input_kind, EXEC_FLAG_ALLOW_DEBUGGING | EXEC_FLAG_IS_REPL | EXEC_FLAG_SOURCE_IS_VSTR, NULL);
         if (ret & (PYEXEC_FORCED_EXIT | PYEXEC_RELOAD)) {
             return ret;
         }
+        mp_hal_stdio_mode_raw();
     }
 }
 
diff --git a/shared/runtime/pyexec.h b/shared/runtime/pyexec.h
index 55a3003791cb2..9d1ef2a3cb029 100644
--- a/shared/runtime/pyexec.h
+++ b/shared/runtime/pyexec.h
@@ -51,6 +51,17 @@ extern pyexec_mode_kind_t pyexec_mode_kind;
 #define PYEXEC_DEEP_SLEEP  (0x400)
 #define PYEXEC_RELOAD      (0x800)
 
+#if MICROPY_PYEXEC_ENABLE_EXIT_CODE_HANDLING
+#define PYEXEC_NORMAL_EXIT (0)
+#define PYEXEC_UNHANDLED_EXCEPTION (1)
+#define PYEXEC_KEYBOARD_INTERRUPT (128 + 2) // same as SIG INT exit code
+#define PYEXEC_ABORT (128 + 9)              // same as SIG KILL exit code
+#else
+#define PYEXEC_NORMAL_EXIT (1)
+#define PYEXEC_UNHANDLED_EXCEPTION (0)
+#define PYEXEC_ABORT PYEXEC_FORCED_EXIT
+#endif
+
 int pyexec_raw_repl(void);
 int pyexec_friendly_repl(void);
 // CIRCUITPY-CHANGE: result out argument
diff --git a/shared/timeutils/timeutils.c b/shared/timeutils/timeutils.c
index 4282a0178dd6e..0c6916e06ddd6 100644
--- a/shared/timeutils/timeutils.c
+++ b/shared/timeutils/timeutils.c
@@ -29,12 +29,27 @@
 
 #include "shared/timeutils/timeutils.h"
 
-// LEAPOCH corresponds to 2000-03-01, which is a mod-400 year, immediately
-// after Feb 29. We calculate seconds as a signed integer relative to that.
+// To maintain reasonable compatibility with CPython on embedded systems,
+// and avoid breaking anytime soon, timeutils functions are required to
+// work properly between 1970 and 2099 on all ports.
 //
-// Our timebase is relative to 2000-01-01.
-
-#define LEAPOCH ((31 + 29) * 86400)
+// During that period of time, leap years occur every 4 years without
+// exception, so we can keep the code short for 32 bit machines.
+
+// The last leap day before the required period is Feb 29, 1968.
+// This is the number of days to add to get to that date.
+#define PREV_LEAP_DAY  ((mp_uint_t)(365 + 366 - (31 + 29)))
+#define PREV_LEAP_YEAR 1968
+
+// On ports where either MICROPY_TIME_SUPPORT_Y2100_AND_BEYOND or
+// MICROPY_TIME_SUPPORT_Y1969_AND_BEFORE is enabled, we include extra
+// code to support leap years outside of the 'easy' period.
+// Computation is then made based on 1600 (a mod-400 year).
+// This is the number of days between 1600 and 1968.
+#define QC_BASE_DAY  134409
+#define QC_LEAP_YEAR 1600
+// This is the number of leap days between 1600 and 1970
+#define QC_LEAP_DAYS 89
 
 #define DAYS_PER_400Y (365 * 400 + 97)
 #define DAYS_PER_100Y (365 * 100 + 24)
@@ -42,8 +57,20 @@
 
 static const uint16_t days_since_jan1[] = { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 };
 
+// type used internally to count small integers relative to epoch
+// (using uint when possible produces smaller code on some platforms)
+#if MICROPY_TIME_SUPPORT_Y1969_AND_BEFORE
+typedef mp_int_t relint_t;
+#else
+typedef mp_uint_t relint_t;
+#endif
+
 bool timeutils_is_leap_year(mp_uint_t year) {
+    #if MICROPY_TIME_SUPPORT_Y2100_AND_BEYOND || MICROPY_TIME_SUPPORT_Y1969_AND_BEFORE
     return (year % 4 == 0 && year % 100 != 0) || year % 400 == 0;
+    #else
+    return year % 4 == 0;
+    #endif
 }
 
 // month is one based
@@ -65,67 +92,67 @@ mp_uint_t timeutils_year_day(mp_uint_t year, mp_uint_t month, mp_uint_t date) {
     return yday;
 }
 
-void timeutils_seconds_since_2000_to_struct_time(mp_uint_t t, timeutils_struct_time_t *tm) {
-    // The following algorithm was adapted from musl's __secs_to_tm and adapted
-    // for differences in MicroPython's timebase.
-
-    mp_int_t seconds = t - LEAPOCH;
+void timeutils_seconds_since_1970_to_struct_time(timeutils_timestamp_t seconds, timeutils_struct_time_t *tm) {
+    // The following algorithm was inspired from musl's __secs_to_tm
+    // and simplified to reduce code footprint in the simple case
 
-    mp_int_t days = seconds / 86400;
+    relint_t days = seconds / 86400;
     seconds %= 86400;
+    #if MICROPY_TIME_SUPPORT_Y1969_AND_BEFORE
     if (seconds < 0) {
         seconds += 86400;
         days -= 1;
     }
+    #endif
     tm->tm_hour = seconds / 3600;
     tm->tm_min = seconds / 60 % 60;
     tm->tm_sec = seconds % 60;
 
-    mp_int_t wday = (days + 2) % 7;   // Mar 1, 2000 was a Wednesday (2)
+    relint_t wday = (days + 3) % 7;   // Jan 1, 1970 was a Thursday (3)
+    #if MICROPY_TIME_SUPPORT_Y1969_AND_BEFORE
     if (wday < 0) {
         wday += 7;
     }
+    #endif
     tm->tm_wday = wday;
 
-    mp_int_t qc_cycles = days / DAYS_PER_400Y;
+    days += PREV_LEAP_DAY;
+
+    #if MICROPY_TIME_SUPPORT_Y2100_AND_BEYOND || MICROPY_TIME_SUPPORT_Y1969_AND_BEFORE
+    // rebase day to the oldest supported date (=> always positive)
+    mp_uint_t base_year = QC_LEAP_YEAR;
+    days += QC_BASE_DAY;
+    mp_uint_t qc_cycles = days / DAYS_PER_400Y;
     days %= DAYS_PER_400Y;
-    if (days < 0) {
-        days += DAYS_PER_400Y;
-        qc_cycles--;
-    }
-    mp_int_t c_cycles = days / DAYS_PER_100Y;
+    mp_uint_t c_cycles = days / DAYS_PER_100Y;
     if (c_cycles == 4) {
         c_cycles--;
     }
     days -= (c_cycles * DAYS_PER_100Y);
-
-    mp_int_t q_cycles = days / DAYS_PER_4Y;
+    #else
+    mp_uint_t base_year = PREV_LEAP_YEAR;
+    mp_uint_t qc_cycles = 0;
+    mp_uint_t c_cycles = 0;
+    #endif
+
+    mp_uint_t q_cycles = days / DAYS_PER_4Y;
+    #if MICROPY_TIME_SUPPORT_Y2100_AND_BEYOND || MICROPY_TIME_SUPPORT_Y1969_AND_BEFORE
     if (q_cycles == 25) {
         q_cycles--;
     }
+    #endif
     days -= q_cycles * DAYS_PER_4Y;
 
-    mp_int_t years = days / 365;
+    relint_t years = days / 365;
     if (years == 4) {
         years--;
     }
     days -= (years * 365);
 
-    /* We will compute tm_yday at the very end
-    mp_int_t leap = !years && (q_cycles || !c_cycles);
-
-    tm->tm_yday = days + 31 + 28 + leap;
-    if (tm->tm_yday >= 365 + leap) {
-        tm->tm_yday -= 365 + leap;
-    }
-
-    tm->tm_yday++;  // Make one based
-    */
-
-    tm->tm_year = 2000 + years + 4 * q_cycles + 100 * c_cycles + 400 * qc_cycles;
+    tm->tm_year = base_year + years + 4 * q_cycles + 100 * c_cycles + 400 * qc_cycles;
 
     // Note: days_in_month[0] corresponds to March
-    static const int8_t days_in_month[] = {31, 30, 31, 30, 31, 31, 30, 31, 30, 31, 31, 29};
+    static const uint8_t days_in_month[] = {31, 30, 31, 30, 31, 31, 30, 31, 30, 31, 31, 29};
 
     mp_int_t month;
     for (month = 0; days_in_month[month] <= days; month++) {
@@ -144,21 +171,28 @@ void timeutils_seconds_since_2000_to_struct_time(mp_uint_t t, timeutils_struct_t
 }
 
 // returns the number of seconds, as an integer, since 2000-01-01
-mp_uint_t timeutils_seconds_since_2000(mp_uint_t year, mp_uint_t month,
+timeutils_timestamp_t timeutils_seconds_since_1970(mp_uint_t year, mp_uint_t month,
     mp_uint_t date, mp_uint_t hour, mp_uint_t minute, mp_uint_t second) {
-    return
-        second
-        + minute * 60
-        + hour * 3600
-        + (timeutils_year_day(year, month, date) - 1
-            + ((year - 2000 + 3) / 4) // add a day each 4 years starting with 2001
-            - ((year - 2000 + 99) / 100) // subtract a day each 100 years starting with 2001
-            + ((year - 2000 + 399) / 400) // add a day each 400 years starting with 2001
-            ) * 86400
-        + (year - 2000) * 31536000;
+    #if MICROPY_TIME_SUPPORT_Y2100_AND_BEYOND || MICROPY_TIME_SUPPORT_Y1969_AND_BEFORE
+    mp_uint_t ref_year = QC_LEAP_YEAR;
+    #else
+    mp_uint_t ref_year = PREV_LEAP_YEAR;
+    #endif
+    timeutils_timestamp_t res;
+    res = ((relint_t)year - 1970) * 365;
+    res += (year - (ref_year + 1)) / 4; // add a day each 4 years
+    #if MICROPY_TIME_SUPPORT_Y2100_AND_BEYOND || MICROPY_TIME_SUPPORT_Y1969_AND_BEFORE
+    res -= (year - (ref_year + 1)) / 100; // subtract a day each 100 years
+    res += (year - (ref_year + 1)) / 400; // add a day each 400 years
+    res -= QC_LEAP_DAYS;
+    #endif
+    res += timeutils_year_day(year, month, date) - 1;
+    res *= 86400;
+    res += hour * 3600 + minute * 60 + second;
+    return res;
 }
 
-mp_uint_t timeutils_mktime_2000(mp_uint_t year, mp_int_t month, mp_int_t mday,
+timeutils_timestamp_t timeutils_mktime_1970(mp_uint_t year, mp_int_t month, mp_int_t mday,
     mp_int_t hours, mp_int_t minutes, mp_int_t seconds) {
 
     // Normalize the tuple. This allows things like:
@@ -211,12 +245,16 @@ mp_uint_t timeutils_mktime_2000(mp_uint_t year, mp_int_t month, mp_int_t mday,
             year++;
         }
     }
-    return timeutils_seconds_since_2000(year, month, mday, hours, minutes, seconds);
+    return timeutils_seconds_since_1970(year, month, mday, hours, minutes, seconds);
 }
 
 // Calculate the weekday from the date.
 // The result is zero based with 0 = Monday.
 // by Michael Keith and Tom Craver, 1990.
 int timeutils_calc_weekday(int y, int m, int d) {
-    return ((d += m < 3 ? y-- : y - 2, 23 * m / 9 + d + 4 + y / 4 - y / 100 + y / 400) + 6) % 7;
+    return ((d += m < 3 ? y-- : y - 2, 23 * m / 9 + d + 4 + y / 4
+        #if MICROPY_TIME_SUPPORT_Y2100_AND_BEYOND || MICROPY_TIME_SUPPORT_Y1969_AND_BEFORE
+        - y / 100 + y / 400
+        #endif
+        ) + 6) % 7;
 }
diff --git a/shared/timeutils/timeutils.h b/shared/timeutils/timeutils.h
index b41903d3b2777..35356b462aafc 100644
--- a/shared/timeutils/timeutils.h
+++ b/shared/timeutils/timeutils.h
@@ -27,12 +27,23 @@
 #ifndef MICROPY_INCLUDED_LIB_TIMEUTILS_TIMEUTILS_H
 #define MICROPY_INCLUDED_LIB_TIMEUTILS_TIMEUTILS_H
 
-// CIRCUITPY-CHANGE: MICROPY_EPOCH_IS_1970
-#include "mpconfigport.h"
+#include "py/obj.h"
+#if MICROPY_PY_BUILTINS_FLOAT && MICROPY_FLOAT_IMPL == MICROPY_FLOAT_IMPL_DOUBLE
+#include <math.h> // required for trunc()
+#endif
+
+// `timeutils_timestamp_t` is the type used internally by timeutils to
+// represent timestamps, and is always referenced to 1970.
+// It may not match the platform-specific `mp_timestamp_t`.
+#if MICROPY_TIME_SUPPORT_Y2100_AND_BEYOND || MICROPY_TIME_SUPPORT_Y1969_AND_BEFORE
+typedef long long timeutils_timestamp_t;
+#else
+typedef mp_uint_t timeutils_timestamp_t;
+#endif
 
 // The number of seconds between 1970/1/1 and 2000/1/1 is calculated using:
 // time.mktime((2000,1,1,0,0,0,0,0,0)) - time.mktime((1970,1,1,0,0,0,0,0,0))
-#define TIMEUTILS_SECONDS_1970_TO_2000 (946684800ULL)
+#define TIMEUTILS_SECONDS_1970_TO_2000 (946684800LL)
 
 typedef struct _timeutils_struct_time_t {
     uint16_t tm_year;       // i.e. 2014
@@ -48,66 +59,116 @@ typedef struct _timeutils_struct_time_t {
 bool timeutils_is_leap_year(mp_uint_t year);
 mp_uint_t timeutils_days_in_month(mp_uint_t year, mp_uint_t month);
 mp_uint_t timeutils_year_day(mp_uint_t year, mp_uint_t month, mp_uint_t date);
+int timeutils_calc_weekday(int y, int m, int d);
 
-void timeutils_seconds_since_2000_to_struct_time(mp_uint_t t,
+void timeutils_seconds_since_1970_to_struct_time(timeutils_timestamp_t t,
     timeutils_struct_time_t *tm);
 
 // Year is absolute, month/date are 1-based, hour/minute/second are 0-based.
-mp_uint_t timeutils_seconds_since_2000(mp_uint_t year, mp_uint_t month,
+timeutils_timestamp_t timeutils_seconds_since_1970(mp_uint_t year, mp_uint_t month,
     mp_uint_t date, mp_uint_t hour, mp_uint_t minute, mp_uint_t second);
 
 // Year is absolute, month/mday are 1-based, hours/minutes/seconds are 0-based.
-mp_uint_t timeutils_mktime_2000(mp_uint_t year, mp_int_t month, mp_int_t mday,
+timeutils_timestamp_t timeutils_mktime_1970(mp_uint_t year, mp_int_t month, mp_int_t mday,
     mp_int_t hours, mp_int_t minutes, mp_int_t seconds);
 
+static inline mp_timestamp_t timeutils_obj_get_timestamp(mp_obj_t o_in) {
+    #if MICROPY_PY_BUILTINS_FLOAT && MICROPY_FLOAT_IMPL == MICROPY_FLOAT_IMPL_DOUBLE
+    mp_float_t val = mp_obj_get_float(o_in);
+    return (mp_timestamp_t)MICROPY_FLOAT_C_FUN(trunc)(val);
+    #elif MICROPY_TIMESTAMP_IMPL == MICROPY_TIMESTAMP_IMPL_UINT
+    return mp_obj_get_uint(o_in);
+    #else
+    return mp_obj_get_ll(o_in);
+    #endif
+}
+
+static inline mp_obj_t timeutils_obj_from_timestamp(mp_timestamp_t t) {
+    #if MICROPY_TIMESTAMP_IMPL == MICROPY_TIMESTAMP_IMPL_UINT
+    return mp_obj_new_int_from_uint(t);
+    #else
+    return mp_obj_new_int_from_ll(t);
+    #endif
+}
+
+static inline void timeutils_seconds_since_2000_to_struct_time(mp_timestamp_t t, timeutils_struct_time_t *tm) {
+    timeutils_seconds_since_1970_to_struct_time((timeutils_timestamp_t)(t + TIMEUTILS_SECONDS_1970_TO_2000), tm);
+}
+
+// Year is absolute, month/date are 1-based, hour/minute/second are 0-based.
+static inline mp_timestamp_t timeutils_seconds_since_2000(mp_uint_t year, mp_uint_t month, mp_uint_t date,
+    mp_uint_t hour, mp_uint_t minute, mp_uint_t second) {
+    return (mp_timestamp_t)timeutils_seconds_since_1970(year, month, date, hour, minute, second) - TIMEUTILS_SECONDS_1970_TO_2000;
+}
+
+// Year is absolute, month/mday are 1-based, hours/minutes/seconds are 0-based.
+static inline mp_timestamp_t timeutils_mktime_2000(mp_uint_t year, mp_int_t month, mp_int_t mday,
+    mp_int_t hours, mp_int_t minutes, mp_int_t seconds) {
+    return (mp_timestamp_t)timeutils_mktime_1970(year, month, mday, hours, minutes, seconds) - TIMEUTILS_SECONDS_1970_TO_2000;
+}
+
+
 // Select the Epoch used by the port.
 #if MICROPY_EPOCH_IS_1970
 
-static inline void timeutils_seconds_since_epoch_to_struct_time(uint64_t t, timeutils_struct_time_t *tm) {
-    // TODO this will give incorrect results for dates before 2000/1/1
-    timeutils_seconds_since_2000_to_struct_time((mp_uint_t)(t - TIMEUTILS_SECONDS_1970_TO_2000), tm);
+static inline void timeutils_seconds_since_epoch_to_struct_time(mp_timestamp_t t, timeutils_struct_time_t *tm) {
+    timeutils_seconds_since_1970_to_struct_time(t, tm);
+}
+
+// Year is absolute, month/date are 1-based, hour/minute/second are 0-based.
+static inline mp_timestamp_t timeutils_seconds_since_epoch(mp_uint_t year, mp_uint_t month, mp_uint_t date,
+    mp_uint_t hour, mp_uint_t minute, mp_uint_t second) {
+    return timeutils_seconds_since_1970(year, month, date, hour, minute, second);
 }
 
 // Year is absolute, month/mday are 1-based, hours/minutes/seconds are 0-based.
-static inline uint64_t timeutils_mktime(mp_uint_t year, mp_int_t month, mp_int_t mday, mp_int_t hours, mp_int_t minutes, mp_int_t seconds) {
-    return timeutils_mktime_2000(year, month, mday, hours, minutes, seconds) + TIMEUTILS_SECONDS_1970_TO_2000;
+static inline mp_timestamp_t timeutils_mktime(mp_uint_t year, mp_int_t month, mp_int_t mday,
+    mp_int_t hours, mp_int_t minutes, mp_int_t seconds) {
+    return timeutils_mktime_1970(year, month, mday, hours, minutes, seconds);
 }
 
-// Year is absolute, month/date are 1-based, hour/minute/second are 0-based.
-static inline uint64_t timeutils_seconds_since_epoch(mp_uint_t year, mp_uint_t month,
-    mp_uint_t date, mp_uint_t hour, mp_uint_t minute, mp_uint_t second) {
-    // TODO this will give incorrect results for dates before 2000/1/1
-    return timeutils_seconds_since_2000(year, month, date, hour, minute, second) + TIMEUTILS_SECONDS_1970_TO_2000;
+static inline mp_timestamp_t timeutils_seconds_since_epoch_from_nanoseconds_since_1970(int64_t ns) {
+    return (mp_timestamp_t)(ns / 1000000000LL);
 }
 
-static inline mp_uint_t timeutils_seconds_since_epoch_from_nanoseconds_since_1970(uint64_t ns) {
-    return (mp_uint_t)(ns / 1000000000ULL);
+static inline int64_t timeutils_seconds_since_epoch_to_nanoseconds_since_1970(mp_timestamp_t s) {
+    return (int64_t)s * 1000000000LL;
 }
 
-static inline uint64_t timeutils_nanoseconds_since_epoch_to_nanoseconds_since_1970(uint64_t ns) {
+static inline int64_t timeutils_nanoseconds_since_epoch_to_nanoseconds_since_1970(int64_t ns) {
     return ns;
 }
 
 #else // Epoch is 2000
 
-#define timeutils_seconds_since_epoch_to_struct_time timeutils_seconds_since_2000_to_struct_time
-#define timeutils_seconds_since_epoch timeutils_seconds_since_2000
-#define timeutils_mktime timeutils_mktime_2000
+static inline void timeutils_seconds_since_epoch_to_struct_time(mp_timestamp_t t, timeutils_struct_time_t *tm) {
+    timeutils_seconds_since_2000_to_struct_time(t, tm);
+}
 
-static inline uint64_t timeutils_seconds_since_epoch_to_nanoseconds_since_1970(mp_uint_t s) {
-    return ((uint64_t)s + TIMEUTILS_SECONDS_1970_TO_2000) * 1000000000ULL;
+// Year is absolute, month/date are 1-based, hour/minute/second are 0-based.
+static inline mp_timestamp_t timeutils_seconds_since_epoch(mp_uint_t year, mp_uint_t month, mp_uint_t date,
+    mp_uint_t hour, mp_uint_t minute, mp_uint_t second) {
+    return timeutils_seconds_since_2000(year, month, date, hour, minute, second);
 }
 
-static inline mp_uint_t timeutils_seconds_since_epoch_from_nanoseconds_since_1970(uint64_t ns) {
-    return ns / 1000000000ULL - TIMEUTILS_SECONDS_1970_TO_2000;
+// Year is absolute, month/mday are 1-based, hours/minutes/seconds are 0-based.
+static inline mp_timestamp_t timeutils_mktime(mp_uint_t year, mp_int_t month, mp_int_t mday,
+    mp_int_t hours, mp_int_t minutes, mp_int_t seconds) {
+    return timeutils_mktime_2000(year, month, mday, hours, minutes, seconds);
+}
+
+static inline mp_timestamp_t timeutils_seconds_since_epoch_from_nanoseconds_since_1970(int64_t ns) {
+    return (mp_timestamp_t)(ns / 1000000000LL - TIMEUTILS_SECONDS_1970_TO_2000);
+}
+
+static inline int64_t timeutils_seconds_since_epoch_to_nanoseconds_since_1970(mp_timestamp_t s) {
+    return ((int64_t)s + TIMEUTILS_SECONDS_1970_TO_2000) * 1000000000LL;
 }
 
 static inline int64_t timeutils_nanoseconds_since_epoch_to_nanoseconds_since_1970(int64_t ns) {
-    return ns + TIMEUTILS_SECONDS_1970_TO_2000 * 1000000000ULL;
+    return ns + TIMEUTILS_SECONDS_1970_TO_2000 * 1000000000LL;
 }
 
 #endif
 
-int timeutils_calc_weekday(int y, int m, int d);
-
 #endif // MICROPY_INCLUDED_LIB_TIMEUTILS_TIMEUTILS_H
diff --git a/supervisor/port.h b/supervisor/port.h
index 7e2463032f74f..f0e13e167cce1 100644
--- a/supervisor/port.h
+++ b/supervisor/port.h
@@ -24,13 +24,13 @@ extern uint32_t _ebss;
 safe_mode_t port_init(void);
 
 // Reset the microcontroller completely.
-void reset_cpu(void) NORETURN;
+void reset_cpu(void) MP_NORETURN;
 
 // Reset the microcontroller state.
 void reset_port(void);
 
 // Reset to the bootloader
-void reset_to_bootloader(void) NORETURN;
+void reset_to_bootloader(void) MP_NORETURN;
 
 // Get stack limit address
 uint32_t *port_stack_get_limit(void);
diff --git a/supervisor/shared/safe_mode.h b/supervisor/shared/safe_mode.h
index 8f4037cbe20c3..87f65d867ea62 100644
--- a/supervisor/shared/safe_mode.h
+++ b/supervisor/shared/safe_mode.h
@@ -38,6 +38,6 @@ void set_safe_mode(safe_mode_t safe_mode);
 safe_mode_t wait_for_safe_mode_reset(void);
 
 void safe_mode_on_next_reset(safe_mode_t reason);
-void reset_into_safe_mode(safe_mode_t reason) NORETURN;
+void reset_into_safe_mode(safe_mode_t reason) MP_NORETURN;
 
 void print_safe_mode_message(safe_mode_t reason);
diff --git a/tests/README.md b/tests/README.md
index 21e14eee5e128..534e7e0a05972 100644
--- a/tests/README.md
+++ b/tests/README.md
@@ -1,6 +1,7 @@
 # MicroPython Test Suite
 
-This directory contains tests for most parts of MicroPython.
+This directory contains tests for most parts of MicroPython.  To run it you will need
+CPython 3.8.2 or newer, which is used to validate MicroPython's behaviour.
 
 To run all stable tests, run the "run-tests.py" script in this directory.  By default
 that will run the test suite against the unix port of MicroPython.
@@ -67,16 +68,14 @@ for a full list of command line options.
 
 ### Benchmarking a target
 
-To run tests on a firmware target using `pyboard.py`, run the command line like
+To run tests on a firmware target using a serial port, run the command line like
 this:
 
 ```
-./run-perfbench.py -p -d /dev/ttyACM0 168 100
+./run-perfbench.py -t /dev/ttyACM0 168 100
 ```
 
-* `-p` indicates running on a remote target via pyboard.py, not the host.
-* `-d PORTNAME` is the serial port, `/dev/ttyACM0` is the default if not
-  provided.
+* `-t PORTNAME` is the serial port to use (and it supports shorthand like `a0`).
 * `168` is value `N`, the approximate CPU frequency in MHz (in this case Pyboard
   V1.1 is 168MHz). It's possible to choose other values as well: lower values
   like `10` will run much the tests much quicker, higher values like `1000` will
@@ -136,11 +135,11 @@ Usually you want to know if something is faster or slower than a reference. To
 do this, copy the output of each `run-perfbench.py` run to a text file.
 
 This can be done multiple ways, but one way on Linux/macOS is with the `tee`
-utility: `./run-perfbench.py -p 168 100 | tee pyb-run1.txt`
+utility: `./run-perfbench.py -t a0 168 100 | tee pyb-run1.txt`
 
 Once you have two files with output from two different runs (maybe with
 different code or configuration), compare the runtimes with `./run-perfbench.py
--t pybv-run1.txt pybv-run2.txt` or compare scores with `./run-perfbench.py -s
+-m pybv-run1.txt pybv-run2.txt` or compare scores with `./run-perfbench.py -s
 pybv-run1.txt pybv-run2.txt`:
 
 ```
@@ -204,6 +203,18 @@ internal_bench/bytebuf:
 1 tests performed (3 individual testcases)
 ```
 
+## Serial reliability and performance test
+
+Serial port reliability and performance can be tested using the `serial_test.py` script.
+Pass the name of the port to test against, for example:
+
+    $ ./serial_test.py -t /dev/ttyACM0
+
+If no port is specified then `/dev/ttyACM0` is used as the default.
+
+The test will send data out to the target, and receive data from the target, in various
+chunk sizes.  The throughput of the serial connection will be reported for each sub-test.
+
 ## Test key/certificates
 
 SSL/TLS tests in `multi_net` and `net_inet` use self-signed key/cert pairs
diff --git a/tests/basics/annotate_var.py.exp b/tests/basics/annotate_var.py.exp
deleted file mode 100644
index 9b6536e966b0e..0000000000000
--- a/tests/basics/annotate_var.py.exp
+++ /dev/null
@@ -1,5 +0,0 @@
-False
-1
-(1, 2)
-NameError
-1
diff --git a/tests/basics/array_add.py b/tests/basics/array_add.py
index 76ce59f761e06..e78615541c3cb 100644
--- a/tests/basics/array_add.py
+++ b/tests/basics/array_add.py
@@ -14,3 +14,9 @@
 
 a1.extend(array.array('I', [5]))
 print(a1)
+
+a1.extend([6, 7])
+print(a1)
+
+a1.extend(i for i in (8, 9))
+print(a1)
diff --git a/tests/basics/assign_expr.py.exp b/tests/basics/assign_expr.py.exp
deleted file mode 100644
index 47da56b80d47b..0000000000000
--- a/tests/basics/assign_expr.py.exp
+++ /dev/null
@@ -1,16 +0,0 @@
-4
-True
-2
-4 5
-5
-1 5 5
-5
-2 1
-1 0
-any True
-8
-123
-any True
-8
-[(1, 0), (2, 2), (3, 6), (4, 12)]
-4
diff --git a/tests/basics/assign_expr_scope.py.exp b/tests/basics/assign_expr_scope.py.exp
deleted file mode 100644
index 5c780b382215f..0000000000000
--- a/tests/basics/assign_expr_scope.py.exp
+++ /dev/null
@@ -1,23 +0,0 @@
-scope0
-1
-None
-scope1
-[1]
-1
-None
-scope2
-[0, 1]
-1
-1
-scope3
-[0, 1]
-None
-None
-scope4
-[0, 1]
-1
-1
-scope5
-[0, 1]
-1
-None
diff --git a/tests/basics/async_await.py.exp b/tests/basics/async_await.py.exp
deleted file mode 100644
index b51c388a9339e..0000000000000
--- a/tests/basics/async_await.py.exp
+++ /dev/null
@@ -1,32 +0,0 @@
-4
-3
-2
-1
-0
-0
-1
-0
-0
-2
-1
-0
-0
-1
-0
-0
-3
-2
-1
-0
-0
-1
-0
-0
-2
-1
-0
-0
-1
-0
-0
-finished
diff --git a/tests/basics/async_await2.py.exp b/tests/basics/async_await2.py.exp
deleted file mode 100644
index fc9ff0aa535fc..0000000000000
--- a/tests/basics/async_await2.py.exp
+++ /dev/null
@@ -1,5 +0,0 @@
-wait value: 1
-return from send: message from wait(1)
-wait got back: message from main
-x = 100
-got StopIteration
diff --git a/tests/basics/async_def.py.exp b/tests/basics/async_def.py.exp
deleted file mode 100644
index f555ace99ab20..0000000000000
--- a/tests/basics/async_def.py.exp
+++ /dev/null
@@ -1,3 +0,0 @@
-decorator
-foo
-StopIteration
diff --git a/tests/basics/async_for.py.exp b/tests/basics/async_for.py.exp
deleted file mode 100644
index 6f59979c065de..0000000000000
--- a/tests/basics/async_for.py.exp
+++ /dev/null
@@ -1,51 +0,0 @@
-== start ==
-init
-aiter
-init
-anext
-a
-anext
-b
-anext
-c
-anext
-== finish ==
-== start ==
-init
-aiter
-init
-anext
-d
-anext
-e
-anext
-f
-anext
-AsyncIteratorWrapper-def
-== finish ==
-init
-== start ==
-aiter
-init
-anext
-g
-anext
-h
-anext
-i
-anext
-AsyncIteratorWrapper-ghi
-== finish ==
-init
-== start ==
-aiter
-init
-anext
-j
-anext
-k
-anext
-l
-anext
-AsyncIteratorWrapper-jkl
-== finish ==
diff --git a/tests/basics/async_for2.py b/tests/basics/async_for2.py
index bbdb02c49b209..82232d52fc2a1 100644
--- a/tests/basics/async_for2.py
+++ b/tests/basics/async_for2.py
@@ -1,7 +1,7 @@
 # test waiting within "async for" __anext__ function
 
 # CIRCUITPY-CHANGE
-# uPy allows normal generators to be awaitables.
+# MicroPython allows normal generators to be awaitables.
 # CircuitPython does not.
 # In CircuitPython you need to have an __await__ method on an awaitable like in CPython;
 #  and like in CPython, generators do not have __await__.
diff --git a/tests/basics/async_for2.py.exp b/tests/basics/async_for2.py.exp
deleted file mode 100644
index 52bbe90c85376..0000000000000
--- a/tests/basics/async_for2.py.exp
+++ /dev/null
@@ -1,32 +0,0 @@
-init
-aiter
-anext
-f start: 20
-coro yielded: 21
-coro yielded: 22
-f returned: 23
-x 0
-anext
-f start: 20
-coro yielded: 21
-coro yielded: 22
-f returned: 23
-x 1
-anext
-f start: 20
-coro yielded: 21
-coro yielded: 22
-f returned: 23
-x 2
-anext
-f start: 20
-coro yielded: 21
-coro yielded: 22
-f returned: 23
-x 3
-anext
-f start: 20
-coro yielded: 21
-coro yielded: 22
-f returned: 23
-finished
diff --git a/tests/basics/async_syntaxerror.py.exp b/tests/basics/async_syntaxerror.py.exp
deleted file mode 100644
index 5275689b41383..0000000000000
--- a/tests/basics/async_syntaxerror.py.exp
+++ /dev/null
@@ -1,2 +0,0 @@
-SyntaxError
-SyntaxError
diff --git a/tests/basics/async_with.py.exp b/tests/basics/async_with.py.exp
deleted file mode 100644
index 6bbf84cb4b52c..0000000000000
--- a/tests/basics/async_with.py.exp
+++ /dev/null
@@ -1,11 +0,0 @@
-enter
-body
-exit None None
-finished
-enter
-1
-exit <class 'ValueError'> error
-ValueError
-enter
-exit <class 'BaseException'> 
-BaseException
diff --git a/tests/basics/async_with2.py b/tests/basics/async_with2.py
index 5bac38236fe4a..b18fa6bdee106 100644
--- a/tests/basics/async_with2.py
+++ b/tests/basics/async_with2.py
@@ -1,7 +1,7 @@
 # test waiting within async with enter/exit functions
 
 # CIRCUITPY-CHANGE
-# uPy allows normal generators to be awaitables.
+# MicroPython allows normal generators to be awaitables.
 # CircuitPython does not.
 # In CircuitPython you need to have an __await__ method on an awaitable like in CPython;
 #  and like in CPython, generators do not have __await__.
diff --git a/tests/basics/async_with2.py.exp b/tests/basics/async_with2.py.exp
deleted file mode 100644
index 76b173b4c24a7..0000000000000
--- a/tests/basics/async_with2.py.exp
+++ /dev/null
@@ -1,17 +0,0 @@
-enter
-f start: 10
-coro yielded: 11
-coro yielded: 12
-f returned: 13
-body start
-f start: 30
-coro yielded: 31
-coro yielded: 32
-body f returned: 33
-body end
-exit None None
-f start: 20
-coro yielded: 21
-coro yielded: 22
-f returned: 23
-finished
diff --git a/tests/basics/async_with_break.py.exp b/tests/basics/async_with_break.py.exp
deleted file mode 100644
index d077a88fad0e4..0000000000000
--- a/tests/basics/async_with_break.py.exp
+++ /dev/null
@@ -1,15 +0,0 @@
-enter
-body
-exit None None
-finished
-enter
-body
-exit None None
-finally
-finished
-enter
-body
-exit None None
-finally inner
-finally outer
-finished
diff --git a/tests/basics/async_with_return.py.exp b/tests/basics/async_with_return.py.exp
deleted file mode 100644
index d077a88fad0e4..0000000000000
--- a/tests/basics/async_with_return.py.exp
+++ /dev/null
@@ -1,15 +0,0 @@
-enter
-body
-exit None None
-finished
-enter
-body
-exit None None
-finally
-finished
-enter
-body
-exit None None
-finally inner
-finally outer
-finished
diff --git a/tests/basics/attrtuple2.py b/tests/basics/attrtuple2.py
new file mode 100644
index 0000000000000..081d24b6ae92c
--- /dev/null
+++ b/tests/basics/attrtuple2.py
@@ -0,0 +1,25 @@
+# test os.uname() attrtuple, if available
+try:
+    import os
+except ImportError:
+    print("SKIP")
+    raise SystemExit
+
+try:
+    u = os.uname()
+except AttributeError:
+    print("SKIP")
+    raise SystemExit
+
+# test printing of attrtuple
+print(str(u).find("machine=") > 0)
+
+# test read attr
+print(isinstance(u.machine, str))
+
+# test str modulo operator for attrtuple
+impl_str = ("%s " * len(u)) % u
+test_str = ""
+for val in u:
+    test_str += val + " "
+print(impl_str == test_str)
diff --git a/tests/basics/boundmeth1.py b/tests/basics/boundmeth1.py
index fe1b454688d64..9f08d9bbb259b 100644
--- a/tests/basics/boundmeth1.py
+++ b/tests/basics/boundmeth1.py
@@ -1,6 +1,6 @@
 # tests basics of bound methods
 
-# uPy and CPython differ when printing a bound method, so just print the type
+# MicroPython and CPython differ when printing a bound method, so just print the type
 print(type(repr([].append)))
 
 
diff --git a/tests/basics/builtin_help.py b/tests/basics/builtin_help.py
index 6ec39653fe993..3d4e4f26bd2bb 100644
--- a/tests/basics/builtin_help.py
+++ b/tests/basics/builtin_help.py
@@ -14,4 +14,10 @@
 help(micropython) # help for a module
 help('modules') # list available modules
 
+class A:
+    x = 1
+    y = 2
+    del x
+help(A)
+
 print('done') # so last bit of output is predictable
diff --git a/tests/basics/builtin_pow3_intbig.py b/tests/basics/builtin_pow3_intbig.py
index bedc8b36b7edd..41d2acbc0cc75 100644
--- a/tests/basics/builtin_pow3_intbig.py
+++ b/tests/basics/builtin_pow3_intbig.py
@@ -20,3 +20,8 @@
 print(hex(pow(y, x-1, x))) # Should be 1, since x is prime
 print(hex(pow(y, y-1, x))) # Should be a 'big value'
 print(hex(pow(y, y-1, y))) # Should be a 'big value'
+
+try:
+    print(pow(1, 2, 0))
+except ValueError:
+    print("ValueError")
diff --git a/tests/basics/builtin_range.py b/tests/basics/builtin_range.py
index 66226bad16a6d..9608a8163107e 100644
--- a/tests/basics/builtin_range.py
+++ b/tests/basics/builtin_range.py
@@ -32,13 +32,29 @@
 print(range(1, 4)[0:])
 print(range(1, 4)[1:])
 print(range(1, 4)[:-1])
+print(range(4, 1)[:])
+print(range(4, 1)[0:])
+print(range(4, 1)[1:])
+print(range(4, 1)[:-1])
 print(range(7, -2, -4)[:])
 print(range(1, 100, 5)[5:15:3])
 print(range(1, 100, 5)[15:5:-3])
 print(range(100, 1, -5)[5:15:3])
 print(range(100, 1, -5)[15:5:-3])
+print(range(1, 100, 5)[5:15:-3])
+print(range(1, 100, 5)[15:5:3])
+print(range(100, 1, -5)[5:15:-3])
+print(range(100, 1, -5)[15:5:3])
+print(range(1, 100, 5)[5:15:3])
+print(range(1, 100, 5)[15:5:-3])
+print(range(1, 100, -5)[5:15:3])
+print(range(1, 100, -5)[15:5:-3])
+print(range(1, 100, 5)[5:15:-3])
+print(range(1, 100, 5)[15:5:3])
+print(range(1, 100, -5)[5:15:-3])
+print(range(1, 100, -5)[15:5:3])
 
-# for this case uPy gives a different stop value but the listed elements are still correct
+# for this case MicroPython gives a different stop value but the listed elements are still correct
 print(list(range(7, -2, -4)[2:-2:]))
 
 # zero step
diff --git a/tests/basics/builtin_range_maxsize.py b/tests/basics/builtin_range_maxsize.py
new file mode 100644
index 0000000000000..b0f3a5e5129f1
--- /dev/null
+++ b/tests/basics/builtin_range_maxsize.py
@@ -0,0 +1,38 @@
+try:
+    from sys import maxsize
+except ImportError:
+    print("SKIP")
+    raise SystemExit
+
+# Test the range builtin at extreme values. (https://github.com/micropython/micropython/issues/17684)
+#
+# This is written using asserts instead of prints because the value of `maxsize` differs.
+#
+# Numbers & counts right up against the max of mp_int_t also cause overflows, such as
+# objrange.c:115:14: runtime error: signed integer overflow: 9223372036854775807 + 1 cannot be represented in type 'long int'
+# so just avoid them for the purposes of this test.
+
+r = range(-maxsize + 1, -1)
+assert r.start == -maxsize + 1
+assert r.stop == -1
+assert r[0] == -maxsize + 1
+assert r[1] == -maxsize + 2
+assert r[-1] == -2
+assert r[-2] == -3
+
+ir = iter(r)
+assert next(ir) == -maxsize + 1
+assert next(ir) == -maxsize + 2
+
+r = range(0, maxsize - 1)
+assert len(r) == maxsize - 1
+assert r.stop == maxsize - 1
+
+r = range(maxsize, 0, -1)
+assert len(r) == maxsize
+assert r.start == maxsize
+assert r[0] == maxsize
+assert r[1] == maxsize - 1
+ir = iter(r)
+assert next(ir) == maxsize
+assert next(ir) == maxsize - 1
diff --git a/tests/basics/builtin_setattr.py b/tests/basics/builtin_setattr.py
index e4acb14cac354..2c9a452c32774 100644
--- a/tests/basics/builtin_setattr.py
+++ b/tests/basics/builtin_setattr.py
@@ -21,5 +21,5 @@ def __init__(self):
 try:
     setattr(int, 'to_bytes', 1)
 except (AttributeError, TypeError):
-    # uPy raises AttributeError, CPython raises TypeError
+    # MicroPython raises AttributeError, CPython raises TypeError
     print('AttributeError/TypeError')
diff --git a/tests/basics/builtin_slice.py b/tests/basics/builtin_slice.py
index 3ff3c3dd04d43..cbce3d14ed699 100644
--- a/tests/basics/builtin_slice.py
+++ b/tests/basics/builtin_slice.py
@@ -1,11 +1,44 @@
 # test builtin slice
 
+# ensures that slices passed to user types are heap-allocated and can be
+# safely stored as well as not overridden by subsequent slices.
+
 # print slice
 class A:
     def __getitem__(self, idx):
-        print(idx)
+        print("get", idx)
+        print("abc"[1:])
+        print("get", idx)
+        return idx
+
+    def __setitem__(self, idx, value):
+        print("set", idx)
+        print("abc"[1:])
+        print("set", idx)
+        self.saved_idx = idx
+        return idx
+
+    def __delitem__(self, idx):
+        print("del", idx)
+        print("abc"[1:])
+        print("del", idx)
         return idx
-s = A()[1:2:3]
+
+
+a = A()
+s = a[1:2:3]
+a[4:5:6] = s
+del a[7:8:9]
+
+print(a.saved_idx)
+
+# nested slicing
+print(A()[1 : A()[A()[2:3:4] : 5]])
+
+# tuple slicing
+a[1:2, 4:5, 7:8]
+a[1, 4:5, 7:8, 2]
+a[1:2, a[3:4], 5:6]
 
 # check type
 print(type(s) is slice)
diff --git a/tests/basics/bytes_format_modulo.py.exp b/tests/basics/bytes_format_modulo.py.exp
deleted file mode 100644
index 782b7f91fcbfe..0000000000000
--- a/tests/basics/bytes_format_modulo.py.exp
+++ /dev/null
@@ -1,5 +0,0 @@
-b'%'
-b'=1='
-b'=1=2='
-b'=str='
-b"=b'str'="
diff --git a/tests/basics/class_bind_self.py b/tests/basics/class_bind_self.py
index 813f876446ef2..8bece902ca254 100644
--- a/tests/basics/class_bind_self.py
+++ b/tests/basics/class_bind_self.py
@@ -52,7 +52,7 @@ def f4(self, arg): # generator
 print(C.f8(13))
 print(C.f9(14))
 
-# not working in uPy
+# not working in MicroPython
 #class C(list):
 #    # this acts like a method and binds self
 #    f1 = list.extend
diff --git a/tests/basics/class_descriptor.py b/tests/basics/class_descriptor.py
index 83d31674301d5..feaed2fbb2a43 100644
--- a/tests/basics/class_descriptor.py
+++ b/tests/basics/class_descriptor.py
@@ -1,22 +1,28 @@
 class Descriptor:
     def __get__(self, obj, cls):
-        print('get')
+        print("get")
         print(type(obj) is Main)
         print(cls is Main)
-        return 'result'
+        return "result"
 
     def __set__(self, obj, val):
-        print('set')
+        print("set")
         print(type(obj) is Main)
         print(val)
 
     def __delete__(self, obj):
-        print('delete')
+        print("delete")
         print(type(obj) is Main)
 
+    def __set_name__(self, owner, name):
+        print("set_name", name)
+        print(owner.__name__ == "Main")
+
+
 class Main:
     Forward = Descriptor()
 
+
 m = Main()
 try:
     m.__class__
@@ -26,15 +32,15 @@ class Main:
     raise SystemExit
 
 r = m.Forward
-if 'Descriptor' in repr(r.__class__):
+if "Descriptor" in repr(r.__class__):
     # Target doesn't support descriptors.
-    print('SKIP')
+    print("SKIP")
     raise SystemExit
 
 # Test assignment and deletion.
 
 print(r)
-m.Forward = 'a'
+m.Forward = "a"
 del m.Forward
 
 # Test that lookup of descriptors like __get__ are not passed into __getattr__.
diff --git a/tests/basics/class_inplace_op2.py.exp b/tests/basics/class_inplace_op2.py.exp
deleted file mode 100644
index 8c323b5178ef4..0000000000000
--- a/tests/basics/class_inplace_op2.py.exp
+++ /dev/null
@@ -1,12 +0,0 @@
-__imul__
-__imatmul__
-__ifloordiv__
-__itruediv__
-__imod__
-__ipow__
-__ior__
-__ixor__
-__iand__
-__ilshift__
-__irshift__
-TypeError
diff --git a/tests/basics/class_ordereddict.py.exp b/tests/basics/class_ordereddict.py.exp
deleted file mode 100644
index b723e327515c7..0000000000000
--- a/tests/basics/class_ordereddict.py.exp
+++ /dev/null
@@ -1 +0,0 @@
-['a', 'b', 'c', 'd', 'e']
diff --git a/tests/basics/class_setname_hazard.py b/tests/basics/class_setname_hazard.py
new file mode 100644
index 0000000000000..77c0409346282
--- /dev/null
+++ b/tests/basics/class_setname_hazard.py
@@ -0,0 +1,182 @@
+# Test that __set_name__ can access and mutate its owner argument.
+
+
+def skip_if_no_descriptors():
+    class Descriptor:
+        def __get__(self, obj, cls):
+            return
+
+    class TestClass:
+        Forward = Descriptor()
+
+    a = TestClass()
+    try:
+        a.__class__
+    except AttributeError:
+        # Target doesn't support __class__.
+        print("SKIP")
+        raise SystemExit
+
+    b = a.Forward
+    if "Descriptor" in repr(b.__class__):
+        # Target doesn't support descriptors.
+        print("SKIP")
+        raise SystemExit
+
+
+skip_if_no_descriptors()
+
+
+# Test basic accesses and mutations.
+
+
+class GetSibling:
+    def __set_name__(self, owner, name):
+        print(getattr(owner, name + "_sib"))
+
+
+class GetSiblingTest:
+    desc = GetSibling()
+    desc_sib = 111
+
+
+t110 = GetSiblingTest()
+
+
+class SetSibling:
+    def __set_name__(self, owner, name):
+        setattr(owner, name + "_sib", 121)
+
+
+class SetSiblingTest:
+    desc = SetSibling()
+
+
+t120 = SetSiblingTest()
+
+print(t120.desc_sib)
+
+
+class DelSibling:
+    def __set_name__(self, owner, name):
+        delattr(owner, name + "_sib")
+
+
+class DelSiblingTest:
+    desc = DelSibling()
+    desc_sib = 131
+
+
+t130 = DelSiblingTest()
+
+try:
+    print(t130.desc_sib)
+except AttributeError:
+    print("AttributeError")
+
+
+class GetSelf:
+    x = 211
+
+    def __set_name__(self, owner, name):
+        print(getattr(owner, name).x)
+
+
+class GetSelfTest:
+    desc = GetSelf()
+
+
+t210 = GetSelfTest()
+
+
+class SetSelf:
+    def __set_name__(self, owner, name):
+        setattr(owner, name, 221)
+
+
+class SetSelfTest:
+    desc = SetSelf()
+
+
+t220 = SetSelfTest()
+
+print(t220.desc)
+
+
+class DelSelf:
+    def __set_name__(self, owner, name):
+        delattr(owner, name)
+
+
+class DelSelfTest:
+    desc = DelSelf()
+
+
+t230 = DelSelfTest()
+
+try:
+    print(t230.desc)
+except AttributeError:
+    print("AttributeError")
+
+
+# Test exception behavior.
+
+
+class Raise:
+    def __set_name__(self, owner, name):
+        raise Exception()
+
+
+try:
+
+    class RaiseTest:
+        desc = Raise()
+except Exception as e:  # CPython raises RuntimeError, MicroPython propagates the original exception
+    print("Exception")
+
+
+# Ensure removed/overwritten class members still get __set_name__ called.
+
+
+class SetSpecific:
+    def __init__(self, sib_name, sib_replace):
+        self.sib_name = sib_name
+        self.sib_replace = sib_replace
+
+    def __set_name__(self, owner, name):
+        setattr(owner, self.sib_name, self.sib_replace)
+
+
+class SetReplaceTest:
+    a = SetSpecific("b", 312)  # one of these is changed first
+    b = SetSpecific("a", 311)
+
+
+t310 = SetReplaceTest()
+print(t310.a)
+print(t310.b)
+
+
+class DelSpecific:
+    def __init__(self, sib_name):
+        self.sib_name = sib_name
+
+    def __set_name__(self, owner, name):
+        delattr(owner, self.sib_name)
+
+
+class DelReplaceTest:
+    a = DelSpecific("b")  # one of these is removed first
+    b = DelSpecific("a")
+
+
+t320 = DelReplaceTest()
+try:
+    print(t320.a)
+except AttributeError:
+    print("AttributeError")
+try:
+    print(t320.b)
+except AttributeError:
+    print("AttributeError")
diff --git a/tests/basics/class_setname_hazard_rand.py b/tests/basics/class_setname_hazard_rand.py
new file mode 100644
index 0000000000000..4c9934c3bf068
--- /dev/null
+++ b/tests/basics/class_setname_hazard_rand.py
@@ -0,0 +1,111 @@
+# Test to make sure there's no sequence hazard even when a __set_name__ implementation
+# mutates and reorders the namespace of its owner class.
+# VERY hard bug to prove out except via a stochastic test.
+
+
+try:
+    from random import choice
+    import re
+except ImportError:
+    print("SKIP")
+    raise SystemExit
+
+
+def skip_if_no_descriptors():
+    class Descriptor:
+        def __get__(self, obj, cls):
+            return
+
+    class TestClass:
+        Forward = Descriptor()
+
+    a = TestClass()
+    try:
+        a.__class__
+    except AttributeError:
+        # Target doesn't support __class__.
+        print("SKIP")
+        raise SystemExit
+
+    b = a.Forward
+    if "Descriptor" in repr(b.__class__):
+        # Target doesn't support descriptors.
+        print("SKIP")
+        raise SystemExit
+
+
+skip_if_no_descriptors()
+
+letters = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+
+# Would be r"[A-Z]{5}", but not all ports support the {n} quantifier.
+junk_re = re.compile(r"[A-Z][A-Z][A-Z][A-Z][A-Z]")
+
+
+def junk_fill(obj, n=10):  # Add randomly-generated attributes to an object.
+    for i in range(n):
+        name = "".join(choice(letters) for j in range(5))
+        setattr(obj, name, object())
+
+
+def junk_clear(obj):  # Remove attributes added by junk_fill.
+    to_del = [name for name in dir(obj) if junk_re.match(name)]
+    for name in to_del:
+        delattr(obj, name)
+
+
+def junk_sequencer():
+    global runs
+    try:
+        while True:
+            owner, name = yield
+            runs[name] = runs.get(name, 0) + 1
+            junk_fill(owner)
+    finally:
+        junk_clear(owner)
+
+
+class JunkMaker:
+    def __set_name__(self, owner, name):
+        global seq
+        seq.send((owner, name))
+
+
+runs = {}
+seq = junk_sequencer()
+next(seq)
+
+
+class Main:
+    a = JunkMaker()
+    b = JunkMaker()
+    c = JunkMaker()
+    d = JunkMaker()
+    e = JunkMaker()
+    f = JunkMaker()
+    g = JunkMaker()
+    h = JunkMaker()
+    i = JunkMaker()
+    j = JunkMaker()
+    k = JunkMaker()
+    l = JunkMaker()
+    m = JunkMaker()
+    n = JunkMaker()
+    o = JunkMaker()
+    p = JunkMaker()
+    q = JunkMaker()
+    r = JunkMaker()
+    s = JunkMaker()
+    t = JunkMaker()
+    u = JunkMaker()
+    v = JunkMaker()
+    w = JunkMaker()
+    x = JunkMaker()
+    y = JunkMaker()
+    z = JunkMaker()
+
+
+seq.close()
+
+for k in letters.lower():
+    print(k, runs.get(k, 0))
diff --git a/tests/basics/del_attr.py b/tests/basics/del_attr.py
index 8487b97e311d0..90a8a5a6f833d 100644
--- a/tests/basics/del_attr.py
+++ b/tests/basics/del_attr.py
@@ -35,5 +35,5 @@ def f():
 try:
     del int.to_bytes
 except (AttributeError, TypeError):
-    # uPy raises AttributeError, CPython raises TypeError
+    # MicroPython raises AttributeError, CPython raises TypeError
     print('AttributeError/TypeError')
diff --git a/tests/basics/del_global.py b/tests/basics/del_global.py
index d740357b0332d..e1aa074b97a43 100644
--- a/tests/basics/del_global.py
+++ b/tests/basics/del_global.py
@@ -14,7 +14,7 @@ def do_del():
 try:
     do_del()
 except: # NameError:
-    # FIXME uPy returns KeyError for this
+    # FIXME MicroPython returns KeyError for this
     print("NameError")
 
 # delete globals using a list
diff --git a/tests/basics/del_name.py b/tests/basics/del_name.py
index c92be54d3b655..8393b2df92a72 100644
--- a/tests/basics/del_name.py
+++ b/tests/basics/del_name.py
@@ -10,7 +10,7 @@
 try:
     del x
 except: # NameError:
-    # FIXME uPy returns KeyError for this
+    # FIXME MicroPython returns KeyError for this
     print("NameError")
 
 class C:
diff --git a/tests/basics/dict_views.py b/tests/basics/dict_views.py
index a82f47b6be26f..45f3238f1c624 100644
--- a/tests/basics/dict_views.py
+++ b/tests/basics/dict_views.py
@@ -6,6 +6,11 @@
 # print a view with more than one item
 print({1:1, 2:1}.values())
 
+# `bool` and `len` unary ops
+for d in ({}, {1: 2}, {1: 2, 3: 4}):
+    for op in (bool, len):
+        print(op(d.keys()), op(d.values()), op(d.items()))
+
 # unsupported binary op on a dict values view
 try:
     {1:1}.values() + 1
diff --git a/tests/basics/exception_chain.py b/tests/basics/exception_chain.py
index 579756c85fa20..96c06c847ab37 100644
--- a/tests/basics/exception_chain.py
+++ b/tests/basics/exception_chain.py
@@ -1,5 +1,12 @@
 # CIRCUITPY-CHANGE: exception chaining is supported
 
+import sys
+
+# The unix minimal build doesn't enable MICROPY_WARNINGS (required for this test).
+if getattr(sys.implementation, "_build", None) == "minimal":
+    print("SKIP")
+    raise SystemExit
+
 try:
     Exception().__cause__
 except AttributeError:
diff --git a/tests/basics/frozenset_set.py b/tests/basics/frozenset_set.py
index 3bf456acfd70f..2b3c683260989 100644
--- a/tests/basics/frozenset_set.py
+++ b/tests/basics/frozenset_set.py
@@ -8,5 +8,5 @@
 # "Instances of set are compared to instances of frozenset based on their
 # members. For example:"
 print(set('abc') == frozenset('abc'))
-# This doesn't work in uPy
+# This doesn't work in MicroPython
 #print(set('abc') in set([frozenset('abc')]))
diff --git a/tests/basics/fun_code_colines.py b/tests/basics/fun_code_colines.py
new file mode 100644
index 0000000000000..a8867770eddf1
--- /dev/null
+++ b/tests/basics/fun_code_colines.py
@@ -0,0 +1,81 @@
+# Check that we have sensical bytecode offsets in function.__code__.co_lines
+
+def f1(x, y, obj, obj2, obj3):
+    a = x + y # line 4: bc+4 line+4
+    b = x - y # line 5: bc+4 line+1
+    # line 6
+    # line 7
+    # line 8
+    # line 9
+    # line 10
+    # line 11
+    # line 12
+    # line 13
+    # line 14
+    # line 15
+    # line 16
+    # line 17
+    # line 18
+    # line 19
+    c = a * b # line 20: bc+4 line+15
+    obj.a.b.c.d.e.f.g.h.i.j.k.l.m.n.o.p.q.r.s.t.u.v.w.x.y.z.fun() # line 21: bc+31 line+1; bc+27 line+0
+    # line 22
+    # line 23
+    # line 24: bc+0 line+3
+    # line 25
+    # line 26
+    # line 27: bc+0 line+3
+    # line 28
+    # line 29
+    obj2.a.b.c.d.e.f.g.h.i.j.k.l.m.n.o.p.q.r.s.t.u.v.w.x.y.z.fun() # line 30: bc+31 line+3; bc+27 line+0
+    # line 31
+    # line 32
+    # line 33: bc+0 line+3
+    # line 34
+    # line 35
+    # line 36
+    # line 37
+    # line 38
+    # line 39
+    # line 40
+    # line 41
+    # line 42
+    # line 43
+    # line 44
+    # line 45
+    # line 46
+    # line 47
+    # line 48
+    # line 49
+    # line 50
+    # line 51
+    # line 52
+    # line 53
+    # line 54
+    # line 55
+    # line 56
+    # line 57
+    # line 58
+    # line 59
+    return obj3.a.b.c.d.e.f.g.h.i.j.k.l.m.n.o.p.q.r.s.t.u.v.w.x.y.z.fun() # line 60: bc+31 line+27; bc+27 line+0
+
+def f2(x, y):
+    a = x + y # line 63
+    b = x - y # line 64
+    return a * b # line 65
+
+try:
+    f1.__code__.co_lines
+except AttributeError:
+    print("SKIP")
+    raise SystemExit
+
+print("f1")
+for start, end, line_no in f1.__code__.co_lines():
+    print("line {} start: {}".format(line_no, start))
+    print("line {} end: {}".format(line_no, end))
+
+print("f2")
+for start, end, line_no in f2.__code__.co_lines():
+    print("line {} start: {}".format(line_no, start))
+    print("line {} end: {}".format(line_no, end))
diff --git a/tests/basics/fun_code_colines.py.exp b/tests/basics/fun_code_colines.py.exp
new file mode 100644
index 0000000000000..19bd4ef6e2a5a
--- /dev/null
+++ b/tests/basics/fun_code_colines.py.exp
@@ -0,0 +1,20 @@
+f1
+line 4 start: 0
+line 4 end: 4
+line 5 start: 4
+line 5 end: 8
+line 20 start: 8
+line 20 end: 12
+line 21 start: 12
+line 21 end: 70
+line 30 start: 70
+line 30 end: 128
+line 60 start: 128
+line 60 end: 186
+f2
+line 63 start: 0
+line 63 end: 4
+line 64 start: 4
+line 64 end: 8
+line 65 start: 8
+line 65 end: 12
diff --git a/tests/basics/fun_code_full.py b/tests/basics/fun_code_full.py
new file mode 100644
index 0000000000000..538863631a6e0
--- /dev/null
+++ b/tests/basics/fun_code_full.py
@@ -0,0 +1,38 @@
+# Test function.__code__ attributes not available with MICROPY_PY_BUILTINS_CODE <= MICROPY_PY_BUILTINS_CODE_BASIC
+
+try:
+    (lambda: 0).__code__.co_code
+except AttributeError:
+    print("SKIP")
+    raise SystemExit
+
+def f(x, y):
+    a = x + y
+    b = x - y
+    return a * b
+
+code = f.__code__
+
+print(type(code.co_code)) # both bytes (but mpy and cpy have different instruction sets)
+print(code.co_consts) # (not necessarily the same set, but in this function they are)
+print(code.co_filename.rsplit('/')[-1]) # same terminal filename but might be different paths on other ports
+print(type(code.co_firstlineno)) # both ints (but mpy points to first line inside, cpy points to declaration)
+print(code.co_name)
+print(iter(code.co_names) is not None) # both iterable (but mpy returns dict with names as keys, cpy only the names; and not necessarily the same set)
+
+co_lines = code.co_lines()
+
+l = list(co_lines)
+first_start = l[0][0]
+last_end = l[-1][1]
+print(first_start) # co_lines should start at the start of the bytecode
+print(len(code.co_code) - last_end) # and end at the end of the bytecode
+
+prev_end = 0
+for start, end, line_no in l:
+    if end != prev_end:
+        print("non-contiguous")
+        break # the offset ranges should be contiguous
+    prev_end = end
+else:
+    print("contiguous")
diff --git a/tests/basics/fun_code_full.py.exp b/tests/basics/fun_code_full.py.exp
new file mode 100644
index 0000000000000..830effadfc695
--- /dev/null
+++ b/tests/basics/fun_code_full.py.exp
@@ -0,0 +1,9 @@
+<class 'bytes'>
+(None,)
+fun_code_full.py
+<class 'int'>
+f
+True
+0
+0
+non-contiguous
diff --git a/tests/basics/fun_code_lnotab.py b/tests/basics/fun_code_lnotab.py
new file mode 100644
index 0000000000000..9223e5730f0ea
--- /dev/null
+++ b/tests/basics/fun_code_lnotab.py
@@ -0,0 +1,34 @@
+# Test deprecation of co_lnotab
+
+try:
+    (lambda: 0).__code__.co_code
+except AttributeError:
+    print("SKIP")
+    raise SystemExit
+
+
+import unittest
+import sys
+
+
+mpy_is_v2 = getattr(sys.implementation, '_v2', False)
+
+
+def f():
+    pass
+
+
+class Test(unittest.TestCase):
+
+    @unittest.skipIf(mpy_is_v2, "Removed in MicroPython v2 and later.")
+    def test_co_lnotab_exists(self):
+        self.assertIsInstance(f.__code__.co_lnotab, bytes)
+
+    @unittest.skipUnless(mpy_is_v2, "Not removed before MicroPython v2.")
+    def test_co_lnotab_removed(self):
+        with self.assertRaises(AttributeError):
+            f.__code__.co_lnotab
+
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/tests/basics/fun_name.py b/tests/basics/fun_name.py
index b2642280a2a65..8aac35eeafa25 100644
--- a/tests/basics/fun_name.py
+++ b/tests/basics/fun_name.py
@@ -16,7 +16,7 @@ def Fun(self):
     print('SKIP')
     raise SystemExit
 
-# __name__ of a bound native method is not implemented in uPy
+# __name__ of a bound native method is not implemented in MicroPython
 # the test here is to make sure it doesn't crash
 try:
     str((1).to_bytes.__name__)
diff --git a/tests/basics/gc1.py b/tests/basics/gc1.py
index 332bf9744c072..dff9538b14b5c 100644
--- a/tests/basics/gc1.py
+++ b/tests/basics/gc1.py
@@ -15,13 +15,13 @@
 gc.collect()
 
 if hasattr(gc, 'mem_free'):
-    # uPy has these extra functions
+    # MicroPython has these extra functions
     # just test they execute and return an int
     assert type(gc.mem_free()) is int
     assert type(gc.mem_alloc()) is int
 
 if hasattr(gc, 'threshold'):
-    # uPy has this extra function
+    # MicroPython has this extra function
     # check execution and returns
     assert(gc.threshold(1) is None)
     assert(gc.threshold() == 0)
diff --git a/tests/basics/import_instance_method.py b/tests/basics/import_instance_method.py
new file mode 100644
index 0000000000000..d25b70ac5f0bf
--- /dev/null
+++ b/tests/basics/import_instance_method.py
@@ -0,0 +1,38 @@
+# Test importing a method from a class instance.
+# This is not a common thing to do, but ensures MicroPython has the same semantics as CPython.
+
+import sys
+
+if not hasattr(sys, "modules"):
+    print("SKIP")
+    raise SystemExit
+
+
+class A:
+    def __init__(self, value):
+        self.value = value
+
+    def meth(self):
+        return self.value
+
+    def meth_with_arg(self, a):
+        return [self.value, a]
+
+
+# Register a class instance as the module "mod".
+sys.modules["mod"] = A(1)
+
+# Try importing it as a module.
+import mod
+
+print(mod.meth())
+print(mod.meth_with_arg(2))
+
+# Change the module.
+sys.modules["mod"] = A(3)
+
+# Try importing it using "from ... import".
+from mod import meth, meth_with_arg
+
+print(meth())
+print(meth_with_arg(4))
diff --git a/tests/basics/int_64_basics.py b/tests/basics/int_64_basics.py
new file mode 100644
index 0000000000000..ef76793317ec8
--- /dev/null
+++ b/tests/basics/int_64_basics.py
@@ -0,0 +1,161 @@
+# test support for 64-bit long integers
+# (some ports don't support arbitrary precision but do support these)
+
+# this test is adapted from int_big1.py with numbers kept within 64-bit signed range
+
+# to test arbitrary precision integers
+
+x = 1000000000000000000
+xn = -1000000000000000000
+y = 2000000000000000000
+
+# printing
+print(x)
+print(y)
+print('%#X' % (x - x)) # print prefix
+print('{:#,}'.format(x)) # print with commas
+
+# construction
+print(int(x))
+
+# addition
+print(x + 1)
+print(x + y)
+print(x + xn == 0)
+print(bool(x + xn))
+
+# subtraction
+print(x - 1)
+print(x - y)
+print(y - x)
+print(x - x == 0)
+print(bool(x - x))
+
+# multiplication
+print(x * 2)
+print(1090511627776 * 1048500)
+
+# integer division
+print(x // 2)
+print(y // x)
+
+# bit inversion
+print(~x)
+print(~(-x))
+
+# left shift
+print("left shift positive")
+x = 0x40000000
+for i in range(32):
+    x = x << 1
+    print(x)
+
+# right shift
+print("right shift positive")
+x = 0x2000000000000000  # TODO: why can't second-tip bit be set?
+for i in range(64):
+    x = x >> 1
+    print(x)
+
+# left shift of a negative number
+print("left shift negative")
+for i in range(8):
+    print(-10000000000000000 << i)
+    print(-10000000000000001 << i)
+    print(-10000000000000002 << i)
+    print(-10000000000000003 << i)
+    print(-10000000000000004 << i)
+
+
+# right shift of a negative number
+print("right shift negative")
+for i in range(8):
+    print(-1000000000000000000 >> i)
+    print(-1000000000000000001 >> i)
+    print(-1000000000000000002 >> i)
+    print(-1000000000000000003 >> i)
+    print(-1000000000000000004 >> i)
+
+# conversion from string
+print(int("1234567890123456789"))
+print(int("-1234567890123456789"))
+print(int("1234567890abcdef", 16))
+print(int("1234567890ABCDEF", 16))
+print(int("-1234567890ABCDEF", 16))
+print(int("ijklmnopqrsz", 36))
+
+# numbers close to 64-bit limits
+print(int("-9111222333444555666"))
+print(int("9111222333444555666"))
+
+# numbers with preceding 0s
+print(int("-00000000000000000000009111222333444555666"))
+print(int("0000000000000000000000009111222333444555666"))
+
+# invalid characters in string
+try:
+    print(int("1234567890abcdef"))
+except ValueError:
+    print('ValueError');
+try:
+    print(int("123456789\x01"))
+except ValueError:
+    print('ValueError');
+
+# test parsing ints just on threshold of small to big
+# for 32 bit archs
+x = 1073741823 # small
+x = -1073741823 # small
+x = 1073741824 # big
+x = -1073741824 # big
+# for 64 bit archs
+x = 4611686018427387903 # small
+x = -4611686018427387903 # small
+x = 4611686018427387904 # big
+x = -4611686018427387904 # big
+
+# sys.maxsize is a constant bigint, so test it's compatible with dynamic ones
+import sys
+if hasattr(sys, "maxsize"):
+    print(sys.maxsize - 1 + 1 == sys.maxsize)
+else:
+    print(True)  # No maxsize property in this config
+
+# test extraction of big int value via mp_obj_get_int_maybe
+x = 1 << 62
+print('a' * (x + 4 - x))
+
+# test overflow check in mp_obj_get_int_maybe
+x = 1 << 32
+r = None
+try:
+    r = range(0, x)
+except OverflowError:
+    # 32-bit target, correctly handled the overflow of x
+    print("ok")
+if r is not None:
+    if len(r) == x:
+        # 64-bit target, everything is just a small-int
+        print("ok")
+    else:
+        # 32-bit target that did not handle the overflow of x
+        print("unhandled overflow")
+
+# negative shifts are invalid
+try:
+    print((1 << 48) >> -4)
+except ValueError as e:
+    print(e)
+
+try:
+    print((1 << 48) << -6)
+except ValueError as e:
+    print(e)
+
+# Test that the most extreme 64 bit integer values all parse with int()
+print(int("-9223372036854775807"))
+print(int("-9223372036854775808"))
+print(int("9223372036854775807"))
+
+# Test that the most negative 64 bit integer can be formed via arithmetic
+print(-9223372036854775807-1)
diff --git a/tests/basics/int_big_to_small.py b/tests/basics/int_big_to_small.py
index 64280d0c635f5..c92d263fc2837 100644
--- a/tests/basics/int_big_to_small.py
+++ b/tests/basics/int_big_to_small.py
@@ -5,6 +5,17 @@
     print("SKIP")
     raise SystemExit
 
+# Skip this test on "REPR B" where (1<<29 + 1) is not a small int.
+k = 1 << 29
+micropython.heap_lock()
+try:
+    k = k + 1
+except MemoryError:
+    print("SKIP")
+    raise SystemExit
+finally:
+    micropython.heap_unlock()
+
 # All less than small int max.
 for d in (0, 27, 1<<29, -1861, -(1<<29)):
     i = 1<<70
diff --git a/tests/basics/int_big_to_small_int29.py b/tests/basics/int_big_to_small_int29.py
new file mode 100644
index 0000000000000..438a74d2bc6a4
--- /dev/null
+++ b/tests/basics/int_big_to_small_int29.py
@@ -0,0 +1,22 @@
+try:
+    import micropython
+    micropython.heap_lock
+except:
+    print("SKIP")
+    raise SystemExit
+
+# All less than small int max.
+for d in (0, 27, 1<<28, -1861, -(1<<28)):
+    i = 1<<70
+    print(i)
+    j = (1<<70) + d
+    print(j)
+    # k should now be a small int.
+    k = j - i
+    print(k)
+
+    # Now verify that working with k doesn't allocate (i.e. it's a small int).
+    micropython.heap_lock()
+    print(k + 20)
+    print(k // 20)
+    micropython.heap_unlock()
diff --git a/tests/basics/int_big_to_small_int29.py.exp b/tests/basics/int_big_to_small_int29.py.exp
new file mode 100644
index 0000000000000..0920101924aa8
--- /dev/null
+++ b/tests/basics/int_big_to_small_int29.py.exp
@@ -0,0 +1,25 @@
+1180591620717411303424
+1180591620717411303424
+0
+20
+0
+1180591620717411303424
+1180591620717411303451
+27
+47
+1
+1180591620717411303424
+1180591620717679738880
+268435456
+268435476
+13421772
+1180591620717411303424
+1180591620717411301563
+-1861
+-1841
+-94
+1180591620717411303424
+1180591620717142867968
+-268435456
+-268435436
+-13421773
diff --git a/tests/basics/io_buffered_writer.py b/tests/basics/io_buffered_writer.py
index 11df0324e2467..3cfee0103f777 100644
--- a/tests/basics/io_buffered_writer.py
+++ b/tests/basics/io_buffered_writer.py
@@ -1,10 +1,10 @@
-import io
-
 try:
+    import io
+
     io.BytesIO
     io.BufferedWriter
-except AttributeError:
-    print("SKIP")
+except (AttributeError, ImportError):
+    print('SKIP')
     raise SystemExit
 
 bts = io.BytesIO()
@@ -28,3 +28,27 @@
 
 # hashing a BufferedWriter
 print(type(hash(buf)))
+
+# Test failing flush()
+class MyIO(io.IOBase):
+    def __init__(self):
+        self.count = 0
+
+    def write(self, buf):
+        self.count += 1
+        if self.count < 3:
+            return None
+        print("writing", buf)
+        return len(buf)
+
+
+buf = io.BufferedWriter(MyIO(), 8)
+
+buf.write(b"foobar")
+
+for _ in range(4):
+    try:
+        buf.flush()
+        print("flushed")
+    except OSError:
+        print("OSError")
diff --git a/tests/basics/io_buffered_writer.py.exp b/tests/basics/io_buffered_writer.py.exp
index 2209348f5af45..d61eb148b453c 100644
--- a/tests/basics/io_buffered_writer.py.exp
+++ b/tests/basics/io_buffered_writer.py.exp
@@ -4,3 +4,8 @@ b'foobarfoobar'
 b'foobarfoobar'
 b'foo'
 <class 'int'>
+OSError
+OSError
+writing bytearray(b'foobar')
+flushed
+flushed
diff --git a/tests/basics/io_bytesio_cow.py b/tests/basics/io_bytesio_cow.py
index 2edb7136a9691..543c12ad42ab2 100644
--- a/tests/basics/io_bytesio_cow.py
+++ b/tests/basics/io_bytesio_cow.py
@@ -1,6 +1,12 @@
 # Make sure that write operations on io.BytesIO don't
 # change original object it was constructed from.
-import io
+
+try:
+    import io
+except ImportError:
+    print("SKIP")
+    raise SystemExit
+
 b = b"foobar"
 
 a = io.BytesIO(b)
diff --git a/tests/basics/io_bytesio_ext.py b/tests/basics/io_bytesio_ext.py
index 4d4c60c1363b7..92e715178116c 100644
--- a/tests/basics/io_bytesio_ext.py
+++ b/tests/basics/io_bytesio_ext.py
@@ -1,5 +1,11 @@
 # Extended stream operations on io.BytesIO
-import io
+
+try:
+    import io
+except ImportError:
+    print("SKIP")
+    raise SystemExit
+
 a = io.BytesIO(b"foobar")
 a.seek(10)
 print(a.read(10))
diff --git a/tests/basics/io_bytesio_ext2.py b/tests/basics/io_bytesio_ext2.py
index 414ac90a3b083..f60a6a9a6041e 100644
--- a/tests/basics/io_bytesio_ext2.py
+++ b/tests/basics/io_bytesio_ext2.py
@@ -1,4 +1,9 @@
-import io
+try:
+    import io
+except ImportError:
+    print("SKIP")
+    raise SystemExit
+
 a = io.BytesIO(b"foobar")
 try:
     a.seek(-10)
diff --git a/tests/basics/io_iobase.py b/tests/basics/io_iobase.py
index b2ee5cd63a619..31f2616310e79 100644
--- a/tests/basics/io_iobase.py
+++ b/tests/basics/io_iobase.py
@@ -1,15 +1,17 @@
 import io
 try:
+    import io
+
     io.IOBase
-except AttributeError:
+except (AttributeError, ImportError):
     print("SKIP")
     raise SystemExit
 
 
 class MyIO(io.IOBase):
     def write(self, buf):
-        # CPython and uPy pass in different types for buf (str vs bytearray)
-        print("write", len(buf))
+        # CPython and MicroPython pass in different types for buf (str vs bytearray)
+        print('write', len(buf))
         return len(buf)
 
-print("test", file=MyIO())
+print('test', file=MyIO())
diff --git a/tests/basics/io_stringio1.py b/tests/basics/io_stringio1.py
index 7d355930f5a29..889e3ce697377 100644
--- a/tests/basics/io_stringio1.py
+++ b/tests/basics/io_stringio1.py
@@ -1,4 +1,9 @@
-import io
+try:
+    import io
+except ImportError:
+    print("SKIP")
+    raise SystemExit
+
 a = io.StringIO()
 print('io.StringIO' in repr(a))
 print(a.getvalue())
diff --git a/tests/basics/io_stringio_base.py b/tests/basics/io_stringio_base.py
index 0f65fb3fabc3b..c8890dab73ab7 100644
--- a/tests/basics/io_stringio_base.py
+++ b/tests/basics/io_stringio_base.py
@@ -1,7 +1,11 @@
 # Checks that an instance type inheriting from a native base that uses
 # MP_TYPE_FLAG_ITER_IS_STREAM will still have a getiter.
 
-import io
+try:
+    import io
+except ImportError:
+    print("SKIP")
+    raise SystemExit
 
 a = io.StringIO()
 a.write("hello\nworld\nmicro\npython\n")
diff --git a/tests/basics/io_stringio_with.py b/tests/basics/io_stringio_with.py
index a3aa6ec84e066..0155ad5382dcd 100644
--- a/tests/basics/io_stringio_with.py
+++ b/tests/basics/io_stringio_with.py
@@ -1,4 +1,9 @@
-import io
+try:
+    import io
+except ImportError:
+    print("SKIP")
+    raise SystemExit
+
 # test __enter__/__exit__
 with io.StringIO() as b:
     b.write("foo")
diff --git a/tests/basics/io_write_ext.py b/tests/basics/io_write_ext.py
index 79f7450954e4c..5af1de7a6c3aa 100644
--- a/tests/basics/io_write_ext.py
+++ b/tests/basics/io_write_ext.py
@@ -1,11 +1,12 @@
 # This tests extended (MicroPython-specific) form of write:
 # write(buf, len) and write(buf, offset, len)
-import io
 
 try:
+    import io
+
     io.BytesIO
-except AttributeError:
-    print("SKIP")
+except (AttributeError, ImportError):
+    print('SKIP')
     raise SystemExit
 
 buf = io.BytesIO()
diff --git a/tests/basics/list_pop.py b/tests/basics/list_pop.py
index 87ed456f85174..58bcdd91e414c 100644
--- a/tests/basics/list_pop.py
+++ b/tests/basics/list_pop.py
@@ -10,7 +10,7 @@
 else:
     raise AssertionError("No IndexError raised")
 
-# popping such that list storage shrinks (tests implementation detail of uPy)
+# popping such that list storage shrinks (tests implementation detail of MicroPython)
 l = list(range(20))
 for i in range(len(l)):
     l.pop()
diff --git a/tests/basics/module2.py b/tests/basics/module2.py
index a135601579cd7..d1dc18930f00d 100644
--- a/tests/basics/module2.py
+++ b/tests/basics/module2.py
@@ -1,4 +1,4 @@
-# uPy behaviour only: builtin modules are read-only
+# MicroPython behaviour only: builtin modules are read-only
 import sys
 try:
     sys.x = 1
diff --git a/tests/basics/namedtuple1.py b/tests/basics/namedtuple1.py
index 362c60583ec32..b9689b58423b8 100644
--- a/tests/basics/namedtuple1.py
+++ b/tests/basics/namedtuple1.py
@@ -21,6 +21,9 @@
 
     print(isinstance(t, tuple))
 
+    # a NamedTuple can be used as a tuple
+    print("(%d, %d)" % t)
+
     # Check tuple can compare equal to namedtuple with same elements
     print(t == (t[0], t[1]), (t[0], t[1]) == t)
 
diff --git a/tests/basics/parser.py b/tests/basics/parser.py
index 626b67ad7a941..6ae5f05ba458e 100644
--- a/tests/basics/parser.py
+++ b/tests/basics/parser.py
@@ -7,7 +7,7 @@
     raise SystemExit
 
 # completely empty string
-# uPy and CPy differ for this case
+# MPy and CPy differ for this case
 #try:
 #    compile("", "stdin", "single")
 #except SyntaxError:
diff --git a/tests/basics/python34.py b/tests/basics/python34.py
index 922234d22db93..3071b55eff8bf 100644
--- a/tests/basics/python34.py
+++ b/tests/basics/python34.py
@@ -28,7 +28,7 @@ def test_syntax(code):
 test_syntax("del ()") # can't delete empty tuple (in 3.6 we can)
 
 # from basics/sys1.py
-# uPy prints version 3.4
+# MicroPython prints version 3.4
 import sys
 print(sys.version[:3])
 print(sys.version_info[0], sys.version_info[1])
diff --git a/tests/basics/python36.py.exp b/tests/basics/python36.py.exp
deleted file mode 100644
index 4b65daafa18fe..0000000000000
--- a/tests/basics/python36.py.exp
+++ /dev/null
@@ -1,5 +0,0 @@
-100000
-165
-65535
-123
-83
diff --git a/tests/basics/self_type_check.py b/tests/basics/self_type_check.py
index 3bd5b3eed6058..5f6f6f2ca6585 100644
--- a/tests/basics/self_type_check.py
+++ b/tests/basics/self_type_check.py
@@ -3,6 +3,14 @@
 import skip_if
 skip_if.board_in("gemma_m0", "trinket_m0")
 
+import sys
+
+# Minimal builds usually don't enable MICROPY_BUILTIN_METHOD_CHECK_SELF_ARG,
+# which is required for this test.
+if getattr(sys.implementation, "_build", None) == "minimal":
+    print("SKIP")
+    raise SystemExit
+
 list.append
 
 try:
diff --git a/tests/basics/slice_optimise.py b/tests/basics/slice_optimise.py
new file mode 100644
index 0000000000000..f663e16b8c2f9
--- /dev/null
+++ b/tests/basics/slice_optimise.py
@@ -0,0 +1,23 @@
+# Test that the slice-on-stack optimisation does not break various uses of slice
+# (see MP_TYPE_FLAG_SUBSCR_ALLOWS_STACK_SLICE type option).
+#
+# Note: this test has a corresponding .py.exp file because hashing slice objects
+# was not allowed in CPython until 3.12.
+
+try:
+    from collections import OrderedDict
+except ImportError:
+    print("SKIP")
+    raise SystemExit
+
+# Attempt to index with a slice, error should contain the slice (failed key).
+try:
+    dict()[:]
+except KeyError as e:
+    print("KeyError", e.args)
+
+# Put a slice and another object into an OrderedDict, and retrieve them.
+x = OrderedDict()
+x[:"a"] = 1
+x["b"] = 2
+print(list(x.keys()), list(x.values()))
diff --git a/tests/basics/slice_optimise.py.exp b/tests/basics/slice_optimise.py.exp
new file mode 100644
index 0000000000000..3fa59aae15ae6
--- /dev/null
+++ b/tests/basics/slice_optimise.py.exp
@@ -0,0 +1,2 @@
+KeyError (slice(None, None, None),)
+[slice(None, 'a', None), 'b'] [1, 2]
diff --git a/tests/basics/special_methods2.py.exp b/tests/basics/special_methods2.py.exp
deleted file mode 100644
index a9ae75be55c95..0000000000000
--- a/tests/basics/special_methods2.py.exp
+++ /dev/null
@@ -1,19 +0,0 @@
-__pos__ called
-__pos__ called
-__neg__ called
-__invert__ called
-__mul__ called
-__matmul__ called
-__truediv__ called
-__floordiv__ called
-__iadd__ called
-__isub__ called
-__mod__ called
-__pow__ called
-__or__ called
-__and__ called
-__xor__ called
-__lshift__ called
-__rshift__ called
-['a', 'b', 'c']
-False
diff --git a/tests/basics/string_format.py b/tests/basics/string_format.py
index e8600f5836139..11e7836a73ece 100644
--- a/tests/basics/string_format.py
+++ b/tests/basics/string_format.py
@@ -22,7 +22,17 @@ def test(fmt, *args):
 test("{:4x}", 123)
 test("{:4X}", 123)
 
+test("{:4,d}", 1)
+test("{:4_d}", 1)
+test("{:4_o}", 1)
+test("{:4_b}", 1)
+test("{:4_x}", 1)
+
 test("{:4,d}", 12345678)
+test("{:4_d}", 12345678)
+test("{:4_o}", 12345678)
+test("{:4_b}", 12345678)
+test("{:4_x}", 12345678)
 
 test("{:#4b}", 10)
 test("{:#4o}", 123)
diff --git a/tests/basics/string_format_sep.py b/tests/basics/string_format_sep.py
new file mode 100644
index 0000000000000..de131fdaf3383
--- /dev/null
+++ b/tests/basics/string_format_sep.py
@@ -0,0 +1,9 @@
+try:
+    "%d" % 1
+except TypeError:
+    print("SKIP")
+    raise SystemExit
+
+for v in (0, 0x10, 0x1000, -0x10, -0x1000):
+    for sz in range(1, 12): print(("{:0%d,d}" % sz).format(v))
+    for sz in range(1, 12): print(("{:0%d_x}" % sz).format(v))
diff --git a/tests/basics/string_fstring_debug.py.exp b/tests/basics/string_fstring_debug.py.exp
deleted file mode 100644
index f0309e1c98aa9..0000000000000
--- a/tests/basics/string_fstring_debug.py.exp
+++ /dev/null
@@ -1,9 +0,0 @@
-x=1
-x=00000001
-a x=1 b 2 c
-a x=00000001 b 2 c
-a f() + g("foo") + h()=15 b
-a f() + g("foo") + h()=0000000f b
-a 1,=(1,) b
-a x,y,=(1, 2) b
-a x,1=(1, 1) b
diff --git a/tests/basics/subclass_native_init.py b/tests/basics/subclass_native_init.py
index 64167fa037e0c..102befd551fad 100644
--- a/tests/basics/subclass_native_init.py
+++ b/tests/basics/subclass_native_init.py
@@ -1,5 +1,9 @@
 # test subclassing a native type and overriding __init__
 
+if not hasattr(object, "__init__"):
+    print("SKIP")
+    raise SystemExit
+
 # overriding list.__init__()
 class L(list):
     def __init__(self, a, b):
diff --git a/tests/basics/syntaxerror.py b/tests/basics/syntaxerror.py
index c0702cb24525e..7b6ef9b7550ea 100644
--- a/tests/basics/syntaxerror.py
+++ b/tests/basics/syntaxerror.py
@@ -86,7 +86,7 @@ def test_syntax(code):
 test_syntax("nonlocal a")
 test_syntax("await 1")
 
-# error on uPy, warning on CPy
+# error on MPy, warning on CPy
 #test_syntax("def f():\n a = 1\n global a")
 
 # default except must be last
@@ -98,7 +98,7 @@ def test_syntax(code):
 # non-keyword after keyword
 test_syntax("f(a=1, 2)")
 
-# doesn't error on uPy but should
+# doesn't error on MPy but should
 #test_syntax("f(1, i for i in i)")
 
 # all elements of dict/set must be pairs or singles
diff --git a/tests/basics/sys1.py b/tests/basics/sys1.py
index 7f261aa96459d..02946abc220be 100644
--- a/tests/basics/sys1.py
+++ b/tests/basics/sys1.py
@@ -31,6 +31,12 @@
     # Effectively skip subtests
     print(str)
 
+if hasattr(sys.implementation, '_thread'):
+    print(sys.implementation._thread in ("GIL", "unsafe"))
+else:
+    # Effectively skip subtests
+    print(True)
+
 try:
     print(sys.intern('micropython') == 'micropython')
     has_intern = True
diff --git a/tests/basics/sys_tracebacklimit.py b/tests/basics/sys_tracebacklimit.py
index 3ae372b8d524e..6f575fde65404 100644
--- a/tests/basics/sys_tracebacklimit.py
+++ b/tests/basics/sys_tracebacklimit.py
@@ -30,7 +30,7 @@ def print_exc(e):
         if l.startswith("  File "):
             l = l.split('"')
             print(l[0], l[2])
-        # uPy and CPy tracebacks differ in that CPy prints a source line for
+        # MPy and CPy tracebacks differ in that CPy prints a source line for
         # each traceback entry.  In this case, we know that offending line
         # has 4-space indent, so filter it out.
         elif not l.startswith("    "):
diff --git a/tests/basics/sys_tracebacklimit.py.native.exp b/tests/basics/sys_tracebacklimit.py.native.exp
new file mode 100644
index 0000000000000..f9d30c058564b
--- /dev/null
+++ b/tests/basics/sys_tracebacklimit.py.native.exp
@@ -0,0 +1,22 @@
+ValueError: value
+
+limit 4
+ValueError: value
+
+limit 3
+ValueError: value
+
+limit 2
+ValueError: value
+
+limit 1
+ValueError: value
+
+limit 0
+ValueError: value
+
+limit -1
+ValueError: value
+
+True
+False
diff --git a/tests/basics/try_finally_continue.py.exp b/tests/basics/try_finally_continue.py.exp
deleted file mode 100644
index 2901997b1aa18..0000000000000
--- a/tests/basics/try_finally_continue.py.exp
+++ /dev/null
@@ -1,9 +0,0 @@
-4 0
-continue
-4 1
-continue
-4 2
-continue
-4 3
-continue
-None
diff --git a/tests/basics/tuple1.py b/tests/basics/tuple1.py
index 72bb3f01bff4a..70ae071898e5b 100644
--- a/tests/basics/tuple1.py
+++ b/tests/basics/tuple1.py
@@ -17,7 +17,7 @@
 x += (10, 11, 12)
 print(x)
 
-# construction of tuple from large iterator (tests implementation detail of uPy)
+# construction of tuple from large iterator (tests implementation detail of MicroPython)
 print(tuple(range(20)))
 
 # unsupported unary operation
diff --git a/tests/cmdline/cmd_compile_only.py b/tests/cmdline/cmd_compile_only.py
new file mode 100644
index 0000000000000..89964c1b5bdf2
--- /dev/null
+++ b/tests/cmdline/cmd_compile_only.py
@@ -0,0 +1,13 @@
+# cmdline: -X compile-only
+# test compile-only functionality
+print("This should not be printed")
+x = 1 + 2
+
+
+def hello():
+    return "world"
+
+
+class TestClass:
+    def __init__(self):
+        self.value = 42
diff --git a/tests/cmdline/cmd_compile_only.py.exp b/tests/cmdline/cmd_compile_only.py.exp
new file mode 100644
index 0000000000000..8b137891791fe
--- /dev/null
+++ b/tests/cmdline/cmd_compile_only.py.exp
@@ -0,0 +1 @@
+
diff --git a/tests/cmdline/cmd_compile_only_error.py b/tests/cmdline/cmd_compile_only_error.py
new file mode 100644
index 0000000000000..326937a5c07ef
--- /dev/null
+++ b/tests/cmdline/cmd_compile_only_error.py
@@ -0,0 +1,6 @@
+# cmdline: -X compile-only
+# test compile-only with syntax error
+print("This should not be printed")
+def broken_syntax(
+    # Missing closing parenthesis
+    return "error"
diff --git a/tests/cmdline/cmd_compile_only_error.py.exp b/tests/cmdline/cmd_compile_only_error.py.exp
new file mode 100644
index 0000000000000..3911f71d6244d
--- /dev/null
+++ b/tests/cmdline/cmd_compile_only_error.py.exp
@@ -0,0 +1 @@
+CRASH
\ No newline at end of file
diff --git a/tests/cmdline/cmd_file_variable.py b/tests/cmdline/cmd_file_variable.py
new file mode 100644
index 0000000000000..6cac6744d904e
--- /dev/null
+++ b/tests/cmdline/cmd_file_variable.py
@@ -0,0 +1,5 @@
+# Test that __file__ is set correctly for script execution
+try:
+    print("__file__ =", __file__)
+except NameError:
+    print("__file__ not defined")
diff --git a/tests/cmdline/cmd_file_variable.py.exp b/tests/cmdline/cmd_file_variable.py.exp
new file mode 100644
index 0000000000000..6807569f662b5
--- /dev/null
+++ b/tests/cmdline/cmd_file_variable.py.exp
@@ -0,0 +1 @@
+__file__ = cmdline/cmd_file_variable.py
diff --git a/tests/cmdline/cmd_module_atexit.py b/tests/cmdline/cmd_module_atexit.py
new file mode 100644
index 0000000000000..100bc112777e1
--- /dev/null
+++ b/tests/cmdline/cmd_module_atexit.py
@@ -0,0 +1,16 @@
+# cmdline: -m cmdline.cmd_module_atexit
+#
+# Test running as a module and using sys.atexit.
+
+import sys
+
+if not hasattr(sys, "atexit"):
+    print("SKIP")
+    raise SystemExit
+
+# Verify we ran as a module.
+print(sys.argv)
+
+sys.atexit(lambda: print("done"))
+
+print("start")
diff --git a/tests/cmdline/cmd_module_atexit.py.exp b/tests/cmdline/cmd_module_atexit.py.exp
new file mode 100644
index 0000000000000..2a0f756b1e799
--- /dev/null
+++ b/tests/cmdline/cmd_module_atexit.py.exp
@@ -0,0 +1,3 @@
+['cmdline.cmd_module_atexit', 'cmdline/cmd_module_atexit.py']
+start
+done
diff --git a/tests/cmdline/cmd_module_atexit_exc.py b/tests/cmdline/cmd_module_atexit_exc.py
new file mode 100644
index 0000000000000..88940a7741fb9
--- /dev/null
+++ b/tests/cmdline/cmd_module_atexit_exc.py
@@ -0,0 +1,19 @@
+# cmdline: -m cmdline.cmd_module_atexit_exc
+#
+# Test running as a module and using sys.atexit, with script completion via sys.exit.
+
+import sys
+
+if not hasattr(sys, "atexit"):
+    print("SKIP")
+    raise SystemExit
+
+# Verify we ran as a module.
+print(sys.argv)
+
+sys.atexit(lambda: print("done"))
+
+print("start")
+
+# This will raise SystemExit to finish the script, and atexit should still be run.
+sys.exit(0)
diff --git a/tests/cmdline/cmd_module_atexit_exc.py.exp b/tests/cmdline/cmd_module_atexit_exc.py.exp
new file mode 100644
index 0000000000000..6320d9d2d3011
--- /dev/null
+++ b/tests/cmdline/cmd_module_atexit_exc.py.exp
@@ -0,0 +1,3 @@
+['cmdline.cmd_module_atexit_exc', 'cmdline/cmd_module_atexit_exc.py']
+start
+done
diff --git a/tests/cmdline/cmd_sys_exit_0.py b/tests/cmdline/cmd_sys_exit_0.py
new file mode 100644
index 0000000000000..1294b739e8ff1
--- /dev/null
+++ b/tests/cmdline/cmd_sys_exit_0.py
@@ -0,0 +1,5 @@
+# cmdline:
+# test sys.exit(0) - success exit code
+import sys
+
+sys.exit(0)
diff --git a/tests/cmdline/cmd_sys_exit_0.py.exp b/tests/cmdline/cmd_sys_exit_0.py.exp
new file mode 100644
index 0000000000000..8b137891791fe
--- /dev/null
+++ b/tests/cmdline/cmd_sys_exit_0.py.exp
@@ -0,0 +1 @@
+
diff --git a/tests/cmdline/cmd_sys_exit_error.py b/tests/cmdline/cmd_sys_exit_error.py
new file mode 100644
index 0000000000000..ecac15e94f1bf
--- /dev/null
+++ b/tests/cmdline/cmd_sys_exit_error.py
@@ -0,0 +1,5 @@
+# cmdline:
+# test sys.exit() functionality and exit codes
+import sys
+
+sys.exit(123)
diff --git a/tests/cmdline/cmd_sys_exit_error.py.exp b/tests/cmdline/cmd_sys_exit_error.py.exp
new file mode 100644
index 0000000000000..3911f71d6244d
--- /dev/null
+++ b/tests/cmdline/cmd_sys_exit_error.py.exp
@@ -0,0 +1 @@
+CRASH
\ No newline at end of file
diff --git a/tests/cmdline/cmd_sys_exit_none.py b/tests/cmdline/cmd_sys_exit_none.py
new file mode 100644
index 0000000000000..66e19666589ed
--- /dev/null
+++ b/tests/cmdline/cmd_sys_exit_none.py
@@ -0,0 +1,5 @@
+# cmdline:
+# test sys.exit(None) - should exit with code 0
+import sys
+
+sys.exit(None)
diff --git a/tests/cmdline/cmd_sys_exit_none.py.exp b/tests/cmdline/cmd_sys_exit_none.py.exp
new file mode 100644
index 0000000000000..8b137891791fe
--- /dev/null
+++ b/tests/cmdline/cmd_sys_exit_none.py.exp
@@ -0,0 +1 @@
+
diff --git a/tests/cmdline/repl_autocomplete.py.exp b/tests/cmdline/repl_autocomplete.py.exp
index 2e2397bb028d3..7840e52e8a4a2 100644
--- a/tests/cmdline/repl_autocomplete.py.exp
+++ b/tests/cmdline/repl_autocomplete.py.exp
@@ -1,5 +1,5 @@
-CircuitPython \.\+ version
-Use \.\+
+
+Adafruit CircuitPython \.\+ version
 >>> # tests for autocompletion
 >>> import sys
 >>> not_exist.
@@ -11,4 +11,4 @@ Use \.\+
 >>> i.lower('ABC')
 'abc'
 >>> None.
->>> 
+>>> \$
diff --git a/tests/cmdline/repl_autocomplete_underscore.py b/tests/cmdline/repl_autocomplete_underscore.py
new file mode 100644
index 0000000000000..e685a7fe7ff02
--- /dev/null
+++ b/tests/cmdline/repl_autocomplete_underscore.py
@@ -0,0 +1,33 @@
+# Test REPL autocompletion filtering of underscore attributes
+
+# Start paste mode
+{\x05}
+class TestClass:
+    def __init__(self):
+        self.public_attr = 1
+        self._private_attr = 2
+        self.__very_private = 3
+
+    def public_method(self):
+        pass
+
+    def _private_method(self):
+        pass
+
+    @property
+    def public_property(self):
+        return 42
+
+    @property
+    def _private_property(self):
+        return 99
+
+{\x04}
+# Paste executed
+
+# Create an instance
+obj = TestClass()
+
+# Test tab completion on the instance
+# The tab character after `obj.` and 'a' below triggers the completions
+obj.{\x09}{\x09}a{\x09}
diff --git a/tests/cmdline/repl_autocomplete_underscore.py.exp b/tests/cmdline/repl_autocomplete_underscore.py.exp
new file mode 100644
index 0000000000000..98e6c2aeb05a3
--- /dev/null
+++ b/tests/cmdline/repl_autocomplete_underscore.py.exp
@@ -0,0 +1,41 @@
+
+Adafruit CircuitPython \.\+ version
+>>> # Test REPL autocompletion filtering of underscore attributes
+>>> \$
+>>> # Start paste mode
+>>> \$
+paste mode; Ctrl-C to cancel, Ctrl-D to finish
+=== \$
+=== class TestClass:
+===     def __init__(self):
+===         self.public_attr = 1
+===         self._private_attr = 2
+===         self.__very_private = 3
+=== \$
+===     def public_method(self):
+===         pass
+=== \$
+===     def _private_method(self):
+===         pass
+=== \$
+===     @property
+===     def public_property(self):
+===         return 42
+=== \$
+===     @property
+===     def _private_property(self):
+===         return 99
+=== \$
+=== \$
+>>> # Paste executed
+>>> \$
+>>> # Create an instance
+>>> obj = TestClass()
+>>> \$
+>>> # Test tab completion on the instance
+>>> # The tab character after `obj.` and 'a' below triggers the completions
+>>> obj.public_
+public_attr     public_method   public_property
+>>> obj.public_attr
+1
+>>> \$
diff --git a/tests/cmdline/repl_autoindent.py.exp b/tests/cmdline/repl_autoindent.py.exp
index 9ff83a92870e8..04f00686b208d 100644
--- a/tests/cmdline/repl_autoindent.py.exp
+++ b/tests/cmdline/repl_autoindent.py.exp
@@ -1,22 +1,22 @@
-CircuitPython \.\+ version
-Use \.\+
+
+Adafruit CircuitPython \.\+ version
 >>> # tests for autoindent
 >>> if 1:
 ...     print(1)
-...     
-...     
-... 
+...     \$
+...     \$
+... \$
 1
 >>> if 0:
 ...      print(2)
 ... else:
 ...   print(3)
-... 
+... \$
 3
 >>> if 0:
 ...     print(4)
 ... else:
 ...     print(5)
-... 
+... \$
 5
->>> 
+>>> \$
diff --git a/tests/cmdline/repl_basic.py.exp b/tests/cmdline/repl_basic.py.exp
index 26442b6445589..5bdcc9d6d3246 100644
--- a/tests/cmdline/repl_basic.py.exp
+++ b/tests/cmdline/repl_basic.py.exp
@@ -1,5 +1,5 @@
-CircuitPython \.\+ version
-Use \.\+
+
+Adafruit CircuitPython \.\+ version
 >>> # basic REPL tests
 >>> print(1)
 1
@@ -7,4 +7,4 @@ Use \.\+
 1
 >>> 2
 2
->>> 
+>>> \$
diff --git a/tests/cmdline/repl_cont.py.exp b/tests/cmdline/repl_cont.py.exp
index 6eed4a3e02c47..41f2436ac18a0 100644
--- a/tests/cmdline/repl_cont.py.exp
+++ b/tests/cmdline/repl_cont.py.exp
@@ -1,5 +1,5 @@
-CircuitPython \.\+ version
-Use \.\+
+
+Adafruit CircuitPython \.\+ version
 >>> # check REPL allows to continue input
 >>> 1 \\\\
 ... + 2
@@ -54,4 +54,4 @@ two
 >>> if1 = 2
 >>> print(if1)
 2
->>> 
+>>> \$
diff --git a/tests/cmdline/repl_emacs_keys.py.exp b/tests/cmdline/repl_emacs_keys.py.exp
index 2e8667a8e6ca9..4979f8bbfc3ab 100644
--- a/tests/cmdline/repl_emacs_keys.py.exp
+++ b/tests/cmdline/repl_emacs_keys.py.exp
@@ -1,5 +1,5 @@
-CircuitPython \.\+ version
-Use \.\+
+
+Adafruit CircuitPython \.\+ version
 >>> # REPL tests of GNU-ish readline navigation
 >>> # history buffer navigation
 >>> 1
@@ -16,4 +16,4 @@ Use \.\+
 >>> t = 121
 >>> \.\+
 'foobar'
->>> 
+>>> \$
diff --git a/tests/cmdline/repl_inspect.py.exp b/tests/cmdline/repl_inspect.py.exp
index 8ece5ffc37f5c..30257f31aab93 100644
--- a/tests/cmdline/repl_inspect.py.exp
+++ b/tests/cmdline/repl_inspect.py.exp
@@ -1,6 +1,6 @@
 test
-CircuitPython \.\+ version
-Use \.\+
+
+Adafruit CircuitPython \.\+ version
 >>> # cmdline: -i -c print("test")
 >>> # -c option combined with -i option results in REPL
->>> 
+>>> \$
diff --git a/tests/cmdline/repl_lock.py b/tests/cmdline/repl_lock.py
new file mode 100644
index 0000000000000..77e2e9327401a
--- /dev/null
+++ b/tests/cmdline/repl_lock.py
@@ -0,0 +1,7 @@
+import micropython
+micropython.heap_lock()
+1+1
+micropython.heap_lock()
+None # Cause the repl's line storage to be enlarged ----------------
+micropython.heap_lock()
+raise SystemExit
diff --git a/tests/cmdline/repl_lock.py.exp b/tests/cmdline/repl_lock.py.exp
new file mode 100644
index 0000000000000..e6d63fcf20044
--- /dev/null
+++ b/tests/cmdline/repl_lock.py.exp
@@ -0,0 +1,10 @@
+
+Adafruit CircuitPython \.\+ version
+>>> import micropython
+>>> micropython.heap_lock()
+>>> 1+1
+2
+>>> micropython.heap_lock()
+>>> None # Cause the repl's line storage to be enlarged ----------------
+>>> micropython.heap_lock()
+>>> raise SystemExit
diff --git a/tests/cmdline/repl_micropyinspect.py.exp b/tests/cmdline/repl_micropyinspect.py.exp
index 3c9cbc030c0b5..36bef37c62c6b 100644
--- a/tests/cmdline/repl_micropyinspect.py.exp
+++ b/tests/cmdline/repl_micropyinspect.py.exp
@@ -1,5 +1,5 @@
-CircuitPython \.\+ version
-Use \.\+
+
+Adafruit CircuitPython \.\+ version
 >>> # cmdline: cmdline/repl_micropyinspect
 >>> # setting MICROPYINSPECT environment variable before program exit triggers REPL
->>> 
+>>> \$
diff --git a/tests/cmdline/repl_paste.py b/tests/cmdline/repl_paste.py
new file mode 100644
index 0000000000000..7cec450fce7bf
--- /dev/null
+++ b/tests/cmdline/repl_paste.py
@@ -0,0 +1,90 @@
+# Test REPL paste mode functionality
+
+# Basic paste mode with a simple function
+{\x05}
+def hello():
+    print('Hello from paste mode!')
+hello()
+{\x04}
+
+# Paste mode with multiple indentation levels
+{\x05}
+def calculate(n):
+    if n > 0:
+        for i in range(n):
+            if i % 2 == 0:
+                print(f'Even: {i}')
+            else:
+                print(f'Odd: {i}')
+    else:
+        print('n must be positive')
+
+calculate(5)
+{\x04}
+
+# Paste mode with blank lines
+{\x05}
+def function_with_blanks():
+    print('First line')
+    
+    print('After blank line')
+    
+    
+    print('After two blank lines')
+
+function_with_blanks()
+{\x04}
+
+# Paste mode with class definition and multiple methods
+{\x05}
+class TestClass:
+    def __init__(self, value):
+        self.value = value
+    
+    def display(self):
+        print(f'Value is: {self.value}')
+    
+    def double(self):
+        self.value *= 2
+        return self.value
+
+obj = TestClass(21)
+obj.display()
+print(f'Doubled: {obj.double()}')
+obj.display()
+{\x04}
+
+# Paste mode with exception handling
+{\x05}
+try:
+    x = 1 / 0
+except ZeroDivisionError:
+    print('Caught division by zero')
+finally:
+    print('Finally block executed')
+{\x04}
+
+# Cancel paste mode with Ctrl-C
+{\x05}
+print('This should not execute')
+{\x03}
+
+# Normal REPL still works after cancelled paste
+print('Back to normal REPL')
+
+# Paste mode with syntax error
+{\x05}
+def bad_syntax(:
+    print('Missing parameter')
+{\x04}
+
+# Paste mode with runtime error
+{\x05}
+def will_error():
+    undefined_variable
+    
+will_error()
+{\x04}
+
+# Final test to show REPL is still functioning
+1 + 2 + 3
diff --git a/tests/cmdline/repl_paste.py.exp b/tests/cmdline/repl_paste.py.exp
new file mode 100644
index 0000000000000..cc5ac2f08007d
--- /dev/null
+++ b/tests/cmdline/repl_paste.py.exp
@@ -0,0 +1,133 @@
+
+Adafruit CircuitPython \.\+ version
+>>> # Test REPL paste mode functionality
+>>> \$
+>>> # Basic paste mode with a simple function
+>>> \$
+paste mode; Ctrl-C to cancel, Ctrl-D to finish
+=== \$
+=== def hello():
+===     print('Hello from paste mode!')
+=== hello()
+=== \$
+Hello from paste mode!
+>>> \$
+>>> # Paste mode with multiple indentation levels
+>>> \$
+paste mode; Ctrl-C to cancel, Ctrl-D to finish
+=== \$
+=== def calculate(n):
+===     if n > 0:
+===         for i in range(n):
+===             if i % 2 == 0:
+===                 print(f'Even: {i}')
+===             else:
+===                 print(f'Odd: {i}')
+===     else:
+===         print('n must be positive')
+=== \$
+=== calculate(5)
+=== \$
+Even: 0
+Odd: 1
+Even: 2
+Odd: 3
+Even: 4
+>>> \$
+>>> # Paste mode with blank lines
+>>> \$
+paste mode; Ctrl-C to cancel, Ctrl-D to finish
+=== \$
+=== def function_with_blanks():
+===     print('First line')
+===     \$
+===     print('After blank line')
+===     \$
+===     \$
+===     print('After two blank lines')
+=== \$
+=== function_with_blanks()
+=== \$
+First line
+After blank line
+After two blank lines
+>>> \$
+>>> # Paste mode with class definition and multiple methods
+>>> \$
+paste mode; Ctrl-C to cancel, Ctrl-D to finish
+=== \$
+=== class TestClass:
+===     def __init__(self, value):
+===         self.value = value
+===     \$
+===     def display(self):
+===         print(f'Value is: {self.value}')
+===     \$
+===     def double(self):
+===         self.value *= 2
+===         return self.value
+=== \$
+=== obj = TestClass(21)
+=== obj.display()
+=== print(f'Doubled: {obj.double()}')
+=== obj.display()
+=== \$
+Value is: 21
+Doubled: 42
+Value is: 42
+>>> \$
+>>> # Paste mode with exception handling
+>>> \$
+paste mode; Ctrl-C to cancel, Ctrl-D to finish
+=== \$
+=== try:
+===     x = 1 / 0
+=== except ZeroDivisionError:
+===     print('Caught division by zero')
+=== finally:
+===     print('Finally block executed')
+=== \$
+Caught division by zero
+Finally block executed
+>>> \$
+>>> # Cancel paste mode with Ctrl-C
+>>> \$
+paste mode; Ctrl-C to cancel, Ctrl-D to finish
+=== \$
+=== print('This should not execute')
+=== \$
+>>> \$
+>>> \$
+>>> # Normal REPL still works after cancelled paste
+>>> print('Back to normal REPL')
+Back to normal REPL
+>>> \$
+>>> # Paste mode with syntax error
+>>> \$
+paste mode; Ctrl-C to cancel, Ctrl-D to finish
+=== \$
+=== def bad_syntax(:
+===     print('Missing parameter')
+=== \$
+Traceback (most recent call last):
+  File "<stdin>", line 2
+SyntaxError: invalid syntax
+>>> \$
+>>> # Paste mode with runtime error
+>>> \$
+paste mode; Ctrl-C to cancel, Ctrl-D to finish
+=== \$
+=== def will_error():
+===     undefined_variable
+===     \$
+=== will_error()
+=== \$
+Traceback (most recent call last):
+  File "<stdin>", line 5, in <module>
+  File "<stdin>", line 3, in will_error
+NameError: name 'undefined_variable' isn't defined
+>>> \$
+>>> # Final test to show REPL is still functioning
+>>> 1 + 2 + 3
+6
+>>> \$
diff --git a/tests/cmdline/repl_sys_ps1_ps2.py.exp b/tests/cmdline/repl_sys_ps1_ps2.py.exp
index 452a54fe5ae9b..d4bcf7a44d592 100644
--- a/tests/cmdline/repl_sys_ps1_ps2.py.exp
+++ b/tests/cmdline/repl_sys_ps1_ps2.py.exp
@@ -1,5 +1,5 @@
-CircuitPython \.\+ version
-Use \.\+
+
+Adafruit CircuitPython \.\+ version
 >>> # test changing ps1/ps2
 >>> import sys
 >>> sys.ps1 = "PS1"
diff --git a/tests/cmdline/repl_words_move.py.exp b/tests/cmdline/repl_words_move.py.exp
index ba5c3648cff98..41ad3d8e73351 100644
--- a/tests/cmdline/repl_words_move.py.exp
+++ b/tests/cmdline/repl_words_move.py.exp
@@ -1,5 +1,5 @@
-CircuitPython \.\+ version
-Use \.\+
+
+Adafruit CircuitPython \.\+ version
 >>> # word movement
 >>> # backward-word, start in word
 >>> \.\+
@@ -19,7 +19,7 @@ Use \.\+
 >>> # forward-word on eol. if cursor is moved, this will result in a SyntaxError
 >>> \.\+
 6
->>> 
+>>> \$
 >>> # kill word
 >>> # backward-kill-word, start in word
 >>> \.\+
@@ -33,7 +33,7 @@ Use \.\+
 >>> # forward-kill-word, don't start in word
 >>> \.\+
 3
->>> 
+>>> \$
 >>> # extra move/kill shortcuts
 >>> # ctrl-left
 >>> \.\+
@@ -44,4 +44,4 @@ Use \.\+
 >>> # ctrl-w
 >>> \.\+
 1
->>> 
+>>> \$
diff --git a/tests/cpydiff/core_class_initsubclass.py b/tests/cpydiff/core_class_initsubclass.py
new file mode 100644
index 0000000000000..8683271dcb0f2
--- /dev/null
+++ b/tests/cpydiff/core_class_initsubclass.py
@@ -0,0 +1,21 @@
+"""
+categories: Core,Classes
+description: ``__init_subclass__`` isn't automatically called.
+cause: MicroPython does not currently implement PEP 487.
+workaround: Manually call ``__init_subclass__`` after class creation if needed. e.g.::
+
+    class A(Base):
+        pass
+    A.__init_subclass__()
+
+"""
+
+
+class Base:
+    @classmethod
+    def __init_subclass__(cls):
+        print(f"Base.__init_subclass__({cls.__name__})")
+
+
+class A(Base):
+    pass
diff --git a/tests/cpydiff/core_class_initsubclass_autoclassmethod.py b/tests/cpydiff/core_class_initsubclass_autoclassmethod.py
new file mode 100644
index 0000000000000..b2f7628976c92
--- /dev/null
+++ b/tests/cpydiff/core_class_initsubclass_autoclassmethod.py
@@ -0,0 +1,31 @@
+"""
+categories: Core,Classes
+description: ``__init_subclass__`` isn't an implicit classmethod.
+cause: MicroPython does not currently implement PEP 487. ``__init_subclass__`` is not currently in the list of special-cased class/static methods.
+workaround: Decorate declarations of ``__init_subclass__`` with ``@classmethod``.
+"""
+
+
+def regularize_spelling(text, prefix="bound_"):
+    # for regularizing across the CPython "method" vs MicroPython "bound_method" spelling for the type of a bound classmethod
+    if text.startswith(prefix):
+        return text[len(prefix) :]
+    return text
+
+
+class A:
+    def __init_subclass__(cls):
+        pass
+
+    @classmethod
+    def manual_decorated(cls):
+        pass
+
+
+a = type(A.__init_subclass__).__name__
+b = type(A.manual_decorated).__name__
+
+print(regularize_spelling(a))
+print(regularize_spelling(b))
+if a != b:
+    print("FAIL")
diff --git a/tests/cpydiff/core_class_initsubclass_kwargs.py b/tests/cpydiff/core_class_initsubclass_kwargs.py
new file mode 100644
index 0000000000000..ed5157afeaede
--- /dev/null
+++ b/tests/cpydiff/core_class_initsubclass_kwargs.py
@@ -0,0 +1,22 @@
+"""
+categories: Core,Classes
+description: MicroPython doesn't support parameterized ``__init_subclass__`` class customization.
+cause: MicroPython does not currently implement PEP 487. The MicroPython syntax tree does not include a kwargs node after the class inheritance list.
+workaround: Use class variables or another mechanism to specify base-class customizations.
+"""
+
+
+class Base:
+    @classmethod
+    def __init_subclass__(cls, arg=None, **kwargs):
+        cls.init_subclass_was_called = True
+        print(f"Base.__init_subclass__({cls.__name__}, {arg=!r}, {kwargs=!r})")
+
+
+class A(Base, arg="arg"):
+    pass
+
+
+# Regularize across MicroPython not automatically calling __init_subclass__ either.
+if not getattr(A, "init_subclass_was_called", False):
+    A.__init_subclass__()
diff --git a/tests/cpydiff/core_class_initsubclass_super.py b/tests/cpydiff/core_class_initsubclass_super.py
new file mode 100644
index 0000000000000..d18671a74bf8e
--- /dev/null
+++ b/tests/cpydiff/core_class_initsubclass_super.py
@@ -0,0 +1,22 @@
+"""
+categories: Core,Classes
+description: ``__init_subclass__`` can't be defined a cooperatively-recursive way.
+cause: MicroPython does not currently implement PEP 487. The base object type does not have an ``__init_subclass__`` implementation.
+workaround: Omit the recursive ``__init_subclass__`` call unless it's known that the grandparent also defines it.
+"""
+
+
+class Base:
+    @classmethod
+    def __init_subclass__(cls, **kwargs):
+        cls.init_subclass_was_called = True
+        super().__init_subclass__(**kwargs)
+
+
+class A(Base):
+    pass
+
+
+# Regularize across MicroPython not automatically calling __init_subclass__ either.
+if not getattr(A, "init_subclass_was_called", False):
+    A.__init_subclass__()
diff --git a/tests/cpydiff/core_fstring_concat.py b/tests/cpydiff/core_fstring_concat.py
index 3daa13d75360e..2fbe1b961a1e6 100644
--- a/tests/cpydiff/core_fstring_concat.py
+++ b/tests/cpydiff/core_fstring_concat.py
@@ -1,5 +1,5 @@
 """
-categories: Core
+categories: Core,f-strings
 description: f-strings don't support concatenation with adjacent literals if the adjacent literals contain braces
 cause: MicroPython is optimised for code space.
 workaround: Use the + operator between literal strings when they are not both f-strings
diff --git a/tests/cpydiff/core_fstring_parser.py b/tests/cpydiff/core_fstring_parser.py
index 87cf1e63ed8c2..4964b9707aceb 100644
--- a/tests/cpydiff/core_fstring_parser.py
+++ b/tests/cpydiff/core_fstring_parser.py
@@ -1,5 +1,5 @@
 """
-categories: Core
+categories: Core,f-strings
 description: f-strings cannot support expressions that require parsing to resolve unbalanced nested braces and brackets
 cause: MicroPython is optimised for code space.
 workaround: Always use balanced braces and brackets in expressions inside f-strings
diff --git a/tests/cpydiff/core_fstring_repr.py b/tests/cpydiff/core_fstring_repr.py
index d37fb48db758c..2589a34b7e3b9 100644
--- a/tests/cpydiff/core_fstring_repr.py
+++ b/tests/cpydiff/core_fstring_repr.py
@@ -1,5 +1,5 @@
 """
-categories: Core
+categories: Core,f-strings
 description: f-strings don't support !a conversions
 cause: MicropPython does not implement ascii()
 workaround: None
diff --git a/tests/cpydiff/core_import_all.py b/tests/cpydiff/core_import_all.py
deleted file mode 100644
index 0fbe9d4d4ecd6..0000000000000
--- a/tests/cpydiff/core_import_all.py
+++ /dev/null
@@ -1,10 +0,0 @@
-"""
-categories: Core,import
-description: __all__ is unsupported in __init__.py in MicroPython.
-cause: Not implemented.
-workaround: Manually import the sub-modules directly in __init__.py using ``from . import foo, bar``.
-"""
-
-from modules3 import *
-
-foo.hello()
diff --git a/tests/cpydiff/modules3/__init__.py b/tests/cpydiff/modules3/__init__.py
deleted file mode 100644
index 27a2bf2ad9044..0000000000000
--- a/tests/cpydiff/modules3/__init__.py
+++ /dev/null
@@ -1 +0,0 @@
-__all__ = ["foo"]
diff --git a/tests/cpydiff/modules3/foo.py b/tests/cpydiff/modules3/foo.py
deleted file mode 100644
index dd9b9d4ddd4c4..0000000000000
--- a/tests/cpydiff/modules3/foo.py
+++ /dev/null
@@ -1,2 +0,0 @@
-def hello():
-    print("hello")
diff --git a/tests/cpydiff/modules_errno_enotsup.py b/tests/cpydiff/modules_errno_enotsup.py
new file mode 100644
index 0000000000000..80e5ad9d03220
--- /dev/null
+++ b/tests/cpydiff/modules_errno_enotsup.py
@@ -0,0 +1,10 @@
+"""
+categories: Modules,errno
+description: MicroPython does not include ``ENOTSUP`` as a name for errno 95.
+cause: MicroPython does not implement the ``ENOTSUP`` canonical alias for ``EOPNOTSUPP`` added in CPython 3.2.
+workaround: Use ``errno.EOPNOTSUPP`` in place of ``errno.ENOTSUP``.
+"""
+
+import errno
+
+print(f"{errno.errorcode[errno.EOPNOTSUPP]=!s}")
diff --git a/tests/cpydiff/modules_struct_fewargs.py b/tests/cpydiff/modules_struct_fewargs.py
index 49b2a3213c898..f6346a67938ed 100644
--- a/tests/cpydiff/modules_struct_fewargs.py
+++ b/tests/cpydiff/modules_struct_fewargs.py
@@ -1,6 +1,6 @@
 """
 categories: Modules,struct
-description: Struct pack with too few args, not checked by uPy
+description: Struct pack with too few args, not checked by MicroPython
 cause: Unknown
 workaround: Unknown
 """
diff --git a/tests/cpydiff/modules_struct_manyargs.py b/tests/cpydiff/modules_struct_manyargs.py
index e3b78930f219f..b2ea93b6c9330 100644
--- a/tests/cpydiff/modules_struct_manyargs.py
+++ b/tests/cpydiff/modules_struct_manyargs.py
@@ -1,6 +1,6 @@
 """
 categories: Modules,struct
-description: Struct pack with too many args, not checked by uPy
+description: Struct pack with too many args, not checked by MicroPython
 cause: Unknown
 workaround: Unknown
 """
diff --git a/tests/cpydiff/modules_struct_whitespace_in_format.py b/tests/cpydiff/modules_struct_whitespace_in_format.py
index a7a1d2facdfff..8b609425eb01c 100644
--- a/tests/cpydiff/modules_struct_whitespace_in_format.py
+++ b/tests/cpydiff/modules_struct_whitespace_in_format.py
@@ -1,6 +1,6 @@
 """
 categories: Modules,struct
-description: Struct pack with whitespace in format, whitespace ignored by CPython, error on uPy
+description: Struct pack with whitespace in format, whitespace ignored by CPython, error on MicroPython
 cause: MicroPython is optimised for code size.
 workaround: Don't use spaces in format strings.
 """
diff --git a/tests/cpydiff/syntax_arg_unpacking.py b/tests/cpydiff/syntax_arg_unpacking.py
index e54832ddb9165..7133a8a28272c 100644
--- a/tests/cpydiff/syntax_arg_unpacking.py
+++ b/tests/cpydiff/syntax_arg_unpacking.py
@@ -1,5 +1,5 @@
 """
-categories: Syntax
+categories: Syntax,Unpacking
 description: Argument unpacking does not work if the argument being unpacked is the nth or greater argument where n is the number of bits in an MP_SMALL_INT.
 cause: The implementation uses an MP_SMALL_INT to flag args that need to be unpacked.
 workaround: Use fewer arguments.
diff --git a/tests/cpydiff/syntax_literal_underscore.py b/tests/cpydiff/syntax_literal_underscore.py
new file mode 100644
index 0000000000000..4b1406e9f3f71
--- /dev/null
+++ b/tests/cpydiff/syntax_literal_underscore.py
@@ -0,0 +1,19 @@
+"""
+categories: Syntax,Literals
+description: MicroPython accepts underscores in numeric literals where CPython doesn't
+cause: Different parser implementation
+
+MicroPython's tokenizer ignores underscores in numeric literals, while CPython
+rejects multiple consecutive underscores and underscores after the last digit.
+
+workaround: Remove the underscores not accepted by CPython.
+"""
+
+try:
+    print(eval("1__1"))
+except SyntaxError:
+    print("Should not work")
+try:
+    print(eval("1_"))
+except SyntaxError:
+    print("Should not work")
diff --git a/tests/cpydiff/syntax_spaces.py b/tests/cpydiff/syntax_spaces.py
index 03d25d56199d1..670cefdeac23e 100644
--- a/tests/cpydiff/syntax_spaces.py
+++ b/tests/cpydiff/syntax_spaces.py
@@ -1,8 +1,15 @@
 """
-categories: Syntax,Spaces
-description: uPy requires spaces between literal numbers and keywords, CPy doesn't
-cause: Unknown
-workaround: Unknown
+categories: Syntax,Literals
+description: MicroPython requires spaces between literal numbers and keywords or ".", CPython doesn't
+cause: Different parser implementation
+
+MicroPython's tokenizer treats a sequence like ``1and`` as a single token, while CPython treats it as two tokens.
+
+Since CPython 3.11, when the literal number is followed by a token, this syntax causes a ``SyntaxWarning`` for an "invalid literal". When a literal number is followed by a "." denoting attribute access, CPython does not warn.
+
+workaround: Add a space between the integer literal and the intended next token.
+
+This also fixes the ``SyntaxWarning`` in CPython.
 """
 
 try:
@@ -17,3 +24,7 @@
     print(eval("1if 1else 0"))
 except SyntaxError:
     print("Should have worked")
+try:
+    print(eval("0x1.to_bytes(1)"))
+except SyntaxError:
+    print("Should have worked")
diff --git a/tests/cpydiff/types_complex_parser.py b/tests/cpydiff/types_complex_parser.py
new file mode 100644
index 0000000000000..4a012987d9e48
--- /dev/null
+++ b/tests/cpydiff/types_complex_parser.py
@@ -0,0 +1,14 @@
+"""
+categories: Types,complex
+description: MicroPython's complex() accepts certain incorrect values that CPython rejects
+cause: MicroPython is highly optimized for memory usage.
+workaround: Do not use non-standard complex literals as argument to complex()
+
+MicroPython's ``complex()`` function accepts literals that contain a space and
+no sign between the real and imaginary parts, and interprets it as a plus.
+"""
+
+try:
+    print(complex("1 1j"))
+except ValueError:
+    print("ValueError")
diff --git a/tests/cpydiff/types_float_implicit_conversion.py b/tests/cpydiff/types_float_implicit_conversion.py
index 3726839fac6d1..764c9e4e6ed7a 100644
--- a/tests/cpydiff/types_float_implicit_conversion.py
+++ b/tests/cpydiff/types_float_implicit_conversion.py
@@ -1,6 +1,6 @@
 """
 categories: Types,float
-description: uPy allows implicit conversion of objects in maths operations while CPython does not.
+description: MicroPython allows implicit conversion of objects in maths operations while CPython does not.
 cause: Unknown
 workaround: Objects should be wrapped in ``float(obj)`` for compatibility with CPython.
 """
diff --git a/tests/cpydiff/types_float_rounding.py b/tests/cpydiff/types_float_rounding.py
deleted file mode 100644
index 206e359ed9be7..0000000000000
--- a/tests/cpydiff/types_float_rounding.py
+++ /dev/null
@@ -1,8 +0,0 @@
-"""
-categories: Types,float
-description: uPy and CPython outputs formats may differ
-cause: Unknown
-workaround: Unknown
-"""
-
-print("%.1g" % -9.9)
diff --git a/tests/cpydiff/types_oserror_errnomap.py b/tests/cpydiff/types_oserror_errnomap.py
new file mode 100644
index 0000000000000..6627bd2af4ab7
--- /dev/null
+++ b/tests/cpydiff/types_oserror_errnomap.py
@@ -0,0 +1,48 @@
+"""
+categories: Types,OSError
+description: OSError constructor returns a plain OSError for all errno values, rather than a relevant subtype.
+cause: MicroPython does not include the CPython-standard OSError subclasses.
+workaround: Catch OSError and use its errno attribute to discriminate the cause.
+"""
+
+import errno
+
+errno_list = [  # i.e. the set implemented by micropython
+    errno.EPERM,
+    errno.ENOENT,
+    errno.EIO,
+    errno.EBADF,
+    errno.EAGAIN,
+    errno.ENOMEM,
+    errno.EACCES,
+    errno.EEXIST,
+    errno.ENODEV,
+    errno.EISDIR,
+    errno.EINVAL,
+    errno.EOPNOTSUPP,
+    errno.EADDRINUSE,
+    errno.ECONNABORTED,
+    errno.ECONNRESET,
+    errno.ENOBUFS,
+    errno.ENOTCONN,
+    errno.ETIMEDOUT,
+    errno.ECONNREFUSED,
+    errno.EHOSTUNREACH,
+    errno.EALREADY,
+    errno.EINPROGRESS,
+]
+
+
+def errno_output_type(n):
+    try:
+        raise OSError(n, "")
+    except OSError as e:
+        return f"{type(e).__name__}"
+    except Exception as e:
+        return f"non-OSError {type(e).__name__}"
+    else:
+        return "no error"
+
+
+for n in errno_list:
+    print(errno.errorcode[n], "=", errno_output_type(n))
diff --git a/tests/cpydiff/types_range_limits.py b/tests/cpydiff/types_range_limits.py
new file mode 100644
index 0000000000000..e53d5fd4088f3
--- /dev/null
+++ b/tests/cpydiff/types_range_limits.py
@@ -0,0 +1,26 @@
+"""
+categories: Types,range
+description: Range objects with large start or stop arguments misbehave.
+cause: Intermediate calculations overflow the C mp_int_t type
+workaround: Avoid using such ranges
+"""
+
+from sys import maxsize
+
+# A range including `maxsize-1` cannot be created
+try:
+    print(range(-maxsize - 1, 0))
+except OverflowError:
+    print("OverflowError")
+
+# A range with `stop-start` exceeding sys.maxsize has incorrect len(), while CPython cannot calculate len().
+try:
+    print(len(range(-maxsize, maxsize)))
+except OverflowError:
+    print("OverflowError")
+
+# A range with `stop-start` exceeding sys.maxsize has incorrect len()
+try:
+    print(len(range(-maxsize, maxsize, maxsize)))
+except OverflowError:
+    print("OverflowError")
diff --git a/tests/cpydiff/types_str_formatsep.py b/tests/cpydiff/types_str_formatsep.py
new file mode 100644
index 0000000000000..05d0b8d3d2cf4
--- /dev/null
+++ b/tests/cpydiff/types_str_formatsep.py
@@ -0,0 +1,19 @@
+"""
+categories: Types,str
+description: MicroPython accepts the "," grouping option with any radix, unlike CPython
+cause: To reduce code size, MicroPython does not issue an error for this combination
+workaround: Do not use a format string like ``{:,b}`` if CPython compatibility is required.
+"""
+
+try:
+    print("{:,b}".format(99))
+except ValueError:
+    print("ValueError")
+try:
+    print("{:,x}".format(99))
+except ValueError:
+    print("ValueError")
+try:
+    print("{:,o}".format(99))
+except ValueError:
+    print("ValueError")
diff --git a/tests/cpydiff/types_str_formatsep_float.py b/tests/cpydiff/types_str_formatsep_float.py
new file mode 100644
index 0000000000000..b487cd3758e73
--- /dev/null
+++ b/tests/cpydiff/types_str_formatsep_float.py
@@ -0,0 +1,11 @@
+"""
+categories: Types,str
+description: MicroPython accepts but does not properly implement the "," or "_" grouping character for float values
+cause: To reduce code size, MicroPython does not implement this combination. Grouping characters will not appear in the number's significant digits and will appear at incorrect locations in leading zeros.
+workaround: Do not use a format string like ``{:,f}`` if exact CPython compatibility is required.
+"""
+
+print("{:,f}".format(3141.159))
+print("{:_f}".format(3141.159))
+print("{:011,.2f}".format(3141.159))
+print("{:011_.2f}".format(3141.159))
diff --git a/tests/extmod/asyncio_basic.py.exp b/tests/extmod/asyncio_basic.py.exp
deleted file mode 100644
index 478e22abc8ff6..0000000000000
--- a/tests/extmod/asyncio_basic.py.exp
+++ /dev/null
@@ -1,6 +0,0 @@
-start
-after sleep
-short
-long
-negative
-took 200 400 0
diff --git a/tests/extmod/asyncio_event_queue.py b/tests/extmod/asyncio_event_queue.py
new file mode 100644
index 0000000000000..e0125b1aefe13
--- /dev/null
+++ b/tests/extmod/asyncio_event_queue.py
@@ -0,0 +1,64 @@
+# Ensure that an asyncio task can wait on an Event when the
+# _task_queue is empty
+# https://github.com/micropython/micropython/issues/16569
+
+try:
+    import asyncio
+except ImportError:
+    print("SKIP")
+    raise SystemExit
+
+# This test requires checking that the asyncio scheduler
+# remains active "indefinitely" when the task queue is empty.
+#
+# To check this, we need another independent scheduler that
+# can wait for a certain amount of time. So we have to
+# create one using micropython.schedule() and time.ticks_ms()
+#
+# Technically, this code breaks the rules, as it is clearly
+# documented that Event.set() should _NOT_ be called from a
+# schedule (soft IRQ) because in some cases, a race condition
+# can occur, resulting in a crash. However:
+# - since the risk of a race condition in that specific
+#   case has been analysed and excluded
+# - given that there is no other simple alternative to
+#   write this test case,
+# an exception to the rule was deemed acceptable. See
+# https://github.com/micropython/micropython/pull/16772
+
+import micropython, time
+
+try:
+    micropython.schedule
+except AttributeError:
+    print("SKIP")
+    raise SystemExit
+
+
+evt = asyncio.Event()
+
+
+def schedule_watchdog(end_ticks):
+    if time.ticks_diff(end_ticks, time.ticks_ms()) <= 0:
+        print("asyncio still pending, unlocking event")
+        # Caution: about to call Event.set() from a schedule
+        #          (see the note in the comment above)
+        evt.set()
+        return
+    micropython.schedule(schedule_watchdog, end_ticks)
+
+
+async def foo():
+    print("foo waiting")
+    schedule_watchdog(time.ticks_add(time.ticks_ms(), 100))
+    await evt.wait()
+    print("foo done")
+
+
+async def main():
+    print("main started")
+    await foo()
+    print("main done")
+
+
+asyncio.run(main())
diff --git a/tests/extmod/asyncio_event_queue.py.exp b/tests/extmod/asyncio_event_queue.py.exp
new file mode 100644
index 0000000000000..ee42c96d83ed8
--- /dev/null
+++ b/tests/extmod/asyncio_event_queue.py.exp
@@ -0,0 +1,5 @@
+main started
+foo waiting
+asyncio still pending, unlocking event
+foo done
+main done
diff --git a/tests/extmod/asyncio_heaplock.py b/tests/extmod/asyncio_heaplock.py
index 8326443f0e6c5..9e9908de1cb6a 100644
--- a/tests/extmod/asyncio_heaplock.py
+++ b/tests/extmod/asyncio_heaplock.py
@@ -4,7 +4,11 @@
 # - StreamWriter.write, stream is blocked and data to write is a bytes object
 # - StreamWriter.write, when stream is not blocked
 
-import micropython
+try:
+    import asyncio, micropython
+except ImportError:
+    print("SKIP")
+    raise SystemExit
 
 # strict stackless builds can't call functions without allocating a frame on the heap
 try:
@@ -24,12 +28,6 @@ def f(x):
     print("SKIP")
     raise SystemExit
 
-try:
-    import asyncio
-except ImportError:
-    print("SKIP")
-    raise SystemExit
-
 
 class TestStream:
     def __init__(self, blocked):
diff --git a/tests/extmod/asyncio_iterator_event.py b/tests/extmod/asyncio_iterator_event.py
new file mode 100644
index 0000000000000..f61fefcf051be
--- /dev/null
+++ b/tests/extmod/asyncio_iterator_event.py
@@ -0,0 +1,86 @@
+# Ensure that an asyncio task can wait on an Event when the
+# _task_queue is empty, in the context of an async iterator
+# https://github.com/micropython/micropython/issues/16318
+
+try:
+    import asyncio
+except ImportError:
+    print("SKIP")
+    raise SystemExit
+
+# This test requires checking that the asyncio scheduler
+# remains active "indefinitely" when the task queue is empty.
+#
+# To check this, we need another independent scheduler that
+# can wait for a certain amount of time. So we have to
+# create one using micropython.schedule() and time.ticks_ms()
+#
+# Technically, this code breaks the rules, as it is clearly
+# documented that Event.set() should _NOT_ be called from a
+# schedule (soft IRQ) because in some cases, a race condition
+# can occur, resulting in a crash. However:
+# - since the risk of a race condition in that specific
+#   case has been analysed and excluded
+# - given that there is no other simple alternative to
+#   write this test case,
+# an exception to the rule was deemed acceptable. See
+# https://github.com/micropython/micropython/pull/16772
+
+import micropython, time
+
+try:
+    micropython.schedule
+except AttributeError:
+    print("SKIP")
+    raise SystemExit
+
+ai = None
+
+
+def schedule_watchdog(end_ticks):
+    if time.ticks_diff(end_ticks, time.ticks_ms()) <= 0:
+        print("good: asyncio iterator is still pending, exiting")
+        # Caution: ai.fetch_data() will invoke Event.set()
+        #          (see the note in the comment above)
+        ai.fetch_data(None)
+        return
+    micropython.schedule(schedule_watchdog, end_ticks)
+
+
+async def test(ai):
+    for x in range(3):
+        await asyncio.sleep(0.1)
+        ai.fetch_data("bar {}".format(x))
+
+
+class AsyncIterable:
+    def __init__(self):
+        self.message = None
+        self.evt = asyncio.Event()
+
+    def __aiter__(self):
+        return self
+
+    async def __anext__(self):
+        await self.evt.wait()
+        self.evt.clear()
+        if self.message is None:
+            raise StopAsyncIteration
+        return self.message
+
+    def fetch_data(self, message):
+        self.message = message
+        self.evt.set()
+
+
+async def main():
+    global ai
+    ai = AsyncIterable()
+    asyncio.create_task(test(ai))
+    schedule_watchdog(time.ticks_add(time.ticks_ms(), 500))
+    async for message in ai:
+        print(message)
+    print("end main")
+
+
+asyncio.run(main())
diff --git a/tests/extmod/asyncio_iterator_event.py.exp b/tests/extmod/asyncio_iterator_event.py.exp
new file mode 100644
index 0000000000000..a1893197d02ef
--- /dev/null
+++ b/tests/extmod/asyncio_iterator_event.py.exp
@@ -0,0 +1,5 @@
+bar 0
+bar 1
+bar 2
+good: asyncio iterator is still pending, exiting
+end main
diff --git a/tests/extmod/asyncio_lock.py.exp b/tests/extmod/asyncio_lock.py.exp
deleted file mode 100644
index a37dfcbd2e519..0000000000000
--- a/tests/extmod/asyncio_lock.py.exp
+++ /dev/null
@@ -1,41 +0,0 @@
-False
-True
-False
-have lock
-----
-task start 1
-task start 2
-task start 3
-task have 1 0
-task have 2 0
-task have 3 0
-task have 1 1
-task have 2 1
-task have 3 1
-task have 1 2
-task end 1
-task have 2 2
-task end 2
-task have 3 2
-task end 3
-----
-task have True
-task release False
-task have True
-task release False
-task have again
-task have again
-----
-task got 0
-task release 0
-task cancel 1
-task got 2
-task release 2
-False
-----
-task got 0
-task cancel 1
-task release 0
-task got 2
-task cancel 2
-False
diff --git a/tests/extmod/asyncio_set_exception_handler.py b/tests/extmod/asyncio_set_exception_handler.py
index 5935f0f4ebeaa..0ac4a624224ce 100644
--- a/tests/extmod/asyncio_set_exception_handler.py
+++ b/tests/extmod/asyncio_set_exception_handler.py
@@ -12,7 +12,7 @@ def custom_handler(loop, context):
 
 
 async def task(i):
-    # Raise with 2 args so exception prints the same in uPy and CPython
+    # Raise with 2 args so exception prints the same in MicroPython and CPython
     raise ValueError(i, i + 1)
 
 
diff --git a/tests/extmod/asyncio_wait_for_linked_task.py b/tests/extmod/asyncio_wait_for_linked_task.py
new file mode 100644
index 0000000000000..4dda62d5476c7
--- /dev/null
+++ b/tests/extmod/asyncio_wait_for_linked_task.py
@@ -0,0 +1,66 @@
+# Test asyncio.wait_for, with dependent tasks
+# https://github.com/micropython/micropython/issues/16759
+
+try:
+    import asyncio
+except ImportError:
+    print("SKIP")
+    raise SystemExit
+
+
+# CPython 3.12 deprecated calling get_event_loop() when there is no current event
+# loop, so to make this test run on CPython requires setting the event loop.
+if hasattr(asyncio, "set_event_loop"):
+    asyncio.set_event_loop(asyncio.new_event_loop())
+
+
+class Worker:
+    def __init__(self):
+        self._eventLoop = None
+        self._tasks = []
+
+    def launchTask(self, asyncJob):
+        if self._eventLoop is None:
+            self._eventLoop = asyncio.get_event_loop()
+        return self._eventLoop.create_task(asyncJob)
+
+    async def job(self, prerequisite, taskName):
+        if prerequisite:
+            await prerequisite
+        await asyncio.sleep(0.1)
+        print(taskName, "work completed")
+
+    def planTasks(self):
+        self._tasks.append(self.launchTask(self.job(None, "task0")))
+        self._tasks.append(self.launchTask(self.job(self._tasks[0], "task1")))
+        self._tasks.append(self.launchTask(self.job(self._tasks[1], "task2")))
+
+    async def waitForTask(self, taskIdx):
+        return await self._tasks[taskIdx]
+
+    def syncWaitForTask(self, taskIdx):
+        return self._eventLoop.run_until_complete(self._tasks[taskIdx])
+
+
+async def async_test():
+    print("--- async test")
+    worker = Worker()
+    worker.planTasks()
+    await worker.waitForTask(0)
+    print("-> task0 done")
+    await worker.waitForTask(2)
+    print("-> task2 done")
+
+
+def sync_test():
+    print("--- sync test")
+    worker = Worker()
+    worker.planTasks()
+    worker.syncWaitForTask(0)
+    print("-> task0 done")
+    worker.syncWaitForTask(2)
+    print("-> task2 done")
+
+
+asyncio.get_event_loop().run_until_complete(async_test())
+sync_test()
diff --git a/tests/extmod/asyncio_wait_task.py.exp b/tests/extmod/asyncio_wait_task.py.exp
deleted file mode 100644
index 514a434223315..0000000000000
--- a/tests/extmod/asyncio_wait_task.py.exp
+++ /dev/null
@@ -1,12 +0,0 @@
-start
-task 1
-task 2
-----
-start
-hello
-world
-took 200 200
-task_raise
-ValueError
-task_raise
-ValueError
diff --git a/tests/extmod/binascii_hexlify.py b/tests/extmod/binascii_hexlify.py
index d06029aabaffb..ae90b67336586 100644
--- a/tests/extmod/binascii_hexlify.py
+++ b/tests/extmod/binascii_hexlify.py
@@ -1,5 +1,5 @@
 try:
-    import binascii
+    from binascii import hexlify
 except ImportError:
     print("SKIP")
     raise SystemExit
@@ -10,10 +10,10 @@
     b"\x7f\x80\xff",
     b"1234ABCDabcd",
 ):
-    print(binascii.hexlify(x))
+    print(hexlify(x))
 
 # Two-argument version (now supported in CPython)
-print(binascii.hexlify(b"123", ":"))
+print(hexlify(b"123", ":"))
 
 # zero length buffer
-print(binascii.hexlify(b"", b":"))
+print(hexlify(b"", b":"))
diff --git a/tests/extmod/binascii_unhexlify.py b/tests/extmod/binascii_unhexlify.py
index 731b6a2bd4d10..b08704cba65b2 100644
--- a/tests/extmod/binascii_unhexlify.py
+++ b/tests/extmod/binascii_unhexlify.py
@@ -1,5 +1,5 @@
 try:
-    import binascii
+    from binascii import unhexlify
 except ImportError:
     print("SKIP")
     raise SystemExit
@@ -10,18 +10,18 @@
     b"7f80ff",
     b"313233344142434461626364",
 ):
-    print(binascii.unhexlify(x))
+    print(unhexlify(x))
 
 # CIRCUITPY-CHANGE
 # Unicode strings can be decoded
-print(binascii.unhexlify("313233344142434461626364"))
+print(unhexlify("313233344142434461626364"))
 
 try:
-    a = binascii.unhexlify(b"0")  # odd buffer length
+    a = unhexlify(b"0")  # odd buffer length
 except ValueError:
     print("ValueError")
 
 try:
-    a = binascii.unhexlify(b"gg")  # digit not hex
+    a = unhexlify(b"gg")  # digit not hex
 except ValueError:
     print("ValueError")
diff --git a/tests/extmod/framebuf_blit.py b/tests/extmod/framebuf_blit.py
new file mode 100644
index 0000000000000..b1d98b330a838
--- /dev/null
+++ b/tests/extmod/framebuf_blit.py
@@ -0,0 +1,68 @@
+# Test FrameBuffer.blit method.
+
+try:
+    import framebuf
+except ImportError:
+    print("SKIP")
+    raise SystemExit
+
+
+def printbuf():
+    print("--8<--")
+    for y in range(h):
+        for x in range(w):
+            print("%02x" % buf[(x + y * w)], end="")
+        print()
+    print("-->8--")
+
+
+w = 5
+h = 4
+buf = bytearray(w * h)
+fbuf = framebuf.FrameBuffer(buf, w, h, framebuf.GS8)
+
+fbuf2 = framebuf.FrameBuffer(bytearray(4), 2, 2, framebuf.GS8)
+fbuf2.fill(0xFF)
+
+# Blit another FrameBuffer, at various locations.
+for x, y in ((-1, -1), (0, 0), (1, 1), (4, 3)):
+    fbuf.fill(0)
+    fbuf.blit(fbuf2, x, y)
+    printbuf()
+
+# Blit a bytes object.
+fbuf.fill(0)
+image = (b"\x10\x11\x12\x13", 2, 2, framebuf.GS8)
+fbuf.blit(image, 1, 1)
+printbuf()
+
+# Blit a bytes object that has a stride.
+fbuf.fill(0)
+image = (b"\x20\x21\xff\x22\x23\xff", 2, 2, framebuf.GS8, 3)
+fbuf.blit(image, 1, 1)
+printbuf()
+
+# Blit a bytes object with a bytes palette.
+fbuf.fill(0)
+image = (b"\x00\x01\x01\x00", 2, 2, framebuf.GS8)
+palette = (b"\xa1\xa2", 2, 1, framebuf.GS8)
+fbuf.blit(image, 1, 1, -1, palette)
+printbuf()
+
+# Not enough elements in the tuple.
+try:
+    fbuf.blit((0, 0, 0), 0, 0)
+except ValueError:
+    print("ValueError")
+
+# Too many elements in the tuple.
+try:
+    fbuf.blit((0, 0, 0, 0, 0, 0), 0, 0)
+except ValueError:
+    print("ValueError")
+
+# Bytes too small.
+try:
+    fbuf.blit((b"", 1, 1, framebuf.GS8), 0, 0)
+except ValueError:
+    print("ValueError")
diff --git a/tests/extmod/framebuf_blit.py.exp b/tests/extmod/framebuf_blit.py.exp
new file mode 100644
index 0000000000000..e340f1990c783
--- /dev/null
+++ b/tests/extmod/framebuf_blit.py.exp
@@ -0,0 +1,45 @@
+--8<--
+ff00000000
+0000000000
+0000000000
+0000000000
+-->8--
+--8<--
+ffff000000
+ffff000000
+0000000000
+0000000000
+-->8--
+--8<--
+0000000000
+00ffff0000
+00ffff0000
+0000000000
+-->8--
+--8<--
+0000000000
+0000000000
+0000000000
+00000000ff
+-->8--
+--8<--
+0000000000
+0010110000
+0012130000
+0000000000
+-->8--
+--8<--
+0000000000
+0020210000
+0022230000
+0000000000
+-->8--
+--8<--
+0000000000
+00a1a20000
+00a2a10000
+0000000000
+-->8--
+ValueError
+ValueError
+ValueError
diff --git a/tests/extmod/hashlib_md5.py b/tests/extmod/hashlib_md5.py
index 5f925fc97d02e..ebbe9155e0493 100644
--- a/tests/extmod/hashlib_md5.py
+++ b/tests/extmod/hashlib_md5.py
@@ -1,8 +1,7 @@
 try:
     import hashlib
 except ImportError:
-    # This is neither uPy, nor cPy, so must be uPy with
-    # hashlib module disabled.
+    # MicroPython with hashlib module disabled.
     print("SKIP")
     raise SystemExit
 
diff --git a/tests/extmod/hashlib_sha1.py b/tests/extmod/hashlib_sha1.py
index af23033a591f2..46ffb73fcbe01 100644
--- a/tests/extmod/hashlib_sha1.py
+++ b/tests/extmod/hashlib_sha1.py
@@ -1,8 +1,7 @@
 try:
     import hashlib
 except ImportError:
-    # This is neither uPy, nor cPy, so must be uPy with
-    # hashlib module disabled.
+    # MicroPython with hashlib module disabled.
     print("SKIP")
     raise SystemExit
 
diff --git a/tests/extmod/hashlib_sha256.py b/tests/extmod/hashlib_sha256.py
index 95cd301d160d0..209fcb3987792 100644
--- a/tests/extmod/hashlib_sha256.py
+++ b/tests/extmod/hashlib_sha256.py
@@ -1,8 +1,7 @@
 try:
     import hashlib
 except ImportError:
-    # This is neither uPy, nor cPy, so must be uPy with
-    # hashlib module disabled.
+    # MicroPython with hashlib module disabled.
     print("SKIP")
     raise SystemExit
 
diff --git a/tests/extmod/json_dump.py b/tests/extmod/json_dump.py
index 897d33cc81253..0beb4f5f85698 100644
--- a/tests/extmod/json_dump.py
+++ b/tests/extmod/json_dump.py
@@ -16,11 +16,11 @@
 # dump to a small-int not allowed
 try:
     json.dump(123, 1)
-except (AttributeError, OSError):  # CPython and uPy have different errors
+except (AttributeError, OSError):  # CPython and MicroPython have different errors
     print("Exception")
 
 # dump to an object not allowed
 try:
     json.dump(123, {})
-except (AttributeError, OSError):  # CPython and uPy have different errors
+except (AttributeError, OSError):  # CPython and MicroPython have different errors
     print("Exception")
diff --git a/tests/extmod/json_dump_iobase.py b/tests/extmod/json_dump_iobase.py
index 94d317b87968f..81105e36dccec 100644
--- a/tests/extmod/json_dump_iobase.py
+++ b/tests/extmod/json_dump_iobase.py
@@ -18,7 +18,7 @@ def __init__(self):
 
     def write(self, buf):
         if type(buf) == bytearray:
-            # uPy passes a bytearray, CPython passes a str
+            # MicroPython passes a bytearray, CPython passes a str
             buf = str(buf, "ascii")
         self.buf += buf
         return len(buf)
diff --git a/tests/extmod/json_dump_separators.py b/tests/extmod/json_dump_separators.py
index 4f8e56dceb536..ce39294820fa9 100644
--- a/tests/extmod/json_dump_separators.py
+++ b/tests/extmod/json_dump_separators.py
@@ -25,20 +25,20 @@
     # dump to a small-int not allowed
     try:
         json.dump(123, 1, separators=sep)
-    except (AttributeError, OSError):  # CPython and uPy have different errors
+    except (AttributeError, OSError):  # CPython and MicroPython have different errors
         print("Exception")
 
     # dump to an object not allowed
     try:
         json.dump(123, {}, separators=sep)
-    except (AttributeError, OSError):  # CPython and uPy have different errors
+    except (AttributeError, OSError):  # CPython and MicroPython have different errors
         print("Exception")
 
 
 try:
     s = StringIO()
     json.dump(False, s, separators={"a": 1})
-except (TypeError, ValueError):  # CPython and uPy have different errors
+except (TypeError, ValueError):  # CPython and MicroPython have different errors
     print("Exception")
 
 # invalid separator types
diff --git a/tests/extmod/json_dumps_extra.py b/tests/extmod/json_dumps_extra.py
index a410b0ee0ef63..70efc86645115 100644
--- a/tests/extmod/json_dumps_extra.py
+++ b/tests/extmod/json_dumps_extra.py
@@ -1,4 +1,4 @@
-# test uPy json behaviour that's not valid in CPy
+# test MicroPython json behaviour that's not valid in CPy
 # CIRCUITPY-CHANGE: This behavior matches CPython
 print("SKIP")
 raise SystemExit
diff --git a/tests/extmod/json_dumps_separators.py b/tests/extmod/json_dumps_separators.py
index a3a9ec308f09d..0a95f489a08ec 100644
--- a/tests/extmod/json_dumps_separators.py
+++ b/tests/extmod/json_dumps_separators.py
@@ -39,7 +39,7 @@
 
 try:
     json.dumps(False, separators={"a": 1})
-except (TypeError, ValueError):  # CPython and uPy have different errors
+except (TypeError, ValueError):  # CPython and MicroPython have different errors
     print("Exception")
 
 # invalid separator types
diff --git a/tests/extmod/json_loads.py b/tests/extmod/json_loads.py
index f9073c121e2ef..092402d715d69 100644
--- a/tests/extmod/json_loads.py
+++ b/tests/extmod/json_loads.py
@@ -71,3 +71,27 @@ def my_print(o):
     my_print(json.loads("[null]   a"))
 except ValueError:
     print("ValueError")
+
+# incomplete object declaration
+try:
+    my_print(json.loads('{"a":0,'))
+except ValueError:
+    print("ValueError")
+
+# incomplete nested array declaration
+try:
+    my_print(json.loads('{"a":0, ['))
+except ValueError:
+    print("ValueError")
+
+# incomplete array declaration
+try:
+    my_print(json.loads("[0,"))
+except ValueError:
+    print("ValueError")
+
+# incomplete nested object declaration
+try:
+    my_print(json.loads('[0, {"a":0, '))
+except ValueError:
+    print("ValueError")
diff --git a/tests/extmod/json_loads_bytes.py.exp b/tests/extmod/json_loads_bytes.py.exp
deleted file mode 100644
index c2735a99052d2..0000000000000
--- a/tests/extmod/json_loads_bytes.py.exp
+++ /dev/null
@@ -1,2 +0,0 @@
-[1, 2]
-[None]
diff --git a/tests/extmod/json_loads_int_64.py b/tests/extmod/json_loads_int_64.py
new file mode 100644
index 0000000000000..f6236f1904a87
--- /dev/null
+++ b/tests/extmod/json_loads_int_64.py
@@ -0,0 +1,16 @@
+# Parse 64-bit integers from JSON payloads.
+#
+# This also exercises parsing integers from strings
+# where the value may not be null terminated (last line)
+try:
+    import json
+except ImportError:
+    print("SKIP")
+    raise SystemExit
+
+
+print(json.loads("9111222333444555666"))
+print(json.loads("-9111222333444555666"))
+print(json.loads("9111222333444555666"))
+print(json.loads("-9111222333444555666"))
+print(json.loads('["9111222333444555666777",9111222333444555666]'))
diff --git a/tests/extmod/machine_hard_timer.py b/tests/extmod/machine_hard_timer.py
new file mode 100644
index 0000000000000..8fe42ea850842
--- /dev/null
+++ b/tests/extmod/machine_hard_timer.py
@@ -0,0 +1,45 @@
+import sys
+
+try:
+    from machine import Timer
+    from time import sleep_ms
+except:
+    print("SKIP")
+    raise SystemExit
+
+if sys.platform == "esp8266":
+    timer = Timer(0)
+else:
+    # Hardware timers are not implemented.
+    print("SKIP")
+    raise SystemExit
+
+# Test both hard and soft IRQ handlers and both one-shot and periodic
+# timers. We adjust period in tests/extmod/machine_soft_timer.py, so try
+# adjusting freq here instead. The heap should be locked in hard callbacks
+# and unlocked in soft callbacks.
+
+
+def callback(t):
+    print("callback", mode[1], kind[1], freq, end=" ")
+    try:
+        allocate = bytearray(1)
+        print("unlocked")
+    except MemoryError:
+        print("locked")
+
+
+modes = [(Timer.ONE_SHOT, "one-shot"), (Timer.PERIODIC, "periodic")]
+kinds = [(False, "soft"), (True, "hard")]
+
+for mode in modes:
+    for kind in kinds:
+        for freq in 50, 25:
+            timer.init(
+                mode=mode[0],
+                freq=freq,
+                hard=kind[0],
+                callback=callback,
+            )
+            sleep_ms(90)
+            timer.deinit()
diff --git a/tests/extmod/machine_hard_timer.py.exp b/tests/extmod/machine_hard_timer.py.exp
new file mode 100644
index 0000000000000..26cdc644fdd08
--- /dev/null
+++ b/tests/extmod/machine_hard_timer.py.exp
@@ -0,0 +1,16 @@
+callback one-shot soft 50 unlocked
+callback one-shot soft 25 unlocked
+callback one-shot hard 50 locked
+callback one-shot hard 25 locked
+callback periodic soft 50 unlocked
+callback periodic soft 50 unlocked
+callback periodic soft 50 unlocked
+callback periodic soft 50 unlocked
+callback periodic soft 25 unlocked
+callback periodic soft 25 unlocked
+callback periodic hard 50 locked
+callback periodic hard 50 locked
+callback periodic hard 50 locked
+callback periodic hard 50 locked
+callback periodic hard 25 locked
+callback periodic hard 25 locked
diff --git a/tests/extmod/machine_timer.py b/tests/extmod/machine_timer.py
new file mode 100644
index 0000000000000..ef97ea4e94955
--- /dev/null
+++ b/tests/extmod/machine_timer.py
@@ -0,0 +1,48 @@
+import sys
+
+try:
+    from machine import Timer
+    from time import sleep_ms
+except:
+    print("SKIP")
+    raise SystemExit
+
+if sys.platform in ("esp32", "esp8266", "nrf"):
+    # Software timers aren't implemented on the esp32 and esp8266 ports.
+    # The nrf port doesn't support selection of hard and soft callbacks,
+    # and only allows Timer(period=N), not Timer(freq=N).
+    print("SKIP")
+    raise SystemExit
+else:
+    timer_id = -1
+
+# Test both hard and soft IRQ handlers and both one-shot and periodic
+# timers. We adjust period in tests/extmod/machine_soft_timer.py, so try
+# adjusting freq here instead. The heap should be locked in hard callbacks
+# and unlocked in soft callbacks.
+
+
+def callback(t):
+    print("callback", mode[1], kind[1], freq, end=" ")
+    try:
+        allocate = bytearray(1)
+        print("unlocked")
+    except MemoryError:
+        print("locked")
+
+
+modes = [(Timer.ONE_SHOT, "one-shot"), (Timer.PERIODIC, "periodic")]
+kinds = [(False, "soft"), (True, "hard")]
+
+for mode in modes:
+    for kind in kinds:
+        for freq in 50, 25:
+            timer = Timer(
+                timer_id,
+                mode=mode[0],
+                freq=freq,
+                hard=kind[0],
+                callback=callback,
+            )
+            sleep_ms(90)
+            timer.deinit()
diff --git a/tests/extmod/machine_timer.py.exp b/tests/extmod/machine_timer.py.exp
new file mode 100644
index 0000000000000..26cdc644fdd08
--- /dev/null
+++ b/tests/extmod/machine_timer.py.exp
@@ -0,0 +1,16 @@
+callback one-shot soft 50 unlocked
+callback one-shot soft 25 unlocked
+callback one-shot hard 50 locked
+callback one-shot hard 25 locked
+callback periodic soft 50 unlocked
+callback periodic soft 50 unlocked
+callback periodic soft 50 unlocked
+callback periodic soft 50 unlocked
+callback periodic soft 25 unlocked
+callback periodic soft 25 unlocked
+callback periodic hard 50 locked
+callback periodic hard 50 locked
+callback periodic hard 50 locked
+callback periodic hard 50 locked
+callback periodic hard 25 locked
+callback periodic hard 25 locked
diff --git a/tests/extmod/platform_basic.py b/tests/extmod/platform_basic.py
new file mode 100644
index 0000000000000..eb6f2be13c17a
--- /dev/null
+++ b/tests/extmod/platform_basic.py
@@ -0,0 +1,8 @@
+try:
+    import platform
+except ImportError:
+    print("SKIP")
+    raise SystemExit
+
+print(type(platform.python_compiler()))
+print(type(platform.libc_ver()))
diff --git a/tests/extmod/random_extra_float.py b/tests/extmod/random_extra_float.py
index 3b37ed8dcef2f..03973c583492d 100644
--- a/tests/extmod/random_extra_float.py
+++ b/tests/extmod/random_extra_float.py
@@ -1,12 +1,8 @@
 try:
     import random
-except ImportError:
-    print("SKIP")
-    raise SystemExit
 
-try:
-    random.randint
-except AttributeError:
+    random.random
+except (ImportError, AttributeError):
     print("SKIP")
     raise SystemExit
 
diff --git a/tests/extmod/re_error.py b/tests/extmod/re_error.py
index f61d0913289e1..bd678c9d25156 100644
--- a/tests/extmod/re_error.py
+++ b/tests/extmod/re_error.py
@@ -11,7 +11,7 @@ def test_re(r):
     try:
         re.compile(r)
         print("OK")
-    except:  # uPy and CPy use different errors, so just ignore the type
+    except:  # MPy and CPy use different errors, so just ignore the type
         print("Error")
 
 
diff --git a/tests/extmod/re_start_end_pos.py b/tests/extmod/re_start_end_pos.py
new file mode 100644
index 0000000000000..bd16584374b89
--- /dev/null
+++ b/tests/extmod/re_start_end_pos.py
@@ -0,0 +1,78 @@
+# test start and end pos specification
+
+try:
+    import re
+except ImportError:
+    print("SKIP")
+    raise SystemExit
+
+
+def print_groups(match):
+    print("----")
+    try:
+        if match is not None:
+            i = 0
+            while True:
+                print(match.group(i))
+                i += 1
+    except IndexError:
+        pass
+
+
+p = re.compile(r"o")
+m = p.match("dog")
+print_groups(m)
+
+m = p.match("dog", 1)
+print_groups(m)
+
+m = p.match("dog", 2)
+print_groups(m)
+
+# No match past end of input
+m = p.match("dog", 5)
+print_groups(m)
+
+m = p.match("dog", 0, 1)
+print_groups(m)
+
+# Caret only matches the actual beginning
+p = re.compile(r"^o")
+m = p.match("dog", 1)
+print_groups(m)
+
+# End at beginning means searching empty string
+p = re.compile(r"o")
+m = p.match("dog", 1, 1)
+print_groups(m)
+
+# End before the beginning doesn't match anything
+m = p.match("dog", 2, 1)
+print_groups(m)
+
+# Negative starting values don't crash
+m = p.search("dog", -2)
+print_groups(m)
+
+m = p.search("dog", -2, -5)
+print_groups(m)
+
+# Search also works
+print("--search")
+
+p = re.compile(r"o")
+m = p.search("dog")
+print_groups(m)
+
+m = p.search("dog", 1)
+print_groups(m)
+
+m = p.search("dog", 2)
+print_groups(m)
+
+# Negative starting values don't crash
+m = p.search("dog", -2)
+print_groups(m)
+
+m = p.search("dog", -2, -5)
+print_groups(m)
diff --git a/tests/extmod/re_sub.py b/tests/extmod/re_sub.py
index 3959949724d98..bb9aa111287e6 100644
--- a/tests/extmod/re_sub.py
+++ b/tests/extmod/re_sub.py
@@ -62,7 +62,7 @@ def A():
 except:
     print("invalid group")
 
-# invalid group with very large number (to test overflow in uPy)
+# invalid group with very large number (to test overflow in MicroPython)
 try:
     re.sub("(a)", "b\\199999999999999999999999999999999999999", "a")
 except:
diff --git a/tests/extmod/re_sub_unmatched.py.exp b/tests/extmod/re_sub_unmatched.py.exp
deleted file mode 100644
index 1e5f0fda0554d..0000000000000
--- a/tests/extmod/re_sub_unmatched.py.exp
+++ /dev/null
@@ -1 +0,0 @@
-1-a2
diff --git a/tests/extmod/socket_badconstructor.py b/tests/extmod/socket_badconstructor.py
new file mode 100644
index 0000000000000..4a9d2668c7f1a
--- /dev/null
+++ b/tests/extmod/socket_badconstructor.py
@@ -0,0 +1,22 @@
+# Test passing in bad values to socket.socket constructor.
+
+try:
+    import socket
+except:
+    print("SKIP")
+    raise SystemExit
+
+try:
+    s = socket.socket(None)
+except TypeError:
+    print("TypeError")
+
+try:
+    s = socket.socket(socket.AF_INET, None)
+except TypeError:
+    print("TypeError")
+
+try:
+    s = socket.socket(socket.AF_INET, socket.SOCK_RAW, None)
+except TypeError:
+    print("TypeError")
diff --git a/tests/extmod/socket_fileno.py b/tests/extmod/socket_fileno.py
new file mode 100644
index 0000000000000..da15825e3d56b
--- /dev/null
+++ b/tests/extmod/socket_fileno.py
@@ -0,0 +1,17 @@
+# Test socket.fileno() functionality
+
+try:
+    import socket
+except ImportError:
+    print("SKIP")
+    raise SystemExit
+
+if not hasattr(socket.socket, "fileno"):
+    print("SKIP")
+    raise SystemExit
+
+s = socket.socket()
+print(s.fileno() >= 0)
+
+s.close()
+print(s.fileno())  #  should print -1
diff --git a/tests/extmod/time_mktime.py b/tests/extmod/time_mktime.py
new file mode 100644
index 0000000000000..7fc643dc3cb8c
--- /dev/null
+++ b/tests/extmod/time_mktime.py
@@ -0,0 +1,120 @@
+# test conversion from date tuple to timestamp and back
+
+try:
+    import time
+
+    time.localtime
+except (ImportError, AttributeError):
+    print("SKIP")
+    raise SystemExit
+
+# Range of date expected to work on all MicroPython platforms
+MIN_YEAR = 1970
+MAX_YEAR = 2099
+# CPython properly supported date range:
+# - on Windows: year 1970 to 3000+
+# - on Unix:    year 1583 to 3000+
+
+# Start test from Jan 1, 2001 13:00 (Feb 2000 might already be broken)
+SAFE_DATE = (2001, 1, 1, 13, 0, 0, 0, 0, -1)
+
+
+# mktime function that checks that the result is reversible
+def safe_mktime(date_tuple):
+    try:
+        res = time.mktime(date_tuple)
+        chk = time.localtime(res)
+    except OverflowError:
+        print("safe_mktime:", date_tuple, "overflow error")
+        return None
+    if chk[0:5] != date_tuple[0:5]:
+        print("safe_mktime:", date_tuple[0:5], " -> ", res, " -> ", chk[0:5])
+        return None
+    return res
+
+
+# localtime function that checks that the result is reversible
+def safe_localtime(timestamp):
+    try:
+        res = time.localtime(timestamp)
+        chk = time.mktime(res)
+    except OverflowError:
+        print("safe_localtime:", timestamp, "overflow error")
+        return None
+    if chk != timestamp:
+        print("safe_localtime:", timestamp, " -> ", res, " -> ", chk)
+        return None
+    return res
+
+
+# look for smallest valid timestamps by iterating backwards on tuple
+def test_bwd(date_tuple):
+    curr_stamp = safe_mktime(date_tuple)
+    year = date_tuple[0]
+    month = date_tuple[1] - 1
+    if month < 1:
+        year -= 1
+        month = 12
+    while year >= MIN_YEAR:
+        while month >= 1:
+            next_tuple = (year, month) + date_tuple[2:]
+            next_stamp = safe_mktime(next_tuple)
+            # at this stage, only test consistency and monotonicity
+            if next_stamp is None or next_stamp >= curr_stamp:
+                return date_tuple
+            date_tuple = next_tuple
+            curr_stamp = next_stamp
+            month -= 1
+        year -= 1
+        month = 12
+    return date_tuple
+
+
+# test day-by-day to ensure that every date is properly converted
+def test_fwd(start_date):
+    DAYS_PER_MONTH = (0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31)
+    curr_stamp = safe_mktime(start_date)
+    curr_date = safe_localtime(curr_stamp)
+    while curr_date[0] <= MAX_YEAR:
+        if curr_date[2] < 15:
+            skip_days = 13
+        else:
+            skip_days = 1
+        next_stamp = curr_stamp + skip_days * 86400
+        next_date = safe_localtime(next_stamp)
+        if next_date is None:
+            return curr_date
+        if next_date[2] != curr_date[2] + skip_days:
+            # next month
+            if next_date[2] != 1:
+                print("wrong day of month:", next_date)
+                return curr_date
+            # check the number of days in previous month
+            month_days = DAYS_PER_MONTH[curr_date[1]]
+            if month_days == 28 and curr_date[0] % 4 == 0:
+                if curr_date[0] % 100 != 0 or curr_date[0] % 400 == 0:
+                    month_days += 1
+            if curr_date[2] != month_days:
+                print("wrong day count in prev month:", curr_date[2], "vs", month_days)
+                return curr_date
+            if next_date[1] != curr_date[1] + 1:
+                # next year
+                if curr_date[1] != 12:
+                    print("wrong month count in prev year:", curr_date[1])
+                    return curr_date
+                if next_date[1] != 1:
+                    print("wrong month:", next_date)
+                    return curr_date
+                if next_date[0] != curr_date[0] + 1:
+                    print("wrong year:", next_date)
+                    return curr_date
+        curr_stamp = next_stamp
+        curr_date = next_date
+    return curr_date
+
+
+small_date = test_bwd(SAFE_DATE)
+large_date = test_fwd(small_date)
+print("tested from", small_date[0:3], "to", large_date[0:3])
+print(small_date[0:3], "wday is", small_date[6])
+print(large_date[0:3], "wday is", large_date[6])
diff --git a/tests/extmod/time_res.py b/tests/extmod/time_res.py
index 548bef1f1747c..ef20050b914d7 100644
--- a/tests/extmod/time_res.py
+++ b/tests/extmod/time_res.py
@@ -37,9 +37,12 @@ def test():
         time.sleep_ms(100)
         for func_name, _ in EXPECTED_MAP:
             try:
-                time_func = getattr(time, func_name, None) or globals()[func_name]
+                if func_name.endswith("_time"):
+                    time_func = globals()[func_name]
+                else:
+                    time_func = getattr(time, func_name)
                 now = time_func()  # may raise AttributeError
-            except (KeyError, AttributeError):
+            except AttributeError:
                 continue
             try:
                 results_map[func_name].add(now)
diff --git a/tests/extmod/tls_dtls.py b/tests/extmod/tls_dtls.py
index b2d716769d3f7..753ab2fee4f40 100644
--- a/tests/extmod/tls_dtls.py
+++ b/tests/extmod/tls_dtls.py
@@ -34,9 +34,19 @@ def ioctl(self, req, arg):
 # Wrap the DTLS Server
 dtls_server_ctx = SSLContext(PROTOCOL_DTLS_SERVER)
 dtls_server_ctx.verify_mode = CERT_NONE
-dtls_server = dtls_server_ctx.wrap_socket(server_socket, do_handshake_on_connect=False)
+dtls_server = dtls_server_ctx.wrap_socket(
+    server_socket, do_handshake_on_connect=False, client_id=b"dummy_client_id"
+)
 print("Wrapped DTLS Server")
 
+# wrap DTLS server with invalid client_id
+try:
+    dtls_server = dtls_server_ctx.wrap_socket(
+        server_socket, do_handshake_on_connect=False, client_id=4
+    )
+except OSError:
+    print("Failed to wrap DTLS Server with invalid client_id")
+
 # Wrap the DTLS Client
 dtls_client_ctx = SSLContext(PROTOCOL_DTLS_CLIENT)
 dtls_client_ctx.verify_mode = CERT_NONE
diff --git a/tests/extmod/tls_dtls.py.exp b/tests/extmod/tls_dtls.py.exp
index 78d72bff18816..dbd005d0edfb8 100644
--- a/tests/extmod/tls_dtls.py.exp
+++ b/tests/extmod/tls_dtls.py.exp
@@ -1,3 +1,4 @@
 Wrapped DTLS Server
+Failed to wrap DTLS Server with invalid client_id
 Wrapped DTLS Client
 OK
diff --git a/tests/extmod/ssl_noleak.py b/tests/extmod/tls_noleak.py
similarity index 100%
rename from tests/extmod/ssl_noleak.py
rename to tests/extmod/tls_noleak.py
diff --git a/tests/extmod/tls_threads.py b/tests/extmod/tls_threads.py
new file mode 100644
index 0000000000000..1e0c3d23d2f38
--- /dev/null
+++ b/tests/extmod/tls_threads.py
@@ -0,0 +1,58 @@
+# Ensure that SSL sockets can be allocated from multiple
+# threads without thread safety issues
+
+try:
+    import _thread
+    import io
+    import tls
+    import time
+except ImportError:
+    print("SKIP")
+    raise SystemExit
+
+import unittest
+
+
+class TestSocket(io.IOBase):
+    def write(self, buf):
+        return len(buf)
+
+    def readinto(self, buf):
+        return 0
+
+    def ioctl(self, cmd, arg):
+        return 0
+
+    def setblocking(self, value):
+        pass
+
+
+ITERS = 256
+
+
+class TLSThreads(unittest.TestCase):
+    def test_sslsocket_threaded(self):
+        self.done = False
+        # only run in two threads: too much RAM demand otherwise, and rp2 only
+        # supports two anyhow
+        _thread.start_new_thread(self._alloc_many_sockets, (True,))
+        self._alloc_many_sockets(False)
+        while not self.done:
+            time.sleep(0.1)
+        print("done")
+
+    def _alloc_many_sockets(self, set_done_flag):
+        print("start", _thread.get_ident())
+        ctx = tls.SSLContext(tls.PROTOCOL_TLS_CLIENT)
+        ctx.verify_mode = tls.CERT_NONE
+        for n in range(ITERS):
+            s = TestSocket()
+            s = ctx.wrap_socket(s, do_handshake_on_connect=False)
+            s.close()  # Free associated resources now from thread, not in a GC pass
+        print("done", _thread.get_ident())
+        if set_done_flag:
+            self.done = True
+
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/tests/extmod/uctypes_addressof.py b/tests/extmod/uctypes_addressof.py
index c83089d0f72af..213fcc05eee2b 100644
--- a/tests/extmod/uctypes_addressof.py
+++ b/tests/extmod/uctypes_addressof.py
@@ -12,5 +12,8 @@
     print(uctypes.addressof(uctypes.bytearray_at(1 << i, 8)))
 
 # Test address that is bigger than the greatest small-int but still within the address range.
-large_addr = maxsize + 1
-print(uctypes.addressof(uctypes.bytearray_at(large_addr, 8)) == large_addr)
+try:
+    large_addr = maxsize + 1
+    print(uctypes.addressof(uctypes.bytearray_at(large_addr, 8)) == large_addr)
+except OverflowError:
+    print(True)  # systems with 64-bit bigints will overflow on the above operation
diff --git a/tests/extmod/uctypes_array_load_store.py b/tests/extmod/uctypes_array_load_store.py
index 9de079998566f..695352da57983 100644
--- a/tests/extmod/uctypes_array_load_store.py
+++ b/tests/extmod/uctypes_array_load_store.py
@@ -6,6 +6,13 @@
     print("SKIP")
     raise SystemExit
 
+# 'int' needs to be able to represent UINT64 for this test
+try:
+    int("FF" * 8, 16)
+except OverflowError:
+    print("SKIP")
+    raise SystemExit
+
 N = 5
 
 for endian in ("NATIVE", "LITTLE_ENDIAN", "BIG_ENDIAN"):
diff --git a/tests/extmod/vfs_blockdev_invalid.py b/tests/extmod/vfs_blockdev_invalid.py
index 4d00f4b00273a..29d6bd6b2f9f7 100644
--- a/tests/extmod/vfs_blockdev_invalid.py
+++ b/tests/extmod/vfs_blockdev_invalid.py
@@ -70,8 +70,8 @@ def test(vfs_class):
         try:
             with fs.open("test", "r") as f:
                 print("opened")
-        except OSError as e:
-            print("OSError", e)
+        except Exception as e:
+            print(type(e), e)
 
         # This variant should succeed on open, may fail on read
         # unless the filesystem cached the contents already
@@ -81,8 +81,8 @@ def test(vfs_class):
                 bdev.read_res = res
                 print("read 1", f.read(1))
                 print("read rest", f.read())
-        except OSError as e:
-            print("OSError", e)
+        except Exception as e:
+            print(type(e), e)
 
 
 test(vfs.VfsLfs2)
diff --git a/tests/extmod/vfs_blockdev_invalid.py.exp b/tests/extmod/vfs_blockdev_invalid.py.exp
index 13695e0d88916..0ea0353501de3 100644
--- a/tests/extmod/vfs_blockdev_invalid.py.exp
+++ b/tests/extmod/vfs_blockdev_invalid.py.exp
@@ -2,27 +2,27 @@
 opened
 read 1 a
 read rest aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
-OSError [Errno 5] EIO
+<class 'OSError'> [Errno 5] EIO
 read 1 a
 read rest aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
-OSError [Errno 22] EINVAL
+<class 'OSError'> [Errno 22] EINVAL
 read 1 a
 read rest aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
-OSError [Errno 22] EINVAL
+<class 'OSError'> [Errno 22] EINVAL
 read 1 a
 read rest aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
-OSError [Errno 22] EINVAL
+<class 'TypeError'> can't convert str to int
 read 1 a
 read rest aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
 <class 'VfsFat'>
 opened
 read 1 a
 read rest aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
-OSError [Errno 5] EIO
-OSError [Errno 5] EIO
-OSError [Errno 5] EIO
-OSError [Errno 5] EIO
-OSError [Errno 5] EIO
-OSError [Errno 5] EIO
-OSError [Errno 5] EIO
-OSError [Errno 5] EIO
+<class 'OSError'> [Errno 5] EIO
+<class 'OSError'> [Errno 5] EIO
+<class 'OSError'> [Errno 5] EIO
+<class 'OSError'> [Errno 5] EIO
+<class 'OSError'> [Errno 5] EIO
+<class 'OSError'> [Errno 5] EIO
+<class 'TypeError'> can't convert str to int
+<class 'TypeError'> can't convert str to int
diff --git a/tests/extmod/vfs_fat_ilistdir_del.py b/tests/extmod/vfs_fat_ilistdir_del.py
index a6e24ec92f3b5..964e6b12868eb 100644
--- a/tests/extmod/vfs_fat_ilistdir_del.py
+++ b/tests/extmod/vfs_fat_ilistdir_del.py
@@ -1,8 +1,7 @@
 # Test ilistdir __del__ for VfsFat using a RAM device.
-import gc
 
 try:
-    import os, vfs
+    import gc, os, vfs
 
     vfs.VfsFat
 except (ImportError, AttributeError):
diff --git a/tests/extmod/vfs_lfs.py b/tests/extmod/vfs_lfs.py
index 3ad57fd9c38f1..40d58e9c9f743 100644
--- a/tests/extmod/vfs_lfs.py
+++ b/tests/extmod/vfs_lfs.py
@@ -136,7 +136,7 @@ def test(bdev, vfs_class):
     print(fs.getcwd())
     fs.chdir("../testdir")
     print(fs.getcwd())
-    fs.chdir("../..")
+    fs.chdir("..")
     print(fs.getcwd())
     fs.chdir(".//testdir")
     print(fs.getcwd())
diff --git a/tests/extmod/vfs_lfs_error.py b/tests/extmod/vfs_lfs_error.py
index 2ac7629bfa8fc..73cdf3437330b 100644
--- a/tests/extmod/vfs_lfs_error.py
+++ b/tests/extmod/vfs_lfs_error.py
@@ -1,7 +1,7 @@
 # Test for VfsLittle using a RAM device, testing error handling
 
 try:
-    import vfs
+    import errno, vfs
 
     vfs.VfsLfs1
     vfs.VfsLfs2
@@ -41,14 +41,14 @@ def test(bdev, vfs_class):
     # mkfs with too-small block device
     try:
         vfs_class.mkfs(RAMBlockDevice(1))
-    except OSError:
-        print("mkfs OSError")
+    except OSError as er:
+        print("mkfs OSError", er.errno > 0)
 
     # mount with invalid filesystem
     try:
         vfs_class(bdev)
-    except OSError:
-        print("mount OSError")
+    except OSError as er:
+        print("mount OSError", er.errno > 0)
 
     # set up for following tests
     vfs_class.mkfs(bdev)
@@ -60,60 +60,60 @@ def test(bdev, vfs_class):
     # ilistdir
     try:
         fs.ilistdir("noexist")
-    except OSError:
-        print("ilistdir OSError")
+    except OSError as er:
+        print("ilistdir OSError", er)
 
     # remove
     try:
         fs.remove("noexist")
-    except OSError:
-        print("remove OSError")
+    except OSError as er:
+        print("remove OSError", er)
 
     # rmdir
     try:
         fs.rmdir("noexist")
-    except OSError:
-        print("rmdir OSError")
+    except OSError as er:
+        print("rmdir OSError", er)
 
     # rename
     try:
         fs.rename("noexist", "somethingelse")
-    except OSError:
-        print("rename OSError")
+    except OSError as er:
+        print("rename OSError", er)
 
     # mkdir
     try:
         fs.mkdir("testdir")
-    except OSError:
-        print("mkdir OSError")
+    except OSError as er:
+        print("mkdir OSError", er)
 
     # chdir to nonexistent
     try:
         fs.chdir("noexist")
-    except OSError:
-        print("chdir OSError")
+    except OSError as er:
+        print("chdir OSError", er)
     print(fs.getcwd())  # check still at root
 
     # chdir to file
     try:
         fs.chdir("testfile")
-    except OSError:
-        print("chdir OSError")
+    except OSError as er:
+        print("chdir OSError", er)
     print(fs.getcwd())  # check still at root
 
     # stat
     try:
         fs.stat("noexist")
-    except OSError:
-        print("stat OSError")
+    except OSError as er:
+        print("stat OSError", er)
 
     # error during seek
     with fs.open("testfile", "r") as f:
         f.seek(1 << 30)  # SEEK_SET
         try:
             f.seek(1 << 30, 1)  # SEEK_CUR
-        except OSError:
-            print("seek OSError")
+        except OSError as er:
+            print("seek OSError", er)
 
 
 bdev = RAMBlockDevice(30)
diff --git a/tests/extmod/vfs_lfs_error.py.exp b/tests/extmod/vfs_lfs_error.py.exp
index f4327f6962ec3..440607ed84b22 100644
--- a/tests/extmod/vfs_lfs_error.py.exp
+++ b/tests/extmod/vfs_lfs_error.py.exp
@@ -1,28 +1,28 @@
 test <class 'VfsLfs1'>
-mkfs OSError
-mount OSError
-ilistdir OSError
-remove OSError
-rmdir OSError
-rename OSError
-mkdir OSError
-chdir OSError
+mkfs OSError True
+mount OSError True
+ilistdir OSError [Errno 2] ENOENT
+remove OSError [Errno 2] ENOENT
+rmdir OSError [Errno 2] ENOENT
+rename OSError [Errno 2] ENOENT
+mkdir OSError [Errno 17] EEXIST
+chdir OSError [Errno 2] ENOENT
 /
-chdir OSError
+chdir OSError [Errno 2] ENOENT
 /
-stat OSError
-seek OSError
+stat OSError [Errno 2] ENOENT
+seek OSError [Errno 22] EINVAL
 test <class 'VfsLfs2'>
-mkfs OSError
-mount OSError
-ilistdir OSError
-remove OSError
-rmdir OSError
-rename OSError
-mkdir OSError
-chdir OSError
+mkfs OSError True
+mount OSError True
+ilistdir OSError [Errno 2] ENOENT
+remove OSError [Errno 2] ENOENT
+rmdir OSError [Errno 2] ENOENT
+rename OSError [Errno 2] ENOENT
+mkdir OSError [Errno 17] EEXIST
+chdir OSError [Errno 2] ENOENT
 /
-chdir OSError
+chdir OSError [Errno 2] ENOENT
 /
-stat OSError
-seek OSError
+stat OSError [Errno 2] ENOENT
+seek OSError [Errno 22] EINVAL
diff --git a/tests/extmod/vfs_lfs_ilistdir_del.py b/tests/extmod/vfs_lfs_ilistdir_del.py
index 7b59bc412d983..828c85a258856 100644
--- a/tests/extmod/vfs_lfs_ilistdir_del.py
+++ b/tests/extmod/vfs_lfs_ilistdir_del.py
@@ -1,8 +1,7 @@
 # Test ilistdir __del__ for VfsLittle using a RAM device.
-import gc
 
 try:
-    import vfs
+    import gc, vfs
 
     vfs.VfsLfs2
 except (ImportError, AttributeError):
@@ -71,5 +70,10 @@ def test(bdev, vfs_class):
         fs.open("/test", "w").close()
 
 
-bdev = RAMBlockDevice(30)
+try:
+    bdev = RAMBlockDevice(30)
+except MemoryError:
+    print("SKIP")
+    raise SystemExit
+
 test(bdev, vfs.VfsLfs2)
diff --git a/tests/extmod/vfs_mountinfo.py b/tests/extmod/vfs_mountinfo.py
index f674e80763409..b31dc60ce76d7 100644
--- a/tests/extmod/vfs_mountinfo.py
+++ b/tests/extmod/vfs_mountinfo.py
@@ -5,7 +5,6 @@
 except ImportError:
     print("SKIP")
     raise SystemExit
-import errno
 
 
 class Filesystem:
diff --git a/tests/extmod/vfs_posix.py b/tests/extmod/vfs_posix.py
index d060c0b9c84f3..b3ca2753ba9cf 100644
--- a/tests/extmod/vfs_posix.py
+++ b/tests/extmod/vfs_posix.py
@@ -29,7 +29,21 @@
 print(type(os.stat("/")))
 
 # listdir and ilistdir
-print(type(os.listdir("/")))
+target = "/"
+try:
+    import platform
+
+    # On Android non-root users are permitted full filesystem access only to
+    # selected directories.  To let this test pass on bionic, the internal
+    # user-accessible storage area root is enumerated instead of the
+    # filesystem root.  "/storage/emulated/0" should be there on pretty much
+    # any recent-ish device; querying the proper location requires a JNI
+    # round-trip, not really worth it.
+    if platform.platform().startswith("Android-"):
+        target = "/storage/emulated/0"
+except ImportError:
+    pass
+print(type(os.listdir(target)))
 
 # mkdir
 os.mkdir(temp_dir)
diff --git a/tests/extmod/vfs_posix_ilistdir_del.py b/tests/extmod/vfs_posix_ilistdir_del.py
index 78d7c854c543c..8b5984cd81c05 100644
--- a/tests/extmod/vfs_posix_ilistdir_del.py
+++ b/tests/extmod/vfs_posix_ilistdir_del.py
@@ -1,8 +1,7 @@
 # Test ilistdir __del__ for VfsPosix.
-import gc
 
 try:
-    import os, vfs
+    import gc, os, vfs
 
     vfs.VfsPosix
 except (ImportError, AttributeError):
diff --git a/tests/extmod/vfs_posix_paths.py b/tests/extmod/vfs_posix_paths.py
index b4fedc6716f01..c06318748a327 100644
--- a/tests/extmod/vfs_posix_paths.py
+++ b/tests/extmod/vfs_posix_paths.py
@@ -31,7 +31,7 @@
 fs.mkdir("subdir/one")
 print('listdir("/"):', sorted(i[0] for i in fs.ilistdir("/")))
 print('listdir("."):', sorted(i[0] for i in fs.ilistdir(".")))
-print('getcwd() in {"", "/"}:', fs.getcwd() in {"", "/"})
+print('getcwd() in ("", "/"):', fs.getcwd() in ("", "/"))
 print('chdir("subdir"):', fs.chdir("subdir"))
 print("getcwd():", fs.getcwd())
 print('mkdir("two"):', fs.mkdir("two"))
diff --git a/tests/extmod/vfs_posix_paths.py.exp b/tests/extmod/vfs_posix_paths.py.exp
index ecc13222aaaeb..d6a0960efd249 100644
--- a/tests/extmod/vfs_posix_paths.py.exp
+++ b/tests/extmod/vfs_posix_paths.py.exp
@@ -1,6 +1,6 @@
 listdir("/"): ['subdir']
 listdir("."): ['subdir']
-getcwd() in {"", "/"}: True
+getcwd() in ("", "/"): True
 chdir("subdir"): None
 getcwd(): /subdir
 mkdir("two"): None
diff --git a/tests/extmod/vfs_posix_readonly.py b/tests/extmod/vfs_posix_readonly.py
new file mode 100644
index 0000000000000..e7821381006fd
--- /dev/null
+++ b/tests/extmod/vfs_posix_readonly.py
@@ -0,0 +1,99 @@
+# Test for VfsPosix
+
+try:
+    import gc, os, vfs, errno
+
+    vfs.VfsPosix
+except (ImportError, AttributeError):
+    print("SKIP")
+    raise SystemExit
+
+# We need a directory for testing that doesn't already exist.
+# Skip the test if it does exist.
+temp_dir = "vfs_posix_readonly_test_dir"
+try:
+    os.stat(temp_dir)
+    raise SystemExit("Target directory {} exists".format(temp_dir))
+except OSError:
+    pass
+
+# mkdir (skip test if whole filesystem is readonly)
+try:
+    os.mkdir(temp_dir)
+except OSError as e:
+    if e.errno == errno.EROFS:
+        print("SKIP")
+        raise SystemExit
+
+fs_factory = lambda: vfs.VfsPosix(temp_dir)
+
+# mount
+fs = fs_factory()
+vfs.mount(fs, "/vfs")
+
+with open("/vfs/file", "w") as f:
+    f.write("content")
+
+# test reading works
+with open("/vfs/file") as f:
+    print("file:", f.read())
+
+os.mkdir("/vfs/emptydir")
+
+# umount
+vfs.umount("/vfs")
+
+# mount read-only
+fs = fs_factory()
+vfs.mount(fs, "/vfs", readonly=True)
+
+# test reading works
+with open("/vfs/file") as f:
+    print("file 2:", f.read())
+
+# test writing fails
+try:
+    with open("/vfs/test_write", "w"):
+        pass
+    print("opened")
+except OSError as er:
+    print(repr(er))
+
+# test removing fails
+try:
+    os.unlink("/vfs/file")
+    print("unlinked")
+except OSError as er:
+    print(repr(er))
+
+# test renaming fails
+try:
+    os.rename("/vfs/file2", "/vfs/renamed")
+    print("renamed")
+except OSError as er:
+    print(repr(er))
+
+# test removing directory fails
+try:
+    os.rmdir("/vfs/emptydir")
+    print("rmdir'd")
+except OSError as er:
+    print(repr(er))
+
+# test creating directory fails
+try:
+    os.mkdir("/vfs/emptydir2")
+    print("mkdir'd")
+except OSError as er:
+    print(repr(er))
+
+# umount
+vfs.umount("/vfs")
+
+fs = fs_factory()
+vfs.mount(fs, "/vfs")
+
+os.rmdir("/vfs/emptydir")
+os.unlink("/vfs/file")
+
+os.rmdir(temp_dir)
diff --git a/tests/extmod/vfs_posix_readonly.py.exp b/tests/extmod/vfs_posix_readonly.py.exp
new file mode 100644
index 0000000000000..40e4316775ff3
--- /dev/null
+++ b/tests/extmod/vfs_posix_readonly.py.exp
@@ -0,0 +1,7 @@
+file: content
+file 2: content
+OSError(30,)
+OSError(30,)
+OSError(30,)
+OSError(30,)
+OSError(30,)
diff --git a/tests/extmod/vfs_rom.py b/tests/extmod/vfs_rom.py
index 770b6863b9c43..18ae1f5cf96c8 100644
--- a/tests/extmod/vfs_rom.py
+++ b/tests/extmod/vfs_rom.py
@@ -25,7 +25,7 @@
 # An mpy file with four constant objects: str, bytes, long-int, float.
 test_mpy = (
     # header
-    b"M\x06\x00\x1f"  # mpy file header
+    b"M\x06\x00\x1e"  # mpy file header, -msmall-int-bits=30
     b"\x06"  # n_qstr
     b"\x05"  # n_obj
     # qstrs
@@ -394,6 +394,7 @@ class TestMounted(TestBase):
     def setUp(self):
         self.orig_sys_path = list(sys.path)
         self.orig_cwd = os.getcwd()
+        sys.path = []
         vfs.mount(vfs.VfsRom(self.romfs), "/test_rom")
 
     def tearDown(self):
diff --git a/tests/extmod/websocket_toobig.py b/tests/extmod/websocket_toobig.py
new file mode 100644
index 0000000000000..f4c5a74bbceac
--- /dev/null
+++ b/tests/extmod/websocket_toobig.py
@@ -0,0 +1,28 @@
+try:
+    import io
+    import errno
+    import websocket
+except ImportError:
+    print("SKIP")
+    raise SystemExit
+
+try:
+    buf = "x" * 65536
+except MemoryError:
+    print("SKIP")
+    raise SystemExit
+
+
+# do a websocket write and then return the raw data from the stream
+def ws_write(msg, sz):
+    s = io.BytesIO()
+    ws = websocket.websocket(s)
+    ws.write(msg)
+    s.seek(0)
+    return s.read(sz)
+
+
+try:
+    print(ws_write(buf, 1))
+except OSError as e:
+    print("ioctl: ENOBUFS:", e.errno == errno.ENOBUFS)
diff --git a/tests/extmod/websocket_toobig.py.exp b/tests/extmod/websocket_toobig.py.exp
new file mode 100644
index 0000000000000..3bbd95282fdfe
--- /dev/null
+++ b/tests/extmod/websocket_toobig.py.exp
@@ -0,0 +1 @@
+ioctl: ENOBUFS: True
diff --git a/tests/extmod_hardware/machine_counter.py b/tests/extmod_hardware/machine_counter.py
new file mode 100644
index 0000000000000..62ac1fed47ce7
--- /dev/null
+++ b/tests/extmod_hardware/machine_counter.py
@@ -0,0 +1,90 @@
+# Test machine.Counter implementation
+#
+# IMPORTANT: This test requires hardware connections: the out_pin and in_pin
+# must be wired together.
+
+try:
+    from machine import Counter
+except ImportError:
+    print("SKIP")
+    raise SystemExit
+
+import sys
+from machine import Pin
+
+if "esp32" in sys.platform:
+    id = 0
+    out_pin = 4
+    in_pin = 5
+else:
+    print("Please add support for this test on this platform.")
+    raise SystemExit
+
+import unittest
+
+out_pin = Pin(out_pin, mode=Pin.OUT)
+in_pin = Pin(in_pin, mode=Pin.IN)
+
+
+def toggle(times):
+    for _ in range(times):
+        out_pin(1)
+        out_pin(0)
+
+
+class TestCounter(unittest.TestCase):
+    def setUp(self):
+        out_pin(0)
+        self.counter = Counter(id, in_pin)
+
+    def tearDown(self):
+        self.counter.deinit()
+
+    def assertCounter(self, value):
+        self.assertEqual(self.counter.value(), value)
+
+    def test_connections(self):
+        # Test the hardware connections are correct. If this test fails, all tests will fail.
+        out_pin(1)
+        self.assertEqual(1, in_pin())
+        out_pin(0)
+        self.assertEqual(0, in_pin())
+
+    def test_count_rising(self):
+        self.assertCounter(0)
+        toggle(100)
+        self.assertCounter(100)
+        out_pin(1)
+        self.assertEqual(self.counter.value(0), 101)
+        self.assertCounter(0)  # calling value(0) resets
+        out_pin(0)
+        self.assertCounter(0)  # no rising edge
+        out_pin(1)
+        self.assertCounter(1)
+
+    def test_change_directions(self):
+        self.assertCounter(0)
+        toggle(100)
+        self.assertCounter(100)
+        self.counter.init(in_pin, direction=Counter.DOWN)
+        self.assertCounter(0)  # calling init() zeroes the counter
+        self.counter.value(100)  # need to manually reset the value
+        self.assertCounter(100)
+        toggle(25)
+        self.assertCounter(75)
+
+    def test_count_falling(self):
+        self.counter.init(in_pin, direction=Counter.UP, edge=Counter.FALLING)
+        toggle(20)
+        self.assertCounter(20)
+        out_pin(1)
+        self.assertCounter(20)  # no falling edge
+        out_pin(0)
+        self.assertCounter(21)
+        self.counter.value(-(2**24))
+        toggle(20)
+        self.assertCounter(-(2**24 - 20))
+
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/tests/extmod_hardware/machine_encoder.py b/tests/extmod_hardware/machine_encoder.py
new file mode 100644
index 0000000000000..c218c8bfb646a
--- /dev/null
+++ b/tests/extmod_hardware/machine_encoder.py
@@ -0,0 +1,153 @@
+# Test machine.Encoder implementation
+#
+# IMPORTANT: This test requires hardware connections:
+# - out0_pin and in0_pin must be wired together.
+# - out1_pin and in1_pin must be wired together.
+
+try:
+    from machine import Encoder
+except ImportError:
+    print("SKIP")
+    raise SystemExit
+
+import sys
+import unittest
+from machine import Pin
+from target_wiring import encoder_loopback_id, encoder_loopback_out_pins, encoder_loopback_in_pins
+
+PRINT = False
+PIN_INIT_VALUE = 1
+
+id = encoder_loopback_id
+out0_pin, out1_pin = encoder_loopback_out_pins
+in0_pin, in1_pin = encoder_loopback_in_pins
+
+out0_pin = Pin(out0_pin, mode=Pin.OUT)
+in0_pin = Pin(in0_pin, mode=Pin.IN)
+out1_pin = Pin(out1_pin, mode=Pin.OUT)
+in1_pin = Pin(in1_pin, mode=Pin.IN)
+
+
+class TestEncoder(unittest.TestCase):
+    def setUp(self):
+        out0_pin(PIN_INIT_VALUE)
+        out1_pin(PIN_INIT_VALUE)
+        self.enc = Encoder(id, in0_pin, in1_pin, phases=1)
+        self.enc2 = Encoder(id + 1, in0_pin, in1_pin, phases=2)
+        self.enc4 = Encoder(id + 2, in0_pin, in1_pin, phases=4)
+        self.pulses = 0  # track the expected encoder position in software
+        if PRINT:
+            print(
+                "\nout0_pin() out1_pin() enc.value() enc2.value() enc4.value() |",
+                out0_pin(),
+                out1_pin(),
+                "|",
+                self.enc.value(),
+                self.enc2.value(),
+                self.enc4.value(),
+            )
+
+    def tearDown(self):
+        self.enc.deinit()
+        try:
+            self.enc2.deinit()
+        except:
+            pass
+        try:
+            self.enc4.deinit()
+        except:
+            pass
+
+    def rotate(self, pulses):
+        for _ in range(abs(pulses)):
+            self.pulses += 1 if (pulses > 0) else -1
+            if pulses > 0:
+                if self.pulses % 2:
+                    out0_pin(not out0_pin())
+                else:
+                    out1_pin(not out1_pin())
+            else:
+                if self.pulses % 2:
+                    out1_pin(not out1_pin())
+                else:
+                    out0_pin(not out0_pin())
+        if PRINT:
+            print(
+                "out0_pin() out1_pin() enc.value() enc2.value() enc4.value() pulses self.pulses |",
+                out0_pin(),
+                out1_pin(),
+                "|",
+                self.enc.value(),
+                self.enc2.value(),
+                self.enc4.value(),
+                "|",
+                pulses,
+                self.pulses,
+            )
+
+    def assertPosition(self, value, value2=None, value4=None):
+        self.assertEqual(self.enc.value(), value)
+        if not value2 is None:
+            self.assertEqual(self.enc2.value(), value2)
+        if not value4 is None:
+            self.assertEqual(self.enc4.value(), value4)
+        pass
+
+    @unittest.skipIf(sys.platform == "mimxrt", "cannot read back the pin")
+    def test_connections(self):
+        # Test the hardware connections are correct. If this test fails, all tests will fail.
+        for ch, outp, inp in ((0, out0_pin, in0_pin), (1, out1_pin, in1_pin)):
+            print("Testing channel ", ch)
+            outp(1)
+            self.assertEqual(1, inp())
+            outp(0)
+            self.assertEqual(0, inp())
+
+    def test_basics(self):
+        self.assertPosition(0)
+        self.rotate(100)
+        self.assertPosition(100 // 4, 100 // 2, 100)
+        self.rotate(-100)
+        self.assertPosition(0)
+
+    def test_partial(self):
+        # With phase=1 (default), need 4x pulses to count a rotation
+        self.assertPosition(0)
+        self.rotate(1)
+        self.assertPosition(1, 1, 1)
+        self.rotate(1)
+        self.assertPosition(1, 1, 2)
+        self.rotate(1)
+        self.assertPosition(1, 2, 3)
+        self.rotate(1)
+        self.assertPosition(1, 2, 4)  # +4
+        self.rotate(1)
+        self.assertPosition(2, 3, 5)
+        self.rotate(1)
+        self.assertPosition(2, 3, 6)
+        self.rotate(1)
+        self.assertPosition(2, 4, 7)
+        self.rotate(1)
+        self.assertPosition(2, 4, 8)  # +4
+        self.rotate(-1)
+        self.assertPosition(2, 4, 7)
+        self.rotate(-3)
+        self.assertPosition(1, 2, 4)  # -4
+        self.rotate(-4)
+        self.assertPosition(0, 0, 0)  # -4
+        self.rotate(-1)
+        self.assertPosition(0, 0, -1)
+        self.rotate(-1)
+        self.assertPosition(0, -1, -2)
+        self.rotate(-1)
+        self.assertPosition(0, -1, -3)
+        self.rotate(-1)
+        self.assertPosition(-1, -2, -4)  # -4
+        self.rotate(-1)
+        self.assertPosition(-1, -2, -5)
+        self.rotate(-3)
+        self.assertPosition(-2, -4, -8)  # -4
+
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/tests/extmod_hardware/machine_i2c_target.py b/tests/extmod_hardware/machine_i2c_target.py
new file mode 100644
index 0000000000000..763e6f4771e0f
--- /dev/null
+++ b/tests/extmod_hardware/machine_i2c_target.py
@@ -0,0 +1,307 @@
+# Test machine.I2CTarget.
+#
+# IMPORTANT: This test requires hardware connections: a SoftI2C instance must be
+# wired to a hardware I2C target.  See pin definitions below.
+
+import sys
+
+try:
+    from machine import Pin, SoftI2C, I2CTarget
+except ImportError:
+    print("SKIP")
+    raise SystemExit
+
+import unittest
+
+ADDR = 67
+
+kwargs_target = {}
+
+# Configure pins based on the target.
+if sys.platform == "alif" and sys.implementation._build == "ALIF_ENSEMBLE":
+    args_controller = {"scl": "P1_1", "sda": "P1_0"}
+    args_target = (0,)  # on pins P0_3/P0_2
+elif sys.platform == "esp32":
+    args_controller = {"scl": 5, "sda": 6}
+    args_target = (0,)  # on pins 9/8 for C3 and S3, 18/19 for others
+    kwargs_target = {"scl": 9, "sda": 8}
+elif sys.platform == "rp2":
+    args_controller = {"scl": 5, "sda": 4}
+    args_target = (1,)
+elif sys.platform == "pyboard":
+    if sys.implementation._build == "NUCLEO_WB55":
+        args_controller = {"scl": "B8", "sda": "B9"}
+        args_target = (3,)
+    else:
+        args_controller = {"scl": "X1", "sda": "X2"}
+        args_target = ("X",)
+elif "zephyr-nucleo_wb55rg" in sys.implementation._machine:
+    # PB8=I2C1_SCL, PB9=I2C1_SDA (on Arduino header D15/D14)
+    # PC0=I2C3_SCL, PC1=I2C3_SDA (on Arduino header A0/A1)
+    args_controller = {"scl": Pin(("gpiob", 8)), "sda": Pin(("gpiob", 9))}
+    args_target = ("i2c3",)
+elif "zephyr-rpi_pico" in sys.implementation._machine:
+    args_controller = {"scl": Pin(("gpio0", 5)), "sda": Pin(("gpio0", 4))}
+    args_target = ("i2c1",)  # on gpio7/gpio6
+elif sys.platform == "mimxrt":
+    if "Teensy" in sys.implementation._machine:
+        args_controller = {"scl": "A6", "sda": "A3"}  # D20/D17
+    else:
+        args_controller = {"scl": "D0", "sda": "D1"}
+    args_target = (0,)  # pins 19/18 On Teensy 4.x
+elif sys.platform == "samd":
+    args_controller = {"scl": "D5", "sda": "D1"}
+    args_target = ()
+else:
+    print("Please add support for this test on this platform.")
+    raise SystemExit
+
+
+def config_pull_up():
+    Pin(args_controller["scl"], Pin.OPEN_DRAIN, Pin.PULL_UP)
+    Pin(args_controller["sda"], Pin.OPEN_DRAIN, Pin.PULL_UP)
+
+
+class TestMemory(unittest.TestCase):
+    @classmethod
+    def setUpClass(cls):
+        cls.mem = bytearray(8)
+        cls.i2c = SoftI2C(**args_controller)
+        cls.i2c_target = I2CTarget(*args_target, **kwargs_target, addr=ADDR, mem=cls.mem)
+        config_pull_up()
+
+    @classmethod
+    def tearDownClass(cls):
+        cls.i2c_target.deinit()
+
+    def test_scan(self):
+        self.assertIn(ADDR, self.i2c.scan())
+
+    def test_write(self):
+        self.mem[:] = b"01234567"
+        self.i2c.writeto_mem(ADDR, 0, b"test")
+        self.assertEqual(self.mem, bytearray(b"test4567"))
+        self.i2c.writeto_mem(ADDR, 4, b"TEST")
+        self.assertEqual(self.mem, bytearray(b"testTEST"))
+
+    def test_write_wrap(self):
+        self.mem[:] = b"01234567"
+        self.i2c.writeto_mem(ADDR, 6, b"test")
+        self.assertEqual(self.mem, bytearray(b"st2345te"))
+
+    @unittest.skipIf(sys.platform == "esp32", "write lengths larger than buffer unsupported")
+    def test_write_wrap_large(self):
+        self.mem[:] = b"01234567"
+        self.i2c.writeto_mem(ADDR, 0, b"testTESTmore")
+        self.assertEqual(self.mem, bytearray(b"moreTEST"))
+
+    def test_read(self):
+        self.mem[:] = b"01234567"
+        self.assertEqual(self.i2c.readfrom_mem(ADDR, 0, 4), b"0123")
+        self.assertEqual(self.i2c.readfrom_mem(ADDR, 4, 4), b"4567")
+
+    def test_read_wrap(self):
+        self.mem[:] = b"01234567"
+        self.assertEqual(self.i2c.readfrom_mem(ADDR, 0, 4), b"0123")
+        self.assertEqual(self.i2c.readfrom_mem(ADDR, 2, 4), b"2345")
+        self.assertEqual(self.i2c.readfrom_mem(ADDR, 6, 4), b"6701")
+
+    @unittest.skipIf(sys.platform == "esp32", "read lengths larger than buffer unsupported")
+    def test_read_wrap_large(self):
+        self.mem[:] = b"01234567"
+        self.assertEqual(self.i2c.readfrom_mem(ADDR, 0, 12), b"012345670123")
+
+    def test_write_read(self):
+        self.mem[:] = b"01234567"
+        self.assertEqual(self.i2c.writeto(ADDR, b"\x02"), 1)
+        self.assertEqual(self.i2c.readfrom(ADDR, 4), b"2345")
+
+    @unittest.skipIf(sys.platform == "esp32", "read after read unsupported")
+    def test_write_read_read(self):
+        self.mem[:] = b"01234567"
+        self.assertEqual(self.i2c.writeto(ADDR, b"\x02"), 1)
+        self.assertEqual(self.i2c.readfrom(ADDR, 4), b"2345")
+        self.assertEqual(self.i2c.readfrom(ADDR, 4), b"7012")
+
+
+@unittest.skipUnless(hasattr(I2CTarget, "IRQ_END_READ"), "IRQ unsupported")
+class TestMemoryIRQ(unittest.TestCase):
+    @staticmethod
+    def irq_handler(i2c_target):
+        flags = i2c_target.irq().flags()
+        TestMemoryIRQ.events[TestMemoryIRQ.num_events] = flags
+        TestMemoryIRQ.events[TestMemoryIRQ.num_events + 1] = i2c_target.memaddr
+        TestMemoryIRQ.num_events += 2
+
+    @classmethod
+    def setUpClass(cls):
+        cls.mem = bytearray(8)
+        cls.events = [0] * 8
+        cls.num_events = 0
+        cls.i2c = SoftI2C(**args_controller)
+        cls.i2c_target = I2CTarget(*args_target, **kwargs_target, addr=ADDR, mem=cls.mem)
+        cls.i2c_target.irq(TestMemoryIRQ.irq_handler)
+        config_pull_up()
+
+    @classmethod
+    def tearDownClass(cls):
+        cls.i2c_target.deinit()
+
+    @unittest.skipIf(sys.platform == "esp32", "scan doesn't trigger IRQ_END_WRITE")
+    def test_scan(self):
+        TestMemoryIRQ.num_events = 0
+        self.i2c.scan()
+        self.assertEqual(self.events[: self.num_events], [I2CTarget.IRQ_END_WRITE, 0])
+
+    def test_write(self):
+        TestMemoryIRQ.num_events = 0
+        self.mem[:] = b"01234567"
+        self.i2c.writeto_mem(ADDR, 2, b"test")
+        self.assertEqual(self.mem, bytearray(b"01test67"))
+        self.assertEqual(self.events[: self.num_events], [I2CTarget.IRQ_END_WRITE, 2])
+
+    def test_read(self):
+        TestMemoryIRQ.num_events = 0
+        self.mem[:] = b"01234567"
+        self.assertEqual(self.i2c.readfrom_mem(ADDR, 2, 4), b"2345")
+        self.assertEqual(self.events[: self.num_events], [I2CTarget.IRQ_END_READ, 2])
+
+
+@unittest.skipUnless(hasattr(I2CTarget, "IRQ_WRITE_REQ"), "IRQ unsupported")
+@unittest.skipIf(sys.platform == "mimxrt", "not working")
+@unittest.skipIf(sys.platform == "pyboard", "can't queue more than one byte")
+@unittest.skipIf(sys.platform == "samd", "not working")
+@unittest.skipIf(sys.platform == "zephyr", "must call readinto/write in IRQ handler")
+class TestPolling(unittest.TestCase):
+    @staticmethod
+    def irq_handler(i2c_target, buf=bytearray(1)):
+        flags = i2c_target.irq().flags()
+        if flags & I2CTarget.IRQ_READ_REQ:
+            i2c_target.write(b"0123")
+
+    @classmethod
+    def setUpClass(cls):
+        cls.i2c = SoftI2C(**args_controller)
+        cls.i2c_target = I2CTarget(*args_target, addr=ADDR)
+        cls.i2c_target.irq(
+            TestPolling.irq_handler,
+            I2CTarget.IRQ_WRITE_REQ | I2CTarget.IRQ_READ_REQ,
+            hard=True,
+        )
+        config_pull_up()
+
+    @classmethod
+    def tearDownClass(cls):
+        cls.i2c_target.deinit()
+
+    def test_read(self):
+        # Can't write data up front, must wait until IRQ_READ_REQ.
+        # self.assertEqual(self.i2c_target.write(b"abcd"), 4)
+        self.assertEqual(self.i2c.readfrom(ADDR, 4), b"0123")
+
+    def test_write(self):
+        # Can do the read outside the IRQ, but requires IRQ_WRITE_REQ trigger to be set.
+        self.assertEqual(self.i2c.writeto(ADDR, b"0123"), 4)
+        buf = bytearray(8)
+        self.assertEqual(self.i2c_target.readinto(buf), 4)
+        self.assertEqual(buf, b"0123\x00\x00\x00\x00")
+
+
+@unittest.skipUnless(hasattr(I2CTarget, "IRQ_ADDR_MATCH_READ"), "IRQ unsupported")
+class TestIRQ(unittest.TestCase):
+    @staticmethod
+    def irq_handler(i2c_target, buf=bytearray(1)):
+        flags = i2c_target.irq().flags()
+        TestIRQ.events[TestIRQ.num_events] = flags
+        TestIRQ.num_events += 1
+        if flags & I2CTarget.IRQ_READ_REQ:
+            i2c_target.write(b"Y")
+        if flags & I2CTarget.IRQ_WRITE_REQ:
+            i2c_target.readinto(buf)
+            TestIRQ.events[TestIRQ.num_events] = buf[0]
+            TestIRQ.num_events += 1
+
+    @classmethod
+    def setUpClass(cls):
+        cls.events = [0] * 8
+        cls.num_events = 0
+        cls.i2c = SoftI2C(**args_controller)
+        cls.i2c_target = I2CTarget(*args_target, addr=ADDR)
+        cls.i2c_target.irq(
+            TestIRQ.irq_handler,
+            I2CTarget.IRQ_ADDR_MATCH_READ
+            | I2CTarget.IRQ_ADDR_MATCH_WRITE
+            | I2CTarget.IRQ_WRITE_REQ
+            | I2CTarget.IRQ_READ_REQ
+            | I2CTarget.IRQ_END_READ
+            | I2CTarget.IRQ_END_WRITE,
+            hard=True,
+        )
+        config_pull_up()
+
+    @classmethod
+    def tearDownClass(cls):
+        cls.i2c_target.deinit()
+
+    def test_scan(self):
+        TestIRQ.num_events = 0
+        self.i2c.scan()
+        self.assertEqual(
+            self.events[: self.num_events],
+            [
+                I2CTarget.IRQ_ADDR_MATCH_WRITE,
+                I2CTarget.IRQ_END_WRITE,
+            ],
+        )
+
+    def test_write(self):
+        TestIRQ.num_events = 0
+        self.i2c.writeto(ADDR, b"XYZ")
+        self.assertEqual(
+            self.events[: self.num_events],
+            [
+                I2CTarget.IRQ_ADDR_MATCH_WRITE,
+                I2CTarget.IRQ_WRITE_REQ,
+                ord(b"X"),
+                I2CTarget.IRQ_WRITE_REQ,
+                ord(b"Y"),
+                I2CTarget.IRQ_WRITE_REQ,
+                ord(b"Z"),
+                I2CTarget.IRQ_END_WRITE,
+            ],
+        )
+
+    def test_read(self):
+        TestIRQ.num_events = 0
+        self.assertEqual(self.i2c.readfrom(ADDR, 1), b"Y")
+        self.assertEqual(
+            self.events[: self.num_events],
+            [
+                I2CTarget.IRQ_ADDR_MATCH_READ,
+                I2CTarget.IRQ_READ_REQ,
+                I2CTarget.IRQ_READ_REQ,
+                I2CTarget.IRQ_END_READ,
+            ],
+        )
+
+    def test_write_read(self):
+        TestIRQ.num_events = 0
+        self.i2c.writeto(ADDR, b"X", False)
+        self.assertEqual(self.i2c.readfrom(ADDR, 1), b"Y")
+        self.assertEqual(
+            self.events[: self.num_events],
+            [
+                I2CTarget.IRQ_ADDR_MATCH_WRITE,
+                I2CTarget.IRQ_WRITE_REQ,
+                ord(b"X"),
+                I2CTarget.IRQ_END_WRITE,
+                I2CTarget.IRQ_ADDR_MATCH_READ,
+                I2CTarget.IRQ_READ_REQ,
+                I2CTarget.IRQ_READ_REQ,
+                I2CTarget.IRQ_END_READ,
+            ],
+        )
+
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/tests/feature_check/float.py b/tests/feature_check/float.py
deleted file mode 100644
index d6d2a99d2429d..0000000000000
--- a/tests/feature_check/float.py
+++ /dev/null
@@ -1,13 +0,0 @@
-# detect how many bits of precision the floating point implementation has
-
-try:
-    float
-except NameError:
-    print(0)
-else:
-    if float("1.0000001") == float("1.0"):
-        print(30)
-    elif float("1e300") == float("inf"):
-        print(32)
-    else:
-        print(64)
diff --git a/tests/feature_check/float.py.exp b/tests/feature_check/float.py.exp
deleted file mode 100644
index 900731ffd51ff..0000000000000
--- a/tests/feature_check/float.py.exp
+++ /dev/null
@@ -1 +0,0 @@
-64
diff --git a/tests/feature_check/inlineasm_rv32_zba.py b/tests/feature_check/inlineasm_rv32_zba.py
new file mode 100644
index 0000000000000..81228819042ee
--- /dev/null
+++ b/tests/feature_check/inlineasm_rv32_zba.py
@@ -0,0 +1,10 @@
+# check if RISC-V 32 inline asm supported Zba opcodes
+
+
+@micropython.asm_rv32
+def f():
+    sh1add(a0, a0, a0)
+
+
+f()
+print("rv32_zba")
diff --git a/tests/feature_check/inlineasm_rv32_zba.py.exp b/tests/feature_check/inlineasm_rv32_zba.py.exp
new file mode 100644
index 0000000000000..fde22f5f40090
--- /dev/null
+++ b/tests/feature_check/inlineasm_rv32_zba.py.exp
@@ -0,0 +1 @@
+rv32_zba
diff --git a/tests/feature_check/int_64.py b/tests/feature_check/int_64.py
new file mode 100644
index 0000000000000..4d053782ca82b
--- /dev/null
+++ b/tests/feature_check/int_64.py
@@ -0,0 +1,2 @@
+# Check whether 64-bit long integers are supported
+print(1 << 62)
diff --git a/tests/feature_check/int_64.py.exp b/tests/feature_check/int_64.py.exp
new file mode 100644
index 0000000000000..aef5454e66263
--- /dev/null
+++ b/tests/feature_check/int_64.py.exp
@@ -0,0 +1 @@
+4611686018427387904
diff --git a/tests/feature_check/io_module.py b/tests/feature_check/io_module.py
deleted file mode 100644
index 9094e605316ba..0000000000000
--- a/tests/feature_check/io_module.py
+++ /dev/null
@@ -1,6 +0,0 @@
-try:
-    import io
-
-    print("io")
-except ImportError:
-    print("no")
diff --git a/tests/feature_check/io_module.py.exp b/tests/feature_check/io_module.py.exp
deleted file mode 100644
index e69de29bb2d1d..0000000000000
diff --git a/tests/feature_check/repl_emacs_check.py.exp b/tests/feature_check/repl_emacs_check.py.exp
index 82a4e28ee4f84..5fe8ba1cd2df8 100644
--- a/tests/feature_check/repl_emacs_check.py.exp
+++ b/tests/feature_check/repl_emacs_check.py.exp
@@ -1,5 +1,5 @@
 MicroPython \.\+ version
-Use \.\+
+Type "help()" for more information.
 >>> # Check for emacs keys in REPL
 >>> t = \.\+
 >>> t == 2
diff --git a/tests/feature_check/repl_words_move_check.py.exp b/tests/feature_check/repl_words_move_check.py.exp
index 82a4e28ee4f84..5fe8ba1cd2df8 100644
--- a/tests/feature_check/repl_words_move_check.py.exp
+++ b/tests/feature_check/repl_words_move_check.py.exp
@@ -1,5 +1,5 @@
 MicroPython \.\+ version
-Use \.\+
+Type "help()" for more information.
 >>> # Check for emacs keys in REPL
 >>> t = \.\+
 >>> t == 2
diff --git a/tests/feature_check/target_info.py b/tests/feature_check/target_info.py
index f60f3b319192e..e95530023d7cb 100644
--- a/tests/feature_check/target_info.py
+++ b/tests/feature_check/target_info.py
@@ -19,5 +19,21 @@
     "xtensa",
     "xtensawin",
     "rv32imc",
-][sys_mpy >> 10]
-print(platform, arch)
+    "rv64imc",
+][(sys_mpy >> 10) & 0x0F]
+arch_flags = sys_mpy >> 16
+build = getattr(sys.implementation, "_build", "unknown")
+thread = getattr(sys.implementation, "_thread", None)
+
+# Detect how many bits of precision the floating point implementation has.
+try:
+    if float("1.0000001") == float("1.0"):
+        float_prec = 30
+    elif float("1e300") == float("inf"):
+        float_prec = 32
+    else:
+        float_prec = 64
+except NameError:
+    float_prec = 0
+
+print(platform, arch, arch_flags, build, thread, float_prec, len("α") == 1)
diff --git a/tests/float/cmath_fun.py b/tests/float/cmath_fun.py
index 39011733b02b4..0037d7c65596c 100644
--- a/tests/float/cmath_fun.py
+++ b/tests/float/cmath_fun.py
@@ -51,6 +51,9 @@
             print("%.5g" % ret)
         elif type(ret) == tuple:
             print("%.5g %.5g" % ret)
+        elif f_name == "exp":
+            # exp amplifies REPR_C inaccuracies, so we need to check one digit less
+            print("complex(%.4g, %.4g)" % (real, ret.imag))
         else:
             # some test (eg cmath.sqrt(-0.5)) disagree with CPython with tiny real part
             real = ret.real
diff --git a/tests/float/float_array.py b/tests/float/float_array.py
index 3d128da83819f..cfff3b220c657 100644
--- a/tests/float/float_array.py
+++ b/tests/float/float_array.py
@@ -19,4 +19,10 @@ def test(a):
 test(array("f"))
 test(array("d"))
 
-print("{:.4f}".format(array("f", bytes(array("I", [0x3DCCCCCC])))[0]))
+# hand-crafted floats, including non-standard nan
+for float_hex in (0x3DCCCCCC, 0x7F800024, 0x7FC00004):
+    f = array("f", bytes(array("I", [float_hex])))[0]
+    if type(f) is float:
+        print("{:.4e}".format(f))
+    else:
+        print(f)
diff --git a/tests/float/float_format.py b/tests/float/float_format.py
index 98ed0eb096fa4..0eb8b232b063a 100644
--- a/tests/float/float_format.py
+++ b/tests/float/float_format.py
@@ -2,14 +2,25 @@
 
 # general rounding
 for val in (116, 1111, 1234, 5010, 11111):
-    print("%.0f" % val)
-    print("%.1f" % val)
-    print("%.3f" % val)
+    print("Test on %d / 1000:" % val)
+    for fmt in ("%.5e", "%.3e", "%.1e", "%.0e", "%.3f", "%.1f", "%.0f", "%.3g", "%.1g", "%.0g"):
+        print(fmt, fmt % (val / 1000))
+
+# make sure round-up to the next unit is handled properly
+for val in range(4, 9):
+    divi = 10**val
+    print("Test on 99994 / (10 ** %d):" % val)
+    for fmt in ("%.5e", "%.3e", "%.1e", "%.0e", "%.3f", "%.1f", "%.0f", "%.3g", "%.1g", "%.0g"):
+        print(fmt, fmt % (99994 / divi))
 
 # make sure rounding is done at the correct precision
 for prec in range(8):
     print(("%%.%df" % prec) % 6e-5)
 
+# make sure trailing zeroes are added properly
+for prec in range(8):
+    print(("%%.%df" % prec) % 1e19)
+
 # check certain cases that had a digit value of 10 render as a ":" character
 print("%.2e" % float("9" * 51 + "e-39"))
 print("%.2e" % float("9" * 40 + "e-21"))
diff --git a/tests/float/float_format_accuracy.py b/tests/float/float_format_accuracy.py
new file mode 100644
index 0000000000000..f9467f9c05d89
--- /dev/null
+++ b/tests/float/float_format_accuracy.py
@@ -0,0 +1,73 @@
+# Test accuracy of `repr` conversions.
+# This test also increases code coverage for corner cases.
+
+try:
+    import array, math, random
+except ImportError:
+    print("SKIP")
+    raise SystemExit
+
+# The largest errors come from seldom used very small numbers, near the
+# limit of the representation. So we keep them out of this test to keep
+# the max relative error display useful.
+if float("1e-100") == 0.0:
+    # single-precision
+    float_type = "f"
+    float_size = 4
+    # testing range
+    min_expo = -96  # i.e. not smaller than 1.0e-29
+    # Expected results (given >=50'000 samples):
+    # - MICROPY_FLTCONV_IMPL_EXACT: 100% exact conversions
+    # - MICROPY_FLTCONV_IMPL_APPROX: >=98.53% exact conversions, max relative error <= 1.01e-7
+    min_success = 0.980  # with only 1200 samples, the success rate is lower
+    max_rel_err = 1.1e-7
+    # REPR_C is typically used with FORMAT_IMPL_BASIC, which has a larger error
+    is_REPR_C = float("1.0000001") == float("1.0")
+    if is_REPR_C:  # REPR_C
+        min_success = 0.83
+        max_rel_err = 5.75e-07
+else:
+    # double-precision
+    float_type = "d"
+    float_size = 8
+    # testing range
+    min_expo = -845  # i.e. not smaller than 1.0e-254
+    # Expected results (given >=200'000 samples):
+    # - MICROPY_FLTCONV_IMPL_EXACT: 100% exact conversions
+    # - MICROPY_FLTCONV_IMPL_APPROX: >=99.83% exact conversions, max relative error <= 2.7e-16
+    min_success = 0.997  # with only 1200 samples, the success rate is lower
+    max_rel_err = 2.7e-16
+
+
+# Deterministic pseudorandom generator. Designed to be uniform
+# on mantissa values and exponents, not on the represented number
+def pseudo_randfloat():
+    rnd_buff = bytearray(float_size)
+    for _ in range(float_size):
+        rnd_buff[_] = random.getrandbits(8)
+    return array.array(float_type, rnd_buff)[0]
+
+
+random.seed(42)
+stats = 0
+N = 1200
+max_err = 0
+for _ in range(N):
+    f = pseudo_randfloat()
+    while type(f) is not float or math.isinf(f) or math.isnan(f) or math.frexp(f)[1] <= min_expo:
+        f = pseudo_randfloat()
+
+    str_f = repr(f)
+    f2 = float(str_f)
+    if f2 == f:
+        stats += 1
+    else:
+        error = abs((f2 - f) / f)
+        if max_err < error:
+            max_err = error
+
+print(N, "values converted")
+if stats / N >= min_success and max_err <= max_rel_err:
+    print("float format accuracy OK")
+else:
+    print("FAILED: repr rate=%.3f%% max_err=%.3e" % (100 * stats / N, max_err))
diff --git a/tests/float/float_format_ints.py b/tests/float/float_format_ints.py
index df4444166c5fa..7b7b30c4b340b 100644
--- a/tests/float/float_format_ints.py
+++ b/tests/float/float_format_ints.py
@@ -12,14 +12,42 @@
             print(title, "with format", f_fmt, "gives", f_fmt.format(f))
             print(title, "with format", g_fmt, "gives", g_fmt.format(f))
 
+# The tests below check border cases involving all mantissa bits.
+# In case of REPR_C, where the mantissa is missing two bits, the
+# the string representation for such numbers might not always be exactly
+# the same but nevertheless be correct, so we must allow a few exceptions.
+is_REPR_C = float("1.0000001") == float("1.0")
+
 # 16777215 is 2^24 - 1, the largest integer that can be completely held
 # in a float32.
-print("{:f}".format(16777215))
+val_str = "{:f}".format(16777215)
+
+# When using REPR_C, 16777215.0 is the same as 16777212.0 or 16777214.4
+# (depending on the implementation of pow() function, the result may differ)
+if is_REPR_C and (val_str == "16777212.000000" or val_str == "16777214.400000"):
+    val_str = "16777215.000000"
+
+print(val_str)
+
 # 4294967040 = 16777215 * 128 is the largest integer that is exactly
 # represented by a float32 and that will also fit within a (signed) int32.
 # The upper bound of our integer-handling code is actually double this,
 # but that constant might cause trouble on systems using 32 bit ints.
-print("{:f}".format(2147483520))
+val_str = "{:f}".format(2147483520)
+
+# When using FLOAT_IMPL_FLOAT, 2147483520.0 == 2147483500.0
+# Both representations are valid, the second being "simpler"
+is_float32 = float("1e300") == float("inf")
+if is_float32 and val_str == "2147483500.000000":
+    val_str = "2147483520.000000"
+
+# When using REPR_C, 2147483520.0 is the same as 2147483200.0
+# Both representations are valid, the second being "simpler"
+if is_REPR_C and val_str == "2147483200.000000":
+    val_str = "2147483520.000000"
+
+print(val_str)
+
 # Very large positive integers can be a test for precision and resolution.
 # This is a weird way to represent 1e38 (largest power of 10 for float32).
 print("{:.6e}".format(float("9" * 30 + "e8")))
diff --git a/tests/float/float_parse_doubleprec.py b/tests/float/float_parse_doubleprec.py
index 81fcadcee88b4..c1b0b4823b038 100644
--- a/tests/float/float_parse_doubleprec.py
+++ b/tests/float/float_parse_doubleprec.py
@@ -19,3 +19,9 @@
 print(float("1.00000000000000000000e-307"))
 print(float("10.0000000000000000000e-308"))
 print(float("100.000000000000000000e-309"))
+
+# ensure repr() adds an extra digit when needed for accurate parsing
+print(float(repr(float("2.0") ** 100)) == float("2.0") ** 100)
+
+# ensure repr does not add meaningless extra digits (1.234999999999)
+print(repr(1.2345))
diff --git a/tests/float/float_struct_e.py b/tests/float/float_struct_e.py
index 403fbc5db4cde..ba4134f3393ed 100644
--- a/tests/float/float_struct_e.py
+++ b/tests/float/float_struct_e.py
@@ -32,7 +32,7 @@
     for i in (j, -j):
         x = struct.pack("<e", i)
         v = struct.unpack("<e", x)[0]
-        print("%.7f %s %.15f %s" % (i, x, v, i == v))
+        print("%.7f %s %.7f %s" % (i, x, v, i == v))
 
 # In CPython, packing a float that doesn't fit into a half-float raises OverflowError.
 # But in MicroPython it does not, but rather stores the value as inf.
diff --git a/tests/float/float_struct_e_doubleprec.py b/tests/float/float_struct_e_doubleprec.py
new file mode 100644
index 0000000000000..403fbc5db4cde
--- /dev/null
+++ b/tests/float/float_struct_e_doubleprec.py
@@ -0,0 +1,43 @@
+# Test struct pack/unpack with 'e' typecode.
+
+try:
+    import struct
+except ImportError:
+    print("SKIP")
+    raise SystemExit
+
+test_values = (
+    1e-7,
+    2e-7,
+    1e-6,
+    1e-5,
+    1e-4,
+    1e-3,
+    1e-2,
+    0.1,
+    0,
+    1,
+    2,
+    4,
+    8,
+    10,
+    100,
+    1e3,
+    1e4,
+    6e4,
+    float("inf"),
+)
+
+for j in test_values:
+    for i in (j, -j):
+        x = struct.pack("<e", i)
+        v = struct.unpack("<e", x)[0]
+        print("%.7f %s %.15f %s" % (i, x, v, i == v))
+
+# In CPython, packing a float that doesn't fit into a half-float raises OverflowError.
+# But in MicroPython it does not, but rather stores the value as inf.
+# This test is here for coverage.
+try:
+    struct.pack("e", 1e15)
+except OverflowError:
+    pass
diff --git a/tests/float/float_struct_e_fp30.py b/tests/float/float_struct_e_fp30.py
new file mode 100644
index 0000000000000..6ef84ca063c76
--- /dev/null
+++ b/tests/float/float_struct_e_fp30.py
@@ -0,0 +1,43 @@
+# Test struct pack/unpack with 'e' typecode.
+
+try:
+    import struct
+except ImportError:
+    print("SKIP")
+    raise SystemExit
+
+test_values = (
+    1e-7,
+    2e-7,
+    1e-6,
+    1e-5,
+    1e-4,
+    1e-3,
+    1e-2,
+    0.1,
+    0,
+    1,
+    2,
+    4,
+    8,
+    10,
+    100,
+    1e3,
+    1e4,
+    6e4,
+    float("inf"),
+)
+
+for j in test_values:
+    for i in (j, -j):
+        x = struct.pack("<e", i)
+        v = struct.unpack("<e", x)[0]
+        print("%.7f %s %.5f %s" % (i, x, v, i == v))
+
+# In CPython, packing a float that doesn't fit into a half-float raises OverflowError.
+# But in MicroPython it does not, but rather stores the value as inf.
+# This test is here for coverage.
+try:
+    struct.pack("e", 1e15)
+except OverflowError:
+    pass
diff --git a/tests/float/int_64_float.py b/tests/float/int_64_float.py
new file mode 100644
index 0000000000000..ffdb0c71dbafb
--- /dev/null
+++ b/tests/float/int_64_float.py
@@ -0,0 +1,25 @@
+# test int64 operation with float/complex
+
+i = 1 << 40
+
+# convert int64 to float on rhs
+print("%.5g" % (2.0 * i))
+
+# negative int64 as float
+print("%.5g" % float(-i))
+
+# this should convert to float
+print("%.5g" % (i / 5))
+
+# these should delegate to float
+print("%.5g" % (i * 1.2))
+print("%.5g" % (i / 1.2))
+
+# negative power should produce float
+print("%.5g" % (i**-1))
+print("%.5g" % ((2 + i - i) ** -3))
+
+try:
+    i / 0
+except ZeroDivisionError:
+    print("ZeroDivisionError")
diff --git a/tests/float/math_constants.py b/tests/float/math_constants.py
index 2e4c321052625..21d822a01e3e8 100644
--- a/tests/float/math_constants.py
+++ b/tests/float/math_constants.py
@@ -1,11 +1,30 @@
 # Tests various constants of the math module.
+
+import sys
+
 try:
-    import math
-    from math import exp, cos
+    from array import array
+    from math import e, pi
 except ImportError:
     print("SKIP")
     raise SystemExit
 
-print(math.e == exp(1.0))
+# Hexadecimal representations of e and pi constants.
+e_truth_single = 0x402DF854
+pi_truth_single = 0x40490FDB
+e_truth_double = 0x4005BF0A8B145769
+pi_truth_double = 0x400921FB54442D18
+
+# Detect the floating-point precision of the system, to determine the exact values of
+# the constants (parsing the float from a decimal string can lead to inaccuracies).
+if float("1e300") == float("inf"):
+    # Single precision floats.
+    e_truth = array("f", e_truth_single.to_bytes(4, sys.byteorder))[0]
+    pi_truth = array("f", pi_truth_single.to_bytes(4, sys.byteorder))[0]
+else:
+    # Double precision floats.
+    e_truth = array("d", e_truth_double.to_bytes(8, sys.byteorder))[0]
+    pi_truth = array("d", pi_truth_double.to_bytes(8, sys.byteorder))[0]
 
-print(cos(math.pi))
+print("e:", e == e_truth or (e, e_truth, e - e_truth))
+print("pi:", pi == pi_truth or (pi, pi_truth, pi - pi_truth))
diff --git a/tests/float/math_constants_extra.py b/tests/float/math_constants_extra.py
index dea49aef5a732..756cb45803696 100644
--- a/tests/float/math_constants_extra.py
+++ b/tests/float/math_constants_extra.py
@@ -9,9 +9,12 @@
     raise SystemExit
 
 print(math.tau == 2.0 * math.pi)
+print(math.copysign(1.0, math.tau))
 
 print(math.inf == float("inf"))
 print(-math.inf == -float("inf"))
+print(math.copysign(1.0, math.inf))
 
 print(isnan(math.nan))
 print(isnan(-math.nan))
+print(math.copysign(1.0, math.nan))
diff --git a/tests/float/math_fun_special.py b/tests/float/math_fun_special.py
index e674ec8dfd0df..ecacedec552ec 100644
--- a/tests/float/math_fun_special.py
+++ b/tests/float/math_fun_special.py
@@ -43,10 +43,15 @@
     ("lgamma", lgamma, pos_test_values + [50.0, 100.0]),
 ]
 
+is_REPR_C = float("1.0000001") == float("1.0")
+
 for function_name, function, test_vals in functions:
     for value in test_vals:
         try:
             ans = "{:.4g}".format(function(value))
         except ValueError as e:
             ans = str(e)
+        # a tiny error in REPR_C value for 1.5204998778 causes a wrong rounded value
+        if is_REPR_C and function_name == "erfc" and ans == "1.521":
+            ans = "1.52"
         print("{}({:.4g}) = {}".format(function_name, value, ans))
diff --git a/tests/float/string_format2.py b/tests/float/string_format2.py
index 7a36f4d2f95dc..cdea4c1197249 100644
--- a/tests/float/string_format2.py
+++ b/tests/float/string_format2.py
@@ -144,7 +144,7 @@ def test_fmt(conv, fill, alignment, sign, prefix, width, precision, type, arg):
             for alignment in ("", "<", ">", "=", "^"):
                 for fill in ("", " ", "0", "@"):
                     for sign in ("", "+", "-", " "):
-                        # An empty precision defaults to 6, but when uPy is
+                        # An empty precision defaults to 6, but when MicroPython is
                         # configured to use a float, we can only use a
                         # precision of 6 with numbers less than 10 and still
                         # get results that compare to CPython (which uses
@@ -164,7 +164,7 @@ def test_fmt(conv, fill, alignment, sign, prefix, width, precision, type, arg):
         for alignment in ("", "<", ">", "=", "^"):
             for fill in ("", " ", "0", "@"):
                 for sign in ("", "+", "-", " "):
-                    # An empty precision defaults to 6, but when uPy is
+                    # An empty precision defaults to 6, but when MicroPython is
                     # configured to use a float, we can only use a
                     # precision of 6 with numbers less than 10 and still
                     # get results that compare to CPython (which uses
diff --git a/tests/float/string_format_fp30.py b/tests/float/string_format_fp30.py
deleted file mode 100644
index 5f0b213daa342..0000000000000
--- a/tests/float/string_format_fp30.py
+++ /dev/null
@@ -1,42 +0,0 @@
-def test(fmt, *args):
-    print("{:8s}".format(fmt) + ">" + fmt.format(*args) + "<")
-
-
-test("{:10.4}", 123.456)
-test("{:10.4e}", 123.456)
-test("{:10.4e}", -123.456)
-# test("{:10.4f}", 123.456)
-# test("{:10.4f}", -123.456)
-test("{:10.4g}", 123.456)
-test("{:10.4g}", -123.456)
-test("{:10.4n}", 123.456)
-test("{:e}", 100)
-test("{:f}", 200)
-test("{:g}", 300)
-
-test("{:10.4E}", 123.456)
-test("{:10.4E}", -123.456)
-# test("{:10.4F}", 123.456)
-# test("{:10.4F}", -123.456)
-test("{:10.4G}", 123.456)
-test("{:10.4G}", -123.456)
-
-test("{:06e}", float("inf"))
-test("{:06e}", float("-inf"))
-test("{:06e}", float("nan"))
-
-# The following fails right now
-# test("{:10.1}", 0.0)
-
-print("%.0f" % (1.750000 % 0.08333333333))
-# Below isn't compatible with single-precision float
-# print("%.1f" % (1.750000 % 0.08333333333))
-# print("%.2f" % (1.750000 % 0.08333333333))
-# print("%.12f" % (1.750000 % 0.08333333333))
-
-# tests for errors in format string
-
-try:
-    "{:10.1b}".format(0.0)
-except ValueError:
-    print("ValueError")
diff --git a/tests/float/string_format_modulo.py b/tests/float/string_format_modulo.py
index 3c206b7393588..55314643351db 100644
--- a/tests/float/string_format_modulo.py
+++ b/tests/float/string_format_modulo.py
@@ -6,7 +6,7 @@
 print("%u" % 1.0)
 
 # these 3 have different behaviour in Python 3.x versions
-# uPy raises a TypeError, following Python 3.5 (earlier versions don't)
+# MicroPython raises a TypeError, following Python 3.5 (earlier versions don't)
 # print("%x" % 18.0)
 # print("%o" % 18.0)
 # print("%X" % 18.0)
diff --git a/tests/float/string_format_modulo3.py b/tests/float/string_format_modulo3.py
index f9d9c43cdf42d..f8aeeda20f29c 100644
--- a/tests/float/string_format_modulo3.py
+++ b/tests/float/string_format_modulo3.py
@@ -1,3 +1,3 @@
-# uPy and CPython outputs differ for the following
+# Test corner cases where MicroPython and CPython outputs used to differ in the past
 print("%.1g" % -9.9)  # round up 'g' with '-' sign
 print("%.2g" % 99.9)  # round up
diff --git a/tests/float/string_format_modulo3.py.exp b/tests/float/string_format_modulo3.py.exp
deleted file mode 100644
index 71432b3404519..0000000000000
--- a/tests/float/string_format_modulo3.py.exp
+++ /dev/null
@@ -1,2 +0,0 @@
--10
-100
diff --git a/tests/frozen/frozentest.py b/tests/frozen/frozentest.py
index 78cdd60bf0431..74bdfb3b267f2 100644
--- a/tests/frozen/frozentest.py
+++ b/tests/frozen/frozentest.py
@@ -1,4 +1,4 @@
-print("uPy")
+print("interned")
 print("a long string that is not interned")
 print("a string that has unicode αβγ chars")
 print(b"bytes 1234\x01")
diff --git a/tests/import/builtin_ext.py b/tests/import/builtin_ext.py
index 9d2344d400dae..79ee901ea6774 100644
--- a/tests/import/builtin_ext.py
+++ b/tests/import/builtin_ext.py
@@ -1,3 +1,9 @@
+try:
+    import uos, utime
+except ImportError:
+    print("SKIP")
+    raise SystemExit
+
 # Verify that sys is a builtin.
 import sys
 
diff --git a/tests/import/builtin_import.py b/tests/import/builtin_import.py
index 734498d1be47b..364b0bae912ae 100644
--- a/tests/import/builtin_import.py
+++ b/tests/import/builtin_import.py
@@ -20,3 +20,12 @@
     __import__("xyz", None, None, None, -1)
 except ValueError:
     print("ValueError")
+
+# globals is not checked for level=0
+__import__("builtins", "globals")
+
+# globals must be a dict (or None) for level>0
+try:
+    __import__("builtins", "globals", None, None, 1)
+except TypeError:
+    print("TypeError")
diff --git a/tests/import/import_broken.py b/tests/import/import_broken.py
index 3c7cf4a498528..440922157ef10 100644
--- a/tests/import/import_broken.py
+++ b/tests/import/import_broken.py
@@ -1,3 +1,9 @@
+try:
+    Exception.__class__
+except AttributeError:
+    print("SKIP")
+    raise SystemExit
+
 import sys, pkg
 
 # Modules we import are usually added to sys.modules.
diff --git a/tests/import/import_file.py b/tests/import/import_file.py
index 90ec4e41e77aa..4cf307641c62d 100644
--- a/tests/import/import_file.py
+++ b/tests/import/import_file.py
@@ -1,3 +1,7 @@
+if "__file__" not in globals():
+    print("SKIP")
+    raise SystemExit
+
 import import1b
 
 print(import1b.__file__)
diff --git a/tests/import/import_override.py b/tests/import/import_override.py
index 029ebe54c1f70..0144e78cb9f32 100644
--- a/tests/import/import_override.py
+++ b/tests/import/import_override.py
@@ -2,6 +2,10 @@
 
 
 def custom_import(name, globals, locals, fromlist, level):
+    # CPython always tries to import _io, so just let that through as-is.
+    if name == "_io":
+        return orig_import(name, globals, locals, fromlist, level)
+
     print("import", name, fromlist, level)
 
     class M:
diff --git a/tests/import/import_override.py.exp b/tests/import/import_override.py.exp
deleted file mode 100644
index 365248da6d847..0000000000000
--- a/tests/import/import_override.py.exp
+++ /dev/null
@@ -1,2 +0,0 @@
-import import1b None 0
-456
diff --git a/tests/import/import_override2.py b/tests/import/import_override2.py
new file mode 100644
index 0000000000000..25aac44fe98d0
--- /dev/null
+++ b/tests/import/import_override2.py
@@ -0,0 +1,18 @@
+# test overriding __import__ combined with importing from the filesystem
+
+
+def custom_import(name, globals, locals, fromlist, level):
+    if level > 0:
+        print("import", name, fromlist, level)
+    return orig_import(name, globals, locals, fromlist, level)
+
+
+orig_import = __import__
+try:
+    __import__("builtins").__import__ = custom_import
+except AttributeError:
+    print("SKIP")
+    raise SystemExit
+
+# import calls __import__ behind the scenes
+import pkg7.subpkg1.subpkg2.mod3
diff --git a/tests/import/import_pkg7.py.exp b/tests/import/import_pkg7.py.exp
deleted file mode 100644
index 8f21a615f6a61..0000000000000
--- a/tests/import/import_pkg7.py.exp
+++ /dev/null
@@ -1,8 +0,0 @@
-pkg __name__: pkg7
-pkg __name__: pkg7.subpkg1
-pkg __name__: pkg7.subpkg1.subpkg2
-mod1
-mod2
-mod1.foo
-mod2.bar
-ImportError
diff --git a/tests/import/import_pkg9.py b/tests/import/import_pkg9.py
index 4de028494f1a2..c2e0b618b6969 100644
--- a/tests/import/import_pkg9.py
+++ b/tests/import/import_pkg9.py
@@ -13,4 +13,4 @@
 import pkg9.mod2
 
 pkg9.mod1()
-print(pkg9.mod2.__name__, type(pkg9.mod2).__name__)
+print(pkg9.mod2.__name__, type(pkg9.mod2))
diff --git a/tests/import/import_star.py b/tests/import/import_star.py
new file mode 100644
index 0000000000000..2cb21b877d728
--- /dev/null
+++ b/tests/import/import_star.py
@@ -0,0 +1,59 @@
+# test `from package import *` conventions, including __all__ support
+#
+# This test requires MICROPY_CONFIG_ROM_LEVEL_AT_LEAST_BASIC_FEATURES
+
+try:
+    next(iter([]), 42)
+except TypeError:
+    # 2-argument version of next() not supported
+    # we are probably not at MICROPY_CONFIG_ROM_LEVEL_BASIC_FEATURES
+    print("SKIP")
+    raise SystemExit
+
+# 1. test default visibility
+from pkgstar_default import *
+
+print("visibleFun" in globals())
+print("VisibleClass" in globals())
+print("_hiddenFun" in globals())
+print("_HiddenClass" in globals())
+print(visibleFun())
+
+# 2. test explicit visibility as defined by __all__ (as an array)
+from pkgstar_all_array import *
+
+print("publicFun" in globals())
+print("PublicClass" in globals())
+print("unlistedFun" in globals())
+print("UnlistedClass" in globals())
+print("_privateFun" in globals())
+print("_PrivateClass" in globals())
+print(publicFun())
+# test dynamic import as used in asyncio
+print("dynamicFun" in globals())
+print(dynamicFun())
+
+# 3. test explicit visibility as defined by __all__ (as an tuple)
+from pkgstar_all_tuple import *
+
+print("publicFun2" in globals())
+print("PublicClass2" in globals())
+print("unlistedFun2" in globals())
+print("UnlistedClass2" in globals())
+print(publicFun2())
+
+# 4. test reporting of missing entries in __all__
+try:
+    from pkgstar_all_miss import *
+
+    print("missed detection of incorrect __all__ definition")
+except AttributeError as er:
+    print("AttributeError triggered for bad __all__ definition")
+
+# 5. test reporting of invalid __all__ definition
+try:
+    from pkgstar_all_inval import *
+
+    print("missed detection of incorrect __all__ definition")
+except TypeError as er:
+    print("TypeError triggered for bad __all__ definition")
diff --git a/tests/import/import_star_error.py b/tests/import/import_star_error.py
index 9e1757b6ef5a2..73d9c863d6f51 100644
--- a/tests/import/import_star_error.py
+++ b/tests/import/import_star_error.py
@@ -1,5 +1,10 @@
 # test errors with import *
 
+if not hasattr(object, "__init__"):
+    # target doesn't have MICROPY_CPYTHON_COMPAT enabled, so doesn't check for "import *"
+    print("SKIP")
+    raise SystemExit
+
 # 'import *' is not allowed in function scope
 try:
     exec("def foo(): from x import *")
diff --git a/tests/import/module_getattr.py.exp b/tests/import/module_getattr.py.exp
deleted file mode 100644
index bc59c12aa16bd..0000000000000
--- a/tests/import/module_getattr.py.exp
+++ /dev/null
@@ -1 +0,0 @@
-False
diff --git a/tests/import/pkg7/subpkg1/subpkg2/mod3.py b/tests/import/pkg7/subpkg1/subpkg2/mod3.py
index b0f4279fcf57b..f7f4c1e65f46f 100644
--- a/tests/import/pkg7/subpkg1/subpkg2/mod3.py
+++ b/tests/import/pkg7/subpkg1/subpkg2/mod3.py
@@ -5,7 +5,9 @@
 print(bar)
 
 # attempted relative import beyond top-level package
+# On older versions of CPython (eg 3.8) this is a ValueError, but on
+# newer CPython (eg 3.11) and MicroPython it's an ImportError.
 try:
     from .... import mod1
-except ImportError:
+except (ImportError, ValueError):
     print("ImportError")
diff --git a/tests/import/pkgstar_all_array/__init__.py b/tests/import/pkgstar_all_array/__init__.py
new file mode 100644
index 0000000000000..03b012123fe0c
--- /dev/null
+++ b/tests/import/pkgstar_all_array/__init__.py
@@ -0,0 +1,49 @@
+__all__ = ["publicFun", "PublicClass", "dynamicFun"]
+
+
+# Definitions below should always be imported by a star import
+def publicFun():
+    return 1
+
+
+class PublicClass:
+    def __init__(self):
+        self._val = 1
+
+
+# If __all__ support is enabled, definitions below
+# should not be imported by a star import
+def unlistedFun():
+    return 0
+
+
+class UnlistedClass:
+    def __init__(self):
+        self._val = 0
+
+
+# Definitions below should be not be imported by a star import
+# (they start with an underscore, and are not listed in __all__)
+def _privateFun():
+    return -1
+
+
+class _PrivateClass:
+    def __init__(self):
+        self._val = -1
+
+
+# Test lazy loaded function, as used by extmod/asyncio:
+# Works with a star import only if __all__ support is enabled
+_attrs = {
+    "dynamicFun": "funcs",
+}
+
+
+def __getattr__(attr):
+    mod = _attrs.get(attr, None)
+    if mod is None:
+        raise AttributeError(attr)
+    value = getattr(__import__(mod, globals(), locals(), True, 1), attr)
+    globals()[attr] = value
+    return value
diff --git a/tests/import/pkgstar_all_array/funcs.py b/tests/import/pkgstar_all_array/funcs.py
new file mode 100644
index 0000000000000..7540d70f66bce
--- /dev/null
+++ b/tests/import/pkgstar_all_array/funcs.py
@@ -0,0 +1,2 @@
+def dynamicFun():
+    return 777
diff --git a/tests/import/pkgstar_all_inval/__init__.py b/tests/import/pkgstar_all_inval/__init__.py
new file mode 100644
index 0000000000000..7022476c19be8
--- /dev/null
+++ b/tests/import/pkgstar_all_inval/__init__.py
@@ -0,0 +1 @@
+__all__ = 42
diff --git a/tests/import/pkgstar_all_miss/__init__.py b/tests/import/pkgstar_all_miss/__init__.py
new file mode 100644
index 0000000000000..f9bbb538072bf
--- /dev/null
+++ b/tests/import/pkgstar_all_miss/__init__.py
@@ -0,0 +1,8 @@
+__all__ = ("existingFun", "missingFun")
+
+
+def existingFun():
+    return None
+
+
+# missingFun is not defined, should raise an error on import
diff --git a/tests/import/pkgstar_all_tuple/__init__.py b/tests/import/pkgstar_all_tuple/__init__.py
new file mode 100644
index 0000000000000..433ddc8e97639
--- /dev/null
+++ b/tests/import/pkgstar_all_tuple/__init__.py
@@ -0,0 +1,22 @@
+__all__ = ("publicFun2", "PublicClass2")
+
+
+# Definitions below should always be imported by a star import
+def publicFun2():
+    return 2
+
+
+class PublicClass2:
+    def __init__(self):
+        self._val = 2
+
+
+# If __all__ support is enabled, definitions below
+# should not be imported by a star import
+def unlistedFun2():
+    return 0
+
+
+class UnlistedClass2:
+    def __init__(self):
+        self._val = 0
diff --git a/tests/import/pkgstar_default/__init__.py b/tests/import/pkgstar_default/__init__.py
new file mode 100644
index 0000000000000..4947e4ce7f180
--- /dev/null
+++ b/tests/import/pkgstar_default/__init__.py
@@ -0,0 +1,20 @@
+# When __all__ is undefined, star import should only
+# show objects that do not start with an underscore
+
+
+def visibleFun():
+    return 42
+
+
+class VisibleClass:
+    def __init__(self):
+        self._val = 42
+
+
+def _hiddenFun():
+    return -1
+
+
+class _HiddenClass:
+    def __init__(self):
+        self._val = -1
diff --git a/tests/inlineasm/rv32/asmzba.py b/tests/inlineasm/rv32/asmzba.py
new file mode 100644
index 0000000000000..75f3573c864d6
--- /dev/null
+++ b/tests/inlineasm/rv32/asmzba.py
@@ -0,0 +1,18 @@
+@micropython.asm_rv32
+def test_sh1add(a0, a1):
+    sh1add(a0, a0, a1)
+
+
+@micropython.asm_rv32
+def test_sh2add(a0, a1):
+    sh2add(a0, a0, a1)
+
+
+@micropython.asm_rv32
+def test_sh3add(a0, a1):
+    sh3add(a0, a0, a1)
+
+
+print(hex(test_sh1add(10, 20)))
+print(hex(test_sh2add(10, 20)))
+print(hex(test_sh3add(10, 20)))
diff --git a/tests/inlineasm/rv32/asmzba.py.exp b/tests/inlineasm/rv32/asmzba.py.exp
new file mode 100644
index 0000000000000..5f56bd95642a4
--- /dev/null
+++ b/tests/inlineasm/rv32/asmzba.py.exp
@@ -0,0 +1,3 @@
+0x28
+0x3c
+0x64
diff --git a/tests/inlineasm/thumb/asmerrors.py b/tests/inlineasm/thumb/asmerrors.py
new file mode 100644
index 0000000000000..a26f9322540fd
--- /dev/null
+++ b/tests/inlineasm/thumb/asmerrors.py
@@ -0,0 +1,4 @@
+try:
+    exec("@micropython.asm_thumb\ndef l():\n    a = di(a2, a2, -1)")
+except SyntaxError as e:
+    print(e)
diff --git a/tests/inlineasm/thumb/asmerrors.py.exp b/tests/inlineasm/thumb/asmerrors.py.exp
new file mode 100644
index 0000000000000..7590f171e5184
--- /dev/null
+++ b/tests/inlineasm/thumb/asmerrors.py.exp
@@ -0,0 +1 @@
+expecting an assembler instruction
diff --git a/tests/inlineasm/xtensa/asmargs.py b/tests/inlineasm/xtensa/asmargs.py
new file mode 100644
index 0000000000000..2bfccfcc69bb2
--- /dev/null
+++ b/tests/inlineasm/xtensa/asmargs.py
@@ -0,0 +1,44 @@
+# test passing arguments
+
+
+@micropython.asm_xtensa
+def arg0():
+    movi(a2, 1)
+
+
+print(arg0())
+
+
+@micropython.asm_xtensa
+def arg1(a2):
+    addi(a2, a2, 1)
+
+
+print(arg1(1))
+
+
+@micropython.asm_xtensa
+def arg2(a2, a3):
+    add(a2, a2, a3)
+
+
+print(arg2(1, 2))
+
+
+@micropython.asm_xtensa
+def arg3(a2, a3, a4):
+    add(a2, a2, a3)
+    add(a2, a2, a4)
+
+
+print(arg3(1, 2, 3))
+
+
+@micropython.asm_xtensa
+def arg4(a2, a3, a4, a5):
+    add(a2, a2, a3)
+    add(a2, a2, a4)
+    add(a2, a2, a5)
+
+
+print(arg4(1, 2, 3, 4))
diff --git a/tests/inlineasm/xtensa/asmargs.py.exp b/tests/inlineasm/xtensa/asmargs.py.exp
new file mode 100644
index 0000000000000..e33a6964f46e8
--- /dev/null
+++ b/tests/inlineasm/xtensa/asmargs.py.exp
@@ -0,0 +1,5 @@
+1
+2
+3
+6
+10
diff --git a/tests/inlineasm/xtensa/asmarith.py b/tests/inlineasm/xtensa/asmarith.py
new file mode 100644
index 0000000000000..1c0934eb7a631
--- /dev/null
+++ b/tests/inlineasm/xtensa/asmarith.py
@@ -0,0 +1,119 @@
+@micropython.asm_xtensa
+def f1(a2):
+    abs_(a2, a2)
+
+
+for value in (10, -10, 0):
+    print(f1(value))
+
+
+ADDMI_TEMPLATE = """
+@micropython.asm_xtensa
+def f1(a2) -> int:
+    addmi(a2, a2, {})
+print(f1(0))
+"""
+
+for value in (-32768, -32767, 32512, 32513, 0):
+    try:
+        exec(ADDMI_TEMPLATE.format(value))
+    except SyntaxError as error:
+        print(error)
+
+
+@micropython.asm_xtensa
+def a2(a2, a3) -> int:
+    addx2(a2, a2, a3)
+
+
+@micropython.asm_xtensa
+def a4(a2, a3) -> int:
+    addx4(a2, a2, a3)
+
+
+@micropython.asm_xtensa
+def a8(a2, a3) -> int:
+    addx8(a2, a2, a3)
+
+
+@micropython.asm_xtensa
+def s2(a2, a3) -> int:
+    subx2(a2, a2, a3)
+
+
+@micropython.asm_xtensa
+def s4(a2, a3) -> int:
+    subx4(a2, a2, a3)
+
+
+@micropython.asm_xtensa
+def s8(a2, a3) -> int:
+    subx8(a2, a2, a3)
+
+
+for first, second in ((100, 100), (-100, 100), (-100, -100), (100, -100)):
+    print("a2", a2(first, second))
+    print("a4", a4(first, second))
+    print("a8", a8(first, second))
+    print("s2", s2(first, second))
+    print("s4", s4(first, second))
+    print("s8", s8(first, second))
+
+
+@micropython.asm_xtensa
+def f5(a2) -> int:
+    neg(a2, a2)
+
+
+for value in (0, -100, 100):
+    print(f5(value))
+
+
+@micropython.asm_xtensa
+def f6():
+    movi(a2, 0x100)
+    movi(a3, 1)
+    add(a2, a2, a3)
+    addi(a2, a2, 1)
+    addi(a2, a2, -2)
+    sub(a2, a2, a3)
+
+
+print(hex(f6()))
+
+
+@micropython.asm_xtensa
+def f7():
+    movi(a2, 0x10FF)
+    movi(a3, 1)
+    and_(a4, a2, a3)
+    or_(a4, a4, a3)
+    movi(a3, 0x200)
+    xor(a2, a4, a3)
+
+
+print(hex(f7()))
+
+
+@micropython.asm_xtensa
+def f8(a2, a3):
+    add_n(a2, a2, a3)
+
+
+print(f8(100, 200))
+
+
+@micropython.asm_xtensa
+def f9(a2):
+    addi_n(a2, a2, 1)
+
+
+print(f9(100))
+
+
+@micropython.asm_xtensa
+def f10(a2, a3) -> uint:
+    mull(a2, a2, a3)
+
+
+print(hex(f10(0xC0000000, 2)))
diff --git a/tests/inlineasm/xtensa/asmarith.py.exp b/tests/inlineasm/xtensa/asmarith.py.exp
new file mode 100644
index 0000000000000..7aba46a27d9b5
--- /dev/null
+++ b/tests/inlineasm/xtensa/asmarith.py.exp
@@ -0,0 +1,40 @@
+10
+10
+0
+-32768
+-32767 is not a multiple of 256
+32512
+'addmi' integer 32513 isn't within range -32768..32512
+0
+a2 300
+a4 500
+a8 900
+s2 100
+s4 300
+s8 700
+a2 -100
+a4 -300
+a8 -700
+s2 -300
+s4 -500
+s8 -900
+a2 -300
+a4 -500
+a8 -900
+s2 -100
+s4 -300
+s8 -700
+a2 100
+a4 300
+a8 700
+s2 300
+s4 500
+s8 900
+0
+100
+-100
+0xff
+0x201
+300
+101
+0x80000000
diff --git a/tests/inlineasm/xtensa/asmbranch.py b/tests/inlineasm/xtensa/asmbranch.py
new file mode 100644
index 0000000000000..22bcd5a7c71a3
--- /dev/null
+++ b/tests/inlineasm/xtensa/asmbranch.py
@@ -0,0 +1,299 @@
+# test branch instructions
+
+
+@micropython.asm_xtensa
+def tball(a2, a3) -> int:
+    mov(a4, a2)
+    movi(a2, 0)
+    ball(a4, a3, end)
+    movi(a2, -1)
+    label(end)
+
+
+print(tball(0xFFFFFFFF, 0xFFFFFFFF))
+print(tball(0xFFFEFFFF, 0xFFFFFFFF))
+print(tball(0x00000000, 0xFFFFFFFF))
+print(tball(0xFFFFFFFF, 0x01010101))
+
+
+@micropython.asm_xtensa
+def tbany(a2, a3) -> int:
+    mov(a4, a2)
+    movi(a2, 0)
+    bany(a4, a3, end)
+    movi(a2, -1)
+    label(end)
+
+
+print(tbany(0xFFFFFFFF, 0xFFFFFFFF))
+print(tbany(0xFFFEFFFF, 0xFFFFFFFF))
+print(tbany(0x00000000, 0xFFFFFFFF))
+print(tbany(0xFFFFFFFF, 0x01010101))
+
+
+@micropython.asm_xtensa
+def tbbc(a2, a3) -> int:
+    mov(a4, a2)
+    movi(a2, 0)
+    bbc(a4, a3, end)
+    movi(a2, -1)
+    label(end)
+
+
+print(tbbc(0xFFFFFFFF, 4))
+print(tbbc(0xFFFEFFFF, 16))
+print(tbbc(0x00000000, 1))
+
+
+BBCI_TEMPLATE = """
+@micropython.asm_xtensa
+def tbbci(a2) -> int:
+    mov(a3, a2)
+    movi(a2, 0)
+    bbci(a3, {}, end)
+    movi(a2, -1)
+    label(end)
+
+print(tbbci({}))
+"""
+
+
+for value, bit in ((0xFFFFFFFF, 4), (0xFFFEFFFF, 16), (0x00000000, 1)):
+    try:
+        exec(BBCI_TEMPLATE.format(bit, value))
+    except SyntaxError as error:
+        print(error)
+
+
+@micropython.asm_xtensa
+def tbbs(a2, a3) -> int:
+    mov(a4, a2)
+    movi(a2, 0)
+    bbs(a4, a3, end)
+    movi(a2, -1)
+    label(end)
+
+
+print(tbbs(0x00000000, 4))
+print(tbbs(0x00010000, 16))
+print(tbbs(0xFFFFFFFF, 1))
+
+
+BBSI_TEMPLATE = """
+@micropython.asm_xtensa
+def tbbsi(a2) -> int:
+    mov(a3, a2)
+    movi(a2, 0)
+    bbsi(a3, {}, end)
+    movi(a2, -1)
+    label(end)
+
+print(tbbsi({}))
+"""
+
+
+for value, bit in ((0x00000000, 4), (0x00010000, 16), (0xFFFFFFFF, 1)):
+    try:
+        exec(BBSI_TEMPLATE.format(bit, value))
+    except SyntaxError as error:
+        print(error)
+
+
+@micropython.asm_xtensa
+def tbeq(a2, a3) -> int:
+    mov(a4, a2)
+    movi(a2, 0)
+    beq(a4, a3, end)
+    movi(a2, -1)
+    label(end)
+
+
+print(tbeq(0x00000000, 0x00000000))
+print(tbeq(0x00010000, 0x00000000))
+print(tbeq(0xFFFFFFFF, 0xFFFFFFFF))
+
+
+@micropython.asm_xtensa
+def tbeqz(a2) -> int:
+    mov(a3, a2)
+    movi(a2, 0)
+    beqz(a3, end)
+    movi(a2, -1)
+    label(end)
+
+
+print(tbeqz(0))
+print(tbeqz(0x12345678))
+print(tbeqz(-1))
+
+
+@micropython.asm_xtensa
+def tbge(a2, a3) -> int:
+    mov(a4, a2)
+    movi(a2, 0)
+    bge(a4, a3, end)
+    movi(a2, -1)
+    label(end)
+
+
+print(tbge(0x00000000, 0x00000000))
+print(tbge(0x00010000, 0x00000000))
+print(tbge(0xF0000000, 0xFFFFFFFF))
+
+
+@micropython.asm_xtensa
+def tbgeu(a2, a3) -> int:
+    mov(a4, a2)
+    movi(a2, 0)
+    bgeu(a4, a3, end)
+    movi(a2, -1)
+    label(end)
+
+
+print(tbgeu(0x00000000, 0x00000000))
+print(tbgeu(0x00010000, 0x00000000))
+print(tbgeu(0xF0000000, 0xFFFFFFFF))
+print(tbgeu(0xFFFFFFFF, 0xF0000000))
+
+
+@micropython.asm_xtensa
+def tbgez(a2) -> int:
+    mov(a3, a2)
+    movi(a2, 0)
+    bgez(a3, end)
+    movi(a2, -1)
+    label(end)
+
+
+print(tbgez(0))
+print(tbgez(0x12345678))
+print(tbgez(-1))
+
+
+@micropython.asm_xtensa
+def tblt(a2, a3) -> int:
+    mov(a4, a2)
+    movi(a2, 0)
+    blt(a4, a3, end)
+    movi(a2, -1)
+    label(end)
+
+
+print(tblt(0x00000000, 0x00000000))
+print(tblt(0x00010000, 0x00000000))
+print(tblt(0xF0000000, 0xFFFFFFFF))
+
+
+@micropython.asm_xtensa
+def tbltu(a2, a3) -> int:
+    mov(a4, a2)
+    movi(a2, 0)
+    bltu(a4, a3, end)
+    movi(a2, -1)
+    label(end)
+
+
+print(tbltu(0x00000000, 0x00000000))
+print(tbltu(0x00010000, 0x00000000))
+print(tbltu(0xF0000000, 0xFFFFFFFF))
+print(tbltu(0xFFFFFFFF, 0xF0000000))
+
+
+@micropython.asm_xtensa
+def tbltz(a2) -> int:
+    mov(a3, a2)
+    movi(a2, 0)
+    bltz(a3, end)
+    movi(a2, -1)
+    label(end)
+
+
+print(tbltz(0))
+print(tbltz(0x12345678))
+print(tbltz(-1))
+
+
+@micropython.asm_xtensa
+def tbnall(a2, a3) -> int:
+    mov(a4, a2)
+    movi(a2, 0)
+    bnall(a4, a3, end)
+    movi(a2, -1)
+    label(end)
+
+
+print(tbnall(0xFFFFFFFF, 0xFFFFFFFF))
+print(tbnall(0xFFFEFFFF, 0xFFFFFFFF))
+print(tbnall(0x00000000, 0xFFFFFFFF))
+print(tbnall(0xFFFFFFFF, 0x01010101))
+
+
+@micropython.asm_xtensa
+def tbne(a2, a3) -> int:
+    mov(a4, a2)
+    movi(a2, 0)
+    bne(a4, a3, end)
+    movi(a2, -1)
+    label(end)
+
+
+print(tbne(0x00000000, 0x00000000))
+print(tbne(0x00010000, 0x00000000))
+print(tbne(0xFFFFFFFF, 0xFFFFFFFF))
+
+
+@micropython.asm_xtensa
+def tbnez(a2) -> int:
+    mov(a3, a2)
+    movi(a2, 0)
+    bnez(a3, end)
+    movi(a2, -1)
+    label(end)
+
+
+print(tbnez(0))
+print(tbnez(0x12345678))
+print(tbnez(-1))
+
+
+@micropython.asm_xtensa
+def tbnone(a2, a3) -> int:
+    mov(a4, a2)
+    movi(a2, 0)
+    bnone(a4, a3, end)
+    movi(a2, -1)
+    label(end)
+
+
+print(tbnone(0xFFFFFFFF, 0xFFFFFFFF))
+print(tbnone(0xFFFEFFFF, 0xFFFFFFFF))
+print(tbnone(0x00000000, 0xFFFFFFFF))
+print(tbnone(0x10101010, 0x01010101))
+
+
+@micropython.asm_xtensa
+def tbeqz_n(a2) -> int:
+    mov(a3, a2)
+    movi(a2, 0)
+    beqz_n(a3, end)
+    movi(a2, -1)
+    label(end)
+
+
+print(tbeqz_n(0))
+print(tbeqz_n(0x12345678))
+print(tbeqz_n(-1))
+
+
+@micropython.asm_xtensa
+def tbnez_n(a2) -> int:
+    mov(a3, a2)
+    movi(a2, 0)
+    bnez(a3, end)
+    movi(a2, -1)
+    label(end)
+
+
+print(tbnez_n(0))
+print(tbnez_n(0x12345678))
+print(tbnez_n(-1))
diff --git a/tests/inlineasm/xtensa/asmbranch.py.exp b/tests/inlineasm/xtensa/asmbranch.py.exp
new file mode 100644
index 0000000000000..319a4b435ef2f
--- /dev/null
+++ b/tests/inlineasm/xtensa/asmbranch.py.exp
@@ -0,0 +1,66 @@
+0
+-1
+-1
+0
+0
+0
+-1
+0
+-1
+0
+0
+-1
+0
+0
+-1
+0
+0
+-1
+0
+0
+0
+-1
+0
+0
+-1
+-1
+0
+0
+-1
+0
+0
+-1
+0
+0
+0
+-1
+-1
+-1
+0
+-1
+-1
+0
+-1
+-1
+-1
+0
+-1
+0
+0
+-1
+-1
+0
+-1
+-1
+0
+0
+-1
+-1
+0
+0
+0
+-1
+-1
+-1
+0
+0
diff --git a/tests/inlineasm/xtensa/asmjump.py b/tests/inlineasm/xtensa/asmjump.py
new file mode 100644
index 0000000000000..f41c9482319da
--- /dev/null
+++ b/tests/inlineasm/xtensa/asmjump.py
@@ -0,0 +1,26 @@
+@micropython.asm_xtensa
+def jump() -> int:
+    movi(a2, 0)
+    j(NEXT)
+    addi(a2, a2, 1)
+    j(DONE)
+    label(NEXT)
+    addi(a2, a2, 2)
+    label(DONE)
+
+
+print(jump())
+
+
+@micropython.asm_xtensa
+def jumpx() -> int:
+    call0(ENTRY)
+    label(ENTRY)
+    movi(a2, 0)
+    addi(a3, a0, 12)
+    jx(a3)
+    movi(a2, 1)
+    movi(a2, 2)
+
+
+print(jumpx())
diff --git a/tests/inlineasm/xtensa/asmjump.py.exp b/tests/inlineasm/xtensa/asmjump.py.exp
new file mode 100644
index 0000000000000..51993f072d583
--- /dev/null
+++ b/tests/inlineasm/xtensa/asmjump.py.exp
@@ -0,0 +1,2 @@
+2
+2
diff --git a/tests/inlineasm/xtensa/asmloadstore.py b/tests/inlineasm/xtensa/asmloadstore.py
new file mode 100644
index 0000000000000..b185e30520cc9
--- /dev/null
+++ b/tests/inlineasm/xtensa/asmloadstore.py
@@ -0,0 +1,98 @@
+import array
+
+# On the 8266 the generated code gets put into the IRAM segment, which is only
+# word-addressable.  Therefore, to test byte and halfword load/store opcodes
+# some memory must be reserved in the DRAM segment.
+
+BYTE_DATA = array.array("B", (0x11, 0x22, 0x33, 0x44))
+WORD_DATA = array.array("h", (100, 200, -100, -200))
+DWORD_DATA = array.array("i", (100_000, -200_000, 300_000, -400_000))
+
+
+@micropython.asm_xtensa
+def tl32r() -> int:
+    nop()
+    j(CODE)
+    align(4)
+    label(DATA)
+    data(1, 1, 2, 3, 4, 5, 6, 7)
+    align(4)
+    label(CODE)
+    nop_n()
+    nop_n()
+    l32r(a2, DATA)
+
+
+print(hex(tl32r()))
+
+
+@micropython.asm_xtensa
+def tl32i() -> uint:
+    call0(ENTRY)
+    label(ENTRY)
+    l32i(a2, a0, 0)
+
+
+print(hex(tl32i()))
+
+
+@micropython.asm_xtensa
+def tl8ui(a2) -> uint:
+    mov(a3, a2)
+    l8ui(a2, a3, 1)
+
+
+print(hex(tl8ui(BYTE_DATA)))
+
+
+@micropython.asm_xtensa
+def tl16ui(a2) -> uint:
+    mov(a3, a2)
+    l16ui(a2, a3, 2)
+
+
+print(tl16ui(WORD_DATA))
+
+
+@micropython.asm_xtensa
+def tl16si(a2) -> int:
+    mov(a3, a2)
+    l16si(a2, a3, 6)
+
+
+print(tl16si(WORD_DATA))
+
+
+@micropython.asm_xtensa
+def ts8i(a2, a3):
+    s8i(a3, a2, 1)
+
+
+ts8i(BYTE_DATA, 0xFF)
+print(BYTE_DATA)
+
+
+@micropython.asm_xtensa
+def ts16i(a2, a3):
+    s16i(a3, a2, 2)
+
+
+ts16i(WORD_DATA, -123)
+print(WORD_DATA)
+
+
+@micropython.asm_xtensa
+def ts32i(a2, a3) -> uint:
+    s32i(a3, a2, 4)
+
+
+ts32i(DWORD_DATA, -123456)
+print(DWORD_DATA)
+
+
+@micropython.asm_xtensa
+def tl32i_n(a2) -> uint:
+    l32i_n(a2, a2, 8)
+
+
+print(tl32i_n(DWORD_DATA))
diff --git a/tests/inlineasm/xtensa/asmloadstore.py.exp b/tests/inlineasm/xtensa/asmloadstore.py.exp
new file mode 100644
index 0000000000000..e6672df6f8132
--- /dev/null
+++ b/tests/inlineasm/xtensa/asmloadstore.py.exp
@@ -0,0 +1,9 @@
+0x4030201
+0xf8002022
+0x22
+200
+-200
+array('B', [17, 255, 51, 68])
+array('h', [100, -123, -100, -200])
+array('i', [100000, -123456, 300000, -400000])
+300000
diff --git a/tests/inlineasm/xtensa/asmmisc.py b/tests/inlineasm/xtensa/asmmisc.py
new file mode 100644
index 0000000000000..271ab836625dc
--- /dev/null
+++ b/tests/inlineasm/xtensa/asmmisc.py
@@ -0,0 +1,25 @@
+@micropython.asm_xtensa
+def tnop(a2, a3, a4, a5):
+    nop()
+
+
+out2 = tnop(0x100, 0x200, 0x300, 0x400)
+print(out2 == 0x100)
+
+
+@micropython.asm_xtensa
+def tnop_n(a2, a3, a4, a5):
+    nop_n()
+
+
+out2 = tnop_n(0x100, 0x200, 0x300, 0x400)
+print(out2 == 0x100)
+
+
+@micropython.asm_xtensa
+def tmov_n(a2, a3):
+    mov_n(a4, a3)
+    add(a2, a4, a3)
+
+
+print(tmov_n(0, 1))
diff --git a/tests/inlineasm/xtensa/asmmisc.py.exp b/tests/inlineasm/xtensa/asmmisc.py.exp
new file mode 100644
index 0000000000000..eefaa35daf0f1
--- /dev/null
+++ b/tests/inlineasm/xtensa/asmmisc.py.exp
@@ -0,0 +1,3 @@
+True
+True
+2
diff --git a/tests/inlineasm/xtensa/asmshift.py b/tests/inlineasm/xtensa/asmshift.py
new file mode 100644
index 0000000000000..271ca1ccd494c
--- /dev/null
+++ b/tests/inlineasm/xtensa/asmshift.py
@@ -0,0 +1,137 @@
+@micropython.asm_xtensa
+def lsl1(a2):
+    slli(a2, a2, 1)
+
+
+print(hex(lsl1(0x123)))
+
+
+@micropython.asm_xtensa
+def lsl23(a2):
+    slli(a2, a2, 23)
+
+
+print(hex(lsl23(1)))
+
+
+@micropython.asm_xtensa
+def lsr1(a2):
+    srli(a2, a2, 1)
+
+
+print(hex(lsr1(0x123)))
+
+
+@micropython.asm_xtensa
+def lsr15(a2):
+    srli(a2, a2, 15)
+
+
+print(hex(lsr15(0x80000000)))
+
+
+@micropython.asm_xtensa
+def asr1(a2):
+    srai(a2, a2, 1)
+
+
+print(hex(asr1(0x123)))
+
+
+@micropython.asm_xtensa
+def asr31(a2):
+    srai(a2, a2, 31)
+
+
+print(hex(asr31(0x80000000)))
+
+
+@micropython.asm_xtensa
+def lsl1r(a2):
+    movi(a3, 1)
+    ssl(a3)
+    sll(a2, a2)
+
+
+print(hex(lsl1r(0x123)))
+
+
+@micropython.asm_xtensa
+def lsr1r(a2):
+    movi(a3, 1)
+    ssr(a3)
+    srl(a2, a2)
+
+
+print(hex(lsr1r(0x123)))
+
+
+@micropython.asm_xtensa
+def asr1r(a2):
+    movi(a3, 1)
+    ssr(a3)
+    sra(a2, a2)
+
+
+print(hex(asr1r(0x123)))
+
+
+@micropython.asm_xtensa
+def sll9(a2):
+    ssai(9)
+    sll(a2, a2)
+
+
+print(hex(sll9(1)))
+
+
+@micropython.asm_xtensa
+def srlr(a2, a3):
+    ssa8l(a3)
+    srl(a2, a2)
+
+
+print(hex(srlr(0x12340000, 2)))
+
+
+@micropython.asm_xtensa
+def sllr(a2, a3):
+    ssa8b(a3)
+    sll(a2, a2)
+
+
+print(hex(sllr(0x1234, 2)))
+
+
+@micropython.asm_xtensa
+def srcr(a2, a3, a4):
+    ssr(a4)
+    src(a2, a2, a3)
+
+
+print(hex(srcr(0x00000001, 0x80000000, 2)))
+
+
+@micropython.asm_xtensa
+def srai24(a2):
+    srai(a2, a2, 24)
+
+
+print(hex(srai24(0x12345678)))
+
+
+@micropython.asm_xtensa
+def nsar(a2, a3):
+    nsa(a2, a3)
+
+
+print(nsar(0x12345678, 0))
+print(nsar(0x12345678, -1))
+
+
+@micropython.asm_xtensa
+def nsaur(a2, a3):
+    nsau(a2, a3)
+
+
+print(nsaur(0x12345678, 0))
diff --git a/tests/inlineasm/xtensa/asmshift.py.exp b/tests/inlineasm/xtensa/asmshift.py.exp
new file mode 100644
index 0000000000000..3e2bb3b4aefa9
--- /dev/null
+++ b/tests/inlineasm/xtensa/asmshift.py.exp
@@ -0,0 +1,17 @@
+0x246
+0x800000
+0x91
+0x10000
+0x91
+-0x1
+0x246
+0x91
+0x91
+0x800000
+0x1234
+0x12340000
+0x60000000
+0x12
+31
+31
+32
diff --git a/tests/internal_bench/class_create-0-empty.py b/tests/internal_bench/class_create-0-empty.py
new file mode 100644
index 0000000000000..1fd8ccd925715
--- /dev/null
+++ b/tests/internal_bench/class_create-0-empty.py
@@ -0,0 +1,11 @@
+import bench
+
+
+def test(num):
+    for i in range(num // 40):
+
+        class X:
+            pass
+
+
+bench.run(test)
diff --git a/tests/internal_bench/class_create-1-slots.py b/tests/internal_bench/class_create-1-slots.py
new file mode 100644
index 0000000000000..9b3e4b9570da2
--- /dev/null
+++ b/tests/internal_bench/class_create-1-slots.py
@@ -0,0 +1,12 @@
+import bench
+
+
+def test(num):
+    l = ["x"]
+    for i in range(num // 40):
+
+        class X:
+            __slots__ = l
+
+
+bench.run(test)
diff --git a/tests/internal_bench/class_create-1.1-slots5.py b/tests/internal_bench/class_create-1.1-slots5.py
new file mode 100644
index 0000000000000..ccac77dec9daa
--- /dev/null
+++ b/tests/internal_bench/class_create-1.1-slots5.py
@@ -0,0 +1,12 @@
+import bench
+
+
+def test(num):
+    l = ["a", "b", "c", "d", "x"]
+    for i in range(num // 40):
+
+        class X:
+            __slots__ = l
+
+
+bench.run(test)
diff --git a/tests/internal_bench/class_create-2-classattr.py b/tests/internal_bench/class_create-2-classattr.py
new file mode 100644
index 0000000000000..049a7dab170c1
--- /dev/null
+++ b/tests/internal_bench/class_create-2-classattr.py
@@ -0,0 +1,11 @@
+import bench
+
+
+def test(num):
+    for i in range(num // 40):
+
+        class X:
+            x = 1
+
+
+bench.run(test)
diff --git a/tests/internal_bench/class_create-2.1-classattr5.py b/tests/internal_bench/class_create-2.1-classattr5.py
new file mode 100644
index 0000000000000..5051e7dcca70d
--- /dev/null
+++ b/tests/internal_bench/class_create-2.1-classattr5.py
@@ -0,0 +1,15 @@
+import bench
+
+
+def test(num):
+    for i in range(num // 40):
+
+        class X:
+            a = 0
+            b = 0
+            c = 0
+            d = 0
+            x = 1
+
+
+bench.run(test)
diff --git a/tests/internal_bench/class_create-2.3-classattr5objs.py b/tests/internal_bench/class_create-2.3-classattr5objs.py
new file mode 100644
index 0000000000000..74540865dcd14
--- /dev/null
+++ b/tests/internal_bench/class_create-2.3-classattr5objs.py
@@ -0,0 +1,20 @@
+import bench
+
+
+class Class:
+    pass
+
+
+def test(num):
+    instance = Class()
+    for i in range(num // 40):
+
+        class X:
+            a = instance
+            b = instance
+            c = instance
+            d = instance
+            x = instance
+
+
+bench.run(test)
diff --git a/tests/internal_bench/class_create-3-instancemethod.py b/tests/internal_bench/class_create-3-instancemethod.py
new file mode 100644
index 0000000000000..e8c201cb2c3c6
--- /dev/null
+++ b/tests/internal_bench/class_create-3-instancemethod.py
@@ -0,0 +1,12 @@
+import bench
+
+
+def test(num):
+    for i in range(num // 40):
+
+        class X:
+            def x(self):
+                pass
+
+
+bench.run(test)
diff --git a/tests/internal_bench/class_create-4-classmethod.py b/tests/internal_bench/class_create-4-classmethod.py
new file mode 100644
index 0000000000000..f34962bc67117
--- /dev/null
+++ b/tests/internal_bench/class_create-4-classmethod.py
@@ -0,0 +1,13 @@
+import bench
+
+
+def test(num):
+    for i in range(num // 40):
+
+        class X:
+            @classmethod
+            def x(cls):
+                pass
+
+
+bench.run(test)
diff --git a/tests/internal_bench/class_create-4.1-classmethod_implicit.py b/tests/internal_bench/class_create-4.1-classmethod_implicit.py
new file mode 100644
index 0000000000000..f2d1fcfd18821
--- /dev/null
+++ b/tests/internal_bench/class_create-4.1-classmethod_implicit.py
@@ -0,0 +1,12 @@
+import bench
+
+
+def test(num):
+    for i in range(num // 40):
+
+        class X:
+            def __new__(cls):
+                pass
+
+
+bench.run(test)
diff --git a/tests/internal_bench/class_create-5-staticmethod.py b/tests/internal_bench/class_create-5-staticmethod.py
new file mode 100644
index 0000000000000..0633556667544
--- /dev/null
+++ b/tests/internal_bench/class_create-5-staticmethod.py
@@ -0,0 +1,13 @@
+import bench
+
+
+def test(num):
+    for i in range(num // 40):
+
+        class X:
+            @staticmethod
+            def x():
+                pass
+
+
+bench.run(test)
diff --git a/tests/internal_bench/class_create-6-getattribute.py b/tests/internal_bench/class_create-6-getattribute.py
new file mode 100644
index 0000000000000..10a4fe7ce8d9f
--- /dev/null
+++ b/tests/internal_bench/class_create-6-getattribute.py
@@ -0,0 +1,12 @@
+import bench
+
+
+def test(num):
+    for i in range(num // 40):
+
+        class X:
+            def __getattribute__(self, name):
+                pass
+
+
+bench.run(test)
diff --git a/tests/internal_bench/class_create-6.1-getattr.py b/tests/internal_bench/class_create-6.1-getattr.py
new file mode 100644
index 0000000000000..b4b9ba2f5525b
--- /dev/null
+++ b/tests/internal_bench/class_create-6.1-getattr.py
@@ -0,0 +1,12 @@
+import bench
+
+
+def test(num):
+    for i in range(num // 40):
+
+        class X:
+            def __getattr__(self, name):
+                pass
+
+
+bench.run(test)
diff --git a/tests/internal_bench/class_create-6.2-property.py b/tests/internal_bench/class_create-6.2-property.py
new file mode 100644
index 0000000000000..cf847b6dc9c9f
--- /dev/null
+++ b/tests/internal_bench/class_create-6.2-property.py
@@ -0,0 +1,13 @@
+import bench
+
+
+def test(num):
+    for i in range(num // 40):
+
+        class X:
+            @property
+            def x(self):
+                pass
+
+
+bench.run(test)
diff --git a/tests/internal_bench/class_create-6.3-descriptor.py b/tests/internal_bench/class_create-6.3-descriptor.py
new file mode 100644
index 0000000000000..7b0a635726380
--- /dev/null
+++ b/tests/internal_bench/class_create-6.3-descriptor.py
@@ -0,0 +1,17 @@
+import bench
+
+
+class D:
+    def __get__(self, instance, owner=None):
+        pass
+
+
+def test(num):
+    descriptor = D()
+    for i in range(num // 40):
+
+        class X:
+            x = descriptor
+
+
+bench.run(test)
diff --git a/tests/internal_bench/class_create-7-inherit.py b/tests/internal_bench/class_create-7-inherit.py
new file mode 100644
index 0000000000000..f48fb215e0ab8
--- /dev/null
+++ b/tests/internal_bench/class_create-7-inherit.py
@@ -0,0 +1,14 @@
+import bench
+
+
+def test(num):
+    class B:
+        pass
+
+    for i in range(num // 40):
+
+        class X(B):
+            pass
+
+
+bench.run(test)
diff --git a/tests/internal_bench/class_create-7.1-inherit_initsubclass.py b/tests/internal_bench/class_create-7.1-inherit_initsubclass.py
new file mode 100644
index 0000000000000..0660fa86258fe
--- /dev/null
+++ b/tests/internal_bench/class_create-7.1-inherit_initsubclass.py
@@ -0,0 +1,16 @@
+import bench
+
+
+def test(num):
+    class B:
+        @classmethod
+        def __init_subclass__(cls):
+            pass
+
+    for i in range(num // 40):
+
+        class X(B):
+            pass
+
+
+bench.run(test)
diff --git a/tests/internal_bench/class_create-8-metaclass_setname.py b/tests/internal_bench/class_create-8-metaclass_setname.py
new file mode 100644
index 0000000000000..e4515b54279d1
--- /dev/null
+++ b/tests/internal_bench/class_create-8-metaclass_setname.py
@@ -0,0 +1,17 @@
+import bench
+
+
+class D:
+    def __set_name__(self, owner, name):
+        pass
+
+
+def test(num):
+    descriptor = D()
+    for i in range(num // 40):
+
+        class X:
+            x = descriptor
+
+
+bench.run(test)
diff --git a/tests/internal_bench/class_create-8.1-metaclass_setname5.py b/tests/internal_bench/class_create-8.1-metaclass_setname5.py
new file mode 100644
index 0000000000000..5daa3f8471bca
--- /dev/null
+++ b/tests/internal_bench/class_create-8.1-metaclass_setname5.py
@@ -0,0 +1,21 @@
+import bench
+
+
+class D:
+    def __set_name__(self, owner, name):
+        pass
+
+
+def test(num):
+    descriptor = D()
+    for i in range(num // 40):
+
+        class X:
+            a = descriptor
+            b = descriptor
+            c = descriptor
+            d = descriptor
+            x = descriptor
+
+
+bench.run(test)
diff --git a/tests/internal_bench/class_instance-0-object.py b/tests/internal_bench/class_instance-0-object.py
new file mode 100644
index 0000000000000..401c8ea7e3cc2
--- /dev/null
+++ b/tests/internal_bench/class_instance-0-object.py
@@ -0,0 +1,11 @@
+import bench
+
+X = object
+
+
+def test(num):
+    for i in range(num // 5):
+        x = X()
+
+
+bench.run(test)
diff --git a/tests/internal_bench/class_instance-0.1-object-gc.py b/tests/internal_bench/class_instance-0.1-object-gc.py
new file mode 100644
index 0000000000000..7c475963a8e81
--- /dev/null
+++ b/tests/internal_bench/class_instance-0.1-object-gc.py
@@ -0,0 +1,13 @@
+import bench
+import gc
+
+X = object
+
+
+def test(num):
+    for i in range(num // 5):
+        x = X()
+    gc.collect()
+
+
+bench.run(test)
diff --git a/tests/internal_bench/class_instance-1-empty.py b/tests/internal_bench/class_instance-1-empty.py
new file mode 100644
index 0000000000000..617d47a86e92b
--- /dev/null
+++ b/tests/internal_bench/class_instance-1-empty.py
@@ -0,0 +1,13 @@
+import bench
+
+
+class X:
+    pass
+
+
+def test(num):
+    for i in range(num // 5):
+        x = X()
+
+
+bench.run(test)
diff --git a/tests/internal_bench/class_instance-1.1-classattr.py b/tests/internal_bench/class_instance-1.1-classattr.py
new file mode 100644
index 0000000000000..4e667533d4aa1
--- /dev/null
+++ b/tests/internal_bench/class_instance-1.1-classattr.py
@@ -0,0 +1,13 @@
+import bench
+
+
+class X:
+    x = 0
+
+
+def test(num):
+    for i in range(num // 5):
+        x = X()
+
+
+bench.run(test)
diff --git a/tests/internal_bench/class_instance-1.2-func.py b/tests/internal_bench/class_instance-1.2-func.py
new file mode 100644
index 0000000000000..21bf7a1ac48fc
--- /dev/null
+++ b/tests/internal_bench/class_instance-1.2-func.py
@@ -0,0 +1,14 @@
+import bench
+
+
+class X:
+    def f(self):
+        pass
+
+
+def test(num):
+    for i in range(num // 5):
+        x = X()
+
+
+bench.run(test)
diff --git a/tests/internal_bench/class_instance-1.3-empty-gc.py b/tests/internal_bench/class_instance-1.3-empty-gc.py
new file mode 100644
index 0000000000000..a5108ef8e8156
--- /dev/null
+++ b/tests/internal_bench/class_instance-1.3-empty-gc.py
@@ -0,0 +1,15 @@
+import bench
+import gc
+
+
+class X:
+    pass
+
+
+def test(num):
+    for i in range(num // 5):
+        x = X()
+    gc.collect()
+
+
+bench.run(test)
diff --git a/tests/internal_bench/class_instance-2-init.py b/tests/internal_bench/class_instance-2-init.py
new file mode 100644
index 0000000000000..86619d3154840
--- /dev/null
+++ b/tests/internal_bench/class_instance-2-init.py
@@ -0,0 +1,14 @@
+import bench
+
+
+class X:
+    def __init__(self):
+        pass
+
+
+def test(num):
+    for i in range(num // 5):
+        x = X()
+
+
+bench.run(test)
diff --git a/tests/internal_bench/class_instance-2.1-init_super.py b/tests/internal_bench/class_instance-2.1-init_super.py
new file mode 100644
index 0000000000000..38bca5fef877a
--- /dev/null
+++ b/tests/internal_bench/class_instance-2.1-init_super.py
@@ -0,0 +1,14 @@
+import bench
+
+
+class X:
+    def __init__(self):
+        return super().__init__()
+
+
+def test(num):
+    for i in range(num // 5):
+        x = X()
+
+
+bench.run(test)
diff --git a/tests/internal_bench/class_instance-2.2-new.py b/tests/internal_bench/class_instance-2.2-new.py
new file mode 100644
index 0000000000000..dc5e78ea5ef98
--- /dev/null
+++ b/tests/internal_bench/class_instance-2.2-new.py
@@ -0,0 +1,14 @@
+import bench
+
+
+class X:
+    def __new__(cls):
+        return super().__new__(cls)
+
+
+def test(num):
+    for i in range(num // 5):
+        x = X()
+
+
+bench.run(test)
diff --git a/tests/internal_bench/class_instance-3-del.py b/tests/internal_bench/class_instance-3-del.py
new file mode 100644
index 0000000000000..af700f72a94a8
--- /dev/null
+++ b/tests/internal_bench/class_instance-3-del.py
@@ -0,0 +1,14 @@
+import bench
+
+
+class X:
+    def __del__(self):
+        pass
+
+
+def test(num):
+    for i in range(num // 5):
+        x = X()
+
+
+bench.run(test)
diff --git a/tests/internal_bench/class_instance-3.1-del-gc.py b/tests/internal_bench/class_instance-3.1-del-gc.py
new file mode 100644
index 0000000000000..311c71c3571b0
--- /dev/null
+++ b/tests/internal_bench/class_instance-3.1-del-gc.py
@@ -0,0 +1,16 @@
+import bench
+import gc
+
+
+class X:
+    def __del__(self):
+        pass
+
+
+def test(num):
+    for i in range(num // 5):
+        x = X()
+    gc.collect()
+
+
+bench.run(test)
diff --git a/tests/internal_bench/class_instance-4-slots.py b/tests/internal_bench/class_instance-4-slots.py
new file mode 100644
index 0000000000000..51b067fedf0b7
--- /dev/null
+++ b/tests/internal_bench/class_instance-4-slots.py
@@ -0,0 +1,13 @@
+import bench
+
+
+class X:
+    __slots__ = ["x"]
+
+
+def test(num):
+    for i in range(num // 5):
+        x = X()
+
+
+bench.run(test)
diff --git a/tests/internal_bench/class_instance-4.1-slots5.py b/tests/internal_bench/class_instance-4.1-slots5.py
new file mode 100644
index 0000000000000..8f5c2ecb456d8
--- /dev/null
+++ b/tests/internal_bench/class_instance-4.1-slots5.py
@@ -0,0 +1,13 @@
+import bench
+
+
+class X:
+    __slots__ = ["a", "b", "c", "d", "x"]
+
+
+def test(num):
+    for i in range(num // 5):
+        x = X()
+
+
+bench.run(test)
diff --git a/tests/internal_bench/var-6.2-instance-speciallookup.py b/tests/internal_bench/var-6.2-instance-speciallookup.py
new file mode 100644
index 0000000000000..fee12b2f930c3
--- /dev/null
+++ b/tests/internal_bench/var-6.2-instance-speciallookup.py
@@ -0,0 +1,19 @@
+import bench
+
+
+class Foo:
+    def __init__(self):
+        self.num = 20000000
+
+    def __delattr__(self, name):  # just trigger the 'special lookups' flag on the class
+        pass
+
+
+def test(num):
+    o = Foo()
+    i = 0
+    while i < o.num:
+        i += 1
+
+
+bench.run(test)
diff --git a/tests/internal_bench/var-6.3-instance-property.py b/tests/internal_bench/var-6.3-instance-property.py
new file mode 100644
index 0000000000000..b4426ef7928e1
--- /dev/null
+++ b/tests/internal_bench/var-6.3-instance-property.py
@@ -0,0 +1,17 @@
+import bench
+
+
+class Foo:
+    @property
+    def num(self):
+        return 20000000
+
+
+def test(num):
+    o = Foo()
+    i = 0
+    while i < o.num:
+        i += 1
+
+
+bench.run(test)
diff --git a/tests/internal_bench/var-6.4-instance-descriptor.py b/tests/internal_bench/var-6.4-instance-descriptor.py
new file mode 100644
index 0000000000000..b4df69f878f10
--- /dev/null
+++ b/tests/internal_bench/var-6.4-instance-descriptor.py
@@ -0,0 +1,20 @@
+import bench
+
+
+class Descriptor:
+    def __get__(self, instance, owner=None):
+        return 20000000
+
+
+class Foo:
+    num = Descriptor()
+
+
+def test(num):
+    o = Foo()
+    i = 0
+    while i < o.num:
+        i += 1
+
+
+bench.run(test)
diff --git a/tests/internal_bench/var-6.5-instance-getattr.py b/tests/internal_bench/var-6.5-instance-getattr.py
new file mode 100644
index 0000000000000..3b2ef6721105f
--- /dev/null
+++ b/tests/internal_bench/var-6.5-instance-getattr.py
@@ -0,0 +1,16 @@
+import bench
+
+
+class Foo:
+    def __getattr__(self, name):
+        return 20000000
+
+
+def test(num):
+    o = Foo()
+    i = 0
+    while i < o.num:
+        i += 1
+
+
+bench.run(test)
diff --git a/tests/internal_bench/var-6.6-instance-builtin_ordered.py b/tests/internal_bench/var-6.6-instance-builtin_ordered.py
new file mode 100644
index 0000000000000..02d7525230192
--- /dev/null
+++ b/tests/internal_bench/var-6.6-instance-builtin_ordered.py
@@ -0,0 +1,12 @@
+import bench
+
+
+def test(num):
+    i = 0
+    o = set()  # object with largest rom-frozen ordered locals_dict
+    n = "__contains__"  # last element in that dict for longest lookup
+    while i < num:
+        i += hasattr(o, n)  # True, converts to 1
+
+
+bench.run(test)
diff --git a/tests/internal_bench/var-9-getattr.py b/tests/internal_bench/var-9-getattr.py
new file mode 100644
index 0000000000000..69d2bfed2e0ac
--- /dev/null
+++ b/tests/internal_bench/var-9-getattr.py
@@ -0,0 +1,16 @@
+import bench
+
+
+class Foo:
+    pass
+
+
+def test(num):
+    o = Foo()
+    o.num = num
+    i = 0
+    while i < getattr(o, "num", num):
+        i += 1
+
+
+bench.run(test)
diff --git a/tests/internal_bench/var-9.1-getattr_default.py b/tests/internal_bench/var-9.1-getattr_default.py
new file mode 100644
index 0000000000000..e803d39b32667
--- /dev/null
+++ b/tests/internal_bench/var-9.1-getattr_default.py
@@ -0,0 +1,15 @@
+import bench
+
+
+class Foo:
+    pass
+
+
+def test(num):
+    o = Foo()
+    i = 0
+    while i < getattr(o, "num", num):
+        i += 1
+
+
+bench.run(test)
diff --git a/tests/internal_bench/var-9.2-getattr_default_special.py b/tests/internal_bench/var-9.2-getattr_default_special.py
new file mode 100644
index 0000000000000..c48ec0742cff6
--- /dev/null
+++ b/tests/internal_bench/var-9.2-getattr_default_special.py
@@ -0,0 +1,16 @@
+import bench
+
+
+class Foo:
+    def __delattr__(self, name):  # just trigger the 'special lookups' flag on the class
+        pass
+
+
+def test(num):
+    o = Foo()
+    i = 0
+    while i < getattr(o, "num", num):
+        i += 1
+
+
+bench.run(test)
diff --git a/tests/internal_bench/var-9.3-except_ok.py b/tests/internal_bench/var-9.3-except_ok.py
new file mode 100644
index 0000000000000..efc1a8f858cd0
--- /dev/null
+++ b/tests/internal_bench/var-9.3-except_ok.py
@@ -0,0 +1,23 @@
+import bench
+
+
+class Foo:
+    pass
+
+
+def test(num):
+    o = Foo()
+    o.num = num
+
+    def get():
+        try:
+            return o.num
+        except AttributeError:
+            return num
+
+    i = 0
+    while i < get():
+        i += 1
+
+
+bench.run(test)
diff --git a/tests/internal_bench/var-9.4-except_selfinduced.py b/tests/internal_bench/var-9.4-except_selfinduced.py
new file mode 100644
index 0000000000000..544609ca4b6b3
--- /dev/null
+++ b/tests/internal_bench/var-9.4-except_selfinduced.py
@@ -0,0 +1,22 @@
+import bench
+
+
+class Foo:
+    pass
+
+
+def test(num):
+    o = Foo()
+
+    def get():
+        try:
+            raise AttributeError
+        except AttributeError:
+            return num
+
+    i = 0
+    while i < get():
+        i += 1
+
+
+bench.run(test)
diff --git a/tests/internal_bench/var-9.5-except_error.py b/tests/internal_bench/var-9.5-except_error.py
new file mode 100644
index 0000000000000..caf83fa46ab3d
--- /dev/null
+++ b/tests/internal_bench/var-9.5-except_error.py
@@ -0,0 +1,22 @@
+import bench
+
+
+class Foo:
+    pass
+
+
+def test(num):
+    o = Foo()
+
+    def get():
+        try:
+            return o.num
+        except AttributeError:
+            return num
+
+    i = 0
+    while i < get():
+        i += 1
+
+
+bench.run(test)
diff --git a/tests/internal_bench/var-9.6-except_error_special.py b/tests/internal_bench/var-9.6-except_error_special.py
new file mode 100644
index 0000000000000..8bc395b4d7ef8
--- /dev/null
+++ b/tests/internal_bench/var-9.6-except_error_special.py
@@ -0,0 +1,23 @@
+import bench
+
+
+class Foo:
+    def __delattr__(self, name):  # just trigger the 'special lookups' flag on the class
+        pass
+
+
+def test(num):
+    o = Foo()
+
+    def get():
+        try:
+            return o.num
+        except AttributeError:
+            return num
+
+    i = 0
+    while i < get():
+        i += 1
+
+
+bench.run(test)
diff --git a/tests/io/builtin_print_file.py b/tests/io/builtin_print_file.py
index 822356a6cc305..e00f58635a9d2 100644
--- a/tests/io/builtin_print_file.py
+++ b/tests/io/builtin_print_file.py
@@ -13,5 +13,5 @@
 
 try:
     print(file=1)
-except (AttributeError, OSError):  # CPython and uPy differ in error message
+except (AttributeError, OSError):  # CPython and MicroPython differ in error message
     print("Error")
diff --git a/tests/io/file_seek.py b/tests/io/file_seek.py
index 3990df8409051..b9f9593786fe6 100644
--- a/tests/io/file_seek.py
+++ b/tests/io/file_seek.py
@@ -30,5 +30,5 @@
 try:
     f.seek(1)
 except (OSError, ValueError):
-    # CPy raises ValueError, uPy raises OSError
+    # CPy raises ValueError, MPy raises OSError
     print("OSError or ValueError")
diff --git a/tests/micropython/builtin_execfile.py b/tests/micropython/builtin_execfile.py
index 75a867bb94023..4fd4d66d4ee25 100644
--- a/tests/micropython/builtin_execfile.py
+++ b/tests/micropython/builtin_execfile.py
@@ -75,3 +75,24 @@ def open(self, file, mode):
 
 # Unmount the VFS object.
 vfs.umount(fs)
+
+
+class EvilFilesystem:
+    def mount(self, readonly, mkfs):
+        print("mount", readonly, mkfs)
+
+    def umount(self):
+        print("umount")
+
+    def open(self, file, mode):
+        return None
+
+
+fs = EvilFilesystem()
+vfs.mount(fs, "/test_mnt")
+try:
+    execfile("/test_mnt/test.py")
+    print("ExecFile succeeded")
+except OSError:
+    print("OSError")
+vfs.umount(fs)
diff --git a/tests/micropython/builtin_execfile.py.exp b/tests/micropython/builtin_execfile.py.exp
index 49703d570763d..d93dee547b6ea 100644
--- a/tests/micropython/builtin_execfile.py.exp
+++ b/tests/micropython/builtin_execfile.py.exp
@@ -5,3 +5,6 @@ open /test.py rb
 123
 TypeError
 umount
+mount False False
+OSError
+umount
diff --git a/tests/micropython/const_error.py b/tests/micropython/const_error.py
index d35be530a7c8d..950360e4dc782 100644
--- a/tests/micropython/const_error.py
+++ b/tests/micropython/const_error.py
@@ -18,8 +18,6 @@ def test_syntax(code):
 
 # these operations are not supported within const
 test_syntax("A = const(1 @ 2)")
-test_syntax("A = const(1 / 2)")
-test_syntax("A = const(1 ** -2)")
 test_syntax("A = const(1 << -2)")
 test_syntax("A = const(1 >> -2)")
 test_syntax("A = const(1 % 0)")
diff --git a/tests/micropython/const_error.py.exp b/tests/micropython/const_error.py.exp
index 3edc3efe9c3e9..bef69eb32ea7d 100644
--- a/tests/micropython/const_error.py.exp
+++ b/tests/micropython/const_error.py.exp
@@ -5,5 +5,3 @@ SyntaxError
 SyntaxError
 SyntaxError
 SyntaxError
-SyntaxError
-SyntaxError
diff --git a/tests/micropython/const_float.py b/tests/micropython/const_float.py
new file mode 100644
index 0000000000000..c3a0df0276bf8
--- /dev/null
+++ b/tests/micropython/const_float.py
@@ -0,0 +1,23 @@
+# test constant optimisation, with consts that are floats
+
+from micropython import const
+
+# check we can make consts from floats
+F1 = const(2.5)
+F2 = const(-0.3)
+print(type(F1), F1)
+print(type(F2), F2)
+
+# check arithmetic with floats
+F3 = const(F1 + F2)
+F4 = const(F1**2)
+print(F3, F4)
+
+# check int operations with float results
+F5 = const(1 / 2)
+F6 = const(2**-2)
+print(F5, F6)
+
+# note: we also test float expression folding when
+#       we're compiling test cases in tests/float, as
+#       many expressions are resolved at compile time.
diff --git a/tests/micropython/const_float.py.exp b/tests/micropython/const_float.py.exp
new file mode 100644
index 0000000000000..17a86a6d936c2
--- /dev/null
+++ b/tests/micropython/const_float.py.exp
@@ -0,0 +1,4 @@
+<class 'float'> 2.5
+<class 'float'> -0.3
+2.2 6.25
+0.5 0.25
diff --git a/tests/micropython/const_math.py b/tests/micropython/const_math.py
new file mode 100644
index 0000000000000..7ee5edc6d3240
--- /dev/null
+++ b/tests/micropython/const_math.py
@@ -0,0 +1,18 @@
+# Test expressions based on math module constants
+try:
+    import math
+except ImportError:
+    print("SKIP")
+    raise SystemExit
+
+from micropython import const
+
+# check that we can make consts from math constants
+# (skip if the target has MICROPY_COMP_MODULE_CONST disabled)
+try:
+    exec("two_pi = const(2.0 * math.pi)")
+except SyntaxError:
+    print("SKIP")
+    raise SystemExit
+
+print(math.cos(two_pi))
diff --git a/tests/micropython/const_math.py.exp b/tests/micropython/const_math.py.exp
new file mode 100644
index 0000000000000..d3827e75a5cad
--- /dev/null
+++ b/tests/micropython/const_math.py.exp
@@ -0,0 +1 @@
+1.0
diff --git a/tests/micropython/decorator_error.py b/tests/micropython/decorator_error.py
index 94772ac1e5fef..b5eae65b29209 100644
--- a/tests/micropython/decorator_error.py
+++ b/tests/micropython/decorator_error.py
@@ -1,4 +1,4 @@
-# test syntax errors for uPy-specific decorators
+# test syntax errors for MicroPython-specific decorators
 
 
 def test_syntax(code):
diff --git a/tests/micropython/emg_exc.py b/tests/micropython/emg_exc.py
index a74757d028ff2..cf918b3dc8ac5 100644
--- a/tests/micropython/emg_exc.py
+++ b/tests/micropython/emg_exc.py
@@ -1,10 +1,9 @@
 # test that emergency exceptions work
 
-import micropython
 import sys
 
 try:
-    import io
+    import io, micropython
 except ImportError:
     print("SKIP")
     raise SystemExit
diff --git a/tests/micropython/emg_exc.py.native.exp b/tests/micropython/emg_exc.py.native.exp
new file mode 100644
index 0000000000000..879fa7ef5b943
--- /dev/null
+++ b/tests/micropython/emg_exc.py.native.exp
@@ -0,0 +1 @@
+ValueError(1,)
diff --git a/tests/micropython/extreme_exc.py b/tests/micropython/extreme_exc.py
index ad819e408fd82..17323b566d3b5 100644
--- a/tests/micropython/extreme_exc.py
+++ b/tests/micropython/extreme_exc.py
@@ -1,6 +1,10 @@
 # test some extreme cases of allocating exceptions and tracebacks
 
-import micropython
+try:
+    import micropython
+except ImportError:
+    print("SKIP")
+    raise SystemExit
 
 # Check for stackless build, which can't call functions without
 # allocating a frame on the heap.
diff --git a/tests/micropython/heap_lock.py b/tests/micropython/heap_lock.py
index f2892a6dc581e..209a3143461a5 100644
--- a/tests/micropython/heap_lock.py
+++ b/tests/micropython/heap_lock.py
@@ -1,6 +1,10 @@
 # check that heap_lock/heap_unlock work as expected
 
-import micropython
+try:
+    import micropython
+except ImportError:
+    print("SKIP")
+    raise SystemExit
 
 l = []
 l2 = list(range(100))
diff --git a/tests/micropython/heap_locked.py b/tests/micropython/heap_locked.py
index d9e5b5d4090af..d9d99493dd6b7 100644
--- a/tests/micropython/heap_locked.py
+++ b/tests/micropython/heap_locked.py
@@ -1,8 +1,10 @@
 # test micropython.heap_locked()
 
-import micropython
+try:
+    import micropython
 
-if not hasattr(micropython, "heap_locked"):
+    micropython.heap_locked
+except (AttributeError, ImportError):
     print("SKIP")
     raise SystemExit
 
diff --git a/tests/micropython/heapalloc.py b/tests/micropython/heapalloc.py
index e19f8d0255deb..010bf878a07b0 100644
--- a/tests/micropython/heapalloc.py
+++ b/tests/micropython/heapalloc.py
@@ -1,6 +1,10 @@
 # check that we can do certain things without allocating heap memory
 
-import micropython
+try:
+    import micropython
+except ImportError:
+    print("SKIP")
+    raise SystemExit
 
 # Check for stackless build, which can't call functions without
 # allocating a frame on heap.
diff --git a/tests/micropython/heapalloc_exc_compressed.py b/tests/micropython/heapalloc_exc_compressed.py
index aa071d641c21c..96fe3ca4f7e00 100644
--- a/tests/micropython/heapalloc_exc_compressed.py
+++ b/tests/micropython/heapalloc_exc_compressed.py
@@ -1,4 +1,10 @@
-import micropython
+try:
+    import micropython
+
+    micropython.heap_lock
+except (ImportError, AttributeError):
+    print("SKIP")
+    raise SystemExit
 
 # Tests both code paths for built-in exception raising.
 # mp_obj_new_exception_msg_varg (exception requires decompression at raise-time to format)
diff --git a/tests/micropython/heapalloc_exc_compressed_emg_exc.py b/tests/micropython/heapalloc_exc_compressed_emg_exc.py
index 48ce9dd69e6e2..31d937b8f9345 100644
--- a/tests/micropython/heapalloc_exc_compressed_emg_exc.py
+++ b/tests/micropython/heapalloc_exc_compressed_emg_exc.py
@@ -1,4 +1,10 @@
-import micropython
+try:
+    import micropython
+
+    micropython.heap_lock
+except (ImportError, AttributeError):
+    print("SKIP")
+    raise SystemExit
 
 # Does the full test from heapalloc_exc_compressed.py but while the heap is
 # locked (this can only work when the emergency exception buf is enabled).
diff --git a/tests/micropython/heapalloc_exc_raise.py b/tests/micropython/heapalloc_exc_raise.py
index 99810e0075064..917ccf42f1e16 100644
--- a/tests/micropython/heapalloc_exc_raise.py
+++ b/tests/micropython/heapalloc_exc_raise.py
@@ -1,6 +1,12 @@
 # Test that we can raise and catch (preallocated) exception
 # without memory allocation.
-import micropython
+try:
+    import micropython
+
+    micropython.heap_lock
+except (ImportError, AttributeError):
+    print("SKIP")
+    raise SystemExit
 
 e = ValueError("error")
 
diff --git a/tests/micropython/heapalloc_fail_bytearray.py b/tests/micropython/heapalloc_fail_bytearray.py
index 1bf7ddd600b93..9ee73d1c583f2 100644
--- a/tests/micropython/heapalloc_fail_bytearray.py
+++ b/tests/micropython/heapalloc_fail_bytearray.py
@@ -1,6 +1,12 @@
 # test handling of failed heap allocation with bytearray
 
-import micropython
+try:
+    import micropython
+
+    micropython.heap_lock
+except (ImportError, AttributeError):
+    print("SKIP")
+    raise SystemExit
 
 
 class GetSlice:
diff --git a/tests/micropython/heapalloc_fail_dict.py b/tests/micropython/heapalloc_fail_dict.py
index ce2d158bd09c6..04c79183578ff 100644
--- a/tests/micropython/heapalloc_fail_dict.py
+++ b/tests/micropython/heapalloc_fail_dict.py
@@ -1,6 +1,12 @@
 # test handling of failed heap allocation with dict
 
-import micropython
+try:
+    import micropython
+
+    micropython.heap_lock
+except (ImportError, AttributeError):
+    print("SKIP")
+    raise SystemExit
 
 # create dict
 x = 1
diff --git a/tests/micropython/heapalloc_fail_list.py b/tests/micropython/heapalloc_fail_list.py
index 9a2e9a555f3e2..7afb6dc1019b3 100644
--- a/tests/micropython/heapalloc_fail_list.py
+++ b/tests/micropython/heapalloc_fail_list.py
@@ -1,6 +1,12 @@
 # test handling of failed heap allocation with list
 
-import micropython
+try:
+    import micropython
+
+    micropython.heap_lock
+except (ImportError, AttributeError):
+    print("SKIP")
+    raise SystemExit
 
 
 class GetSlice:
diff --git a/tests/micropython/heapalloc_fail_memoryview.py b/tests/micropython/heapalloc_fail_memoryview.py
index da2d1abffa634..17e3e1262472c 100644
--- a/tests/micropython/heapalloc_fail_memoryview.py
+++ b/tests/micropython/heapalloc_fail_memoryview.py
@@ -1,6 +1,12 @@
 # test handling of failed heap allocation with memoryview
 
-import micropython
+try:
+    import micropython
+
+    micropython.heap_lock
+except (ImportError, AttributeError):
+    print("SKIP")
+    raise SystemExit
 
 
 class GetSlice:
diff --git a/tests/micropython/heapalloc_fail_set.py b/tests/micropython/heapalloc_fail_set.py
index 3c347660ad763..0c4d85eef62a8 100644
--- a/tests/micropython/heapalloc_fail_set.py
+++ b/tests/micropython/heapalloc_fail_set.py
@@ -1,6 +1,12 @@
 # test handling of failed heap allocation with set
 
-import micropython
+try:
+    import micropython
+
+    micropython.heap_lock
+except (ImportError, AttributeError):
+    print("SKIP")
+    raise SystemExit
 
 # create set
 x = 1
diff --git a/tests/micropython/heapalloc_fail_tuple.py b/tests/micropython/heapalloc_fail_tuple.py
index de79385e3e3cb..11718a8107b3a 100644
--- a/tests/micropython/heapalloc_fail_tuple.py
+++ b/tests/micropython/heapalloc_fail_tuple.py
@@ -1,6 +1,12 @@
 # test handling of failed heap allocation with tuple
 
-import micropython
+try:
+    import micropython
+
+    micropython.heap_lock
+except (ImportError, AttributeError):
+    print("SKIP")
+    raise SystemExit
 
 # create tuple
 x = 1
diff --git a/tests/micropython/heapalloc_inst_call.py b/tests/micropython/heapalloc_inst_call.py
index 14d8826bf06ce..f78aa3cf87798 100644
--- a/tests/micropython/heapalloc_inst_call.py
+++ b/tests/micropython/heapalloc_inst_call.py
@@ -1,6 +1,13 @@
 # Test that calling clazz.__call__() with up to at least 3 arguments
 # doesn't require heap allocation.
-import micropython
+
+try:
+    import micropython
+
+    micropython.heap_lock
+except (ImportError, AttributeError):
+    print("SKIP")
+    raise SystemExit
 
 
 class Foo0:
diff --git a/tests/micropython/heapalloc_int_from_bytes.py b/tests/micropython/heapalloc_int_from_bytes.py
index 5fe50443ae335..3310ea95d1472 100644
--- a/tests/micropython/heapalloc_int_from_bytes.py
+++ b/tests/micropython/heapalloc_int_from_bytes.py
@@ -1,6 +1,13 @@
 # Test that int.from_bytes() for small number of bytes generates
 # small int.
-import micropython
+
+try:
+    import micropython
+
+    micropython.heap_lock
+except (ImportError, AttributeError):
+    print("SKIP")
+    raise SystemExit
 
 micropython.heap_lock()
 print(int.from_bytes(b"1", "little"))
diff --git a/tests/micropython/heapalloc_slice.py b/tests/micropython/heapalloc_slice.py
new file mode 100644
index 0000000000000..62d96595c719e
--- /dev/null
+++ b/tests/micropython/heapalloc_slice.py
@@ -0,0 +1,18 @@
+# slice operations that don't require allocation
+try:
+    from micropython import heap_lock, heap_unlock
+except (ImportError, AttributeError):
+    heap_lock = heap_unlock = lambda: 0
+
+b = bytearray(range(10))
+
+m = memoryview(b)
+
+heap_lock()
+
+b[3:5] = b"aa"
+m[5:7] = b"bb"
+
+heap_unlock()
+
+print(b)
diff --git a/tests/micropython/heapalloc_str.py b/tests/micropython/heapalloc_str.py
index 39aa56ccd7834..6372df5d37b13 100644
--- a/tests/micropython/heapalloc_str.py
+++ b/tests/micropython/heapalloc_str.py
@@ -1,5 +1,12 @@
 # String operations which don't require allocation
-import micropython
+
+try:
+    import micropython
+
+    micropython.heap_lock
+except (ImportError, AttributeError):
+    print("SKIP")
+    raise SystemExit
 
 micropython.heap_lock()
 
diff --git a/tests/micropython/heapalloc_super.py b/tests/micropython/heapalloc_super.py
index 51afae3d83d06..6839eee330acd 100644
--- a/tests/micropython/heapalloc_super.py
+++ b/tests/micropython/heapalloc_super.py
@@ -1,5 +1,12 @@
 # test super() operations which don't require allocation
-import micropython
+
+try:
+    import micropython
+
+    micropython.heap_lock
+except (ImportError, AttributeError):
+    print("SKIP")
+    raise SystemExit
 
 # Check for stackless build, which can't call functions without
 # allocating a frame on heap.
diff --git a/tests/micropython/heapalloc_traceback.py.native.exp b/tests/micropython/heapalloc_traceback.py.native.exp
new file mode 100644
index 0000000000000..d6ac26aa829e1
--- /dev/null
+++ b/tests/micropython/heapalloc_traceback.py.native.exp
@@ -0,0 +1,3 @@
+StopIteration
+StopIteration: 
+
diff --git a/tests/micropython/heapalloc_yield_from.py b/tests/micropython/heapalloc_yield_from.py
index 950717189087d..9d4f8c6940f16 100644
--- a/tests/micropython/heapalloc_yield_from.py
+++ b/tests/micropython/heapalloc_yield_from.py
@@ -1,6 +1,12 @@
 # Check that yield-from can work without heap allocation
 
-import micropython
+try:
+    import micropython
+
+    micropython.heap_lock
+except (ImportError, AttributeError):
+    print("SKIP")
+    raise SystemExit
 
 
 # Yielding from a function generator
diff --git a/tests/micropython/import_mpy_native.py b/tests/micropython/import_mpy_native.py
index ad63e025db2c8..59181b203bba9 100644
--- a/tests/micropython/import_mpy_native.py
+++ b/tests/micropython/import_mpy_native.py
@@ -54,12 +54,13 @@ def open(self, path, mode):
 
 # these are the test .mpy files
 # CIRCUITPY-CHANGE
-valid_header = bytes([ord("C"), 6, mpy_arch, 31])
+small_int_bits = 31
+valid_header = bytes([77, 6, (mpy_arch & 0x3F), small_int_bits])
 # fmt: off
 user_files = {
     # bad architecture (mpy_arch needed for sub-version)
     # CIRCUITPY-CHANGE
-    '/mod0.mpy': bytes([ord('C'), 6, 0xfc | mpy_arch, 31]),
+    '/mod0.mpy': bytes([ord('C'), 6, 0xfc | (mpy_arch & 3), small_int_bits]),
 
     # test loading of viper and asm
     '/mod1.mpy': valid_header + (
diff --git a/tests/micropython/import_mpy_native_gc.py b/tests/micropython/import_mpy_native_gc.py
index 0d5b79f0a8dd4..5159cc9e9f9cf 100644
--- a/tests/micropython/import_mpy_native_gc.py
+++ b/tests/micropython/import_mpy_native_gc.py
@@ -57,9 +57,13 @@ def open(self, path, mode):
 # CIRCUITPY-CHANGE: 'C' instead of 'M' mpy marker.
 features0_file_contents = {
     # -march=x64
-    0x806: b'C\x06\n\x1f\x02\x004build/features0.native.mpy\x00\x12factorial\x00\x8a\x02\xe93\x00\x00\x00\xf3\x0f\x1e\xfaSH\x8b\x1d\x7f\x00\x00\x00\xbe\x02\x00\x00\x00\xffS\x18\xbf\x01\x00\x00\x00H\x85\xc0u\x0cH\x8bC \xbe\x02\x00\x00\x00[\xff\xe0H\x0f\xaf\xf8H\xff\xc8\xeb\xe6\xf3\x0f\x1e\xfaATUSH\x8b\x1dI\x00\x00\x00H\x8bG\x08L\x8bc(H\x8bx\x08A\xff\xd4H\x8d5#\x00\x00\x00H\x89\xc5H\x8b\x051\x00\x00\x00\x0f\xb7x\x02\xffShH\x89\xefA\xff\xd4H\x8b\x03[]A\\\xc3\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x05\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00 \x11$\r&\xa5 \x01"\xff',
+    0x806: b"C\x06\x0b\x1f\x03\x002build/test_x64.native.mpy\x00\x08add1\x00\x0cunused\x00\x91B\xe9I\x00\x00\x00H\x8b\x05\xf4\x00\x00\x00H\x8b\x00\xc3H\x8b\x05\xf9\x00\x00\x00\xbe\x02\x00\x00\x00\x8b8H\x8b\x05\xdb\x00\x00\x00H\x8b@ \xff\xe0H\x8b\x05\xce\x00\x00\x00S\xbe\x02\x00\x00\x00H\x8bX \xffP\x18\xbe\x02\x00\x00\x00H\x8dx\x01H\x89\xd8[\xff\xe0AVAUATUSH\x8b\x1d\xa3\x00\x00\x00H\x8bG\x08L\x8bk(H\x8bx\x08A\xff\xd5L\x8b5\x95\x00\x00\x00L\x8bchH\x8d5r\x00\x00\x00H\x89\xc5H\x8b\x05\x88\x00\x00\x00A\x0f\xb7~\x04\xc7\x00@\xe2\x01\x00A\xff\xd4H\x8d5C\x00\x00\x00\xbfV\x00\x00\x00A\xff\xd4A\x0f\xb7~\x02H\x8d5\x1f\x00\x00\x00A\xff\xd4H\x89\xefA\xff\xd5H\x8b\x03[]A\\A]A^\xc3\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00+\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x10\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x05\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00P\x04\x11@\rB\tD\xaf4\x016\xad8\x01:\xaf<\x01>\xff",
     # -march=armv6m
-    0x1006: b"C\x06\x12\x1f\x02\x004build/features0.native.mpy\x00\x12factorial\x00\x88\x02\x18\xe0\x00\x00\x10\xb5\tK\tJ{D\x9cX\x02!\xe3h\x98G\x03\x00\x01 \x00+\x02\xd0XC\x01;\xfa\xe7\x02!#i\x98G\x10\xbd\xc0Fj\x00\x00\x00\x00\x00\x00\x00\xf8\xb5\nN\nK~D\xf4XChgiXh\xb8G\x05\x00\x07K\x08I\xf3XyDX\x88ck\x98G(\x00\xb8G h\xf8\xbd\xc0F:\x00\x00\x00\x00\x00\x00\x00\x04\x00\x00\x00\x1e\x00\x00\x00\x00\x00\x00\x00\x05\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00 \x11<\r>\xa58\x01:\xff",
+    0x1006: b"C\x06\x13\x1f\x03\x008build/test_armv6m.native.mpy\x00\x08add1\x00\x0cunused\x00\x8eb0\xe0\x00\x00\x00\x00\x00\x00\x02K\x03J{D\x9bX\x18hpG\xd0\x00\x00\x00\x00\x00\x00\x00\x10\xb5\x05K\x05I\x06J{D\x9aX[X\x10h\x02!\x1bi\x98G\x10\xbd\xb8\x00\x00\x00\x00\x00\x00\x00\x08\x00\x00\x00\x10\xb5\x06K\x06J{D\x9bX\x02!\x1ci\xdbh\x98G\x02!\x010\xa0G\x10\xbd\xc0F\x96\x00\x00\x00\x00\x00\x00\x00\xf7\xb5\x12O\x12K\x7fD\xfdX\x12Lki|D\x00\x93ChXh\x00\x9b\x98G\x0fK\x01\x90\x0fJ\xfbXnk\x1a`\x0eK!\x00\xffX\xb8\x88\xb0G!\x00V \x081\xb0G!\x00x\x88\x101\xb0G\x01\x98\x00\x9b\x98G(h\xfe\xbd\xc0Fr\x00\x00\x00\x00\x00\x00\x00R\x00\x00\x00\x08\x00\x00\x00@\xe2\x01\x00\x04\x00\x00\x00\x00\x00\x00\x00\t\x00\x00\x00\x00\x00\x00\x00\x1d\x00\x00\x00\x00\x00\x00\x00A\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00P\x04\x11p\rr\tt\xafd\x01f\xadh\x01j\xafl\x01n\xff",
+    # -march=xtensawin
+    0x2806: b"C\x06+\x1f\x03\x00>build/test_xtensawin.native.mpy\x00\x08add1\x00\x0cunused\x00\x8a\x12\x06\x16\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x10\x00\x00\x00\x08\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x006A\x00\x81\xf9\xff(\x08\x1d\xf0\x00\x006A\x00\x91\xfb\xff\x81\xf5\xff\xa8\t\x88H\x0c+\xe0\x08\x00-\n\x1d\xf0\x00\x006A\x00\x81\xf0\xff\xad\x02xH\x888\x0c+\xe0\x08\x00\x0c+\x1b\xaa\xe0\x07\x00-\n\x1d\xf06A\x00a\xe9\xff\x88\x122&\x05\xa2(\x01\xe0\x03\x00q\xe6\xff\x81\xea\xff\x92\xa7\x89\xa0\x99\x11H\xd6]\n\xb1\xe3\xff\xa2\x17\x02\x99\x08\xe0\x04\x00\xb1\xe2\xff\\j\xe0\x04\x00\xb1\xe1\xff\xa2\x17\x01\xe0\x04\x00\xad\x05\xe0\x03\x00(\x06\x1d\xf0p\x18\x04\x00\x00\x00\x00@\x00\x00\x00\x00\x00\x00\x00(\x00\x00\x00\x00\x00\x00\x00\x1c\x00\x00\x00\x11\x02\r\x04\x07\x06\x03\t\x0c\xaf\x01\x01\x03\xad\x05\x01\x07\xaf\t\x01\x0b\xff",
+    # -march=rv32imc
+    0x2C06: b'C\x06/\x1f\x03\x00:build/test_rv32imc.native.mpy\x00\x08add1\x00\x0cunused\x00\x8fb\x97\x0f\x00\x00g\x80\x0f\x05\x97\x07\x00\x00\x83\xa7\x07\x0e\x88C\x82\x80\x97\x07\x00\x00\x83\xa7G\r\x17\x07\x00\x00\x03\'\xc7\r\x9cK\x08C\x89E\x82\x87A\x11\x97\x07\x00\x00\x83\xa7\xa7\x0b"\xc4\x80K\xdcG\x06\xc6\x89E\x82\x97\xa2\x87"D\xb2@\x89E\x05\x05A\x01\x82\x87\\A\x01\x11"\xcc\x17\x04\x00\x00\x03$$\tN\xc6\xc8C\x83)D\x01\x06\xce&\xcaJ\xc8R\xc4\x82\x99\x17\n\x00\x00\x03*\xca\x07\x03)D\x03\xaa\x84\xf9g\x03UJ\x00\x93\x87\x07$\x17\x07\x00\x00\x03\'\x07\x07\x1c\xc3\x97\x05\x00\x00\x93\x85\xe5\x03\x02\x99\x97\x05\x00\x00\x93\x85\xc5\x03\x13\x05`\x05\x02\x99\x03U*\x00\x97\x05\x00\x00\x93\x85%\x03\x02\x99&\x85\x82\x99\x08@\xf2@bD\xd2DBI\xb2I"J\x05a\x82\x80\x00\x00\x00\x00\x00\x00\x08\x00\x00\x00\x00\x00\x00\x00\x14\x00\x00\x00\x00\x00\x00\x00,\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00P\x04\x11t\rv\xafx\xadz\t|\xafh\x01j\xadl\x01n\xafp\x01r\xff',
 }
 
 # Populate armv7m-derived archs based on armv6m.
@@ -67,7 +71,7 @@ def open(self, path, mode):
     features0_file_contents[arch] = features0_file_contents[0x1006]
 
 # Check that a .mpy exists for the target (ignore sub-version in lookup).
-sys_implementation_mpy = sys.implementation._mpy & ~(3 << 8)
+sys_implementation_mpy = (sys.implementation._mpy & ~(3 << 8)) & 0xFFFF
 if sys_implementation_mpy not in features0_file_contents:
     print("SKIP")
     raise SystemExit
diff --git a/tests/micropython/kbd_intr.py b/tests/micropython/kbd_intr.py
index 81977aaa52f6f..e1ed7185ef0a2 100644
--- a/tests/micropython/kbd_intr.py
+++ b/tests/micropython/kbd_intr.py
@@ -1,10 +1,10 @@
 # test the micropython.kbd_intr() function
 
-import micropython
-
 try:
+    import micropython
+
     micropython.kbd_intr
-except AttributeError:
+except (ImportError, AttributeError):
     print("SKIP")
     raise SystemExit
 
diff --git a/tests/micropython/meminfo.py b/tests/micropython/meminfo.py
index 9df341fbb8334..f4dd8fdb6042c 100644
--- a/tests/micropython/meminfo.py
+++ b/tests/micropython/meminfo.py
@@ -1,12 +1,14 @@
 # tests meminfo functions in micropython module
 
-import micropython
+try:
+    import micropython
 
-# these functions are not always available
-if not hasattr(micropython, "mem_info"):
+    micropython.mem_info
+except (ImportError, AttributeError):
     print("SKIP")
-else:
-    micropython.mem_info()
-    micropython.mem_info(1)
-    micropython.qstr_info()
-    micropython.qstr_info(1)
+    raise SystemExit
+
+micropython.mem_info()
+micropython.mem_info(1)
+micropython.qstr_info()
+micropython.qstr_info(1)
diff --git a/tests/micropython/memstats.py b/tests/micropython/memstats.py
index dee3a4ce2f225..0e2e7b1c0b326 100644
--- a/tests/micropython/memstats.py
+++ b/tests/micropython/memstats.py
@@ -1,17 +1,19 @@
 # tests meminfo functions in micropython module
 
-import micropython
+try:
+    import micropython
 
-# these functions are not always available
-if not hasattr(micropython, "mem_total"):
+    micropython.mem_total
+except (ImportError, AttributeError):
     print("SKIP")
-else:
-    t = micropython.mem_total()
-    c = micropython.mem_current()
-    p = micropython.mem_peak()
+    raise SystemExit
 
-    l = list(range(10000))
+t = micropython.mem_total()
+c = micropython.mem_current()
+p = micropython.mem_peak()
 
-    print(micropython.mem_total() > t)
-    print(micropython.mem_current() > c)
-    print(micropython.mem_peak() > p)
+l = list(range(10000))
+
+print(micropython.mem_total() > t)
+print(micropython.mem_current() > c)
+print(micropython.mem_peak() > p)
diff --git a/tests/micropython/opt_level.py b/tests/micropython/opt_level.py
index dd5493a7a3cb8..789197d8825bf 100644
--- a/tests/micropython/opt_level.py
+++ b/tests/micropython/opt_level.py
@@ -1,4 +1,10 @@
-import micropython as micropython
+# test micropython.opt_level()
+
+try:
+    import micropython
+except ImportError:
+    print("SKIP")
+    raise SystemExit
 
 # check we can get and set the level
 micropython.opt_level(0)
diff --git a/tests/micropython/opt_level_lineno.py b/tests/micropython/opt_level_lineno.py
index 40650b6819221..4ca76625de49a 100644
--- a/tests/micropython/opt_level_lineno.py
+++ b/tests/micropython/opt_level_lineno.py
@@ -1,7 +1,24 @@
-import micropython as micropython
+# test micropython.opt_level() and line numbers
+
+try:
+    import micropython
+except ImportError:
+    print("SKIP")
+    raise SystemExit
 
 # check that level 3 doesn't store line numbers
 # the expected output is that any line is printed as "line 1"
 micropython.opt_level(3)
-# CIRCUITPY-CHANGE: use traceback.print_exception() instead of sys.print_exception()
-exec("try:\n xyz\nexcept NameError as er:\n import traceback\n traceback.print_exception(er)")
+
+# force bytecode emitter, because native emitter doesn't store line numbers
+exec("""
+@micropython.bytecode
+def f():
+    try:
+        xyz
+    except NameError as er:
+        # CIRCUITPY-CHANGE: use traceback.print_exception() instead of sys.print_exception()
+        import traceback
+        traceback.print_exception(er)
+f()
+""")
diff --git a/tests/micropython/opt_level_lineno.py.exp b/tests/micropython/opt_level_lineno.py.exp
index 469b90ba7938a..b50f0628c81fb 100644
--- a/tests/micropython/opt_level_lineno.py.exp
+++ b/tests/micropython/opt_level_lineno.py.exp
@@ -1,3 +1,3 @@
 Traceback (most recent call last):
-  File "<string>", line 1, in <module>
+  File "<string>", line 1, in f
 NameError: name 'xyz' isn't defined
diff --git a/tests/micropython/ringio_big.py b/tests/micropython/ringio_big.py
new file mode 100644
index 0000000000000..ddbbae12a630c
--- /dev/null
+++ b/tests/micropython/ringio_big.py
@@ -0,0 +1,29 @@
+# Check that micropython.RingIO works correctly.
+
+try:
+    import micropython
+
+    micropython.RingIO
+except (ImportError, AttributeError):
+    print("SKIP")
+    raise SystemExit
+
+try:
+    # The maximum possible size
+    micropython.RingIO(bytearray(65535))
+    micropython.RingIO(65534)
+
+    try:
+        # Buffer may not be too big
+        micropython.RingIO(bytearray(65536))
+    except ValueError as ex:
+        print(type(ex))
+
+    try:
+        # Size may not be too big
+        micropython.RingIO(65535)
+    except ValueError as ex:
+        print(type(ex))
+except MemoryError:
+    print("SKIP")
+    raise SystemExit
diff --git a/tests/micropython/ringio_big.py.exp b/tests/micropython/ringio_big.py.exp
new file mode 100644
index 0000000000000..72af34b383872
--- /dev/null
+++ b/tests/micropython/ringio_big.py.exp
@@ -0,0 +1,2 @@
+<class 'ValueError'>
+<class 'ValueError'>
diff --git a/tests/micropython/schedule.py b/tests/micropython/schedule.py
index 6a91459ea3d54..f3dd32661267b 100644
--- a/tests/micropython/schedule.py
+++ b/tests/micropython/schedule.py
@@ -1,10 +1,10 @@
 # test micropython.schedule() function
 
-import micropython
-
 try:
+    import micropython
+
     micropython.schedule
-except AttributeError:
+except (ImportError, AttributeError):
     print("SKIP")
     raise SystemExit
 
diff --git a/tests/micropython/stack_use.py b/tests/micropython/stack_use.py
index 266885d9d1897..5d36fdca2fe01 100644
--- a/tests/micropython/stack_use.py
+++ b/tests/micropython/stack_use.py
@@ -1,7 +1,11 @@
 # tests stack_use function in micropython module
-import micropython
 
-if not hasattr(micropython, "stack_use"):
+try:
+    import micropython
+
+    micropython.stack_use
+except (ImportError, AttributeError):
     print("SKIP")
-else:
-    print(type(micropython.stack_use()))  # output varies
+    raise SystemExit
+
+print(type(micropython.stack_use()))  # output varies
diff --git a/tests/micropython/test_normalize_newlines.py b/tests/micropython/test_normalize_newlines.py
new file mode 100644
index 0000000000000..f19aaa69a3f75
--- /dev/null
+++ b/tests/micropython/test_normalize_newlines.py
@@ -0,0 +1,14 @@
+# Test for normalize_newlines functionality
+# This test verifies that test framework handles various newline combinations correctly
+
+# Note: This is more of an integration test since normalize_newlines is in the test framework
+# The actual testing happens when this test is run through run-tests.py
+
+print("Testing newline handling")
+print("Line 1\r\nLine 2")  # Windows-style line ending - should be normalized
+print("Line 3")            # Normal line
+print("Line 4")            # Normal line
+print("Line 5\nLine 6")    # Unix-style line ending - already normalized
+
+# Test that literal \r in strings is preserved
+print(repr("test\rstring"))  # Should show 'test\rstring' not 'test\nstring'
diff --git a/tests/micropython/test_normalize_newlines.py.exp b/tests/micropython/test_normalize_newlines.py.exp
new file mode 100644
index 0000000000000..c4395468cf109
--- /dev/null
+++ b/tests/micropython/test_normalize_newlines.py.exp
@@ -0,0 +1,8 @@
+Testing newline handling
+Line 1
+Line 2
+Line 3
+Line 4
+Line 5
+Line 6
+'test\rstring'
diff --git a/tests/micropython/viper_large_jump.py b/tests/micropython/viper_large_jump.py
new file mode 100644
index 0000000000000..1c5913dec1ea2
--- /dev/null
+++ b/tests/micropython/viper_large_jump.py
@@ -0,0 +1,20 @@
+COUNT = 600
+
+
+try:
+    code = """
+@micropython.viper
+def f() -> int:
+    x = 0
+    while x < 10:
+"""
+    for i in range(COUNT):
+        code += "        x += 1\n"
+    code += "    return x"
+    exec(code)
+except MemoryError:
+    print("SKIP-TOO-LARGE")
+    raise SystemExit
+
+
+print(f())
diff --git a/tests/micropython/viper_large_jump.py.exp b/tests/micropython/viper_large_jump.py.exp
new file mode 100644
index 0000000000000..e9f960cf4ac4e
--- /dev/null
+++ b/tests/micropython/viper_large_jump.py.exp
@@ -0,0 +1 @@
+600
diff --git a/tests/micropython/viper_ptr16_load_boundary.py b/tests/micropython/viper_ptr16_load_boundary.py
new file mode 100644
index 0000000000000..0d4c3105b685b
--- /dev/null
+++ b/tests/micropython/viper_ptr16_load_boundary.py
@@ -0,0 +1,39 @@
+# Test boundary conditions for various architectures
+
+GET_TEMPLATE = """
+@micropython.viper
+def get{off}(src: ptr16) -> uint:
+    return uint(src[{off}])
+print(hex(get{off}(buffer)))
+"""
+
+
+BIT_THRESHOLDS = (5, 8, 11, 12)
+SIZE = 2
+
+
+@micropython.viper
+def get_index(src: ptr16, i: int) -> int:
+    return src[i]
+
+
+def data(start, len):
+    output = bytearray(len)
+    for idx in range(len):
+        output[idx] = (start + idx) & 0xFF
+    return output
+
+
+buffer = bytearray((((1 << max(BIT_THRESHOLDS)) + 1) // 1024) * 1024)
+val = 0
+for bit in BIT_THRESHOLDS:
+    print("---", bit)
+    pre, idx, post = ((1 << bit) - (2 * SIZE), (1 << bit) - (1 * SIZE), 1 << bit)
+    buffer[pre:post] = data(val, 3 * SIZE)
+    val = val + (3 * SIZE)
+
+    pre, idx, post = pre // SIZE, idx // SIZE, post // SIZE
+    print(hex(get_index(buffer, pre)), hex(get_index(buffer, idx)), hex(get_index(buffer, post)))
+    exec(GET_TEMPLATE.format(off=pre))
+    exec(GET_TEMPLATE.format(off=idx))
+    exec(GET_TEMPLATE.format(off=post))
diff --git a/tests/micropython/viper_ptr16_load_boundary.py.exp b/tests/micropython/viper_ptr16_load_boundary.py.exp
new file mode 100644
index 0000000000000..56f1d32290468
--- /dev/null
+++ b/tests/micropython/viper_ptr16_load_boundary.py.exp
@@ -0,0 +1,20 @@
+--- 5
+0x100 0x302 0x504
+0x100
+0x302
+0x504
+--- 8
+0x706 0x908 0xb0a
+0x706
+0x908
+0xb0a
+--- 11
+0xd0c 0xf0e 0x1110
+0xd0c
+0xf0e
+0x1110
+--- 12
+0x1312 0x1514 0x1716
+0x1312
+0x1514
+0x1716
diff --git a/tests/micropython/viper_ptr16_store_boundary.py b/tests/micropython/viper_ptr16_store_boundary.py
new file mode 100644
index 0000000000000..7c774d4d1ca18
--- /dev/null
+++ b/tests/micropython/viper_ptr16_store_boundary.py
@@ -0,0 +1,63 @@
+# Test boundary conditions for various architectures
+
+SET_TEMPLATE = """
+@micropython.viper
+def set{off}(dest: ptr16):
+    saved = dest
+    dest[{off}] = {val}
+    assert int(saved) == int(dest)
+"""
+
+BIT_THRESHOLDS = (5, 8, 11, 12)
+SIZE = 2
+MASK = (1 << (8 * SIZE)) - 1
+
+next_int = 1
+test_buffer = bytearray(SIZE)
+
+
+def next_value() -> uint:
+    global next_int
+    global test_buffer
+    for index in range(1, SIZE):
+        test_buffer[index - 1] = test_buffer[index]
+    test_buffer[SIZE - 1] = next_int
+    next_int += 1
+    output = 0
+    for byte in test_buffer:
+        output = (output << 8) | byte
+    return output & MASK
+
+
+def get_index(src, i):
+    return src[i * SIZE] + (src[(i * SIZE) + 1] << 8)
+
+
+@micropython.viper
+def set_index(dest: ptr16, i: int, val: uint):
+    saved = dest
+    dest[i] = val
+    assert int(saved) == int(dest)
+
+
+try:
+    buffer = bytearray((((1 << max(BIT_THRESHOLDS)) // 1024) + 1) * 1024)
+
+    for bit in BIT_THRESHOLDS:
+        offset = (1 << bit) - (2 * SIZE)
+        for index in range(0, 3 * SIZE, SIZE):
+            exec(SET_TEMPLATE.format(off=(offset + index) // SIZE, val=next_value()))
+except MemoryError:
+    print("SKIP-TOO-LARGE")
+    raise SystemExit
+
+
+for bit in BIT_THRESHOLDS:
+    print("---", bit)
+    offset = (1 << bit) - (2 * SIZE)
+    for index in range(0, 3 * SIZE, SIZE):
+        globals()["set{}".format((offset + index) // SIZE)](buffer)
+        print(hex(get_index(buffer, (offset + index) // SIZE)))
+    for index in range(0, 3 * SIZE, SIZE):
+        set_index(buffer, (offset + index) // SIZE, next_value())
+        print(hex(get_index(buffer, (offset + index) // SIZE)))
diff --git a/tests/micropython/viper_ptr16_store_boundary.py.exp b/tests/micropython/viper_ptr16_store_boundary.py.exp
new file mode 100644
index 0000000000000..007a50b3edafb
--- /dev/null
+++ b/tests/micropython/viper_ptr16_store_boundary.py.exp
@@ -0,0 +1,28 @@
+--- 5
+0x1
+0x102
+0x203
+0xc0d
+0xd0e
+0xe0f
+--- 8
+0x304
+0x405
+0x506
+0xf10
+0x1011
+0x1112
+--- 11
+0x607
+0x708
+0x809
+0x1213
+0x1314
+0x1415
+--- 12
+0x90a
+0xa0b
+0xb0c
+0x1516
+0x1617
+0x1718
diff --git a/tests/micropython/viper_ptr32_load_boundary.py b/tests/micropython/viper_ptr32_load_boundary.py
new file mode 100644
index 0000000000000..971d1113c49bb
--- /dev/null
+++ b/tests/micropython/viper_ptr32_load_boundary.py
@@ -0,0 +1,39 @@
+# Test boundary conditions for various architectures
+
+GET_TEMPLATE = """
+@micropython.viper
+def get{off}(src: ptr32) -> uint:
+    return uint(src[{off}])
+print(hex(get{off}(buffer)))
+"""
+
+
+BIT_THRESHOLDS = (5, 8, 11, 12)
+SIZE = 4
+
+
+@micropython.viper
+def get_index(src: ptr32, i: int) -> int:
+    return src[i]
+
+
+def data(start, len):
+    output = bytearray(len)
+    for idx in range(len):
+        output[idx] = (start + idx) & 0xFF
+    return output
+
+
+buffer = bytearray((((1 << max(BIT_THRESHOLDS)) + 1) // 1024) * 1024)
+val = 0
+for bit in BIT_THRESHOLDS:
+    print("---", bit)
+    pre, idx, post = (((1 << bit) - (2 * SIZE)), ((1 << bit) - (1 * SIZE)), (1 << bit))
+    buffer[pre:post] = data(val, 3 * SIZE)
+    val = val + (3 * SIZE)
+
+    pre, idx, post = pre // SIZE, idx // SIZE, post // SIZE
+    print(hex(get_index(buffer, pre)), hex(get_index(buffer, idx)), hex(get_index(buffer, post)))
+    exec(GET_TEMPLATE.format(off=pre))
+    exec(GET_TEMPLATE.format(off=idx))
+    exec(GET_TEMPLATE.format(off=post))
diff --git a/tests/micropython/viper_ptr32_load_boundary.py.exp b/tests/micropython/viper_ptr32_load_boundary.py.exp
new file mode 100644
index 0000000000000..1e22a8b361333
--- /dev/null
+++ b/tests/micropython/viper_ptr32_load_boundary.py.exp
@@ -0,0 +1,20 @@
+--- 5
+0x3020100 0x7060504 0xb0a0908
+0x3020100
+0x7060504
+0xb0a0908
+--- 8
+0xf0e0d0c 0x13121110 0x17161514
+0xf0e0d0c
+0x13121110
+0x17161514
+--- 11
+0x1b1a1918 0x1f1e1d1c 0x23222120
+0x1b1a1918
+0x1f1e1d1c
+0x23222120
+--- 12
+0x27262524 0x2b2a2928 0x2f2e2d2c
+0x27262524
+0x2b2a2928
+0x2f2e2d2c
diff --git a/tests/micropython/viper_ptr32_store_boundary.py b/tests/micropython/viper_ptr32_store_boundary.py
new file mode 100644
index 0000000000000..96ca74ad3ca70
--- /dev/null
+++ b/tests/micropython/viper_ptr32_store_boundary.py
@@ -0,0 +1,68 @@
+# Test boundary conditions for various architectures
+
+SET_TEMPLATE = """
+@micropython.viper
+def set{off}(dest: ptr32):
+    saved = dest
+    dest[{off}] = {val}
+    assert int(saved) == int(dest)
+"""
+
+BIT_THRESHOLDS = (5, 8, 11, 12)
+SIZE = 4
+MASK = (1 << (8 * SIZE)) - 1
+
+next_int = 1
+test_buffer = bytearray(SIZE)
+
+
+def next_value() -> uint:
+    global next_int
+    global test_buffer
+    for index in range(1, SIZE):
+        test_buffer[index - 1] = test_buffer[index]
+    test_buffer[SIZE - 1] = next_int
+    next_int += 1
+    output = 0
+    for byte in test_buffer:
+        output = (output << 8) | byte
+    return output & MASK
+
+
+def get_index(src, i):
+    return (
+        src[i * SIZE]
+        + (src[(i * SIZE) + 1] << 8)
+        + (src[(i * SIZE) + 2] << 16)
+        + (src[(i * SIZE) + 3] << 24)
+    )
+
+
+@micropython.viper
+def set_index(dest: ptr32, i: int, val: uint):
+    saved = dest
+    dest[i] = val
+    assert int(dest) == int(saved)
+
+
+try:
+    buffer = bytearray((((1 << max(BIT_THRESHOLDS)) // 1024) + 1) * 1024)
+
+    for bit in BIT_THRESHOLDS:
+        offset = (1 << bit) - (2 * SIZE)
+        for index in range(0, 3 * SIZE, SIZE):
+            exec(SET_TEMPLATE.format(off=(offset + index) // SIZE, val=next_value()))
+except MemoryError:
+    print("SKIP-TOO-LARGE")
+    raise SystemExit
+
+
+for bit in BIT_THRESHOLDS:
+    print("---", bit)
+    offset = (1 << bit) - (2 * SIZE)
+    for index in range(0, 3 * SIZE, SIZE):
+        globals()["set{}".format((offset + index) // SIZE)](buffer)
+        print(hex(get_index(buffer, (offset + index) // SIZE)))
+    for index in range(0, 3 * SIZE, SIZE):
+        set_index(buffer, (offset + index) // SIZE, next_value())
+        print(hex(get_index(buffer, (offset + index) // SIZE)))
diff --git a/tests/micropython/viper_ptr32_store_boundary.py.exp b/tests/micropython/viper_ptr32_store_boundary.py.exp
new file mode 100644
index 0000000000000..7a9a51624743e
--- /dev/null
+++ b/tests/micropython/viper_ptr32_store_boundary.py.exp
@@ -0,0 +1,28 @@
+--- 5
+0x1
+0x102
+0x10203
+0xa0b0c0d
+0xb0c0d0e
+0xc0d0e0f
+--- 8
+0x1020304
+0x2030405
+0x3040506
+0xd0e0f10
+0xe0f1011
+0xf101112
+--- 11
+0x4050607
+0x5060708
+0x6070809
+0x10111213
+0x11121314
+0x12131415
+--- 12
+0x708090a
+0x8090a0b
+0x90a0b0c
+0x13141516
+0x14151617
+0x15161718
diff --git a/tests/micropython/viper_ptr8_load_boundary.py b/tests/micropython/viper_ptr8_load_boundary.py
new file mode 100644
index 0000000000000..57e06da5709ab
--- /dev/null
+++ b/tests/micropython/viper_ptr8_load_boundary.py
@@ -0,0 +1,38 @@
+# Test boundary conditions for various architectures
+
+GET_TEMPLATE = """
+@micropython.viper
+def get{off}(src: ptr8) -> uint:
+    return uint(src[{off}])
+print(hex(get{off}(buffer)))
+"""
+
+
+BIT_THRESHOLDS = (5, 8, 11, 12)
+SIZE = 1
+
+
+@micropython.viper
+def get_index(src: ptr8, i: int) -> int:
+    return src[i]
+
+
+def data(start, len):
+    output = bytearray(len)
+    for idx in range(len):
+        output[idx] = (start + idx) & 0xFF
+    return output
+
+
+buffer = bytearray((((1 << max(BIT_THRESHOLDS)) + 1) // 1024) * 1024)
+val = 0
+for bit in BIT_THRESHOLDS:
+    print("---", bit)
+    pre, idx, post = (((1 << bit) - (2 * SIZE)), ((1 << bit) - (1 * SIZE)), (1 << bit))
+    buffer[pre:post] = data(val, 3 * SIZE)
+    val = val + (3 * SIZE)
+
+    print(hex(get_index(buffer, pre)), hex(get_index(buffer, idx)), hex(get_index(buffer, post)))
+    exec(GET_TEMPLATE.format(off=pre))
+    exec(GET_TEMPLATE.format(off=idx))
+    exec(GET_TEMPLATE.format(off=post))
diff --git a/tests/micropython/viper_ptr8_load_boundary.py.exp b/tests/micropython/viper_ptr8_load_boundary.py.exp
new file mode 100644
index 0000000000000..a0e423686b8fa
--- /dev/null
+++ b/tests/micropython/viper_ptr8_load_boundary.py.exp
@@ -0,0 +1,20 @@
+--- 5
+0x0 0x1 0x2
+0x0
+0x1
+0x2
+--- 8
+0x3 0x4 0x5
+0x3
+0x4
+0x5
+--- 11
+0x6 0x7 0x8
+0x6
+0x7
+0x8
+--- 12
+0x9 0xa 0xb
+0x9
+0xa
+0xb
diff --git a/tests/micropython/viper_ptr8_store_boundary.py b/tests/micropython/viper_ptr8_store_boundary.py
new file mode 100644
index 0000000000000..68b76fd598b88
--- /dev/null
+++ b/tests/micropython/viper_ptr8_store_boundary.py
@@ -0,0 +1,63 @@
+# Test boundary conditions for various architectures
+
+SET_TEMPLATE = """
+@micropython.viper
+def set{off}(dest: ptr8):
+    saved = dest
+    dest[{off}] = {val}
+    assert int(saved) == int(dest)
+"""
+
+BIT_THRESHOLDS = (5, 8, 11, 12)
+SIZE = 1
+MASK = (1 << (8 * SIZE)) - 1
+
+next_int = 1
+test_buffer = bytearray(SIZE)
+
+
+def next_value() -> uint:
+    global next_int
+    global test_buffer
+    for index in range(1, SIZE):
+        test_buffer[index - 1] = test_buffer[index]
+    test_buffer[SIZE - 1] = next_int
+    next_int += 1
+    output = 0
+    for byte in test_buffer:
+        output = (output << 8) | byte
+    return output & MASK
+
+
+def get_index(src: ptr8, i: int):
+    return src[i]
+
+
+@micropython.viper
+def set_index(dest: ptr8, i: int, val: uint):
+    saved = dest
+    dest[i] = val
+    assert int(dest) == int(saved)
+
+
+try:
+    buffer = bytearray((((1 << max(BIT_THRESHOLDS)) // 1024) + 1) * 1024)
+
+    for bit in BIT_THRESHOLDS:
+        offset = (1 << bit) - (2 * SIZE)
+        for index in range(0, 3 * SIZE, SIZE):
+            exec(SET_TEMPLATE.format(off=(offset + index) // SIZE, val=next_value()))
+except MemoryError:
+    print("SKIP-TOO-LARGE")
+    raise SystemExit
+
+
+for bit in BIT_THRESHOLDS:
+    print("---", bit)
+    offset = (1 << bit) - (2 * SIZE)
+    for index in range(0, 3 * SIZE, SIZE):
+        globals()["set{}".format((offset + index) // SIZE)](buffer)
+        print(hex(get_index(buffer, (offset + index) // SIZE)))
+    for index in range(0, 3 * SIZE, SIZE):
+        set_index(buffer, (offset + index) // SIZE, next_value())
+        print(hex(get_index(buffer, (offset + index) // SIZE)))
diff --git a/tests/micropython/viper_ptr8_store_boundary.py.exp b/tests/micropython/viper_ptr8_store_boundary.py.exp
new file mode 100644
index 0000000000000..621295d81a896
--- /dev/null
+++ b/tests/micropython/viper_ptr8_store_boundary.py.exp
@@ -0,0 +1,28 @@
+--- 5
+0x1
+0x2
+0x3
+0xd
+0xe
+0xf
+--- 8
+0x4
+0x5
+0x6
+0x10
+0x11
+0x12
+--- 11
+0x7
+0x8
+0x9
+0x13
+0x14
+0x15
+--- 12
+0xa
+0xb
+0xc
+0x16
+0x17
+0x18
diff --git a/tests/misc/non_compliant.py b/tests/misc/non_compliant.py
index 31c9fa17c3bed..8608f2322f8e8 100644
--- a/tests/misc/non_compliant.py
+++ b/tests/misc/non_compliant.py
@@ -39,7 +39,7 @@
 except NotImplementedError:
     print("NotImplementedError")
 
-# uPy raises TypeError, should be ValueError
+# MicroPython raises TypeError, should be ValueError
 try:
     "%c" % b"\x01\x02"
 except (TypeError, ValueError):
@@ -100,10 +100,10 @@
     print("NotImplementedError")
 
 # CIRCUITPY-CHANGE: We do check these.
-# struct pack with too many args, not checked by uPy
+# struct pack with too many args, not checked by MicroPython
 # print(struct.pack("bb", 1, 2, 3))
 
-# struct pack with too few args, not checked by uPy
+# struct pack with too few args, not checked by MicroPython
 # print(struct.pack("bb", 1))
 
 # array slice assignment with unsupported RHS
diff --git a/tests/misc/non_compliant_lexer.py b/tests/misc/non_compliant_lexer.py
index e1c21f3d713c4..04c605953e705 100644
--- a/tests/misc/non_compliant_lexer.py
+++ b/tests/misc/non_compliant_lexer.py
@@ -11,7 +11,7 @@ def test(code):
         print("NotImplementedError")
 
 
-# uPy requires spaces between literal numbers and keywords, CPy doesn't
+# MPy requires spaces between literal numbers and keywords, CPy doesn't
 try:
     eval("1and 0")
 except SyntaxError:
diff --git a/tests/misc/print_exception.py.native.exp b/tests/misc/print_exception.py.native.exp
new file mode 100644
index 0000000000000..59e856ae3c44a
--- /dev/null
+++ b/tests/misc/print_exception.py.native.exp
@@ -0,0 +1,18 @@
+caught
+Exception: msg
+
+caught
+Exception: fail
+
+finally
+caught
+Exception: fail
+
+reraise
+Exception: fail
+
+caught
+Exception: fail
+
+AttributeError: 'function' object has no attribute 'X'
+
diff --git a/tests/misc/rge_sm.py b/tests/misc/rge_sm.py
index 5e071687c495d..33aa4edb7427a 100644
--- a/tests/misc/rge_sm.py
+++ b/tests/misc/rge_sm.py
@@ -39,14 +39,6 @@ def solve(self, finishtime):
             if not self.iterate():
                 break
 
-    def solveNSteps(self, nSteps):
-        for i in range(nSteps):
-            if not self.iterate():
-                break
-
-    def series(self):
-        return zip(*self.Trajectory)
-
 
 # 1-loop RGES for the main parameters of the SM
 # couplings are: g1, g2, g3 of U(1), SU(2), SU(3); yt (top Yukawa), lambda (Higgs quartic)
@@ -55,70 +47,36 @@ def series(self):
     lambda *a: 41.0 / 96.0 / math.pi**2 * a[1] ** 3,  # g1
     lambda *a: -19.0 / 96.0 / math.pi**2 * a[2] ** 3,  # g2
     lambda *a: -42.0 / 96.0 / math.pi**2 * a[3] ** 3,  # g3
-    lambda *a: 1.0
-    / 16.0
-    / math.pi**2
-    * (
-        9.0 / 2.0 * a[4] ** 3
-        - 8.0 * a[3] ** 2 * a[4]
-        - 9.0 / 4.0 * a[2] ** 2 * a[4]
-        - 17.0 / 12.0 * a[1] ** 2 * a[4]
+    lambda *a: (
+        1.0
+        / 16.0
+        / math.pi**2
+        * (
+            9.0 / 2.0 * a[4] ** 3
+            - 8.0 * a[3] ** 2 * a[4]
+            - 9.0 / 4.0 * a[2] ** 2 * a[4]
+            - 17.0 / 12.0 * a[1] ** 2 * a[4]
+        )
     ),  # yt
-    lambda *a: 1.0
-    / 16.0
-    / math.pi**2
-    * (
-        24.0 * a[5] ** 2
-        + 12.0 * a[4] ** 2 * a[5]
-        - 9.0 * a[5] * (a[2] ** 2 + 1.0 / 3.0 * a[1] ** 2)
-        - 6.0 * a[4] ** 4
-        + 9.0 / 8.0 * a[2] ** 4
-        + 3.0 / 8.0 * a[1] ** 4
-        + 3.0 / 4.0 * a[2] ** 2 * a[1] ** 2
+    lambda *a: (
+        1.0
+        / 16.0
+        / math.pi**2
+        * (
+            24.0 * a[5] ** 2
+            + 12.0 * a[4] ** 2 * a[5]
+            - 9.0 * a[5] * (a[2] ** 2 + 1.0 / 3.0 * a[1] ** 2)
+            - 6.0 * a[4] ** 4
+            + 9.0 / 8.0 * a[2] ** 4
+            + 3.0 / 8.0 * a[1] ** 4
+            + 3.0 / 4.0 * a[2] ** 2 * a[1] ** 2
+        )
     ),  # lambda
 )
 
 
-def drange(start, stop, step):
-    r = start
-    while r < stop:
-        yield r
-        r += step
-
-
-def phaseDiagram(system, trajStart, trajPlot, h=0.1, tend=1.0, range=1.0):
-    tstart = 0.0
-    for i in drange(0, range, 0.1 * range):
-        for j in drange(0, range, 0.1 * range):
-            rk = RungeKutta(system, trajStart(i, j), tstart, h)
-            rk.solve(tend)
-            # draw the line
-            for tr in rk.Trajectory:
-                x, y = trajPlot(tr)
-                print(x, y)
-            print()
-            # draw the arrow
-            continue
-            l = (len(rk.Trajectory) - 1) / 3
-            if l > 0 and 2 * l < len(rk.Trajectory):
-                p1 = rk.Trajectory[l]
-                p2 = rk.Trajectory[2 * l]
-                x1, y1 = trajPlot(p1)
-                x2, y2 = trajPlot(p2)
-                dx = -0.5 * (y2 - y1)  # orthogonal to line
-                dy = 0.5 * (x2 - x1)  # orthogonal to line
-                # l = math.sqrt(dx*dx + dy*dy)
-                # if abs(l) > 1e-3:
-                #    l = 0.1 / l
-                #    dx *= l
-                #    dy *= l
-                print(x1 + dx, y1 + dy)
-                print(x2, y2)
-                print(x1 - dx, y1 - dy)
-                print()
-
-
 def singleTraj(system, trajStart, h=0.02, tend=1.0):
+    is_REPR_C = float("1.0000001") == float("1.0")
     tstart = 0.0
 
     # compute the trajectory
@@ -130,10 +88,15 @@ def singleTraj(system, trajStart, h=0.02, tend=1.0):
 
     for i in range(len(rk.Trajectory)):
         tr = rk.Trajectory[i]
-        print(" ".join(["{:.4f}".format(t) for t in tr]))
-
+        tr_str = " ".join(["{:.4f}".format(t) for t in tr])
+        if is_REPR_C:
+            # allow two small deviations for REPR_C
+            if tr_str == "1.0000 0.3559 0.6485 1.1944 0.9271 0.1083":
+                tr_str = "1.0000 0.3559 0.6485 1.1944 0.9272 0.1083"
+            if tr_str == "16.0000 0.3894 0.5793 0.7017 0.5686 -0.0168":
+                tr_str = "16.0000 0.3894 0.5793 0.7017 0.5686 -0.0167"
+        print(tr_str)
 
-# phaseDiagram(sysSM, (lambda i, j: [0.354, 0.654, 1.278, 0.8 + 0.2 * i, 0.1 + 0.1 * j]), (lambda a: (a[4], a[5])), h=0.1, tend=math.log(10**17))
 
 # initial conditions at M_Z
 singleTraj(sysSM, [0.354, 0.654, 1.278, 0.983, 0.131], h=0.5, tend=math.log(10**17))  # true values
diff --git a/tests/misc/sys_exc_info.py b/tests/misc/sys_exc_info.py
index d7e8a2d943b5e..c076dd572b07b 100644
--- a/tests/misc/sys_exc_info.py
+++ b/tests/misc/sys_exc_info.py
@@ -8,13 +8,14 @@
 
 
 def f():
-    print(sys.exc_info()[0:2])
+    e = sys.exc_info()
+    print(e[0], e[1])
 
 
 try:
     raise ValueError("value", 123)
 except:
-    print(sys.exc_info()[0:2])
+    print(sys.exc_info()[0], sys.exc_info()[1])
     f()
 
 # Outside except block, sys.exc_info() should be back to None's
diff --git a/tests/misc/sys_settrace_cov.py b/tests/misc/sys_settrace_cov.py
new file mode 100644
index 0000000000000..579c8a4a25e50
--- /dev/null
+++ b/tests/misc/sys_settrace_cov.py
@@ -0,0 +1,23 @@
+import sys
+
+try:
+    sys.settrace
+except AttributeError:
+    print("SKIP")
+    raise SystemExit
+
+
+def trace_tick_handler(frame, event, arg):
+    print("FRAME", frame)
+    print("LASTI", frame.f_lasti)
+    return None
+
+
+def f():
+    x = 3
+    return x
+
+
+sys.settrace(trace_tick_handler)
+f()
+sys.settrace(None)
diff --git a/tests/misc/sys_settrace_cov.py.exp b/tests/misc/sys_settrace_cov.py.exp
new file mode 100644
index 0000000000000..423d78ec42b89
--- /dev/null
+++ b/tests/misc/sys_settrace_cov.py.exp
@@ -0,0 +1,2 @@
+FRAME <frame at 0x\[0-9a-f\]\+, file '\.\*/sys_settrace_cov.py', line \\d\+, code f>
+LASTI \\d\+
diff --git a/tests/multi_extmod/machine_i2c_target_irq.py b/tests/multi_extmod/machine_i2c_target_irq.py
new file mode 100644
index 0000000000000..eafd9dfdca838
--- /dev/null
+++ b/tests/multi_extmod/machine_i2c_target_irq.py
@@ -0,0 +1,137 @@
+# Test I2CTarget IRQs and clock stretching.
+#
+# Requires two instances with their SCL and SDA lines connected together.
+# Any combination of the below supported boards can be used.
+#
+# Notes:
+# - pull-up resistors may be needed
+# - alif use 1.8V signalling
+
+import sys
+import time
+from machine import I2C, I2CTarget
+
+if not hasattr(I2CTarget, "IRQ_ADDR_MATCH_READ"):
+    print("SKIP")
+    raise SystemExit
+
+ADDR = 67
+clock_stretch_us = 200
+
+# Configure pins based on the target.
+if sys.platform == "alif":
+    i2c_args = (1,)  # pins P3_7/P3_6
+    i2c_kwargs = {}
+elif sys.platform == "mimxrt":
+    i2c_args = (0,)  # pins 19/18 on Teensy 4.x
+    i2c_kwargs = {}
+    clock_stretch_us = 50  # mimxrt cannot delay too long in the IRQ handler
+elif sys.platform == "rp2":
+    i2c_args = (0,)
+    i2c_kwargs = {"scl": 9, "sda": 8}
+elif sys.platform == "pyboard":
+    i2c_args = ("Y",)
+    i2c_kwargs = {}
+elif sys.platform == "samd":
+    i2c_args = ()  # pins SCL/SDA
+    i2c_kwargs = {}
+elif "zephyr-rpi_pico" in sys.implementation._machine:
+    i2c_args = ("i2c1",)  # on gpio7/gpio6
+    i2c_kwargs = {}
+else:
+    print("Please add support for this test on this platform.")
+    raise SystemExit
+
+
+def simple_irq(i2c_target):
+    flags = i2c_target.irq().flags()
+    if flags & I2CTarget.IRQ_ADDR_MATCH_READ:
+        print("IRQ_ADDR_MATCH_READ")
+    if flags & I2CTarget.IRQ_ADDR_MATCH_WRITE:
+        print("IRQ_ADDR_MATCH_WRITE")
+
+    # Force clock stretching.
+    time.sleep_us(clock_stretch_us)
+
+
+class I2CTargetMemory:
+    def __init__(self, i2c_target, mem):
+        self.buf1 = bytearray(1)
+        self.mem = mem
+        self.memaddr = 0
+        self.state = 0
+        i2c_target.irq(
+            self.irq,
+            I2CTarget.IRQ_ADDR_MATCH_WRITE | I2CTarget.IRQ_READ_REQ | I2CTarget.IRQ_WRITE_REQ,
+            hard=True,
+        )
+
+    def irq(self, i2c_target):
+        # Force clock stretching.
+        time.sleep_us(clock_stretch_us)
+
+        flags = i2c_target.irq().flags()
+        if flags & I2CTarget.IRQ_ADDR_MATCH_WRITE:
+            self.state = 0
+        if flags & I2CTarget.IRQ_READ_REQ:
+            self.buf1[0] = self.mem[self.memaddr]
+            self.memaddr += 1
+            i2c_target.write(self.buf1)
+        if flags & I2CTarget.IRQ_WRITE_REQ:
+            i2c_target.readinto(self.buf1)
+            if self.state == 0:
+                self.state = 1
+                self.memaddr = self.buf1[0]
+            else:
+                self.mem[self.memaddr] = self.buf1[0]
+                self.memaddr += 1
+        self.memaddr %= len(self.mem)
+
+        # Force clock stretching.
+        time.sleep_us(clock_stretch_us)
+
+
+# I2C controller
+def instance0():
+    i2c = I2C(*i2c_args, **i2c_kwargs)
+    multitest.next()
+    for iteration in range(2):
+        print("controller iteration", iteration)
+        multitest.wait("target stage 1")
+        i2c.writeto_mem(ADDR, 2, "0123")
+        multitest.broadcast("controller stage 2")
+        multitest.wait("target stage 3")
+        print(i2c.readfrom_mem(ADDR, 2, 4))
+        multitest.broadcast("controller stage 4")
+    print("done")
+
+
+# I2C target
+def instance1():
+    multitest.next()
+
+    for iteration in range(2):
+        print("target iteration", iteration)
+        buf = bytearray(b"--------")
+        if iteration == 0:
+            # Use built-in memory capability of I2CTarget.
+            i2c_target = I2CTarget(*i2c_args, **i2c_kwargs, addr=ADDR, mem=buf)
+            i2c_target.irq(
+                simple_irq,
+                I2CTarget.IRQ_ADDR_MATCH_READ | I2CTarget.IRQ_ADDR_MATCH_WRITE,
+                hard=True,
+            )
+        else:
+            # Implement a memory device by hand.
+            i2c_target = I2CTarget(*i2c_args, **i2c_kwargs, addr=ADDR)
+            I2CTargetMemory(i2c_target, buf)
+
+        multitest.broadcast("target stage 1")
+        multitest.wait("controller stage 2")
+        print(buf)
+        multitest.broadcast("target stage 3")
+        multitest.wait("controller stage 4")
+
+        i2c_target.deinit()
+
+    print("done")
diff --git a/tests/multi_extmod/machine_i2c_target_irq.py.exp b/tests/multi_extmod/machine_i2c_target_irq.py.exp
new file mode 100644
index 0000000000000..a17c8f43858b3
--- /dev/null
+++ b/tests/multi_extmod/machine_i2c_target_irq.py.exp
@@ -0,0 +1,15 @@
+--- instance0 ---
+controller iteration 0
+b'0123'
+controller iteration 1
+b'0123'
+done
+--- instance1 ---
+target iteration 0
+IRQ_ADDR_MATCH_WRITE
+bytearray(b'--0123--')
+IRQ_ADDR_MATCH_WRITE
+IRQ_ADDR_MATCH_READ
+target iteration 1
+bytearray(b'--0123--')
+done
diff --git a/tests/multi_extmod/machine_i2c_target_memory.py b/tests/multi_extmod/machine_i2c_target_memory.py
new file mode 100644
index 0000000000000..6b3f0d03eb7fe
--- /dev/null
+++ b/tests/multi_extmod/machine_i2c_target_memory.py
@@ -0,0 +1,79 @@
+# Test basic use of I2CTarget and a memory buffer.
+#
+# Requires two instances with their SCL and SDA lines connected together.
+# Any combination of the below supported boards can be used.
+#
+# Notes:
+# - pull-up resistors may be needed
+# - alif use 1.8V signalling
+
+import sys
+from machine import I2C, I2CTarget
+
+ADDR = 67
+
+# Configure pins based on the target.
+if sys.platform == "alif":
+    i2c_args = (1,)  # pins P3_7/P3_6
+    i2c_kwargs = {}
+elif sys.platform == "esp32":
+    i2c_args = (1,)  # on pins 9/8
+    i2c_kwargs = {}
+elif sys.platform == "mimxrt":
+    i2c_args = (0,)  # pins 19/18 on Teensy 4.x
+    i2c_kwargs = {}
+elif sys.platform == "rp2":
+    i2c_args = (0,)
+    i2c_kwargs = {"scl": 9, "sda": 8}
+elif sys.platform == "pyboard":
+    i2c_args = ("Y",)
+    i2c_kwargs = {}
+elif sys.platform == "samd":
+    i2c_args = ()  # pins SCL/SDA
+    i2c_kwargs = {}
+elif "zephyr-rpi_pico" in sys.implementation._machine:
+    i2c_args = ("i2c1",)  # on gpio7/gpio6
+    i2c_kwargs = {}
+else:
+    print("Please add support for this test on this platform.")
+    raise SystemExit
+
+
+def simple_irq(i2c_target):
+    flags = i2c_target.irq().flags()
+    if flags & I2CTarget.IRQ_END_READ:
+        print("IRQ_END_READ", i2c_target.memaddr)
+    if flags & I2CTarget.IRQ_END_WRITE:
+        print("IRQ_END_WRITE", i2c_target.memaddr)
+
+
+# I2C controller
+def instance0():
+    i2c = I2C(*i2c_args, **i2c_kwargs)
+    multitest.next()
+    for iteration in range(2):
+        print("controller iteration", iteration)
+        multitest.wait("target stage 1")
+        i2c.writeto_mem(ADDR, 2 + iteration, "0123")
+        multitest.broadcast("controller stage 2")
+        multitest.wait("target stage 3")
+        print(i2c.readfrom_mem(ADDR, 2 + iteration, 4))
+        multitest.broadcast("controller stage 4")
+    print("done")
+
+
+# I2C target
+def instance1():
+    buf = bytearray(b"--------")
+    i2c_target = I2CTarget(*i2c_args, **i2c_kwargs, addr=ADDR, mem=buf)
+    i2c_target.irq(simple_irq)
+    multitest.next()
+    for iteration in range(2):
+        print("target iteration", iteration)
+        multitest.broadcast("target stage 1")
+        multitest.wait("controller stage 2")
+        print(buf)
+        multitest.broadcast("target stage 3")
+        multitest.wait("controller stage 4")
+    i2c_target.deinit()
+    print("done")
diff --git a/tests/multi_extmod/machine_i2c_target_memory.py.exp b/tests/multi_extmod/machine_i2c_target_memory.py.exp
new file mode 100644
index 0000000000000..71386cfe769d9
--- /dev/null
+++ b/tests/multi_extmod/machine_i2c_target_memory.py.exp
@@ -0,0 +1,16 @@
+--- instance0 ---
+controller iteration 0
+b'0123'
+controller iteration 1
+b'0123'
+done
+--- instance1 ---
+target iteration 0
+IRQ_END_WRITE 2
+bytearray(b'--0123--')
+IRQ_END_READ 2
+target iteration 1
+IRQ_END_WRITE 3
+bytearray(b'--00123-')
+IRQ_END_READ 3
+done
diff --git a/tests/perf_bench/bm_fft.py b/tests/perf_bench/bm_fft.py
index 9a2d03d11b97c..e35c1216c139f 100644
--- a/tests/perf_bench/bm_fft.py
+++ b/tests/perf_bench/bm_fft.py
@@ -15,7 +15,7 @@ def reverse(x, bits):
 
     # Initialization
     n = len(vector)
-    levels = int(math.log(n) / math.log(2))
+    levels = int(round(math.log(n) / math.log(2)))
     coef = (2 if inverse else -2) * cmath.pi / n
     exptable = [cmath.rect(1, i * coef) for i in range(n // 2)]
     vector = [vector[reverse(i, levels)] for i in range(n)]  # Copy with bit-reversed permutation
diff --git a/tests/perf_bench/bm_pidigits.py b/tests/perf_bench/bm_pidigits.py
index bdaa73cec7e9f..c935f103c5b78 100644
--- a/tests/perf_bench/bm_pidigits.py
+++ b/tests/perf_bench/bm_pidigits.py
@@ -5,6 +5,12 @@
 # This benchmark stresses big integer arithmetic.
 # Adapted from code on: http://benchmarksgame.alioth.debian.org/
 
+try:
+    int("0x10000000000000000", 16)
+except:
+    print("SKIP")  # No support for >64-bit integers
+    raise SystemExit
+
 
 def compose(a, b):
     aq, ar, as_, at = a
diff --git a/tests/perf_bench/core_import_mpy_multi.py b/tests/perf_bench/core_import_mpy_multi.py
index 8affa157fa0c5..67deec0508801 100644
--- a/tests/perf_bench/core_import_mpy_multi.py
+++ b/tests/perf_bench/core_import_mpy_multi.py
@@ -6,7 +6,7 @@
     print("SKIP")
     raise SystemExit
 
-# This is the test.py file that is compiled to test.mpy below.
+# This is the test.py file that is compiled to test.mpy below. mpy-cross must be invoked with `-msmall-int-bits=30`.
 """
 class A:
     def __init__(self, arg):
@@ -23,7 +23,7 @@ def f():
     x = ("const tuple", None, False, True, 1, 2, 3)
 result = 123
 """
-file_data = b'M\x06\x00\x1f\x14\x03\x0etest.py\x00\x0f\x02A\x00\x02f\x00\x0cresult\x00/-5#\x82I\x81{\x81w\x82/\x81\x05\x81\x17Iom\x82\x13\x06arg\x00\x05\x1cthis will be a string object\x00\x06\x1bthis will be a bytes object\x00\n\x07\x05\x0bconst tuple\x00\x01\x02\x03\x07\x011\x07\x012\x07\x013\x81\\\x10\n\x01\x89\x07d`T2\x00\x10\x024\x02\x16\x022\x01\x16\x03"\x80{\x16\x04Qc\x02\x81d\x00\x08\x02(DD\x11\x05\x16\x06\x10\x02\x16\x072\x00\x16\x082\x01\x16\t2\x02\x16\nQc\x03`\x1a\x08\x08\x12\x13@\xb1\xb0\x18\x13Qc@\t\x08\t\x12` Qc@\t\x08\n\x12``Qc\x82@ \x0e\x03\x80\x08+)##\x12\x0b\x12\x0c\x12\r\x12\x0e*\x04Y\x12\x0f\x12\x10\x12\x11*\x03Y#\x00\xc0#\x01\xc0#\x02\xc0Qc'
+file_data = b'M\x06\x00\x1e\x14\x03\x0etest.py\x00\x0f\x02A\x00\x02f\x00\x0cresult\x00/-5#\x82I\x81{\x81w\x82/\x81\x05\x81\x17Iom\x82\x13\x06arg\x00\x05\x1cthis will be a string object\x00\x06\x1bthis will be a bytes object\x00\n\x07\x05\x0bconst tuple\x00\x01\x02\x03\x07\x011\x07\x012\x07\x013\x81\\\x10\n\x01\x89\x07d`T2\x00\x10\x024\x02\x16\x022\x01\x16\x03"\x80{\x16\x04Qc\x02\x81d\x00\x08\x02(DD\x11\x05\x16\x06\x10\x02\x16\x072\x00\x16\x082\x01\x16\t2\x02\x16\nQc\x03`\x1a\x08\x08\x12\x13@\xb1\xb0\x18\x13Qc@\t\x08\t\x12` Qc@\t\x08\n\x12``Qc\x82@ \x0e\x03\x80\x08+)##\x12\x0b\x12\x0c\x12\r\x12\x0e*\x04Y\x12\x0f\x12\x10\x12\x11*\x03Y#\x00\xc0#\x01\xc0#\x02\xc0Qc'
 
 
 class File(io.IOBase):
diff --git a/tests/perf_bench/core_import_mpy_single.py b/tests/perf_bench/core_import_mpy_single.py
index 4d9aa67bf2f0e..f472bb6476278 100644
--- a/tests/perf_bench/core_import_mpy_single.py
+++ b/tests/perf_bench/core_import_mpy_single.py
@@ -8,7 +8,7 @@
     print("SKIP")
     raise SystemExit
 
-# This is the test.py file that is compiled to test.mpy below.
+# This is the test.py file that is compiled to test.mpy below. mpy-cross must be invoked with `-msmall-int-bits=30`.
 # Many known and unknown names/strings are included to test the linking process.
 """
 class A0:
@@ -78,7 +78,7 @@ def f1():
     x = ("const tuple 9", None, False, True, 1, 2, 3)
 result = 123
 """
-file_data = 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+file_data = 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 class File(io.IOBase):
diff --git a/tests/run-internalbench.py b/tests/run-internalbench.py
index c9f783e474c9c..99c6304afe9d6 100755
--- a/tests/run-internalbench.py
+++ b/tests/run-internalbench.py
@@ -8,6 +8,10 @@
 from glob import glob
 from collections import defaultdict
 
+run_tests_module = __import__("run-tests")
+sys.path.append(run_tests_module.base_path("../tools"))
+import pyboard
+
 if os.name == "nt":
     MICROPYTHON = os.getenv(
         "MICROPY_MICROPYTHON", "../ports/windows/build-standard/micropython.exe"
@@ -15,13 +19,39 @@
 else:
     MICROPYTHON = os.getenv("MICROPY_MICROPYTHON", "../ports/unix/build-standard/micropython")
 
+injected_bench_code = b"""
+import time
+
+class bench_class:
+    ITERS = 20000000
+
+    @staticmethod
+    def run(test):
+        t = time.ticks_us()
+        test(bench_class.ITERS)
+        t = time.ticks_diff(time.ticks_us(), t)
+        s, us = divmod(t, 1_000_000)
+        print("{}.{:06}".format(s, us))
+
+import sys
+sys.modules['bench'] = bench_class
+"""
+
 
-def run_tests(pyb, test_dict):
+def execbench(pyb, filename, iters):
+    with open(filename, "rb") as f:
+        pyfile = f.read()
+    code = (injected_bench_code + pyfile).replace(b"20000000", str(iters).encode("utf-8"))
+    return pyb.exec(code).replace(b"\r\n", b"\n")
+
+
+def run_tests(pyb, test_dict, iters):
     test_count = 0
     testcase_count = 0
 
     for base_test, tests in sorted(test_dict.items()):
         print(base_test + ":")
+        baseline = None
         for test_file in tests:
             # run MicroPython
             if pyb is None:
@@ -36,20 +66,25 @@ def run_tests(pyb, test_dict):
                 # run on pyboard
                 pyb.enter_raw_repl()
                 try:
-                    output_mupy = pyb.execfile(test_file).replace(b"\r\n", b"\n")
+                    output_mupy = execbench(pyb, test_file[0], iters)
                 except pyboard.PyboardError:
                     output_mupy = b"CRASH"
 
-            output_mupy = float(output_mupy.strip())
+            try:
+                output_mupy = float(output_mupy.strip())
+            except ValueError:
+                output_mupy = -1
             test_file[1] = output_mupy
             testcase_count += 1
 
-        test_count += 1
-        baseline = None
-        for t in tests:
             if baseline is None:
-                baseline = t[1]
-            print("    %.3fs (%+06.2f%%) %s" % (t[1], (t[1] * 100 / baseline) - 100, t[0]))
+                baseline = test_file[1]
+            print(
+                "    %.3fs (%+06.2f%%) %s"
+                % (test_file[1], (test_file[1] * 100 / baseline) - 100, test_file[0])
+            )
+
+        test_count += 1
 
     print("{} tests performed ({} individual testcases)".format(test_count, testcase_count))
 
@@ -58,27 +93,47 @@ def run_tests(pyb, test_dict):
 
 
 def main():
-    cmd_parser = argparse.ArgumentParser(description="Run tests for MicroPython.")
-    cmd_parser.add_argument("--pyboard", action="store_true", help="run the tests on the pyboard")
+    cmd_parser = argparse.ArgumentParser(
+        formatter_class=argparse.RawDescriptionHelpFormatter,
+        description=f"""Run and manage tests for MicroPython.
+
+{run_tests_module.test_instance_description}
+{run_tests_module.test_directory_description}
+""",
+        epilog=run_tests_module.test_instance_epilog,
+    )
+    cmd_parser.add_argument(
+        "-t", "--test-instance", default="unix", help="the MicroPython instance to test"
+    )
+    cmd_parser.add_argument(
+        "-b", "--baudrate", default=115200, help="the baud rate of the serial device"
+    )
+    cmd_parser.add_argument("-u", "--user", default="micro", help="the telnet login username")
+    cmd_parser.add_argument("-p", "--password", default="python", help="the telnet login password")
+    cmd_parser.add_argument(
+        "-d", "--test-dirs", nargs="*", help="input test directories (if no files given)"
+    )
+    cmd_parser.add_argument(
+        "-I",
+        "--iters",
+        type=int,
+        default=200_000,
+        help="number of test iterations, only for remote instances (default 200,000)",
+    )
     cmd_parser.add_argument("files", nargs="*", help="input test files")
     args = cmd_parser.parse_args()
 
     # Note pyboard support is copied over from run-tests.py, not tests, and likely needs revamping
-    if args.pyboard:
-        import pyboard
-
-        pyb = pyboard.Pyboard("/dev/ttyACM0")
-        pyb.enter_raw_repl()
-    else:
-        pyb = None
+    pyb = run_tests_module.get_test_instance(
+        args.test_instance, args.baudrate, args.user, args.password
+    )
 
     if len(args.files) == 0:
-        if pyb is None:
-            # run PC tests
-            test_dirs = ("internal_bench",)
+        if args.test_dirs:
+            test_dirs = tuple(args.test_dirs)
         else:
-            # run pyboard tests
-            test_dirs = ("basics", "float", "pyb")
+            test_dirs = ("internal_bench",)
+
         tests = sorted(
             test_file
             for test_files in (glob("{}/*.py".format(dir)) for dir in test_dirs)
@@ -95,7 +150,7 @@ def main():
             continue
         test_dict[m.group(1)].append([t, None])
 
-    if not run_tests(pyb, test_dict):
+    if not run_tests(pyb, test_dict, args.iters):
         sys.exit(1)
 
 
diff --git a/tests/run-multitests.py b/tests/run-multitests.py
index 387eec7018bb3..e5458ffe0d00c 100755
--- a/tests/run-multitests.py
+++ b/tests/run-multitests.py
@@ -15,6 +15,8 @@
 import subprocess
 import tempfile
 
+run_tests_module = __import__("run-tests")
+
 test_dir = os.path.abspath(os.path.dirname(__file__))
 
 if os.path.abspath(sys.path[0]) == test_dir:
@@ -130,6 +132,11 @@ def get_host_ip(_ip_cache=[]):
     return _ip_cache[0]
 
 
+def decode(output):
+    # Convenience function to convert raw process or serial output to ASCII
+    return str(output, "ascii", "backslashreplace")
+
+
 class PyInstance:
     def __init__(self):
         pass
@@ -188,7 +195,7 @@ def run_script(self, script):
             output = p.stdout
         except subprocess.CalledProcessError as er:
             err = er
-        return str(output.strip(), "ascii"), err
+        return decode(output.strip()), err
 
     def start_script(self, script):
         self.popen = subprocess.Popen(
@@ -215,7 +222,7 @@ def readline(self):
             self.finished = self.popen.poll() is not None
             return None, None
         else:
-            return str(out.rstrip(), "ascii"), None
+            return decode(out.rstrip()), None
 
     def write(self, data):
         self.popen.stdin.write(data)
@@ -227,21 +234,12 @@ def is_finished(self):
     def wait_finished(self):
         self.popen.wait()
         out = self.popen.stdout.read()
-        return str(out, "ascii"), ""
+        return decode(out), ""
 
 
 class PyInstancePyboard(PyInstance):
-    @staticmethod
-    def map_device_shortcut(device):
-        if device[0] == "a" and device[1:].isdigit():
-            return "/dev/ttyACM" + device[1:]
-        elif device[0] == "u" and device[1:].isdigit():
-            return "/dev/ttyUSB" + device[1:]
-        else:
-            return device
-
     def __init__(self, device):
-        device = self.map_device_shortcut(device)
+        device = device
         self.device = device
         self.pyb = pyboard.Pyboard(device)
         self.pyb.enter_raw_repl()
@@ -262,7 +260,7 @@ def run_script(self, script):
             output = self.pyb.exec_(script)
         except pyboard.PyboardError as er:
             err = er
-        return str(output.strip(), "ascii"), err
+        return decode(output.strip()), err
 
     def start_script(self, script):
         self.pyb.enter_raw_repl()
@@ -281,13 +279,13 @@ def readline(self):
         if out.endswith(b"\x04"):
             self.finished = True
             out = out[:-1]
-            err = str(self.pyb.read_until(1, b"\x04"), "ascii")
+            err = decode(self.pyb.read_until(1, b"\x04"))
             err = err[:-1]
             if not out and not err:
                 return None, None
         else:
             err = None
-        return str(out.rstrip(), "ascii"), err
+        return decode(out.rstrip()), err
 
     def write(self, data):
         self.pyb.serial.write(data)
@@ -297,7 +295,7 @@ def is_finished(self):
 
     def wait_finished(self):
         out, err = self.pyb.follow(10, None)
-        return str(out, "ascii"), str(err, "ascii")
+        return decode(out), decode(err)
 
 
 def prepare_test_file_list(test_files):
@@ -488,9 +486,7 @@ def print_diff(a, b):
 
 
 def run_tests(test_files, instances_truth, instances_test):
-    skipped_tests = []
-    passed_tests = []
-    failed_tests = []
+    test_results = []
 
     for test_file, num_instances in test_files:
         instances_str = "|".join(str(instances_test[i]) for i in range(num_instances))
@@ -526,13 +522,13 @@ def run_tests(test_files, instances_truth, instances_test):
         # Print result of test
         if skip:
             print("skip")
-            skipped_tests.append(test_file)
+            test_results.append((test_file, "skip", ""))
         elif output_test == output_truth:
             print("pass")
-            passed_tests.append(test_file)
+            test_results.append((test_file, "pass", ""))
         else:
             print("FAIL")
-            failed_tests.append(test_file)
+            test_results.append((test_file, "fail", ""))
             if not cmd_args.show_output:
                 print("### TEST ###")
                 print(output_test, end="")
@@ -549,15 +545,7 @@ def run_tests(test_files, instances_truth, instances_test):
         if cmd_args.show_output:
             print()
 
-    print("{} tests performed".format(len(skipped_tests) + len(passed_tests) + len(failed_tests)))
-    print("{} tests passed".format(len(passed_tests)))
-
-    if skipped_tests:
-        print("{} tests skipped: {}".format(len(skipped_tests), " ".join(skipped_tests)))
-    if failed_tests:
-        print("{} tests failed: {}".format(len(failed_tests), " ".join(failed_tests)))
-
-    return not failed_tests
+    return test_results
 
 
 def main():
@@ -565,16 +553,24 @@ def main():
 
     cmd_parser = argparse.ArgumentParser(
         description="Run network tests for MicroPython",
+        epilog=(
+            run_tests_module.test_instance_epilog
+            + "Each instance arg can optionally have custom env provided, eg. <cmd>,ENV=VAR,ENV=VAR...\n"
+        ),
         formatter_class=argparse.RawTextHelpFormatter,
     )
     cmd_parser.add_argument(
         "-s", "--show-output", action="store_true", help="show test output after running"
     )
     cmd_parser.add_argument(
-        "-t", "--trace-output", action="store_true", help="trace test output while running"
+        "-c", "--trace-output", action="store_true", help="trace test output while running"
     )
     cmd_parser.add_argument(
-        "-i", "--instance", action="append", default=[], help="instance(s) to run the tests on"
+        "-t",
+        "--test-instance",
+        action="append",
+        default=[],
+        help="instance(s) to run the tests on",
     )
     cmd_parser.add_argument(
         "-p",
@@ -583,13 +579,11 @@ def main():
         default=1,
         help="repeat the test with this many permutations of the instance order",
     )
-    cmd_parser.epilog = (
-        "Supported instance types:\r\n"
-        " -i pyb:<port>   physical device (eg. pyboard) on provided repl port.\n"
-        " -i micropython  unix micropython instance, path customised with MICROPY_MICROPYTHON env.\n"
-        " -i cpython      desktop python3 instance, path customised with MICROPY_CPYTHON3 env.\n"
-        " -i exec:<path>  custom program run on provided path.\n"
-        "Each instance arg can optionally have custom env provided, eg. <cmd>,ENV=VAR,ENV=VAR...\n"
+    cmd_parser.add_argument(
+        "-r",
+        "--result-dir",
+        default=run_tests_module.base_path("results"),
+        help="directory for test results",
     )
     cmd_parser.add_argument("files", nargs="+", help="input test files")
     cmd_args = cmd_parser.parse_args()
@@ -603,33 +597,36 @@ def main():
     instances_truth = [PyInstanceSubProcess([PYTHON_TRUTH]) for _ in range(max_instances)]
 
     instances_test = []
-    for i in cmd_args.instance:
+    for i in cmd_args.test_instance:
         # Each instance arg is <cmd>,ENV=VAR,ENV=VAR...
         i = i.split(",")
         cmd = i[0]
         env = i[1:]
         if cmd.startswith("exec:"):
             instances_test.append(PyInstanceSubProcess([cmd[len("exec:") :]], env))
-        elif cmd == "micropython":
+        elif cmd == "unix":
             instances_test.append(PyInstanceSubProcess([MICROPYTHON], env))
         elif cmd == "cpython":
             instances_test.append(PyInstanceSubProcess([CPYTHON3], env))
-        elif cmd.startswith("pyb:"):
-            instances_test.append(PyInstancePyboard(cmd[len("pyb:") :]))
+        elif cmd == "webassembly" or cmd.startswith("execpty:"):
+            print("unsupported instance string: {}".format(cmd), file=sys.stderr)
+            sys.exit(2)
         else:
-            print("unknown instance string: {}".format(cmd), file=sys.stderr)
-            sys.exit(1)
+            device = run_tests_module.convert_device_shortcut_to_real_device(cmd)
+            instances_test.append(PyInstancePyboard(device))
 
     for _ in range(max_instances - len(instances_test)):
         instances_test.append(PyInstanceSubProcess([MICROPYTHON]))
 
+    os.makedirs(cmd_args.result_dir, exist_ok=True)
     all_pass = True
     try:
         for i, instances_test_permutation in enumerate(itertools.permutations(instances_test)):
             if i >= cmd_args.permutations:
                 break
 
-            all_pass &= run_tests(test_files, instances_truth, instances_test_permutation)
+            test_results = run_tests(test_files, instances_truth, instances_test_permutation)
+            all_pass &= run_tests_module.create_test_report(cmd_args, test_results)
 
     finally:
         for i in instances_truth:
diff --git a/tests/run-natmodtests.py b/tests/run-natmodtests.py
index 340a7f004b061..6d2a975b82a0b 100755
--- a/tests/run-natmodtests.py
+++ b/tests/run-natmodtests.py
@@ -9,7 +9,7 @@
 import sys
 import argparse
 
-# CIRCUITPY-CHANGE: no pyboard
+run_tests_module = __import__("run-tests")
 
 # Paths for host executables
 CPYTHON3 = os.getenv("MICROPY_CPYTHON3", "python3")
@@ -72,6 +72,7 @@ def open(self, path, mode):
 # CIRCUITPY-CHANGE: no vfs, but still have os
 os.mount(__FS(), '/__remote')
 sys.path.insert(0, '/__remote')
+{import_prelude}
 sys.modules['{}'] = __import__('__injected')
 """
 
@@ -108,7 +109,7 @@ def run_script(self, script):
             output = self.pyb.exec_(script)
             output = output.replace(b"\r\n", b"\n")
             return output, None
-        except pyboard.PyboardError as er:
+        except run_tests_module.pyboard.PyboardError as er:
             return b"", er
 
 
@@ -131,7 +132,15 @@ def detect_architecture(target):
         return platform, arch, None
 
 
-def run_tests(target_truth, target, args, stats, resolved_arch):
+def run_tests(target_truth, target, args, resolved_arch):
+    global injected_import_hook_code
+
+    prelude = ""
+    if args.begin:
+        prelude = args.begin.read()
+    injected_import_hook_code = injected_import_hook_code.replace("{import_prelude}", prelude)
+
+    test_results = []
     for test_file in args.files:
         # Find supported test
         test_file_basename = os.path.basename(test_file)
@@ -154,9 +163,11 @@ def run_tests(target_truth, target, args, stats, resolved_arch):
             with open(NATMOD_EXAMPLE_DIR + test_mpy, "rb") as f:
                 test_script += b"__buf=" + bytes(repr(f.read()), "ascii") + b"\n"
         except OSError:
-            print("----  {} - mpy file not compiled".format(test_file))
+            test_results.append((test_file, "skip", "mpy file not compiled"))
+            print("skip  {} - mpy file not compiled".format(test_file))
             continue
         test_script += bytes(injected_import_hook_code.format(test_module), "ascii")
+        test_script += b"print('START TEST')\n"
         test_script += test_file_data
 
         # Run test under MicroPython
@@ -164,8 +175,18 @@ def run_tests(target_truth, target, args, stats, resolved_arch):
 
         # Work out result of test
         extra = ""
+        result_out = result_out.removeprefix(b"START TEST\n")
         if error is None and result_out == b"SKIP\n":
             result = "SKIP"
+        elif (
+            error is not None
+            and error.args[0] == "exception"
+            and error.args[1] == b""
+            and b"MemoryError" in error.args[2]
+        ):
+            # Test had a MemoryError before anything (should be at least "START TEST")
+            # was printed, so the test is too big for the target.
+            result = "LRGE"
         elif error is not None:
             result = "FAIL"
             extra = " - " + str(error)
@@ -186,40 +207,63 @@ def run_tests(target_truth, target, args, stats, resolved_arch):
                 result = "pass"
 
         # Accumulate statistics
-        stats["total"] += 1
         if result == "pass":
-            stats["pass"] += 1
+            test_results.append((test_file, "pass", ""))
         elif result == "SKIP":
-            stats["skip"] += 1
+            test_results.append((test_file, "skip", ""))
+        elif result == "LRGE":
+            test_results.append((test_file, "skip", "too large"))
         else:
-            stats["fail"] += 1
+            test_results.append((test_file, "fail", ""))
 
         # Print result
         print("{:4}  {}{}".format(result, test_file, extra))
 
+    return test_results
+
 
 def main():
     cmd_parser = argparse.ArgumentParser(
-        description="Run dynamic-native-module tests under MicroPython"
+        description="Run dynamic-native-module tests under MicroPython",
+        epilog=run_tests_module.test_instance_epilog,
+        formatter_class=argparse.RawDescriptionHelpFormatter,
     )
     cmd_parser.add_argument(
-        "-p", "--pyboard", action="store_true", help="run tests via pyboard.py"
+        "-t", "--test-instance", default="unix", help="the MicroPython instance to test"
     )
+    cmd_parser.add_argument("--baudrate", default=115200, help="baud rate of the serial device")
+    cmd_parser.add_argument("--user", default="micro", help="telnet login username")
+    cmd_parser.add_argument("--password", default="python", help="telnet login password")
     cmd_parser.add_argument(
-        "-d", "--device", default="/dev/ttyACM0", help="the device for pyboard.py"
+        "-a", "--arch", choices=AVAILABLE_ARCHS, help="override native architecture of the target"
     )
     cmd_parser.add_argument(
-        "-a", "--arch", choices=AVAILABLE_ARCHS, help="override native architecture of the target"
+        "-b",
+        "--begin",
+        type=argparse.FileType("rt"),
+        default=None,
+        help="prologue python file to execute before module import",
+    )
+    cmd_parser.add_argument(
+        "-r",
+        "--result-dir",
+        default=run_tests_module.base_path("results"),
+        help="directory for test results",
     )
     cmd_parser.add_argument("files", nargs="*", help="input test files")
     args = cmd_parser.parse_args()
 
     target_truth = TargetSubprocess([CPYTHON3])
 
-    if args.pyboard:
-        target = TargetPyboard(pyboard.Pyboard(args.device))
-    else:
+    target = run_tests_module.get_test_instance(
+        args.test_instance, args.baudrate, args.user, args.password
+    )
+    if target is None:
+        # Use the unix port of MicroPython.
         target = TargetSubprocess([MICROPYTHON])
+    else:
+        # Use a remote target.
+        target = TargetPyboard(target)
 
     if hasattr(args, "arch") and args.arch is not None:
         target_arch = args.arch
@@ -235,20 +279,14 @@ def main():
         print("platform={} ".format(target_platform), end="")
     print("arch={}".format(target_arch))
 
-    stats = {"total": 0, "pass": 0, "fail": 0, "skip": 0}
-    run_tests(target_truth, target, args, stats, target_arch)
+    os.makedirs(args.result_dir, exist_ok=True)
+    test_results = run_tests(target_truth, target, args, target_arch)
+    res = run_tests_module.create_test_report(args, test_results)
 
     target.close()
     target_truth.close()
 
-    print("{} tests performed".format(stats["total"]))
-    print("{} tests passed".format(stats["pass"]))
-    if stats["fail"]:
-        print("{} tests failed".format(stats["fail"]))
-    if stats["skip"]:
-        print("{} tests skipped".format(stats["skip"]))
-
-    if stats["fail"]:
+    if not res:
         sys.exit(1)
 
 
diff --git a/tests/run-perfbench.py b/tests/run-perfbench.py
index 81d873c45997d..039d11a36111e 100755
--- a/tests/run-perfbench.py
+++ b/tests/run-perfbench.py
@@ -10,10 +10,9 @@
 import argparse
 from glob import glob
 
-sys.path.append("../tools")
-import pyboard
+run_tests_module = __import__("run-tests")
 
-prepare_script_for_target = __import__("run-tests").prepare_script_for_target
+prepare_script_for_target = run_tests_module.prepare_script_for_target
 
 # Paths for host executables
 if os.name == "nt":
@@ -45,12 +44,12 @@ def run_script_on_target(target, script):
     output = b""
     err = None
 
-    if isinstance(target, pyboard.Pyboard):
+    if hasattr(target, "enter_raw_repl"):
         # Run via pyboard interface
         try:
             target.enter_raw_repl()
             output = target.exec_(script)
-        except pyboard.PyboardError as er:
+        except run_tests_module.pyboard.PyboardError as er:
             err = er
     else:
         # Run local executable
@@ -90,9 +89,9 @@ def run_benchmark_on_target(target, script):
 
 
 def run_benchmarks(args, target, param_n, param_m, n_average, test_list):
+    test_results = []
     skip_complex = run_feature_test(target, "complex") != "complex"
     skip_native = run_feature_test(target, "native_check") != "native"
-    target_had_error = False
 
     for test_file in sorted(test_list):
         print(test_file + ": ", end="")
@@ -105,6 +104,7 @@ def run_benchmarks(args, target, param_n, param_m, n_average, test_list):
             and test_file.find("viper_") != -1
         )
         if skip:
+            test_results.append((test_file, "skip", ""))
             print("SKIP")
             continue
 
@@ -122,9 +122,10 @@ def run_benchmarks(args, target, param_n, param_m, n_average, test_list):
                 f.write(test_script)
 
         # Process script through mpy-cross if needed
-        if isinstance(target, pyboard.Pyboard) or args.via_mpy:
+        if hasattr(target, "enter_raw_repl") or args.via_mpy:
             crash, test_script_target = prepare_script_for_target(args, script_text=test_script)
             if crash:
+                test_results.append((test_file, "fail", "preparation"))
                 print("CRASH:", test_script_target)
                 continue
         else:
@@ -162,10 +163,13 @@ def run_benchmarks(args, target, param_n, param_m, n_average, test_list):
                 error = "FAIL truth"
 
         if error is not None:
-            if not error.startswith("SKIP"):
-                target_had_error = True
+            if error.startswith("SKIP"):
+                test_results.append((test_file, "skip", error))
+            else:
+                test_results.append((test_file, "fail", error))
             print(error)
         else:
+            test_results.append((test_file, "pass", ""))
             t_avg, t_sd = compute_stats(times)
             s_avg, s_sd = compute_stats(scores)
             print(
@@ -179,7 +183,7 @@ def run_benchmarks(args, target, param_n, param_m, n_average, test_list):
 
         sys.stdout.flush()
 
-    return target_had_error
+    return test_results
 
 
 def parse_output(filename):
@@ -190,7 +194,13 @@ def parse_output(filename):
         m = int(m.split("=")[1])
         data = []
         for l in f:
-            if ": " in l and ": SKIP" not in l and "CRASH: " not in l:
+            if (
+                ": " in l
+                and ": SKIP" not in l
+                and "CRASH: " not in l
+                and "skipped: " not in l
+                and "failed: " not in l
+            ):
                 name, values = l.strip().split(": ")
                 values = tuple(float(v) for v in values.split())
                 data.append((name,) + values)
@@ -246,17 +256,17 @@ def compute_diff(file1, file2, diff_score):
 def main():
     cmd_parser = argparse.ArgumentParser(description="Run benchmarks for MicroPython")
     cmd_parser.add_argument(
-        "-t", "--diff-time", action="store_true", help="diff time outputs from a previous run"
+        "-m", "--diff-time", action="store_true", help="diff time outputs from a previous run"
     )
     cmd_parser.add_argument(
         "-s", "--diff-score", action="store_true", help="diff score outputs from a previous run"
     )
     cmd_parser.add_argument(
-        "-p", "--pyboard", action="store_true", help="run tests via pyboard.py"
-    )
-    cmd_parser.add_argument(
-        "-d", "--device", default="/dev/ttyACM0", help="the device for pyboard.py"
+        "-t", "--test-instance", default="unix", help="the MicroPython instance to test"
     )
+    cmd_parser.add_argument("--baudrate", default=115200, help="baud rate of the serial device")
+    cmd_parser.add_argument("--user", default="micro", help="telnet login username")
+    cmd_parser.add_argument("--password", default="python", help="telnet login password")
     cmd_parser.add_argument("-a", "--average", default="8", help="averaging number")
     cmd_parser.add_argument(
         "--emit", default="bytecode", help="MicroPython emitter to use (bytecode or native)"
@@ -264,6 +274,12 @@ def main():
     cmd_parser.add_argument("--heapsize", help="heapsize to use (use default if not specified)")
     cmd_parser.add_argument("--via-mpy", action="store_true", help="compile code to .mpy first")
     cmd_parser.add_argument("--mpy-cross-flags", default="", help="flags to pass to mpy-cross")
+    cmd_parser.add_argument(
+        "-r",
+        "--result-dir",
+        default=run_tests_module.base_path("results"),
+        help="directory for test results",
+    )
     cmd_parser.add_argument(
         "N", nargs=1, help="N parameter (approximate target CPU frequency in MHz)"
     )
@@ -282,15 +298,18 @@ def main():
     M = int(args.M[0])
     n_average = int(args.average)
 
-    if args.pyboard:
-        if not args.mpy_cross_flags:
-            args.mpy_cross_flags = "-march=armv7m"
-        target = pyboard.Pyboard(args.device)
-        target.enter_raw_repl()
-    else:
+    target = run_tests_module.get_test_instance(
+        args.test_instance, args.baudrate, args.user, args.password
+    )
+    if target is None:
+        # Use the unix port of MicroPython.
         target = [MICROPYTHON, "-X", "emit=" + args.emit]
         if args.heapsize is not None:
             target.extend(["-X", "heapsize=" + args.heapsize])
+    else:
+        # Use a remote target.
+        if not args.mpy_cross_flags:
+            args.mpy_cross_flags = "-march=armv7m"
 
     if len(args.files) == 0:
         tests_skip = ("benchrun.py",)
@@ -307,13 +326,15 @@ def main():
 
     print("N={} M={} n_average={}".format(N, M, n_average))
 
-    target_had_error = run_benchmarks(args, target, N, M, n_average, tests)
+    os.makedirs(args.result_dir, exist_ok=True)
+    test_results = run_benchmarks(args, target, N, M, n_average, tests)
+    res = run_tests_module.create_test_report(args, test_results)
 
-    if isinstance(target, pyboard.Pyboard):
+    if hasattr(target, "exit_raw_repl"):
         target.exit_raw_repl()
         target.close()
 
-    if target_had_error:
+    if not res:
         sys.exit(1)
 
 
diff --git a/tests/run-tests.py b/tests/run-tests.py
index cb839ae23dcdf..71570292ce7f7 100755
--- a/tests/run-tests.py
+++ b/tests/run-tests.py
@@ -15,13 +15,15 @@
 import threading
 import tempfile
 
-# Maximum time to run a PC-based test, in seconds.
-TEST_TIMEOUT = 30
+# Maximum time to run a single test, in seconds.
+TEST_TIMEOUT = float(os.environ.get("MICROPY_TEST_TIMEOUT", 30))
 
 # See stackoverflow.com/questions/2632199: __file__ nor sys.argv[0]
 # are guaranteed to always work, this one should though.
 BASEPATH = os.path.dirname(os.path.abspath(inspect.getsourcefile(lambda: None)))
 
+RV32_ARCH_FLAGS = {"zba": 1 << 0}
+
 
 def base_path(*p):
     return os.path.abspath(os.path.join(BASEPATH, *p)).replace("\\", "/")
@@ -58,6 +60,23 @@ def base_path(*p):
 # Set PYTHONIOENCODING so that CPython will use utf-8 on systems which set another encoding in the locale
 os.environ["PYTHONIOENCODING"] = "utf-8"
 
+
+def normalize_newlines(data):
+    """Normalize newline variations to \\n.
+
+    Only normalizes actual line endings, not literal \\r characters in strings.
+    Handles \\r\\r\\n and \\r\\n cases to ensure consistent comparison
+    across different platforms and terminals.
+    """
+    if isinstance(data, bytes):
+        # Handle PTY double-newline issue first
+        data = data.replace(b"\r\r\n", b"\n")
+        # Then handle standard Windows line endings
+        data = data.replace(b"\r\n", b"\n")
+        # Don't convert standalone \r as it might be literal content
+    return data
+
+
 # Code to allow a target MicroPython to import an .mpy from RAM
 # Note: the module is named `__injected_test` but it needs to have `__name__` set to
 # `__main__` so that the test sees itself as the main module, eg so unittest works.
@@ -88,31 +107,82 @@ def getcwd(self):
     return ""
   def stat(self, path):
     if path == '__injected_test.mpy':
-      return tuple(0 for _ in range(10))
+      return (0,0,0,0,0,0,0,0,0,0)
     else:
-      raise OSError(-2) # ENOENT
+      raise OSError(2) # ENOENT
   def open(self, path, mode):
+    self.stat(path)
     return __File()
 vfs.mount(__FS(), '/__vfstest')
 os.chdir('/__vfstest')
+{import_prologue}
 __import__('__injected_test')
 """
 
 # Platforms associated with the unix port, values of `sys.platform`.
 PC_PLATFORMS = ("darwin", "linux", "win32")
 
+# Mapping from `sys.platform` to the port name, for special cases.
+# See `platform_to_port()` function.
+platform_to_port_map = {"pyboard": "stm32", "WiPy": "cc3200"}
+platform_to_port_map.update({p: "unix" for p in PC_PLATFORMS})
+
+# Tests to skip for values of the `--via-mpy` argument.
+via_mpy_tests_to_skip = {
+    # Skip the following when mpy is enabled.
+    True: (
+        # These print out the filename and that's expected to match the .py name.
+        "import/import_file.py",
+        "io/argv.py",
+        "misc/sys_settrace_features.py",
+        "misc/sys_settrace_generator.py",
+        "misc/sys_settrace_loop.py",
+    ),
+}
+
+# Tests to skip for specific emitters.
+emitter_tests_to_skip = {
+    # Some tests are known to fail with native emitter.
+    # Remove them from the below when they work.
+    "native": (
+        # These require raise_varargs.
+        "basics/gen_yield_from_close.py",
+        "basics/try_finally_return2.py",
+        "basics/try_reraise.py",
+        "basics/try_reraise2.py",
+        "misc/features.py",
+        # These require checking for unbound local.
+        "basics/annotate_var.py",
+        "basics/del_deref.py",
+        "basics/del_local.py",
+        "basics/scope_implicit.py",
+        "basics/unboundlocal.py",
+        # These require "raise from".
+        "basics/exception_chain.py",
+        # These require stack-allocated slice optimisation.
+        "micropython/heapalloc_slice.py",
+        # These require running the scheduler.
+        "micropython/schedule.py",
+        "extmod/asyncio_event_queue.py",
+        "extmod/asyncio_iterator_event.py",
+        # These require sys.exc_info().
+        "misc/sys_exc_info.py",
+        # These require sys.settrace().
+        "misc/sys_settrace_cov.py",
+        "misc/sys_settrace_features.py",
+        "misc/sys_settrace_generator.py",
+        "misc/sys_settrace_loop.py",
+        # These are bytecode-specific tests.
+        "stress/bytecode_limit.py",
+    ),
+}
+
 # Tests to skip on specific targets.
 # These are tests that are difficult to detect that they should not be run on the given target.
 platform_tests_to_skip = {
-    "esp8266": (
-        "micropython/viper_args.py",  # too large
-        "micropython/viper_binop_arith.py",  # too large
-        "misc/rge_sm.py",  # too large
-    ),
     "minimal": (
         "basics/class_inplace_op.py",  # all special methods not supported
         "basics/subclass_native_init.py",  # native subclassing corner cases not support
-        "misc/rge_sm.py",  # too large
         "micropython/opt_level.py",  # don't assume line numbers are stored
     ),
     "nrf": (
@@ -140,14 +210,6 @@ def open(self, path, mode):
         "thread/thread_lock3.py",
         "thread/thread_shared2.py",
     ),
-    "qemu": (
-        # Skip tests that require Cortex-M4.
-        "inlineasm/thumb/asmfpaddsub.py",
-        "inlineasm/thumb/asmfpcmp.py",
-        "inlineasm/thumb/asmfpldrstr.py",
-        "inlineasm/thumb/asmfpmuldiv.py",
-        "inlineasm/thumb/asmfpsqrt.py",
-    ),
     "webassembly": (
         "basics/string_format_modulo.py",  # can't print nulls to stdout
         "basics/string_strip.py",  # can't print nulls to stdout
@@ -162,6 +224,9 @@ def open(self, path, mode):
         "extmod/asyncio_new_event_loop.py",
         "extmod/asyncio_threadsafeflag.py",
         "extmod/asyncio_wait_for_fwd.py",
+        "extmod/asyncio_event_queue.py",
+        "extmod/asyncio_iterator_event.py",
+        "extmod/asyncio_wait_for_linked_task.py",
         "extmod/binascii_a2b_base64.py",
         "extmod/deflate_compress_memory_error.py",  # tries to allocate unlimited memory
         "extmod/re_stack_overflow.py",
@@ -184,6 +249,89 @@ def open(self, path, mode):
     ),
 }
 
+# These tests don't test float explicitly but rather use it to perform the test.
+tests_requiring_float = (
+    "extmod/asyncio_basic.py",
+    "extmod/asyncio_basic2.py",
+    "extmod/asyncio_cancel_task.py",
+    "extmod/asyncio_event.py",
+    "extmod/asyncio_fair.py",
+    "extmod/asyncio_gather.py",
+    "extmod/asyncio_gather_notimpl.py",
+    "extmod/asyncio_get_event_loop.py",
+    "extmod/asyncio_iterator_event.py",
+    "extmod/asyncio_lock.py",
+    "extmod/asyncio_task_done.py",
+    "extmod/asyncio_wait_for.py",
+    "extmod/asyncio_wait_for_fwd.py",
+    "extmod/asyncio_wait_for_linked_task.py",
+    "extmod/asyncio_wait_task.py",
+    "extmod/json_dumps_float.py",
+    "extmod/json_loads_float.py",
+    "extmod/random_extra_float.py",
+    "extmod/select_poll_eintr.py",
+    "extmod/tls_threads.py",
+    "extmod/uctypes_le_float.py",
+    "extmod/uctypes_native_float.py",
+    "extmod/uctypes_sizeof_float.py",
+    "misc/rge_sm.py",
+    "ports/unix/ffi_float.py",
+    "ports/unix/ffi_float2.py",
+)
+
+# These tests don't test slice explicitly but rather use it to perform the test.
+tests_requiring_slice = (
+    "basics/builtin_range.py",
+    "basics/bytearray1.py",
+    "basics/class_super.py",
+    "basics/containment.py",
+    "basics/errno1.py",
+    "basics/fun_str.py",
+    "basics/generator1.py",
+    "basics/globals_del.py",
+    "basics/memoryview1.py",
+    "basics/memoryview_gc.py",
+    "basics/object1.py",
+    "basics/python34.py",
+    "basics/struct_endian.py",
+    "extmod/btree1.py",
+    "extmod/deflate_decompress.py",
+    "extmod/framebuf16.py",
+    "extmod/framebuf4.py",
+    "extmod/machine1.py",
+    "extmod/time_mktime.py",
+    "extmod/time_res.py",
+    "extmod/tls_sslcontext_ciphers.py",
+    "extmod/vfs_fat_fileio1.py",
+    "extmod/vfs_fat_finaliser.py",
+    "extmod/vfs_fat_more.py",
+    "extmod/vfs_fat_ramdisk.py",
+    "extmod/vfs_fat_ramdisklarge.py",
+    "extmod/vfs_lfs.py",
+    "extmod/vfs_rom.py",
+    "float/string_format_modulo.py",
+    "micropython/builtin_execfile.py",
+    "micropython/extreme_exc.py",
+    "micropython/heapalloc_fail_bytearray.py",
+    "micropython/heapalloc_fail_list.py",
+    "micropython/heapalloc_fail_memoryview.py",
+    "micropython/import_mpy_invalid.py",
+    "micropython/import_mpy_native.py",
+    "micropython/import_mpy_native_gc.py",
+    "misc/non_compliant.py",
+    "misc/rge_sm.py",
+)
+
+# Tests that require `import target_wiring` to work.
+tests_requiring_target_wiring = (
+    "extmod/machine_uart_irq_txidle.py",
+    "extmod/machine_uart_tx.py",
+    "extmod_hardware/machine_encoder.py",
+    "extmod_hardware/machine_uart_irq_break.py",
+    "extmod_hardware/machine_uart_irq_rx.py",
+    "extmod_hardware/machine_uart_irq_rxidle.py",
+)
+
 
 def rm_f(fname):
     if os.path.exists(fname):
@@ -210,22 +358,31 @@ def convert_regex_escapes(line):
     return bytes("".join(cs), "utf8")
 
 
+def platform_to_port(platform):
+    return platform_to_port_map.get(platform, platform)
+
+
+def convert_device_shortcut_to_real_device(device):
+    if device.startswith("port:"):
+        return device.split(":", 1)[1]
+    elif device.startswith("a") and device[1:].isdigit():
+        return "/dev/ttyACM" + device[1:]
+    elif device.startswith("u") and device[1:].isdigit():
+        return "/dev/ttyUSB" + device[1:]
+    elif device.startswith("c") and device[1:].isdigit():
+        return "COM" + device[1:]
+    else:
+        return device
+
+
 def get_test_instance(test_instance, baudrate, user, password):
-    if test_instance.startswith("port:"):
-        _, port = test_instance.split(":", 1)
-    elif test_instance == "unix":
+    if test_instance == "unix":
         return None
     elif test_instance == "webassembly":
         return PyboardNodeRunner()
-    elif test_instance.startswith("a") and test_instance[1:].isdigit():
-        port = "/dev/ttyACM" + test_instance[1:]
-    elif test_instance.startswith("u") and test_instance[1:].isdigit():
-        port = "/dev/ttyUSB" + test_instance[1:]
-    elif test_instance.startswith("c") and test_instance[1:].isdigit():
-        port = "COM" + test_instance[1:]
     else:
         # Assume it's a device path.
-        port = test_instance
+        port = convert_device_shortcut_to_real_device(test_instance)
 
     global pyboard
     sys.path.append(base_path("../tools"))
@@ -245,46 +402,114 @@ def detect_inline_asm_arch(pyb, args):
     return None
 
 
+def map_rv32_arch_flags(flags):
+    mapped_flags = []
+    for extension, bit in RV32_ARCH_FLAGS.items():
+        if flags & bit:
+            mapped_flags.append(extension)
+        flags &= ~bit
+    if flags:
+        raise Exception("Unexpected flag bits set in value {}".format(flags))
+    return mapped_flags
+
+
 def detect_test_platform(pyb, args):
     # Run a script to detect various bits of information about the target test instance.
     output = run_feature_check(pyb, args, "target_info.py")
     if output.endswith(b"CRASH"):
         raise ValueError("cannot detect platform: {}".format(output))
-    platform, arch = str(output, "ascii").strip().split()
+    platform, arch, arch_flags, build, thread, float_prec, unicode = (
+        str(output, "ascii").strip().split()
+    )
     if arch == "None":
         arch = None
     inlineasm_arch = detect_inline_asm_arch(pyb, args)
+    if thread == "None":
+        thread = None
+    float_prec = int(float_prec)
+    unicode = unicode == "True"
+    if arch == "rv32imc":
+        arch_flags = map_rv32_arch_flags(int(arch_flags))
+    else:
+        arch_flags = None
 
     args.platform = platform
     args.arch = arch
+    args.arch_flags = arch_flags
     if arch and not args.mpy_cross_flags:
         args.mpy_cross_flags = "-march=" + arch
+        if arch_flags:
+            args.mpy_cross_flags += " -march-flags=" + ",".join(arch_flags)
     args.inlineasm_arch = inlineasm_arch
+    args.build = build
+    args.thread = thread
+    args.float_prec = float_prec
+    args.unicode = unicode
 
+    # Print the detected information about the target.
     print("platform={}".format(platform), end="")
     if arch:
         print(" arch={}".format(arch), end="")
+        if arch_flags:
+            print(" arch_flags={}".format(",".join(arch_flags)), end="")
     if inlineasm_arch:
         print(" inlineasm={}".format(inlineasm_arch), end="")
-    print()
-
-
-def prepare_script_for_target(args, *, script_filename=None, script_text=None, force_plain=False):
+    if thread:
+        print(" thread={}".format(thread), end="")
+    if float_prec:
+        print(" float={}-bit".format(float_prec), end="")
+    if unicode:
+        print(" unicode", end="")
+
+
+def detect_target_wiring_script(pyb, args):
+    tw_data = b""
+    tw_source = None
+    if args.target_wiring:
+        # A target_wiring path is explicitly provided, so use that.
+        tw_source = args.target_wiring
+        with open(tw_source, "rb") as f:
+            tw_data = f.read()
+    elif hasattr(pyb, "exec_raw") and pyb.exec_raw("import target_wiring") == (b"", b""):
+        # The board already has a target_wiring module available, so use that.
+        tw_source = "on-device"
+    else:
+        port = platform_to_port(args.platform)
+        build = args.build
+        tw_board_exact = None
+        tw_board_partial = None
+        tw_port = None
+        for file in os.listdir("target_wiring"):
+            file_base = file.removesuffix(".py")
+            if file_base == build:
+                # A file matching the target's board/build name.
+                tw_board_exact = file
+            elif file_base.endswith("x") and build.startswith(file_base.removesuffix("x")):
+                # A file with a partial match to the target's board/build name.
+                tw_board_partial = file
+            elif file_base == port:
+                # A file matching the target's port.
+                tw_port = file
+        tw_source = tw_board_exact or tw_board_partial or tw_port
+        if tw_source:
+            with open("target_wiring/" + tw_source, "rb") as f:
+                tw_data = f.read()
+    if tw_source:
+        print(" target_wiring={}".format(tw_source), end="")
+    pyb.target_wiring_script = tw_data
+
+
+def prepare_script_for_target(args, *, script_text=None, force_plain=False):
     if force_plain or (not args.via_mpy and args.emit == "bytecode"):
-        if script_filename is not None:
-            with open(script_filename, "rb") as f:
-                script_text = f.read()
+        # A plain test to run as-is, no processing needed.
+        pass
     elif args.via_mpy:
         tempname = tempfile.mktemp(dir="")
         mpy_filename = tempname + ".mpy"
 
-        if script_filename is None:
-            script_filename = tempname + ".py"
-            cleanup_script_filename = True
-            with open(script_filename, "wb") as f:
-                f.write(script_text)
-        else:
-            cleanup_script_filename = False
+        script_filename = tempname + ".py"
+        with open(script_filename, "wb") as f:
+            f.write(script_text)
 
         try:
             subprocess.check_output(
@@ -300,8 +525,7 @@ def prepare_script_for_target(args, *, script_filename=None, script_text=None, f
             script_text = b"__buf=" + bytes(repr(f.read()), "ascii") + b"\n"
 
         rm_f(mpy_filename)
-        if cleanup_script_filename:
-            rm_f(script_filename)
+        rm_f(script_filename)
 
         script_text += bytes(injected_import_hook_code, "ascii")
     else:
@@ -312,34 +536,61 @@ def prepare_script_for_target(args, *, script_filename=None, script_text=None, f
 
 
 def run_script_on_remote_target(pyb, args, test_file, is_special):
-    had_crash, script = prepare_script_for_target(
-        args, script_filename=test_file, force_plain=is_special
-    )
+    with open(test_file, "rb") as f:
+        script = f.read()
+
+    # If the test is not a special test, prepend it with a print to indicate that it started.
+    # If the print does not execute this means that the test did not even start, eg it was
+    # too large for the target.
+    prepend_start_test = not is_special
+    if prepend_start_test:
+        if script.startswith(b"#"):
+            script = b"print('START TEST')" + script
+        else:
+            script = b"print('START TEST')\n" + script
+
+    had_crash, script = prepare_script_for_target(args, script_text=script, force_plain=is_special)
+
     if had_crash:
         return True, script
 
     try:
         had_crash = False
         pyb.enter_raw_repl()
-        output_mupy = pyb.exec_(script)
+        if test_file.endswith(tests_requiring_target_wiring) and pyb.target_wiring_script:
+            pyb.exec_(
+                "import sys;sys.modules['target_wiring']=__build_class__(lambda:exec("
+                + repr(pyb.target_wiring_script)
+                + "),'target_wiring')"
+            )
+        output_mupy = pyb.exec_(script, timeout=TEST_TIMEOUT)
     except pyboard.PyboardError as e:
         had_crash = True
         if not is_special and e.args[0] == "exception":
-            output_mupy = e.args[1] + e.args[2] + b"CRASH"
+            if prepend_start_test and e.args[1] == b"" and b"MemoryError" in e.args[2]:
+                output_mupy = b"SKIP-TOO-LARGE\n"
+            else:
+                output_mupy = e.args[1] + e.args[2] + b"CRASH"
         else:
             output_mupy = bytes(e.args[0], "ascii") + b"\nCRASH"
+
+    if prepend_start_test:
+        if output_mupy.startswith(b"START TEST\r\n"):
+            output_mupy = output_mupy.removeprefix(b"START TEST\r\n")
+        else:
+            had_crash = True
+
     return had_crash, output_mupy
 
 
-special_tests = [
+tests_with_regex_output = [
     base_path(file)
     for file in (
+        # CIRCUITPY-CHANGE: removal and additions
         "micropython/meminfo.py",
         "basics/bytes_compare3.py",
         "basics/builtin_help.py",
         "thread/thread_exc2.py",
-        # CIRCUITPY-CHANGE: removal and additions
-        # REMOVE "esp32/partition_ota.py",
         "circuitpython/traceback_test.py",
         "circuitpython/traceback_test_chained.py",
     )
@@ -350,10 +601,7 @@ def run_micropython(pyb, args, test_file, test_file_abspath, is_special=False):
     had_crash = False
     if pyb is None:
         # run on PC
-        if (
-            test_file_abspath.startswith((base_path("cmdline/"), base_path("feature_check/")))
-            or test_file_abspath in special_tests
-        ):
+        if test_file_abspath.startswith((base_path("cmdline/"), base_path("feature_check/"))):
             # special handling for tests of the unix cmdline program
             is_special = True
 
@@ -392,6 +640,10 @@ def get(required=False):
                                     return rv
 
                     def send_get(what):
+                        # Detect {\x00} pattern and convert to ctrl-key codes.
+                        ctrl_code = lambda m: bytes([int(m.group(1))])
+                        what = re.sub(rb"{\\x(\d\d)}", ctrl_code, what)
+
                         os.write(master, what)
                         return get()
 
@@ -471,17 +723,17 @@ def send_get(what):
         )
 
     # canonical form for all ports/platforms is to use \n for end-of-line
-    output_mupy = output_mupy.replace(b"\r\n", b"\n")
+    output_mupy = normalize_newlines(output_mupy)
 
     # don't try to convert the output if we should skip this test
-    if had_crash or output_mupy in (b"SKIP\n", b"CRASH"):
+    if had_crash or output_mupy in (b"SKIP\n", b"SKIP-TOO-LARGE\n", b"CRASH"):
         return output_mupy
 
     # skipped special tests will output "SKIP" surrounded by other interpreter debug output
     if is_special and not had_crash and b"\nSKIP\n" in output_mupy:
         return b"SKIP\n"
 
-    if is_special or test_file_abspath in special_tests:
+    if is_special or test_file_abspath in tests_with_regex_output:
         # convert parts of the output that are not stable across runs
         with open(test_file + ".exp", "rb") as f:
             lines_exp = []
@@ -603,30 +855,25 @@ def run_script_on_remote_target(self, args, test_file, is_special):
 
 
 def run_tests(pyb, tests, args, result_dir, num_threads=1):
-    test_count = ThreadSafeCounter()
     testcase_count = ThreadSafeCounter()
-    passed_count = ThreadSafeCounter()
-    failed_tests = ThreadSafeCounter([])
-    skipped_tests = ThreadSafeCounter([])
+    test_results = ThreadSafeCounter([])
 
     skip_tests = set()
     skip_native = False
     skip_int_big = False
+    skip_int_64 = False
     skip_bytearray = False
     skip_set_type = False
     skip_slice = False
     skip_async = False
     skip_const = False
     skip_revops = False
-    skip_io_module = False
     skip_fstring = False
     skip_endian = False
     skip_inlineasm = False
     has_complex = True
     has_coverage = False
 
-    upy_float_precision = 32
-
     if True:
         # Even if we run completely different tests in a different directory,
         # we need to access feature_checks from the same directory as the
@@ -642,6 +889,11 @@ def run_tests(pyb, tests, args, result_dir, num_threads=1):
         if output != b"1000000000000000000000000000000000000000000000\n":
             skip_int_big = True
 
+        # Check if 'long long' precision integers are supported, even if arbitrary precision is not
+        output = run_feature_check(pyb, args, "int_64.py")
+        if output != b"4611686018427387904\n":
+            skip_int_64 = True
+
         # Check if bytearray is supported, and skip such tests if it's not
         output = run_feature_check(pyb, args, "bytearray.py")
         if output != b"bytearray\n":
@@ -672,11 +924,6 @@ def run_tests(pyb, tests, args, result_dir, num_threads=1):
         if output == b"TypeError\n":
             skip_revops = True
 
-        # Check if io module exists, and skip such tests if it doesn't
-        output = run_feature_check(pyb, args, "io_module.py")
-        if output != b"io\n":
-            skip_io_module = True
-
         # Check if fstring feature is enabled, and skip such tests if it doesn't
         output = run_feature_check(pyb, args, "fstring.py")
         if output != b"a=1\n":
@@ -690,13 +937,20 @@ def run_tests(pyb, tests, args, result_dir, num_threads=1):
                 skip_tests.add("inlineasm/thumb/asmbitops.py")
                 skip_tests.add("inlineasm/thumb/asmconst.py")
                 skip_tests.add("inlineasm/thumb/asmdiv.py")
+                skip_tests.add("inlineasm/thumb/asmit.py")
+                skip_tests.add("inlineasm/thumb/asmspecialregs.py")
+            if args.arch not in ("armv7emsp", "armv7emdp"):
                 skip_tests.add("inlineasm/thumb/asmfpaddsub.py")
                 skip_tests.add("inlineasm/thumb/asmfpcmp.py")
                 skip_tests.add("inlineasm/thumb/asmfpldrstr.py")
                 skip_tests.add("inlineasm/thumb/asmfpmuldiv.py")
                 skip_tests.add("inlineasm/thumb/asmfpsqrt.py")
-                skip_tests.add("inlineasm/thumb/asmit.py")
-                skip_tests.add("inlineasm/thumb/asmspecialregs.py")
+
+        if args.inlineasm_arch == "rv32":
+            # Check if @micropython.asm_rv32 supports Zba instructions, and skip such tests if it doesn't
+            output = run_feature_check(pyb, args, "inlineasm_rv32_zba.py")
+            if output != b"rv32_zba\n":
+                skip_tests.add("inlineasm/rv32/asmzba.py")
 
         # Check if emacs repl is supported, and skip such tests if it's not
         t = run_feature_check(pyb, args, "repl_emacs_check.py")
@@ -709,11 +963,6 @@ def run_tests(pyb, tests, args, result_dir, num_threads=1):
             skip_tests.add("cmdline/repl_words_move.py")
 
         upy_byteorder = run_feature_check(pyb, args, "byteorder.py")
-        upy_float_precision = run_feature_check(pyb, args, "float.py")
-        try:
-            upy_float_precision = int(upy_float_precision)
-        except ValueError:
-            upy_float_precision = 0
         has_complex = run_feature_check(pyb, args, "complex.py") == b"complex\n"
         has_coverage = run_feature_check(pyb, args, "coverage.py") == b"coverage\n"
         cpy_byteorder = subprocess.check_output(
@@ -723,24 +972,6 @@ def run_tests(pyb, tests, args, result_dir, num_threads=1):
 
         skip_inlineasm = args.inlineasm_arch is None
 
-    # These tests don't test slice explicitly but rather use it to perform the test
-    misc_slice_tests = (
-        "builtin_range",
-        "bytearray1",
-        "class_super",
-        "containment",
-        "errno1",
-        "fun_str",
-        "generator1",
-        "globals_del",
-        "memoryview1",
-        "memoryview_gc",
-        "object1",
-        "python34",
-        "string_format_modulo",
-        "struct_endian",
-    )
-
     # Some tests shouldn't be run on GitHub Actions
     if os.getenv("GITHUB_ACTIONS") == "true":
         skip_tests.add("thread/stress_schedule.py")  # has reliability issues
@@ -749,30 +980,31 @@ def run_tests(pyb, tests, args, result_dir, num_threads=1):
             # fails with stack overflow on Debug builds
             skip_tests.add("misc/sys_settrace_features.py")
 
-    if upy_float_precision == 0:
-        skip_tests.add("extmod/uctypes_le_float.py")
-        skip_tests.add("extmod/uctypes_native_float.py")
-        skip_tests.add("extmod/uctypes_sizeof_float.py")
-        skip_tests.add("extmod/json_dumps_float.py")
-        skip_tests.add("extmod/json_loads_float.py")
-        skip_tests.add("extmod/random_extra_float.py")
-        skip_tests.add("misc/rge_sm.py")
-    if upy_float_precision < 32:
+    if args.float_prec == 0:
+        skip_tests.update(tests_requiring_float)
+    if args.float_prec < 32:
         skip_tests.add(
             "float/float2int_intbig.py"
         )  # requires fp32, there's float2int_fp30_intbig.py instead
         skip_tests.add(
-            "float/string_format.py"
-        )  # requires fp32, there's string_format_fp30.py instead
+            "float/float_struct_e.py"
+        )  # requires fp32, there's float_struct_e_fp30.py instead
         skip_tests.add("float/bytes_construct.py")  # requires fp32
         skip_tests.add("float/bytearray_construct.py")  # requires fp32
         skip_tests.add("float/float_format_ints_power10.py")  # requires fp32
-    if upy_float_precision < 64:
+    if args.float_prec < 64:
         skip_tests.add("float/float_divmod.py")  # tested by float/float_divmod_relaxed.py instead
         skip_tests.add("float/float2int_doubleprec_intbig.py")
+        skip_tests.add("float/float_struct_e_doubleprec.py")
         skip_tests.add("float/float_format_ints_doubleprec.py")
         skip_tests.add("float/float_parse_doubleprec.py")
 
+    if not args.unicode:
+        skip_tests.add("extmod/json_loads.py")  # tests loading a utf-8 character
+
+    if skip_slice:
+        skip_tests.update(tests_requiring_slice)
+
     if not has_complex:
         skip_tests.add("float/complex1.py")
         skip_tests.add("float/complex1_intbig.py")
@@ -788,8 +1020,8 @@ def run_tests(pyb, tests, args, result_dir, num_threads=1):
         skip_tests.add("cmdline/repl_sys_ps1_ps2.py")
         skip_tests.add("extmod/ssl_poll.py")
 
-    # Skip thread mutation tests on targets that don't have the GIL.
-    if args.platform in PC_PLATFORMS + ("rp2",):
+    # Skip thread mutation tests on targets that have unsafe threading behaviour.
+    if args.thread == "unsafe":
         for t in tests:
             if t.startswith("thread/mutate_"):
                 skip_tests.add(t)
@@ -798,6 +1030,15 @@ def run_tests(pyb, tests, args, result_dir, num_threads=1):
     if args.platform not in PC_PLATFORMS:
         skip_tests.add("basics/exception_chain.py")  # warning is not printed
         skip_tests.add("micropython/meminfo.py")  # output is very different to PC output
+        skip_tests.add("unicode/file1.py")  # requires local file access
+        skip_tests.add("unicode/file2.py")  # requires local file access
+        skip_tests.add("unicode/file_invalid.py")  # requires local file access
+
+    # Skip certain tests when going via a .mpy file.
+    skip_tests.update(via_mpy_tests_to_skip.get(args.via_mpy, ()))
+
+    # Skip emitter-specific tests.
+    skip_tests.update(emitter_tests_to_skip.get(args.emit, ()))
 
     # Skip platform-specific tests.
     skip_tests.update(platform_tests_to_skip.get(args.platform, ()))
@@ -812,49 +1053,6 @@ def run_tests(pyb, tests, args, result_dir, num_threads=1):
             # Works but CPython uses '\' path separator
             skip_tests.add("import/import_file.py")
 
-    # Some tests are known to fail with native emitter
-    # Remove them from the below when they work
-    if args.emit == "native":
-        skip_tests.add("basics/gen_yield_from_close.py")  # require raise_varargs
-        skip_tests.update(
-            {"basics/%s.py" % t for t in "try_reraise try_reraise2".split()}
-        )  # require raise_varargs
-        skip_tests.add("basics/annotate_var.py")  # requires checking for unbound local
-        skip_tests.add("basics/del_deref.py")  # requires checking for unbound local
-        skip_tests.add("basics/del_local.py")  # requires checking for unbound local
-        skip_tests.add("basics/exception_chain.py")  # raise from is not supported
-        skip_tests.add("basics/scope_implicit.py")  # requires checking for unbound local
-        skip_tests.add("basics/sys_tracebacklimit.py")  # requires traceback info
-        skip_tests.add("basics/try_finally_return2.py")  # requires raise_varargs
-        skip_tests.add("basics/unboundlocal.py")  # requires checking for unbound local
-        skip_tests.add("misc/features.py")  # requires raise_varargs
-        # CIRCUITPY-CHANGE
-        skip_tests.update(
-            (
-                "basics/chained_exception.py",
-                "circuitpython/traceback_test.py",
-                "circuitpython/traceback_test_chained.py",
-            )
-        )  # because native doesn't have proper traceback info
-        skip_tests.add(
-            "misc/print_exception.py"
-        )  # because native doesn't have proper traceback info
-        skip_tests.add("misc/sys_exc_info.py")  # sys.exc_info() is not supported for native
-        skip_tests.add("misc/sys_settrace_features.py")  # sys.settrace() not supported
-        skip_tests.add("misc/sys_settrace_generator.py")  # sys.settrace() not supported
-        skip_tests.add("misc/sys_settrace_loop.py")  # sys.settrace() not supported
-        skip_tests.add(
-            "micropython/emg_exc.py"
-        )  # because native doesn't have proper traceback info
-        skip_tests.add(
-            "micropython/heapalloc_traceback.py"
-        )  # because native doesn't have proper traceback info
-        skip_tests.add(
-            "micropython/opt_level_lineno.py"
-        )  # native doesn't have proper traceback info
-        skip_tests.add("micropython/schedule.py")  # native code doesn't check pending events
-        skip_tests.add("stress/bytecode_limit.py")  # bytecode specific test
-
     def run_one_test(test_file):
         test_file = test_file.replace("\\", "/")
         test_file_abspath = os.path.abspath(test_file).replace("\\", "/")
@@ -870,19 +1068,19 @@ def run_one_test(test_file):
 
         test_basename = test_file.replace("..", "_").replace("./", "").replace("/", "_")
         test_name = os.path.splitext(os.path.basename(test_file))[0]
-        is_native = (
-            test_name.startswith("native_")
-            or test_name.startswith("viper_")
-            or args.emit == "native"
-        )
+        is_native = test_name.startswith("native_") or test_name.startswith("viper_")
         is_endian = test_name.endswith("_endian")
-        is_int_big = test_name.startswith("int_big") or test_name.endswith("_intbig")
+        is_int_big = (
+            test_name.startswith("int_big")
+            or test_name.endswith("_intbig")
+            or test_name.startswith("ffi_int")  # these tests contain large integer literals
+        )
+        is_int_64 = test_name.startswith("int_64") or test_name.endswith("_int64")
         is_bytearray = test_name.startswith("bytearray") or test_name.endswith("_bytearray")
         is_set_type = test_name.startswith(("set_", "frozenset")) or test_name.endswith("_set")
-        is_slice = test_name.find("slice") != -1 or test_name in misc_slice_tests
-        is_async = test_name.startswith(("async_", "asyncio_"))
+        is_slice = test_name.find("slice") != -1
+        is_async = test_name.startswith(("async_", "asyncio_")) or test_name.endswith("_async")
         is_const = test_name.startswith("const")
-        is_io_module = test_name.startswith("io_")
         is_fstring = test_name.startswith("string_fstring")
         is_inlineasm = test_name.startswith("asm")
 
@@ -890,19 +1088,19 @@ def run_one_test(test_file):
         skip_it |= skip_native and is_native
         skip_it |= skip_endian and is_endian
         skip_it |= skip_int_big and is_int_big
+        skip_it |= skip_int_64 and is_int_64
         skip_it |= skip_bytearray and is_bytearray
         skip_it |= skip_set_type and is_set_type
         skip_it |= skip_slice and is_slice
         skip_it |= skip_async and is_async
         skip_it |= skip_const and is_const
         skip_it |= skip_revops and "reverse_op" in test_name
-        skip_it |= skip_io_module and is_io_module
         skip_it |= skip_fstring and is_fstring
         skip_it |= skip_inlineasm and is_inlineasm
 
         if skip_it:
             print("skip ", test_file)
-            skipped_tests.append(test_name)
+            test_results.append((test_file, "skip", ""))
             return
 
         # Run the test on the MicroPython target.
@@ -917,7 +1115,11 @@ def run_one_test(test_file):
                 # start-up code (eg boot.py) when preparing to run the next test.
                 pyb.read_until(1, b"raw REPL; CTRL-B to exit\r\n")
             print("skip ", test_file)
-            skipped_tests.append(test_name)
+            test_results.append((test_file, "skip", ""))
+            return
+        elif output_mupy == b"SKIP-TOO-LARGE\n":
+            print("lrge ", test_file)
+            test_results.append((test_file, "skip", "too large"))
             return
 
         # Look at the output of the test to see if unittest was used.
@@ -954,7 +1156,11 @@ def run_one_test(test_file):
             # Expected output is result of running unittest.
             output_expected = None
         else:
-            test_file_expected = test_file + ".exp"
+            # Prefer emitter-specific expected output.
+            test_file_expected = test_file + "." + args.emit + ".exp"
+            if not os.path.isfile(test_file_expected):
+                # Fall back to generic expected output.
+                test_file_expected = test_file + ".exp"
             if os.path.isfile(test_file_expected):
                 # Expected output given by a file, so read that in.
                 with open(test_file_expected, "rb") as f:
@@ -1012,7 +1218,7 @@ def run_one_test(test_file):
         # Print test summary, update counters, and save .exp/.out files if needed.
         if test_passed:
             print("pass ", test_file, extra_info)
-            passed_count.increment()
+            test_results.append((test_file, "pass", ""))
             rm_f(filename_expected)
             rm_f(filename_mupy)
         else:
@@ -1024,9 +1230,7 @@ def run_one_test(test_file):
                 rm_f(filename_expected)  # in case left over from previous failed run
             with open(filename_mupy, "wb") as f:
                 f.write(output_mupy)
-            failed_tests.append((test_name, test_file))
-
-        test_count.increment()
+            test_results.append((test_file, "fail", ""))
 
         # Print a note if this looks like it might have been a misfired unittest
         if not uses_unittest and not test_passed:
@@ -1053,17 +1257,49 @@ def run_one_test(test_file):
             print(line)
         sys.exit(1)
 
-    print(
-        "{} tests performed ({} individual testcases)".format(
-            test_count.value, testcase_count.value
-        )
+    # Return test results.
+    return test_results.value, testcase_count.value
+
+
+# Print a summary of the results and save them to a JSON file.
+# Returns True if everything succeeded, False otherwise.
+def create_test_report(args, test_results, testcase_count=None):
+    passed_tests = list(r for r in test_results if r[1] == "pass")
+    skipped_tests = list(r for r in test_results if r[1] == "skip" and r[2] != "too large")
+    skipped_tests_too_large = list(
+        r for r in test_results if r[1] == "skip" and r[2] == "too large"
     )
-    print("{} tests passed".format(passed_count.value))
+    failed_tests = list(r for r in test_results if r[1] == "fail")
+
+    num_tests_performed = len(passed_tests) + len(failed_tests)
+
+    testcase_count_info = ""
+    if testcase_count is not None:
+        testcase_count_info = " ({} individual testcases)".format(testcase_count)
+    print("{} tests performed{}".format(num_tests_performed, testcase_count_info))
+
+    print("{} tests passed".format(len(passed_tests)))
 
-    skipped_tests = sorted(skipped_tests.value)
     if len(skipped_tests) > 0:
-        print("{} tests skipped: {}".format(len(skipped_tests), " ".join(skipped_tests)))
-    failed_tests = sorted(failed_tests.value)
+        print(
+            "{} tests skipped: {}".format(
+                len(skipped_tests), " ".join(test[0] for test in skipped_tests)
+            )
+        )
+
+    if len(skipped_tests_too_large) > 0:
+        print(
+            "{} tests skipped because they are too large: {}".format(
+                len(skipped_tests_too_large), " ".join(test[0] for test in skipped_tests_too_large)
+            )
+        )
+
+    if len(failed_tests) > 0:
+        print(
+            "{} tests failed: {}".format(
+                len(failed_tests), " ".join(test[0] for test in failed_tests)
+            )
+        )
 
     # Serialize regex added by append_filter.
     def to_json(obj):
@@ -1071,23 +1307,22 @@ def to_json(obj):
             return obj.pattern
         return obj
 
-    with open(os.path.join(result_dir, RESULTS_FILE), "w") as f:
+    with open(os.path.join(args.result_dir, RESULTS_FILE), "w") as f:
         json.dump(
-            {"args": vars(args), "failed_tests": [test[1] for test in failed_tests]},
+            {
+                # The arguments passed on the command-line.
+                "args": vars(args),
+                # A list of all results of the form [(test, result, reason), ...].
+                "results": list(test for test in test_results),
+                # A list of failed tests.  This is deprecated, use the "results" above instead.
+                "failed_tests": [test[0] for test in failed_tests],
+            },
             f,
             default=to_json,
         )
 
-    if len(failed_tests) > 0:
-        print(
-            "{} tests failed: {}".format(
-                len(failed_tests), " ".join(test[0] for test in failed_tests)
-            )
-        )
-        return False
-
-    # all tests succeeded
-    return True
+    # Return True only if all tests succeeded.
+    return len(failed_tests) == 0
 
 
 class append_filter(argparse.Action):
@@ -1104,27 +1339,11 @@ def __call__(self, parser, args, value, option):
         args.filters.append((option, re.compile(value)))
 
 
-def main():
-    cmd_parser = argparse.ArgumentParser(
-        formatter_class=argparse.RawDescriptionHelpFormatter,
-        description="""Run and manage tests for MicroPython.
-
+test_instance_description = """\
 By default the tests are run against the unix port of MicroPython. To run it
 against something else, use the -t option.  See below for details.
-
-Tests are discovered by scanning test directories for .py files or using the
-specified test files. If test files nor directories are specified, the script
-expects to be ran in the tests directory (where this file is located) and the
-builtin tests suitable for the target platform are ran.
-
-When running tests, run-tests.py compares the MicroPython output of the test with the output
-produced by running the test through CPython unless a <test>.exp file is found, in which
-case it is used as comparison.
-
-If a test fails, run-tests.py produces a pair of <test>.out and <test>.exp files in the result
-directory with the MicroPython output and the expectations, respectively.
-""",
-        epilog="""\
+"""
+test_instance_epilog = """\
 The -t option accepts the following for the test instance:
 - unix - use the unix port of MicroPython, specified by the MICROPY_MICROPYTHON
   environment variable (which defaults to the standard variant of either the unix
@@ -1140,7 +1359,35 @@ def main():
 - execpty:<command> - execute a command and attach to the printed /dev/pts/<n> device
 - <a>.<b>.<c>.<d> - connect to the given IPv4 address
 - anything else specifies a serial port
+"""
+
+test_directory_description = """\
+Tests are discovered by scanning test directories for .py files or using the
+specified test files. If test files nor directories are specified, the script
+expects to be ran in the tests directory (where this file is located) and the
+builtin tests suitable for the target platform are ran.
+"""
+
 
+def main():
+    global injected_import_hook_code
+
+    cmd_parser = argparse.ArgumentParser(
+        formatter_class=argparse.RawDescriptionHelpFormatter,
+        description=f"""Run and manage tests for MicroPython.
+
+{test_instance_description}
+{test_directory_description}
+
+When running tests, run-tests.py compares the MicroPython output of the test with the output
+produced by running the test through CPython unless a <test>.exp file is found (or a
+<test>.native.exp file when using the native emitter), in which case it is used as comparison.
+
+If a test fails, run-tests.py produces a pair of <test>.out and <test>.exp files in the result
+directory with the MicroPython output and the expectations, respectively.
+""",
+        epilog=f"""\
+{test_instance_epilog}
 Options -i and -e can be multiple and processed in the order given. Regex
 "search" (vs "match") operation is used. An action (include/exclude) of
 the last matching regex is used:
@@ -1214,8 +1461,25 @@ def main():
         action="store_true",
         help="re-run only the failed tests",
     )
+    cmd_parser.add_argument(
+        "--begin",
+        metavar="PROLOGUE",
+        default=None,
+        help="prologue python file to execute before module import",
+    )
+    cmd_parser.add_argument(
+        "--target-wiring",
+        default=None,
+        help="force the given script to be used as target_wiring.py",
+    )
     args = cmd_parser.parse_args()
 
+    prologue = ""
+    if args.begin:
+        with open(args.begin, "rt") as source:
+            prologue = source.read()
+    injected_import_hook_code = injected_import_hook_code.replace("{import_prologue}", prologue)
+
     if args.print_failures:
         for out in glob(os.path.join(args.result_dir, "*.out")):
             testbase = out[:-4]
@@ -1256,7 +1520,7 @@ def main():
         results_file = os.path.join(args.result_dir, RESULTS_FILE)
         if os.path.exists(results_file):
             with open(results_file, "r") as f:
-                tests = json.load(f)["failed_tests"]
+                tests = list(test[0] for test in json.load(f)["results"] if test[1] == "fail")
         else:
             tests = []
     elif len(args.files) == 0:
@@ -1267,47 +1531,27 @@ def main():
         if args.test_dirs is None:
             test_dirs = (
                 "basics",
-                "circuitpython",  # CIRCUITPY-CHANGE
                 "micropython",
                 "misc",
                 "extmod",
+                "stress",
             )
             if args.inlineasm_arch is not None:
                 test_dirs += ("inlineasm/{}".format(args.inlineasm_arch),)
-            if args.platform == "pyboard":
-                # run pyboard tests
-                test_dirs += ("float", "stress", "ports/stm32")
-            elif args.platform == "mimxrt":
-                test_dirs += ("float", "stress")
-            elif args.platform == "renesas-ra":
-                test_dirs += ("float", "ports/renesas-ra")
-            elif args.platform == "rp2":
-                test_dirs += ("float", "stress", "thread", "ports/rp2")
-            elif args.platform == "esp32":
-                test_dirs += ("float", "stress", "thread")
-            elif args.platform in ("esp8266", "minimal", "samd", "nrf"):
+            if args.thread is not None:
+                test_dirs += ("thread",)
+            if args.float_prec > 0:
                 test_dirs += ("float",)
-            elif args.platform == "WiPy":
-                # run WiPy tests
-                test_dirs += ("ports/cc3200",)
-            elif args.platform in PC_PLATFORMS:
+            if args.unicode:
+                test_dirs += ("unicode",)
+            port_specific_test_dir = "ports/{}".format(platform_to_port(args.platform))
+            if os.path.isdir(port_specific_test_dir):
+                test_dirs += (port_specific_test_dir,)
+            if args.platform in PC_PLATFORMS:
                 # run PC tests
-                test_dirs += (
-                    "float",
-                    "import",
-                    "io",
-                    "stress",
-                    "unicode",
-                    "cmdline",
-                    "ports/unix",
-                )
-            elif args.platform == "qemu":
-                test_dirs += (
-                    "float",
-                    "ports/qemu",
-                )
-            elif args.platform == "webassembly":
-                test_dirs += ("float", "ports/webassembly")
+                test_dirs += ("import",)
+                if args.build != "minimal":
+                    test_dirs += ("cmdline", "io")
         else:
             # run tests from these directories
             test_dirs = args.test_dirs
@@ -1322,6 +1566,13 @@ def main():
         # tests explicitly given
         tests = args.files
 
+    # If any tests need it, prepare the target_wiring script for the target.
+    if pyb and any(test.endswith(tests_requiring_target_wiring) for test in tests):
+        detect_target_wiring_script(pyb, args)
+
+    # End the target information line.
+    print()
+
     if not args.keep_path:
         # Clear search path to make sure tests use only builtin modules, those in
         # extmod, and a path to unittest in case it's needed.
@@ -1342,7 +1593,8 @@ def main():
 
     try:
         os.makedirs(args.result_dir, exist_ok=True)
-        res = run_tests(pyb, tests, args, args.result_dir, args.jobs)
+        test_results, testcase_count = run_tests(pyb, tests, args, args.result_dir, args.jobs)
+        res = create_test_report(args, test_results, testcase_count)
     finally:
         if pyb:
             pyb.close()
diff --git a/tests/serial_test.py b/tests/serial_test.py
new file mode 100755
index 0000000000000..3b5940d91a907
--- /dev/null
+++ b/tests/serial_test.py
@@ -0,0 +1,338 @@
+#!/usr/bin/env python
+#
+# Performance and reliability test for serial port communication.
+#
+# Basic usage:
+#   serial_test.py [-t serial-device]
+#
+# The `serial-device` will default to /dev/ttyACM0.
+
+import argparse
+import random
+import serial
+import sys
+import time
+
+run_tests_module = __import__("run-tests")
+
+echo_test_script = """
+import sys
+bytes_min=%u
+bytes_max=%u
+repeat=%u
+b=memoryview(bytearray(bytes_max))
+for n in range(bytes_min,bytes_max+1):
+    for _ in range(repeat):
+        n2 = sys.stdin.readinto(b[:n])
+        sys.stdout.write(b[:n2])
+"""
+
+read_test_script = """
+bin = True
+try:
+    wr=__import__("pyb").USB_VCP(0).send
+except:
+    import sys
+    if hasattr(sys.stdout,'buffer'):
+        wr=sys.stdout.buffer.write
+    else:
+        wr=sys.stdout.write
+        bin = False
+b=bytearray(%u)
+if bin:
+    wr('BIN')
+    for i in range(len(b)):
+        b[i] = i & 0xff
+else:
+    wr('TXT')
+    for i in range(len(b)):
+        b[i] = 0x20 + (i & 0x3f)
+for _ in range(%d):
+    wr(b)
+"""
+
+
+write_test_script_verified = """
+import sys
+try:
+    rd=__import__("pyb").USB_VCP(0).recv
+except:
+    rd=sys.stdin.readinto
+b=bytearray(%u)
+for _ in range(%u):
+    n = rd(b)
+    fail = 0
+    for i in range(n):
+        if b[i] != 32 + (i & 0x3f):
+            fail += 1
+    if fail:
+        sys.stdout.write(b'ER%%05u' %% fail)
+    else:
+        sys.stdout.write(b'OK%%05u' %% n)
+"""
+
+write_test_script_unverified = """
+import sys
+try:
+    rd=__import__("pyb").USB_VCP(0).recv
+except:
+    rd=sys.stdin.readinto
+b=bytearray(%u)
+for _ in range(%u):
+    n = rd(b)
+    if n != len(b):
+        sys.stdout.write(b'ER%%05u' %% n)
+    else:
+        sys.stdout.write(b'OK%%05u' %% n)
+"""
+
+
+class TestError(Exception):
+    pass
+
+
+def drain_input(ser):
+    time.sleep(0.1)
+    while ser.inWaiting() > 0:
+        data = ser.read(ser.inWaiting())
+        time.sleep(0.1)
+
+
+def send_script(ser, script):
+    ser.write(b"\x03\x01\x04")  # break, raw-repl, soft-reboot
+    drain_input(ser)
+    chunk_size = 32
+    for i in range(0, len(script), chunk_size):
+        ser.write(script[i : i + chunk_size])
+        time.sleep(0.01)
+    ser.write(b"\x04")  # eof
+    ser.flush()
+    response = ser.read(2)
+    if response != b"OK":
+        response += ser.read(ser.inWaiting())
+        raise TestError("could not send script", response)
+
+
+def echo_test(ser_repl, ser_data):
+    global test_passed
+
+    # Make the test data deterministic.
+    random.seed(0)
+
+    # Set parameters for the test.
+    # Go just a bit above the size of a USB high-speed packet.
+    bytes_min = 1
+    bytes_max = 520
+    num_repeat = 1
+
+    # Load and run the write_test_script.
+    script = bytes(echo_test_script % (bytes_min, bytes_max, num_repeat), "ascii")
+    send_script(ser_repl, script)
+
+    # A selection of printable bytes for echo data.
+    printable_bytes = list(range(48, 58)) + list(range(65, 91)) + list(range(97, 123))
+
+    # Write data to the device and record the echo'd data.
+    # Use a different selection of random printable characters for each
+    # echo, to make it easier to debug when the echo doesn't match.
+    num_errors = 0
+    echo_results = []
+    for num_bytes in range(bytes_min, bytes_max + 1):
+        print(f"DATA ECHO: {num_bytes} / {bytes_max}", end="\r")
+        for repeat in range(num_repeat):
+            rand_bytes = list(random.choice(printable_bytes) for _ in range(8))
+            buf = bytes(random.choice(rand_bytes) for _ in range(num_bytes))
+            ser_data.write(buf)
+            buf2 = ser_data.read(len(buf))
+            match = buf == buf2
+            num_errors += not match
+            echo_results.append((match, buf, buf2))
+        if num_errors > 8:
+            # Stop early if there are too many errors.
+            break
+    ser_repl.write(b"\x03")
+
+    # Print results.
+    if all(match for match, _, _ in echo_results):
+        print("DATA ECHO: OK for {}-{} bytes at a time".format(bytes_min, bytes_max))
+    else:
+        test_passed = False
+        print("DATA ECHO: FAIL     ")
+        for match, buf, buf2 in echo_results:
+            print("  sent", len(buf), buf)
+            if match:
+                print("  echo match")
+            else:
+                print("  echo", len(buf), buf2)
+
+
+def read_test(ser_repl, ser_data, bufsize, nbuf):
+    global test_passed
+
+    assert bufsize % 256 == 0  # for verify to work
+
+    # how long to wait for data from device
+    # (if UART TX is also enabled then it can take 1.4s to send
+    # out a 16KB butter at 115200bps)
+    READ_TIMEOUT_S = 2
+
+    # Load and run the read_test_script.
+    script = bytes(read_test_script % (bufsize, nbuf), "ascii")
+    send_script(ser_repl, script)
+
+    # Read from the device the type of data that it will send (BIN or TXT).
+    data_type = ser_data.read(3)
+
+    # Read data from the device, check it is correct, and measure throughput.
+    n = 0
+    last_byte = None
+    t_start = time.time()
+    remain = nbuf * bufsize
+    total_data = bytearray(remain)
+    while remain:
+        t0 = time.monotonic_ns()
+        while ser_data.inWaiting() == 0:
+            if time.monotonic_ns() - t0 > READ_TIMEOUT_S * 1e9:
+                # timeout waiting for data from device
+                break
+            time.sleep(0.0001)
+        if not ser_data.inWaiting():
+            test_passed = False
+            print("ERROR: timeout waiting for data")
+            print(total_data[:n])
+            return 0
+        to_read = min(ser_data.inWaiting(), remain)
+        data = ser_data.read(to_read)
+        remain -= len(data)
+        print(f"{n} / {nbuf * bufsize}", end="\r")
+        total_data[n : n + len(data)] = data
+        n += len(data)
+    t_end = time.time()
+    for i in range(0, len(total_data)):
+        if data_type == b"BIN":
+            wanted = i & 0xFF
+        else:
+            wanted = 0x20 + (i & 0x3F)
+        if total_data[i] != wanted:
+            test_passed = False
+            print("ERROR: data mismatch:", i, wanted, total_data[i])
+    ser_repl.write(b"\x03")  # break
+    t = t_end - t_start
+
+    # Print results.
+    print(
+        "DATA IN: bufsize=%u, read %u bytes in %.2f msec = %.2f kibytes/sec = %.2f MBits/sec"
+        % (bufsize, n, t * 1000, n / 1024 / t, n * 8 / 1000000 / t)
+    )
+
+    return n / t
+
+
+def write_test(ser_repl, ser_data, bufsize, nbuf, verified):
+    global test_passed
+
+    # Load and run the write_test_script.
+    if verified:
+        script = write_test_script_verified
+    else:
+        script = write_test_script_unverified
+    script = bytes(script % (bufsize, nbuf), "ascii")
+    send_script(ser_repl, script)
+    drain_input(ser_repl)
+
+    # Write data to the device, check it is correct, and measure throughput.
+    n = 0
+    t_start = time.time()
+    buf = bytearray(bufsize)
+    for i in range(len(buf)):
+        buf[i] = 32 + (i & 0x3F)  # don't want to send ctrl chars!
+    for i in range(nbuf):
+        ser_data.write(buf)
+        n += len(buf)
+        print(f"{n} / {nbuf * bufsize}", end="\r")
+        response = ser_repl.read(7)
+        if response != b"OK%05u" % bufsize:
+            test_passed = False
+            print("ERROR: bad response, expecting OK%05u, got %r" % (bufsize, response))
+    t_end = time.time()
+    ser_repl.write(b"\x03")  # break
+    t = t_end - t_start
+
+    # Print results.
+    print(
+        "DATA OUT: verify=%d, bufsize=%u, wrote %u bytes in %.2f msec = %.2f kibytes/sec = %.2f MBits/sec"
+        % (verified, bufsize, n, t * 1000, n / 1024 / t, n * 8 / 1000000 / t)
+    )
+
+    return n / t
+
+
+def do_test(dev_repl, dev_data=None, time_per_subtest=1):
+    if dev_data is None:
+        print("REPL and data on", dev_repl)
+        ser_repl = serial.Serial(dev_repl, baudrate=115200, timeout=1)
+        ser_data = ser_repl
+    else:
+        print("REPL on", dev_repl)
+        print("data on", dev_data)
+        ser_repl = serial.Serial(dev_repl, baudrate=115200, timeout=1)
+        ser_data = serial.Serial(dev_data, baudrate=115200, timeout=1)
+
+    # Do echo test first, and abort if it doesn't pass.
+    echo_test(ser_repl, ser_data)
+    if not test_passed:
+        return
+
+    # Do read and write throughput test.
+    for test_func, test_args, bufsize in (
+        (read_test, (), 256),
+        (write_test, (True,), 128),
+        (write_test, (False,), 128),
+    ):
+        nbuf = 128
+        while bufsize <= 16384:
+            rate = test_func(ser_repl, ser_data, bufsize, nbuf, *test_args)
+            bufsize *= 2
+            if rate:
+                # Adjust the amount of data based on the rate, to keep each subtest
+                # at around time_per_subtest seconds long.
+                nbuf = max(min(128, int(rate * time_per_subtest / bufsize)), 1)
+
+    ser_repl.close()
+    ser_data.close()
+
+
+def main():
+    global test_passed
+
+    cmd_parser = argparse.ArgumentParser(
+        description="Test performance and reliability of serial port communication.",
+        epilog=run_tests_module.test_instance_epilog,
+        formatter_class=argparse.RawTextHelpFormatter,
+    )
+    cmd_parser.add_argument(
+        "-t",
+        "--test-instance",
+        default="a0",
+        help="MicroPython instance to test",
+    )
+    cmd_parser.add_argument(
+        "--time-per-subtest", default="1", help="approximate time to take per subtest (in seconds)"
+    )
+    args = cmd_parser.parse_args()
+
+    dev_repl = run_tests_module.convert_device_shortcut_to_real_device(args.test_instance)
+
+    test_passed = True
+    try:
+        do_test(dev_repl, None, float(args.time_per_subtest))
+    except TestError as er:
+        test_passed = False
+        print("ERROR:", er)
+
+    if not test_passed:
+        sys.exit(1)
+
+
+if __name__ == "__main__":
+    main()
diff --git a/tests/stress/bytecode_limit.py b/tests/stress/bytecode_limit.py
index 948d7668da551..0a72b66fa05b6 100644
--- a/tests/stress/bytecode_limit.py
+++ b/tests/stress/bytecode_limit.py
@@ -1,19 +1,29 @@
 # Test the limits of bytecode generation.
 
+import sys
+
+# Tune the test parameters based on the target's bytecode generator.
+if hasattr(sys.implementation, "_mpy"):
+    # Target can load .mpy files so generated bytecode uses 1 byte per qstr.
+    number_of_body_copies = (433, 432, 431, 399)
+else:
+    # Target can't load .mpy files so generated bytecode uses 2 bytes per qstr.
+    number_of_body_copies = (401, 400, 399, 398)
+
 body = " with f()()() as a:\n  try:\n   f()()()\n  except Exception:\n   pass\n"
 
 # Test overflow of jump offset.
 # Print results at the end in case an intermediate value of n fails with MemoryError.
 results = []
-for n in (433, 432, 431, 430):
+for n in number_of_body_copies:
     try:
         exec("cond = 0\nif cond:\n" + body * n + "else:\n print('cond false')\n")
-        results.append((n, "ok"))
+        results.append("ok")
     except MemoryError:
         print("SKIP")
         raise SystemExit
-    except RuntimeError:
-        results.append((n, "RuntimeError"))
+    except RuntimeError as er:
+        results.append(repr(er))
 print(results)
 
 # Test changing size of code info (source line/bytecode mapping) due to changing
diff --git a/tests/stress/bytecode_limit.py.exp b/tests/stress/bytecode_limit.py.exp
index cda52b1b97348..50511665f0076 100644
--- a/tests/stress/bytecode_limit.py.exp
+++ b/tests/stress/bytecode_limit.py.exp
@@ -1,4 +1,4 @@
 cond false
 cond false
-[(433, 'RuntimeError'), (432, 'RuntimeError'), (431, 'ok'), (430, 'ok')]
+["RuntimeError('bytecode overflow',)", "RuntimeError('bytecode overflow',)", 'ok', 'ok']
 [123]
diff --git a/tests/stress/dict_copy.py b/tests/stress/dict_copy.py
index 73d3a5b51d601..f9b742e20f716 100644
--- a/tests/stress/dict_copy.py
+++ b/tests/stress/dict_copy.py
@@ -1,6 +1,11 @@
 # copying a large dictionary
 
-a = {i: 2 * i for i in range(1000)}
+try:
+    a = {i: 2 * i for i in range(1000)}
+except MemoryError:
+    print("SKIP")
+    raise SystemExit
+
 b = a.copy()
 for i in range(1000):
     print(i, b[i])
diff --git a/tests/stress/dict_create.py b/tests/stress/dict_create.py
index e9db40a8e6c5b..91a83a12f9d85 100644
--- a/tests/stress/dict_create.py
+++ b/tests/stress/dict_create.py
@@ -3,6 +3,10 @@
 d = {}
 x = 1
 while x < 1000:
-    d[x] = x
+    try:
+        d[x] = x
+    except MemoryError:
+        print("SKIP")
+        raise SystemExit
     x += 1
 print(d[500])
diff --git a/tests/stress/fun_call_limit.py b/tests/stress/fun_call_limit.py
index b802aadd558c0..69f8aa5aec413 100644
--- a/tests/stress/fun_call_limit.py
+++ b/tests/stress/fun_call_limit.py
@@ -16,14 +16,16 @@ def test(n):
 
 
 # If the port has at least 32-bits then this test should pass.
-print(test(29))
+print(test(28))
 
 # This test should fail on all ports (overflows a small int).
 print(test(70))
 
-# Check that there is a correct transition to the limit of too many args before *args.
+# 28 is the biggest number that will pass on a 32-bit port using object
+# representation B, which has 1<<28 still fitting in a positive small int.
 reached_limit = False
-for i in range(30, 70):
+any_test_succeeded = False
+for i in range(28, 70):
     result = test(i)
     if reached_limit:
         if result != "SyntaxError":
@@ -34,3 +36,5 @@ def test(n):
         else:
             if result != i + 4:
                 print("FAIL")
+            any_test_succeeded = True
+assert any_test_succeeded  # At least one iteration must have passed
diff --git a/tests/stress/fun_call_limit.py.exp b/tests/stress/fun_call_limit.py.exp
index 53d2b28043015..491abbfa8be72 100644
--- a/tests/stress/fun_call_limit.py.exp
+++ b/tests/stress/fun_call_limit.py.exp
@@ -1,2 +1,2 @@
-33
+32
 SyntaxError
diff --git a/tests/stress/qstr_limit.py b/tests/stress/qstr_limit.py
index 08b10a039f509..c7bd437f3adc1 100644
--- a/tests/stress/qstr_limit.py
+++ b/tests/stress/qstr_limit.py
@@ -12,8 +12,8 @@ def make_id(n, base="a"):
     var = make_id(l)
     try:
         exec(var + "=1", g)
-    except RuntimeError:
-        print("RuntimeError", l)
+    except RuntimeError as er:
+        print("RuntimeError", er, l)
         continue
     print(var in g)
 
@@ -26,16 +26,16 @@ def f(**k):
 for l in range(254, 259):
     try:
         exec("f({}=1)".format(make_id(l)))
-    except RuntimeError:
-        print("RuntimeError", l)
+    except RuntimeError as er:
+        print("RuntimeError", er, l)
 
 # type construction
 for l in range(254, 259):
     id = make_id(l)
     try:
-        print(type(id, (), {}).__name__)
-    except RuntimeError:
-        print("RuntimeError", l)
+        print(type(id, (), {}))
+    except RuntimeError as er:
+        print("RuntimeError", er, l)
 
 
 # hasattr, setattr, getattr
@@ -48,28 +48,20 @@ class A:
     a = A()
     try:
         setattr(a, id, 123)
-    except RuntimeError:
-        print("RuntimeError", l)
+    except RuntimeError as er:
+        print("RuntimeError", er, l)
     try:
         print(hasattr(a, id), getattr(a, id))
-    except RuntimeError:
-        print("RuntimeError", l)
+    except RuntimeError as er:
+        print("RuntimeError", er, l)
 
 # format with keys
 for l in range(254, 259):
     id = make_id(l)
     try:
         print(("{" + id + "}").format(**{id: l}))
-    except RuntimeError:
-        print("RuntimeError", l)
-
-# modulo format with keys
-for l in range(254, 259):
-    id = make_id(l)
-    try:
-        print(("%(" + id + ")d") % {id: l})
-    except RuntimeError:
-        print("RuntimeError", l)
+    except RuntimeError as er:
+        print("RuntimeError", er, l)
 
 # import module
 # (different OS's have different results so only run those that are consistent)
@@ -78,8 +70,8 @@ class A:
         __import__(make_id(l))
     except ImportError:
         print("ok", l)
-    except RuntimeError:
-        print("RuntimeError", l)
+    except RuntimeError as er:
+        print("RuntimeError", er, l)
 
 # import package
 for l in (100, 101, 102, 128, 129):
@@ -87,5 +79,5 @@ class A:
         exec("import " + make_id(l) + "." + make_id(l, "A"))
     except ImportError:
         print("ok", l)
-    except RuntimeError:
-        print("RuntimeError", l)
+    except RuntimeError as er:
+        print("RuntimeError", er, l)
diff --git a/tests/stress/qstr_limit.py.exp b/tests/stress/qstr_limit.py.exp
index 455761bc71e4a..2349adf220f98 100644
--- a/tests/stress/qstr_limit.py.exp
+++ b/tests/stress/qstr_limit.py.exp
@@ -1,43 +1,38 @@
 True
 True
-RuntimeError 256
-RuntimeError 257
-RuntimeError 258
+RuntimeError name too long 256
+RuntimeError name too long 257
+RuntimeError name too long 258
 {'abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrst': 1}
 {'abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstu': 1}
-RuntimeError 256
-RuntimeError 257
-RuntimeError 258
-abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrst
-abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstu
-RuntimeError 256
-RuntimeError 257
-RuntimeError 258
+RuntimeError name too long 256
+RuntimeError name too long 257
+RuntimeError name too long 258
+<class 'abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrst'>
+<class 'abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstu'>
+RuntimeError name too long 256
+RuntimeError name too long 257
+RuntimeError name too long 258
 True 123
 True 123
-RuntimeError 256
-RuntimeError 256
-RuntimeError 257
-RuntimeError 257
-RuntimeError 258
-RuntimeError 258
+RuntimeError name too long 256
+RuntimeError name too long 256
+RuntimeError name too long 257
+RuntimeError name too long 257
+RuntimeError name too long 258
+RuntimeError name too long 258
 254
 255
-RuntimeError 256
-RuntimeError 257
-RuntimeError 258
-254
-255
-RuntimeError 256
-RuntimeError 257
-RuntimeError 258
+RuntimeError name too long 256
+RuntimeError name too long 257
+RuntimeError name too long 258
 ok 100
 ok 101
-RuntimeError 256
-RuntimeError 257
-RuntimeError 258
+RuntimeError name too long 256
+RuntimeError name too long 257
+RuntimeError name too long 258
 ok 100
 ok 101
 ok 102
-RuntimeError 128
-RuntimeError 129
+RuntimeError name too long 128
+RuntimeError name too long 129
diff --git a/tests/stress/qstr_limit_str_modulo.py b/tests/stress/qstr_limit_str_modulo.py
new file mode 100644
index 0000000000000..90b9f4364ec6f
--- /dev/null
+++ b/tests/stress/qstr_limit_str_modulo.py
@@ -0,0 +1,21 @@
+# Test interning qstrs that go over the qstr length limit (255 bytes in default configuration).
+# The tests here are specifically for str formatting with %.
+
+try:
+    "" % ()
+except TypeError:
+    print("SKIP")
+    raise SystemExit
+
+
+def make_id(n, base="a"):
+    return "".join(chr(ord(base) + i % 26) for i in range(n))
+
+
+# modulo format with keys
+for l in range(254, 259):
+    id = make_id(l)
+    try:
+        print(("%(" + id + ")d") % {id: l})
+    except RuntimeError as er:
+        print("RuntimeError", er, l)
diff --git a/tests/stress/qstr_limit_str_modulo.py.exp b/tests/stress/qstr_limit_str_modulo.py.exp
new file mode 100644
index 0000000000000..3632c85bffea3
--- /dev/null
+++ b/tests/stress/qstr_limit_str_modulo.py.exp
@@ -0,0 +1,5 @@
+254
+255
+RuntimeError name too long 256
+RuntimeError name too long 257
+RuntimeError name too long 258
diff --git a/tests/stress/recursive_iternext.py b/tests/stress/recursive_iternext.py
index bbc389e726237..c737f1e36d70a 100644
--- a/tests/stress/recursive_iternext.py
+++ b/tests/stress/recursive_iternext.py
@@ -1,4 +1,8 @@
 # This tests that recursion with iternext doesn't lead to segfault.
+#
+# This test segfaults CPython, but that's not a bug as CPython doesn't enforce
+# limits on C recursion - see
+# https://github.com/python/cpython/issues/58218#issuecomment-1093570209
 try:
     enumerate
     filter
@@ -9,49 +13,25 @@
     print("SKIP")
     raise SystemExit
 
-# We need to pick an N that is large enough to hit the recursion
-# limit, but not too large that we run out of heap memory.
-try:
-    # large stack/heap, eg unix
-    [0] * 80000
-    N = 5000
-except:
-    try:
-        # medium, eg pyboard
-        [0] * 10000
-        N = 1000
-    except:
-        # small, eg esp8266
-        N = 100
-
-try:
-    x = (1, 2)
-    for i in range(N):
-        x = enumerate(x)
-    tuple(x)
-except RuntimeError:
-    print("RuntimeError")
 
-try:
+# Progressively build a bigger nested iterator structure (10 at a time for speed),
+# and then try to evaluate it via tuple(x) which makes deep recursive function calls.
+#
+# Eventually this should raise a RuntimeError as MicroPython runs out of stack.
+# It shouldn't ever raise a MemoryError, if it does then somehow MicroPython has
+# run out of heap (for the nested structure) before running out of stack.
+def recurse_iternext(nested_fn):
     x = (1, 2)
-    for i in range(N):
-        x = filter(None, x)
-    tuple(x)
-except RuntimeError:
-    print("RuntimeError")
+    while True:
+        for _ in range(10):
+            x = nested_fn(x)
+        try:
+            tuple(x)
+        except RuntimeError:
+            print("RuntimeError")
+            break
 
-try:
-    x = (1, 2)
-    for i in range(N):
-        x = map(max, x, ())
-    tuple(x)
-except RuntimeError:
-    print("RuntimeError")
 
-try:
-    x = (1, 2)
-    for i in range(N):
-        x = zip(x)
-    tuple(x)
-except RuntimeError:
-    print("RuntimeError")
+# Test on various nested iterator structures
+for nested_fn in [enumerate, lambda x: filter(None, x), lambda x: map(max, x, ()), zip]:
+    recurse_iternext(nested_fn)
diff --git a/tests/target_wiring/EK_RA6M2.py b/tests/target_wiring/EK_RA6M2.py
new file mode 100644
index 0000000000000..7d4a8cbbd6484
--- /dev/null
+++ b/tests/target_wiring/EK_RA6M2.py
@@ -0,0 +1,8 @@
+# Target wiring for EK_RA6M2.
+#
+# Connect:
+# - P601 to P602
+
+# UART(9) is on P602/P601.
+uart_loopback_args = (9,)
+uart_loopback_kwargs = {}
diff --git a/tests/target_wiring/NUCLEO_WB55.py b/tests/target_wiring/NUCLEO_WB55.py
new file mode 100644
index 0000000000000..ad7c120d3770e
--- /dev/null
+++ b/tests/target_wiring/NUCLEO_WB55.py
@@ -0,0 +1,8 @@
+# Target wiring for NUCLEO_WB55.
+#
+# Connect:
+# - PA2 to PA3
+
+# LPUART(1) is on PA2/PA3.
+uart_loopback_args = ("LP1",)
+uart_loopback_kwargs = {}
diff --git a/tests/target_wiring/PYBx.py b/tests/target_wiring/PYBx.py
new file mode 100644
index 0000000000000..10ce520ef0af4
--- /dev/null
+++ b/tests/target_wiring/PYBx.py
@@ -0,0 +1,8 @@
+# Target wiring for PYBV10, PYBV11, PYBLITEV10, PYBD_SF2, PYBD_SF3, PYBD_SF6.
+#
+# Connect:
+# - X1 to X2
+
+# UART("XA") is on X1/X2  (usually UART(4) on PA0/PA1).
+uart_loopback_args = ("XA",)
+uart_loopback_kwargs = {}
diff --git a/tests/target_wiring/ZEPHYR_NUCLEO_WB55RG.py b/tests/target_wiring/ZEPHYR_NUCLEO_WB55RG.py
new file mode 100644
index 0000000000000..c7ca2ac26f794
--- /dev/null
+++ b/tests/target_wiring/ZEPHYR_NUCLEO_WB55RG.py
@@ -0,0 +1,7 @@
+# Target wiring for zephyr nucleo_wb55rg.
+#
+# Connect:
+# - TX=PC0 to RX=PC1
+
+uart_loopback_args = ("lpuart1",)
+uart_loopback_kwargs = {}
diff --git a/tests/target_wiring/alif.py b/tests/target_wiring/alif.py
new file mode 100644
index 0000000000000..18f3cbe7e5e0d
--- /dev/null
+++ b/tests/target_wiring/alif.py
@@ -0,0 +1,7 @@
+# Target wiring for general alif board.
+#
+# Connect:
+# - UART1 TX and RX, usually P0_5 and P0_4
+
+uart_loopback_args = (1,)
+uart_loopback_kwargs = {}
diff --git a/tests/target_wiring/esp32.py b/tests/target_wiring/esp32.py
new file mode 100644
index 0000000000000..2767cd5acb2e8
--- /dev/null
+++ b/tests/target_wiring/esp32.py
@@ -0,0 +1,12 @@
+# Target wiring for general esp32 board.
+#
+# Connect:
+# - GPIO4 to GPIO5
+# - GPIO12 to GPIO13
+
+uart_loopback_args = (1,)
+uart_loopback_kwargs = {"tx": 4, "rx": 5}
+
+encoder_loopback_id = 0
+encoder_loopback_out_pins = (4, 12)
+encoder_loopback_in_pins = (5, 13)
diff --git a/tests/target_wiring/mimxrt.py b/tests/target_wiring/mimxrt.py
new file mode 100644
index 0000000000000..669e9095990db
--- /dev/null
+++ b/tests/target_wiring/mimxrt.py
@@ -0,0 +1,7 @@
+# Target wiring for general mimxrt board.
+#
+# Connect:
+# - UART1 TX and RX, usually D0 and D1
+
+uart_loopback_args = (1,)
+uart_loopback_kwargs = {}
diff --git a/tests/target_wiring/nrf.py b/tests/target_wiring/nrf.py
new file mode 100644
index 0000000000000..6979dd28ee595
--- /dev/null
+++ b/tests/target_wiring/nrf.py
@@ -0,0 +1,7 @@
+# Target wiring for general nrf board.
+#
+# Connect:
+# - UART0 TX and RX
+
+uart_loopback_args = (0,)
+uart_loopback_kwargs = {}
diff --git a/tests/target_wiring/rp2.py b/tests/target_wiring/rp2.py
new file mode 100644
index 0000000000000..cb0fa0d626339
--- /dev/null
+++ b/tests/target_wiring/rp2.py
@@ -0,0 +1,7 @@
+# Target wiring for general rp2 board.
+#
+# Connect:
+# - GPIO0 to GPIO1
+
+uart_loopback_args = (0,)
+uart_loopback_kwargs = {"tx": "GPIO0", "rx": "GPIO1"}
diff --git a/tests/target_wiring/samd.py b/tests/target_wiring/samd.py
new file mode 100644
index 0000000000000..887c43a242f9b
--- /dev/null
+++ b/tests/target_wiring/samd.py
@@ -0,0 +1,7 @@
+# Target wiring for general samd board.
+#
+# Connect:
+# - D0 to D1
+
+uart_loopback_args = ()
+uart_loopback_kwargs = {"tx": "D1", "rx": "D0"}
diff --git a/tests/thread/disable_irq.py b/tests/thread/disable_irq.py
index 3f1ac74f30877..596e3e477b9c8 100644
--- a/tests/thread/disable_irq.py
+++ b/tests/thread/disable_irq.py
@@ -1,8 +1,14 @@
 # Ensure that disabling IRQs creates mutual exclusion between threads
 # (also tests nesting of disable_irq across threads)
-import machine
-import time
-import _thread
+
+# CIRCUITPY-CHANGE: no machine
+try:
+    import machine
+    import time
+    import _thread
+except ImportError:
+    print("SKIP")
+    raise SystemExit
 
 if not hasattr(machine, "disable_irq"):
     print("SKIP")
diff --git a/tests/thread/mutate_bytearray.py b/tests/thread/mutate_bytearray.py
index b4664781a1522..7116d291cfeec 100644
--- a/tests/thread/mutate_bytearray.py
+++ b/tests/thread/mutate_bytearray.py
@@ -2,6 +2,7 @@
 #
 # MIT license; Copyright (c) 2016 Damien P. George on behalf of Pycom Ltd
 
+import time
 import _thread
 
 # the shared bytearray
@@ -36,7 +37,7 @@ def th(n, lo, hi):
 
 # busy wait for threads to finish
 while n_finished < n_thread:
-    pass
+    time.sleep(0)
 
 # check bytearray has correct contents
 print(len(ba))
diff --git a/tests/thread/mutate_dict.py b/tests/thread/mutate_dict.py
index 3777af66248c6..dd5f69e6c5d66 100644
--- a/tests/thread/mutate_dict.py
+++ b/tests/thread/mutate_dict.py
@@ -2,6 +2,7 @@
 #
 # MIT license; Copyright (c) 2016 Damien P. George on behalf of Pycom Ltd
 
+import time
 import _thread
 
 # the shared dict
@@ -38,7 +39,7 @@ def th(n, lo, hi):
 
 # busy wait for threads to finish
 while n_finished < n_thread:
-    pass
+    time.sleep(0)
 
 # check dict has correct contents
 print(sorted(di.items()))
diff --git a/tests/thread/mutate_instance.py b/tests/thread/mutate_instance.py
index 306ad91c95cfa..63f7fb1e23df8 100644
--- a/tests/thread/mutate_instance.py
+++ b/tests/thread/mutate_instance.py
@@ -2,6 +2,7 @@
 #
 # MIT license; Copyright (c) 2016 Damien P. George on behalf of Pycom Ltd
 
+import time
 import _thread
 
 
@@ -40,7 +41,7 @@ def th(n, lo, hi):
 
 # busy wait for threads to finish
 while n_finished < n_thread:
-    pass
+    time.sleep(0)
 
 # check user instance has correct contents
 print(user.a, user.b, user.c)
diff --git a/tests/thread/mutate_list.py b/tests/thread/mutate_list.py
index 6f1e8812541a0..d7398a2f1e0b4 100644
--- a/tests/thread/mutate_list.py
+++ b/tests/thread/mutate_list.py
@@ -2,6 +2,7 @@
 #
 # MIT license; Copyright (c) 2016 Damien P. George on behalf of Pycom Ltd
 
+import time
 import _thread
 
 # the shared list
@@ -39,7 +40,7 @@ def th(n, lo, hi):
 
 # busy wait for threads to finish
 while n_finished < n_thread:
-    pass
+    time.sleep(0)
 
 # check list has correct contents
 li.sort()
diff --git a/tests/thread/mutate_set.py b/tests/thread/mutate_set.py
index 2d9a3e0ce9efd..7dcefa1d113f9 100644
--- a/tests/thread/mutate_set.py
+++ b/tests/thread/mutate_set.py
@@ -2,6 +2,7 @@
 #
 # MIT license; Copyright (c) 2016 Damien P. George on behalf of Pycom Ltd
 
+import time
 import _thread
 
 # the shared set
@@ -33,7 +34,7 @@ def th(n, lo, hi):
 
 # busy wait for threads to finish
 while n_finished < n_thread:
-    pass
+    time.sleep(0)
 
 # check set has correct contents
 print(sorted(se))
diff --git a/tests/thread/stress_aes.py b/tests/thread/stress_aes.py
index d8d0acd568a7a..ca25f8ad2fd57 100644
--- a/tests/thread/stress_aes.py
+++ b/tests/thread/stress_aes.py
@@ -277,7 +277,7 @@ def thread_entry(n_loop):
         n_thread = 2
         n_loop = 2
     else:
-        n_thread = 20
+        n_thread = 10
         n_loop = 5
     for i in range(n_thread):
         _thread.start_new_thread(thread_entry, (n_loop,))
diff --git a/tests/thread/stress_recurse.py b/tests/thread/stress_recurse.py
index 73b3a40f33daa..ec8b43fe8fc22 100644
--- a/tests/thread/stress_recurse.py
+++ b/tests/thread/stress_recurse.py
@@ -2,6 +2,7 @@
 #
 # MIT license; Copyright (c) 2016 Damien P. George on behalf of Pycom Ltd
 
+import time
 import _thread
 
 
@@ -24,5 +25,5 @@ def thread_entry():
 
 # busy wait for thread to finish
 while not finished:
-    pass
+    time.sleep(0)
 print("done")
diff --git a/tests/thread/stress_schedule.py b/tests/thread/stress_schedule.py
index 97876f0f77ca8..362d71aa12e38 100644
--- a/tests/thread/stress_schedule.py
+++ b/tests/thread/stress_schedule.py
@@ -27,6 +27,8 @@ def task(x):
     n += 1
 
 
+# This function must always use the bytecode emitter so it bounces the GIL when running.
+@micropython.bytecode
 def thread():
     while thread_run:
         try:
@@ -46,7 +48,7 @@ def thread():
 # Wait up to 10 seconds for 10000 tasks to be scheduled.
 t = time.ticks_ms()
 while n < _NUM_TASKS and time.ticks_diff(time.ticks_ms(), t) < _TIMEOUT_MS:
-    pass
+    time.sleep(0)
 
 # Stop all threads.
 thread_run = False
diff --git a/tests/thread/thread_coop.py b/tests/thread/thread_coop.py
index aefc4af074db5..85cda789c936e 100644
--- a/tests/thread/thread_coop.py
+++ b/tests/thread/thread_coop.py
@@ -7,6 +7,7 @@
 import _thread
 import sys
 from time import ticks_ms, ticks_diff, sleep_ms
+import micropython
 
 
 done = False
@@ -21,6 +22,8 @@
     MAX_DELTA = 100
 
 
+# This function must always use the bytecode emitter so the VM can bounce the GIL when running.
+@micropython.bytecode
 def busy_thread():
     while not done:
         pass
diff --git a/tests/thread/thread_exc1.py b/tests/thread/thread_exc1.py
index cd87740929103..cd6599983c141 100644
--- a/tests/thread/thread_exc1.py
+++ b/tests/thread/thread_exc1.py
@@ -2,6 +2,7 @@
 #
 # MIT license; Copyright (c) 2016 Damien P. George on behalf of Pycom Ltd
 
+import time
 import _thread
 
 
@@ -34,5 +35,5 @@ def thread_entry():
 
 # busy wait for threads to finish
 while n_finished < n_thread:
-    pass
+    time.sleep(0)
 print("done")
diff --git a/tests/thread/thread_exc2.py.native.exp b/tests/thread/thread_exc2.py.native.exp
new file mode 100644
index 0000000000000..9b2e715ef8dfc
--- /dev/null
+++ b/tests/thread/thread_exc2.py.native.exp
@@ -0,0 +1,3 @@
+Unhandled exception in thread started by <function thread_entry at 0x\[0-9a-f\]\+>
+ValueError: 
+done
diff --git a/tests/thread/thread_gc1.py b/tests/thread/thread_gc1.py
index b36ea9d4c8421..45c17cc17bed3 100644
--- a/tests/thread/thread_gc1.py
+++ b/tests/thread/thread_gc1.py
@@ -2,6 +2,7 @@
 #
 # MIT license; Copyright (c) 2016 Damien P. George on behalf of Pycom Ltd
 
+import time
 import gc
 import _thread
 
@@ -44,6 +45,6 @@ def thread_entry(n):
 
 # busy wait for threads to finish
 while n_finished < n_thread:
-    pass
+    time.sleep(0)
 
 print(n_correct == n_finished)
diff --git a/tests/thread/thread_ident1.py b/tests/thread/thread_ident1.py
index 2a3732eff53dc..08cfd3eb36e8a 100644
--- a/tests/thread/thread_ident1.py
+++ b/tests/thread/thread_ident1.py
@@ -2,6 +2,7 @@
 #
 # MIT license; Copyright (c) 2016 Damien P. George on behalf of Pycom Ltd
 
+import time
 import _thread
 
 
@@ -27,6 +28,6 @@ def thread_entry():
 new_tid = _thread.start_new_thread(thread_entry, ())
 
 while not finished:
-    pass
+    time.sleep(0)
 
 print("done", type(new_tid) == int, new_tid == tid)
diff --git a/tests/thread/thread_lock3.py b/tests/thread/thread_lock3.py
index a927dc6829e15..c5acfa21b7dc6 100644
--- a/tests/thread/thread_lock3.py
+++ b/tests/thread/thread_lock3.py
@@ -2,6 +2,7 @@
 #
 # MIT license; Copyright (c) 2016 Damien P. George on behalf of Pycom Ltd
 
+import time
 import _thread
 
 lock = _thread.allocate_lock()
@@ -26,4 +27,4 @@ def thread_entry(idx):
 
 # busy wait for threads to finish
 while n_finished < n_thread:
-    pass
+    time.sleep(0)
diff --git a/tests/thread/thread_lock4.py b/tests/thread/thread_lock4_intbig.py
similarity index 100%
rename from tests/thread/thread_lock4.py
rename to tests/thread/thread_lock4_intbig.py
diff --git a/tests/thread/thread_shared1.py b/tests/thread/thread_shared1.py
index 251e26fae6ca3..c2e33abcec7ee 100644
--- a/tests/thread/thread_shared1.py
+++ b/tests/thread/thread_shared1.py
@@ -2,6 +2,7 @@
 #
 # MIT license; Copyright (c) 2016 Damien P. George on behalf of Pycom Ltd
 
+import time
 import _thread
 
 
@@ -40,5 +41,5 @@ def thread_entry(n, tup):
 
 # busy wait for threads to finish
 while n_finished < n_thread:
-    pass
+    time.sleep(0)
 print(tup)
diff --git a/tests/thread/thread_shared2.py b/tests/thread/thread_shared2.py
index a1223c2b94f40..4ce9057ca017e 100644
--- a/tests/thread/thread_shared2.py
+++ b/tests/thread/thread_shared2.py
@@ -3,6 +3,7 @@
 #
 # MIT license; Copyright (c) 2016 Damien P. George on behalf of Pycom Ltd
 
+import time
 import _thread
 
 
@@ -31,5 +32,5 @@ def thread_entry(n, lst, idx):
 
 # busy wait for threads to finish
 while n_finished < n_thread:
-    pass
+    time.sleep(0)
 print(lst)
diff --git a/tests/thread/thread_stacksize1.py b/tests/thread/thread_stacksize1.py
index 140d165cb3497..75e1da9642f95 100644
--- a/tests/thread/thread_stacksize1.py
+++ b/tests/thread/thread_stacksize1.py
@@ -3,6 +3,7 @@
 # MIT license; Copyright (c) 2016 Damien P. George on behalf of Pycom Ltd
 
 import sys
+import time
 import _thread
 
 # different implementations have different minimum sizes
@@ -51,5 +52,5 @@ def thread_entry():
 
 # busy wait for threads to finish
 while n_finished < n_thread:
-    pass
+    time.sleep(0)
 print("done")
diff --git a/tests/thread/thread_stdin.py b/tests/thread/thread_stdin.py
index a469933f19b55..498b0a3a27022 100644
--- a/tests/thread/thread_stdin.py
+++ b/tests/thread/thread_stdin.py
@@ -5,6 +5,7 @@
 # This is a regression test for https://github.com/micropython/micropython/issues/15230
 # on rp2, but doubles as a general property to test across all ports.
 import sys
+import time
 import _thread
 
 try:
@@ -38,7 +39,7 @@ def is_done(self):
 # have run yet. The actual delay is <20ms but spinning here instead of
 # sleep(0.1) means the test can run on MP builds without float support.
 while not thread_waiter.is_done():
-    pass
+    time.sleep(0)
 
 # The background thread should have completed its wait by now.
 print(thread_waiter.is_done())
diff --git a/tests/unix/extra_coverage.py b/tests/unix/extra_coverage.py
index 0ea8f7886bfff..ec10a44ff39b3 100644
--- a/tests/unix/extra_coverage.py
+++ b/tests/unix/extra_coverage.py
@@ -6,6 +6,16 @@
 
 import errno
 import io
+import uctypes
+
+# create an int-like variable used for coverage of `mp_obj_get_ll`
+buf = bytearray(b"\xde\xad\xbe\xef")
+struct = uctypes.struct(
+    uctypes.addressof(buf),
+    {"f32": uctypes.UINT32 | 0},
+    uctypes.BIG_ENDIAN,
+)
+deadbeef = struct.f32
 
 data = extra_coverage()
 
@@ -23,6 +33,7 @@
 print(stream.read(1))  # read 1 byte encounters non-blocking error
 print(stream.readline())  # readline encounters non-blocking error
 print(stream.readinto(bytearray(10)))  # readinto encounters non-blocking error
+print(stream.readinto1(bytearray(10)))  # readinto1 encounters non-blocking error
 print(stream.write(b"1"))  # write encounters non-blocking error
 print(stream.write1(b"1"))  # write1 encounters non-blocking error
 stream.set_buf(b"123")
@@ -38,6 +49,28 @@
 stream.set_error(0)
 print(stream.ioctl(0, bytearray(10)))  # successful ioctl call
 
+print("# stream.readinto")
+
+# stream.readinto will read 3 bytes then try to read more to fill the buffer,
+# but on the second attempt will encounter EIO and should raise that error.
+stream.set_error(errno.EIO)
+stream.set_buf(b"123")
+buf = bytearray(4)
+try:
+    stream.readinto(buf)
+except OSError as er:
+    print("OSError", er.errno == errno.EIO)
+print(buf)
+
+# stream.readinto1 will read 3 bytes then should return them immediately, and
+# not encounter the EIO.
+stream.set_error(errno.EIO)
+stream.set_buf(b"123")
+buf = bytearray(4)
+print(stream.readinto1(buf), buf)
+
+print("# stream textio")
+
 stream2 = data[3]  # is textio
 print(stream2.read(1))  # read 1 byte encounters non-blocking error with textio stream
 
@@ -92,7 +125,7 @@
 
 print(returns_NULL())
 
-# test for freeze_mpy
+# test for freeze_mpy (importing prints several lines)
 import frozentest
 
 print(frozentest.__file__)
diff --git a/tests/unix/extra_coverage.py.exp b/tests/unix/extra_coverage.py.exp
index 4cd8b8666d270..cdb1145569497 100644
--- a/tests/unix/extra_coverage.py.exp
+++ b/tests/unix/extra_coverage.py.exp
@@ -2,25 +2,41 @@
 -123 +123  123
 -0123
 123
-123
-1ABCDEF
+123f
+123F
+7fffffffffffffff
+7FFFFFFFFFFFFFFF
+18446744073709551615
+789f
+789F
 ab abc ' abc' ' True' 'Tru'
 
 false true
 (null)
 -2147483648
 2147483648
-80000000
-80000000
+8000000f
+8000000F
 abc
 %
+.a  .
+<%>
+<aaaa>
+<true>
+<43690>
+<43690>
+<43690>
+<test>
+<1000.000000>
+<True>
+<9223372036854775807>
 # GC
-0x0
-0x0
+0
+0
 # GC part 2
 pass
 # tracked allocation
-m_tracked_head = 0x0
+m_tracked_head = 0
 0 1
 1 1
 2 1
@@ -37,7 +53,7 @@ m_tracked_head = 0x0
 5 1
 6 1
 7 1
-m_tracked_head = 0x0
+m_tracked_head = 0
 # vstr
 tests
 sts
@@ -91,6 +107,16 @@ data
 12345
 6
 -1
+0
+1
+0
+0.000000
+deadbeef
+c0ffee777c0ffee
+deadbeef
+0deadbeef
+c0ffee
+000c0ffee
 # runtime utils
 TypeError: unsupported type for __abs__: 'str'
 TypeError: unsupported types for __divmod__: 'str', 'str'
@@ -99,12 +125,10 @@ TypeError: unsupported types for __divmod__: 'str', 'str'
 2
 OverflowError: overflow converting long int to machine word
 OverflowError: overflow converting long int to machine word
+TypeError: can't convert NoneType to int
+TypeError: can't convert NoneType to int
 ValueError: 
 Warning: test
-# format float
-?
-+1e+00
-+1e+00
 # binary
 123
 456
@@ -124,6 +148,13 @@ unlocked
 KeyboardInterrupt: 
 KeyboardInterrupt: 
 10
+loop
+scheduled function
+loop
+scheduled function
+loop
+scheduled function
+scheduled function
 # ringbuf
 99 0
 98 1
@@ -185,11 +216,17 @@ None
 None
 None
 None
+None
 b'123'
 b'123'
 b'123'
 OSError
 0
+# stream.readinto
+OSError True
+bytearray(b'123\x00')
+3 bytearray(b'123\x00')
+# stream textio
 None
 None
 cpp None
@@ -215,7 +252,7 @@ b'\x00\xff'
 frzmpy4 1
 frzmpy4 2
 NULL
-uPy
+interned
 a long string that is not interned
 a string that has unicode αβγ chars
 b'bytes 1234\x01'
diff --git a/tests/unix/ffi_float2.py b/tests/unix/ffi_float2.py
index bbed6966627e1..eac6cd106cf43 100644
--- a/tests/unix/ffi_float2.py
+++ b/tests/unix/ffi_float2.py
@@ -29,4 +29,5 @@ def ffi_open(names):
 
 for fun in (tgammaf,):
     for val in (0.5, 1, 1.0, 1.5, 4, 4.0):
-        print("%.6f" % fun(val))
+        # limit to 5 decimals in order to pass with REPR_C with FORMAT_IMPL_BASIC
+        print("%.5f" % fun(val))
diff --git a/tests/unix/ffi_float2.py.exp b/tests/unix/ffi_float2.py.exp
index 58fc6a01acb07..4c750e223a3a6 100644
--- a/tests/unix/ffi_float2.py.exp
+++ b/tests/unix/ffi_float2.py.exp
@@ -1,6 +1,6 @@
-1.772454
-1.000000
-1.000000
-0.886227
-6.000000
-6.000000
+1.77245
+1.00000
+1.00000
+0.88623
+6.00000
+6.00000
diff --git a/tests/unix/mod_os.py b/tests/unix/mod_os.py
index f69fa45b2b22a..468f6badd1e75 100644
--- a/tests/unix/mod_os.py
+++ b/tests/unix/mod_os.py
@@ -1,6 +1,9 @@
 # This module is not entirely compatible with CPython
 import os
 
+if not hasattr(os, "getenv"):
+    print("SKIP")
+    raise SystemExit
 
 os.putenv("TEST_VARIABLE", "TEST_VALUE")
 
diff --git a/tests/unix/time_mktime_localtime.py b/tests/unix/time_mktime_localtime.py
index d1c03c103d704..df5d6cda690a2 100644
--- a/tests/unix/time_mktime_localtime.py
+++ b/tests/unix/time_mktime_localtime.py
@@ -1,4 +1,8 @@
-import time
+try:
+    import time
+except ImportError:
+    print("SKIP")
+    raise SystemExit
 
 DAYS_PER_MONTH = [0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]
 
diff --git a/tools/analyze_heap_dump.py b/tools/analyze_heap_dump.py
index ac1bb0c8ce592..a7be95db7d9f3 100755
--- a/tools/analyze_heap_dump.py
+++ b/tools/analyze_heap_dump.py
@@ -82,7 +82,7 @@
     help="Draw the ownership graph of blocks on the heap",
 )
 @click.option("--analyze-snapshots", default="last", type=click.Choice(["all", "last"]))
-def do_all_the_things(  # noqa: C901: too complex
+def do_all_the_things(  # noqa: C901 too complex
     ram_filename,
     bin_filename,
     map_filename,
diff --git a/tools/boardgen.py b/tools/boardgen.py
index 39bedf71cd0c8..3723e7ce31b83 100644
--- a/tools/boardgen.py
+++ b/tools/boardgen.py
@@ -108,6 +108,10 @@ def add_board_pin_name(self, board_pin_name, hidden=False):
             )
         )
 
+    # Iterate over board pin names in consistent sorted order.
+    def board_pin_names(self):
+        return sorted(self._board_pin_names, key=lambda x: x[0])
+
     # Override this to handle an af specified in af.csv.
     def add_af(self, af_idx, af_name, af):
         raise NotImplementedError
@@ -295,7 +299,7 @@ def print_board_locals_dict(self, out_source):
             file=out_source,
         )
         for pin in self.available_pins():
-            for board_pin_name, board_hidden in pin._board_pin_names:
+            for board_pin_name, board_hidden in pin.board_pin_names():
                 if board_hidden:
                     # Don't include hidden pins in Pins.board.
                     continue
@@ -389,7 +393,7 @@ def print_defines(self, out_header, cpu=True, board=True):
 
             # #define pin_BOARDNAME (pin_CPUNAME)
             if board:
-                for board_pin_name, _board_hidden in pin._board_pin_names:
+                for board_pin_name, _board_hidden in pin.board_pin_names():
                     # Note: Hidden board pins are still available to C via the macro.
                     # Note: The RHS isn't wrapped in (), which is necessary to make the
                     # STATIC_AF_ macro work on STM32.
diff --git a/tools/cc1 b/tools/cc1
index 827d5886a04f5..aa2534f01e7bb 100755
--- a/tools/cc1
+++ b/tools/cc1
@@ -23,8 +23,8 @@ import re
 # TODO somehow make them externally configurable
 
 # this is the path to the true C compiler
-cc1_path = '/usr/lib/gcc/x86_64-unknown-linux-gnu/5.3.0/cc1'
-#cc1_path = '/usr/lib/gcc/arm-none-eabi/5.3.0/cc1'
+cc1_path = "/usr/lib/gcc/x86_64-unknown-linux-gnu/5.3.0/cc1"
+# cc1_path = '/usr/lib/gcc/arm-none-eabi/5.3.0/cc1'
 
 # this must be the same as MICROPY_QSTR_BYTES_IN_HASH
 bytes_in_qstr_hash = 2
@@ -41,11 +41,16 @@ print_debug = False
 ################################################################################
 
 # precompile regexs
-re_preproc_line = re.compile(r'# [0-9]+ ')
-re_map_entry = re.compile(r'\{.+?\(MP_QSTR_([A-Za-z0-9_]+)\).+\},')
-re_mp_obj_dict_t = re.compile(r'(?P<head>(static )?const mp_obj_dict_t (?P<id>[a-z0-9_]+) = \{ \.base = \{&mp_type_dict\}, \.map = \{ \.all_keys_are_qstrs = 1, \.is_fixed = 1, \.is_ordered = )1(?P<tail>, \.used = .+ };)$')
-re_mp_map_t = re.compile(r'(?P<head>(static )?const mp_map_t (?P<id>[a-z0-9_]+) = \{ \.all_keys_are_qstrs = 1, \.is_fixed = 1, \.is_ordered = )1(?P<tail>, \.used = .+ };)$')
-re_mp_rom_map_elem_t = re.compile(r'static const mp_rom_map_elem_t [a-z_0-9]+\[\] = {$')
+re_preproc_line = re.compile(r"# [0-9]+ ")
+re_map_entry = re.compile(r"\{.+?\(MP_QSTR_([A-Za-z0-9_]+)\).+\},")
+re_mp_obj_dict_t = re.compile(
+    r"(?P<head>(static )?const mp_obj_dict_t (?P<id>[a-z0-9_]+) = \{ \.base = \{&mp_type_dict\}, \.map = \{ \.all_keys_are_qstrs = 1, \.is_fixed = 1, \.is_ordered = )1(?P<tail>, \.used = .+ };)$"
+)
+re_mp_map_t = re.compile(
+    r"(?P<head>(static )?const mp_map_t (?P<id>[a-z0-9_]+) = \{ \.all_keys_are_qstrs = 1, \.is_fixed = 1, \.is_ordered = )1(?P<tail>, \.used = .+ };)$"
+)
+re_mp_rom_map_elem_t = re.compile(r"static const mp_rom_map_elem_t [a-z_0-9]+\[\] = {$")
+
 
 # this must match the equivalent function in qstr.c
 def compute_hash(qstr):
@@ -55,18 +60,19 @@ def compute_hash(qstr):
     # Make sure that valid hash is never zero, zero means "hash not computed"
     return (hash & ((1 << (8 * bytes_in_qstr_hash)) - 1)) or 1
 
+
 # this algo must match the equivalent in map.c
 def hash_insert(map, key, value):
     hash = compute_hash(key)
     pos = hash % len(map)
     start_pos = pos
     if print_debug:
-        print('  insert %s: start at %u/%u -- ' % (key, pos, len(map)), end='')
+        print("  insert %s: start at %u/%u -- " % (key, pos, len(map)), end="")
     while True:
         if map[pos] is None:
             # found empty slot, so key is not in table
             if print_debug:
-                print('put at %u' % pos)
+                print("put at %u" % pos)
             map[pos] = (key, value)
             return
         else:
@@ -76,6 +82,7 @@ def hash_insert(map, key, value):
             pos = (pos + 1) % len(map)
             assert pos != start_pos
 
+
 def hash_find(map, key):
     hash = compute_hash(key)
     pos = hash % len(map)
@@ -92,6 +99,7 @@ def hash_find(map, key):
             if pos == start_pos:
                 return attempts, None
 
+
 def process_map_table(file, line, output):
     output.append(line)
 
@@ -101,7 +109,7 @@ def process_map_table(file, line, output):
     while True:
         line = file.readline()
         if len(line) == 0:
-            print('unexpected end of input')
+            print("unexpected end of input")
             sys.exit(1)
         line = line.strip()
         if len(line) == 0:
@@ -110,38 +118,38 @@ def process_map_table(file, line, output):
         if re_preproc_line.match(line):
             # preprocessor line number comment
             continue
-        if line == '};':
+        if line == "};":
             # end of table (we assume it appears on a single line)
             break
         table_contents.append(line)
 
     # make combined string of entries
-    entries_str = ''.join(table_contents)
+    entries_str = "".join(table_contents)
 
     # split into individual entries
     entries = []
     while entries_str:
         # look for single entry, by matching nested braces
         match = None
-        if entries_str[0] == '{':
+        if entries_str[0] == "{":
             nested_braces = 0
             for i in range(len(entries_str)):
-                if entries_str[i] == '{':
+                if entries_str[i] == "{":
                     nested_braces += 1
-                elif entries_str[i] == '}':
+                elif entries_str[i] == "}":
                     nested_braces -= 1
                     if nested_braces == 0:
-                        match = re_map_entry.match(entries_str[:i + 2])
+                        match = re_map_entry.match(entries_str[: i + 2])
                         break
 
         if not match:
-            print('unknown line in table:', entries_str)
+            print("unknown line in table:", entries_str)
             sys.exit(1)
 
         # extract single entry
         line = match.group(0)
         qstr = match.group(1)
-        entries_str = entries_str[len(line):].lstrip()
+        entries_str = entries_str[len(line) :].lstrip()
 
         # add the qstr and the whole line to list of all entries
         entries.append((qstr, line))
@@ -164,28 +172,28 @@ def process_map_table(file, line, output):
         attempts, line = hash_find(map, qstr)
         assert line is not None
         if print_debug:
-            print('  %s lookup took %u attempts' % (qstr, attempts))
+            print("  %s lookup took %u attempts" % (qstr, attempts))
         total_attempts += attempts
-    if len(entries):
+    if entries:
         stats = len(map), len(entries) / len(map), total_attempts / len(entries)
     else:
         stats = 0, 0, 0
     if print_debug:
-        print('  table stats: size=%d, load=%.2f, avg_lookups=%.1f' % stats)
+        print("  table stats: size=%d, load=%.2f, avg_lookups=%.1f" % stats)
 
     # output hash table
     for row in map:
         if row is None:
-            output.append('{ 0, 0 },\n')
+            output.append("{ 0, 0 },\n")
         else:
-            output.append(row[1] + '\n')
-    output.append('};\n')
+            output.append(row[1] + "\n")
+    output.append("};\n")
 
     # skip to next non-blank line
     while True:
         line = file.readline()
         if len(line) == 0:
-            print('unexpected end of input')
+            print("unexpected end of input")
             sys.exit(1)
         line = line.strip()
         if len(line) == 0:
@@ -197,19 +205,20 @@ def process_map_table(file, line, output):
     if match is None:
         match = re_mp_map_t.match(line)
     if match is None:
-        print('expecting mp_obj_dict_t or mp_map_t definition')
+        print("expecting mp_obj_dict_t or mp_map_t definition")
         print(output[0])
         print(line)
         sys.exit(1)
-    line = match.group('head') + '0' + match.group('tail') + '\n'
+    line = match.group("head") + "0" + match.group("tail") + "\n"
     output.append(line)
 
-    return (match.group('id'),) + stats
+    return (match.group("id"),) + stats
+
 
 def process_file(filename):
     output = []
     file_changed = False
-    with open(filename, 'rt') as f:
+    with open(filename, "rt") as f:
         while True:
             line = f.readline()
             if not line:
@@ -218,39 +227,41 @@ def process_file(filename):
                 file_changed = True
                 stats = process_map_table(f, line, output)
                 if print_stats:
-                    print('  [%s: size=%d, load=%.2f, avg_lookups=%.1f]' % stats)
+                    print("  [%s: size=%d, load=%.2f, avg_lookups=%.1f]" % stats)
             else:
                 output.append(line)
 
     if file_changed:
         if print_debug:
-            print('  modifying static maps in', output[0].strip())
-        with open(filename, 'wt') as f:
+            print("  modifying static maps in", output[0].strip())
+        with open(filename, "wt") as f:
             for line in output:
                 f.write(line)
 
+
 def main():
     # run actual C compiler
     # need to quote args that have special characters in them
     def quote(s):
-        if s.find('<') != -1 or s.find('>') != -1:
+        if s.find("<") != -1 or s.find(">") != -1:
             return "'" + s + "'"
         else:
             return s
-    ret = os.system(cc1_path + ' ' + ' '.join(quote(s) for s in sys.argv[1:]))
+
+    ret = os.system(cc1_path + " " + " ".join(quote(s) for s in sys.argv[1:]))
     if ret != 0:
-        ret = (ret & 0x7f) or 127 # make it in range 0-127, but non-zero
+        ret = (ret & 0x7F) or 127  # make it in range 0-127, but non-zero
         sys.exit(ret)
 
-    if sys.argv[1] == '-E':
+    if sys.argv[1] == "-E":
         # CPP has been run, now do our processing stage
         for i, arg in enumerate(sys.argv):
-            if arg == '-o':
+            if arg == "-o":
                 return process_file(sys.argv[i + 1])
 
         print('%s: could not find "-o" option' % (sys.argv[0],))
         sys.exit(1)
-    elif sys.argv[1] == '-fpreprocessed':
+    elif sys.argv[1] == "-fpreprocessed":
         # compiler has been run, nothing more to do
         return
     else:
@@ -258,5 +269,6 @@ def main():
         print('%s: unknown first option "%s"' % (sys.argv[0], sys.argv[1]))
         sys.exit(1)
 
-if __name__ == '__main__':
+
+if __name__ == "__main__":
     main()
diff --git a/tools/chart_code_size.py b/tools/chart_code_size.py
index cd62074fd0d83..f3d9c5bdc40f5 100644
--- a/tools/chart_code_size.py
+++ b/tools/chart_code_size.py
@@ -24,7 +24,7 @@ def parse_hex(h):
 
 @click.command()
 @click.argument("elf_filename")
-def do_all_the_things(elf_filename):  # noqa: C901: too complex
+def do_all_the_things(elf_filename):  # noqa: C901 too complex
     symbol = None
     last_address = 0
     all_symbols = {}
diff --git a/tools/ci.sh b/tools/ci.sh
index cfc9754837f76..132fbd8f81cf3 100755
--- a/tools/ci.sh
+++ b/tools/ci.sh
@@ -9,15 +9,20 @@ fi
 # Ensure known OPEN_MAX (NO_FILES) limit.
 ulimit -n 1024
 
+# Fail on some things which are warnings otherwise
+export MICROPY_MAINTAINER_BUILD=1
+
 ########################################################################################
 # general helper functions
 
 function ci_gcc_arm_setup {
+    sudo apt-get update
     sudo apt-get install gcc-arm-none-eabi libnewlib-arm-none-eabi
     arm-none-eabi-gcc --version
 }
 
 function ci_gcc_riscv_setup {
+    sudo apt-get update
     sudo apt-get install gcc-riscv64-unknown-elf picolibc-riscv64-unknown-elf
     riscv64-unknown-elf-gcc --version
 }
@@ -35,6 +40,7 @@ function ci_picotool_setup {
 # c code formatting
 
 function ci_c_code_formatting_setup {
+    sudo apt-get update
     sudo apt-get install uncrustify
     uncrustify --version
 }
@@ -74,42 +80,69 @@ function ci_code_size_setup {
     ci_picotool_setup
 }
 
+function _ci_is_git_merge {
+    [[ $(git log -1 --format=%P "$1" | wc -w) > 1 ]]
+}
+
 function ci_code_size_build {
     # check the following ports for the change in their code size
-    PORTS_TO_CHECK=bmusxpdv
+    # Override the list by setting PORTS_TO_CHECK in the environment before invoking ci.
+    : ${PORTS_TO_CHECK:=bmusxpdv}
+
     SUBMODULES="lib/asf4 lib/berkeley-db-1.xx lib/btstack lib/cyw43-driver lib/lwip lib/mbedtls lib/micropython-lib lib/nxp_driver lib/pico-sdk lib/stm32lib lib/tinyusb"
 
     # Default GitHub pull request sets HEAD to a generated merge commit
     # between PR branch (HEAD^2) and base branch (i.e. master) (HEAD^1).
     #
     # We want to compare this generated commit with the base branch, to see what
-    # the code size impact would be if we merged this PR.
-    REFERENCE=$(git rev-parse --short HEAD^1)
-    COMPARISON=$(git rev-parse --short HEAD)
+    # the code size impact would be if we merged this PR. During CI we are at a merge commit,
+    # so this tests the merged PR against its merge base.
+    # Override the refs by setting REFERENCE and/or COMPARISON in the environment before invoking ci.
+    : ${COMPARISON:=$(git rev-parse --short HEAD)}
+    : ${REFERENCE:=$(git rev-parse --short ${COMPARISON}^1)}
 
     echo "Comparing sizes of reference ${REFERENCE} to ${COMPARISON}..."
     git log --oneline $REFERENCE..$COMPARISON
 
-    function code_size_build_step {
-        COMMIT=$1
-        OUTFILE=$2
-        IGNORE_ERRORS=$3
-
-        echo "Building ${COMMIT}..."
-        git checkout --detach $COMMIT
-        git submodule update --init $SUBMODULES
-        git show -s
-        tools/metrics.py clean $PORTS_TO_CHECK
-        tools/metrics.py build $PORTS_TO_CHECK | tee $OUTFILE || $IGNORE_ERRORS
-    }
-
-    # build reference, save to size0
-    # ignore any errors with this build, in case master is failing
-    code_size_build_step $REFERENCE ~/size0 true
-    # build PR/branch, save to size1
-    code_size_build_step $COMPARISON ~/size1 false
-
-    unset -f code_size_build_step
+    OLD_BRANCH="$(git rev-parse --abbrev-ref HEAD)"
+
+    ( # Execute in a subshell so the trap & code_size_build_step doesn't leak
+        function code_size_build_step {
+            if [ ! -z "$OLD_BRANCH" ]; then
+                trap 'git checkout "$OLD_BRANCH"' RETURN EXIT ERR
+            fi
+
+            COMMIT=$1
+            OUTFILE=$2
+            IGNORE_ERRORS=$3
+
+            git checkout --detach $COMMIT
+            git submodule update --init $SUBMODULES
+            git show -s
+            tools/metrics.py clean "$PORTS_TO_CHECK"
+            # Allow errors from tools/metrics.py to propagate out of the pipe below.
+            set -o pipefail
+            tools/metrics.py build "$PORTS_TO_CHECK" | tee -a $OUTFILE || $IGNORE_ERRORS
+            return $?
+        }
+
+        # build reference, save to size0
+        # ignore any errors with this build, in case master is failing
+        echo "BUILDING $(git log --format='%s [%h]' -1 ${REFERENCE})" > ~/size0
+        code_size_build_step $REFERENCE ~/size0 true
+        # build PR/branch, save to size1
+        if _ci_is_git_merge "$COMPARISON"; then
+            echo "BUILDING $(git log --oneline -1 --format='%s [merge of %h]' ${COMPARISON}^2)"
+        else
+            echo "BUILDING $(git log --oneline -1 --formta='%s [%h]' ${COMPARISON})"
+        fi > ~/size1
+        code_size_build_step $COMPARISON ~/size1 false
+    )
+}
+
+function ci_code_size_report {
+    # Allow errors from tools/metrics.py to propagate out of the pipe above.
+    (set -o pipefail; tools/metrics.py diff ~/size0 ~/size1 | tee diff)
 }
 
 ########################################################################################
@@ -117,15 +150,12 @@ function ci_code_size_build {
 
 function ci_mpy_format_setup {
     sudo apt-get update
-    sudo apt-get install python2.7
     sudo pip3 install pyelftools
-    python2.7 --version
     python3 --version
 }
 
 function ci_mpy_format_test {
     # Test mpy-tool.py dump feature on bytecode
-    python2.7 ./tools/mpy-tool.py -xd tests/frozen/frozentest.mpy
     python3 ./tools/mpy-tool.py -xd tests/frozen/frozentest.mpy
 
     # Build MicroPython
@@ -143,6 +173,15 @@ function ci_mpy_format_test {
     $micropython ./tools/mpy-tool.py -x -d examples/natmod/features1/features1.mpy
 }
 
+function ci_mpy_cross_debug_emitter {
+    make ${MAKEOPTS} -C mpy-cross
+    mpy_cross=./mpy-cross/build/mpy-cross
+
+    # Make sure the debug emitter does not crash or fail for simple files
+    $mpy_cross -X emit=native -march=debug ./tests/basics/0prelim.py | \
+	    grep -E "ENTRY|EXIT" | wc -l | grep "^2$"
+}
+
 ########################################################################################
 # ports/cc3200
 
@@ -158,14 +197,17 @@ function ci_cc3200_build {
 ########################################################################################
 # ports/esp32
 
-# GitHub tag of ESP-IDF to use for CI (note: must be a tag or a branch)
-IDF_VER=v5.2.2
+# GitHub tag of ESP-IDF to use for CI, extracted from the esp32 dependency lockfile
+# This should end up as a tag name like vX.Y.Z
+# (note: This hacky parsing can be replaced with 'yq' once Ubuntu >=24.04 is in use)
+IDF_VER=v$(grep -A10 "idf:" ports/esp32/lockfiles/dependencies.lock.esp32 | grep "version:" | head -n1 | sed -E 's/ +version: //')
 PYTHON=$(command -v python3 2> /dev/null)
 PYTHON_VER=$(${PYTHON:-python} --version | cut -d' ' -f2)
 
 export IDF_CCACHE_ENABLE=1
 
 function ci_esp32_idf_setup {
+    echo "Using ESP-IDF version $IDF_VER"
     git clone --depth 1 --branch $IDF_VER https://github.com/espressif/esp-idf.git
     # doing a treeless clone isn't quite as good as --shallow-submodules, but it
     # is smaller than full clones and works when the submodule commit isn't a head.
@@ -204,13 +246,28 @@ function ci_esp32_build_s3_c3 {
     make ${MAKEOPTS} -C ports/esp32 BOARD=ESP32_GENERIC_C3
 }
 
+function ci_esp32_build_c2_c5_c6 {
+    ci_esp32_build_common
+
+    make ${MAKEOPTS} -C ports/esp32 BOARD=ESP32_GENERIC_C2
+    make ${MAKEOPTS} -C ports/esp32 BOARD=ESP32_GENERIC_C5
+    make ${MAKEOPTS} -C ports/esp32 BOARD=ESP32_GENERIC_C6
+}
+
+function ci_esp32_build_p4 {
+    ci_esp32_build_common
+
+    make ${MAKEOPTS} -C ports/esp32 BOARD=ESP32_GENERIC_P4
+    make ${MAKEOPTS} -C ports/esp32 BOARD=ESP32_GENERIC_P4 BOARD_VARIANT=C6_WIFI
+}
+
 ########################################################################################
 # ports/esp8266
 
 function ci_esp8266_setup {
     sudo pip3 install pyserial esptool==3.3.1 pyelftools ar
-    wget https://github.com/jepler/esp-open-sdk/releases/download/2018-06-10/xtensa-lx106-elf-standalone.tar.gz
-    zcat xtensa-lx106-elf-standalone.tar.gz | tar x
+    wget https://micropython.org/resources/xtensa-lx106-elf-standalone.tar.gz
+    (set -o pipefail; zcat xtensa-lx106-elf-standalone.tar.gz | tar x)
     # Remove this esptool.py so pip version is used instead
     rm xtensa-lx106-elf/bin/esptool.py
 }
@@ -317,17 +374,52 @@ function ci_qemu_setup_rv32 {
     qemu-system-riscv32 --version
 }
 
-function ci_qemu_build_arm {
+function ci_qemu_setup_rv64 {
+    ci_gcc_riscv_setup
+    sudo apt-get update
+    sudo apt-get install qemu-system
+    qemu-system-riscv64 --version
+}
+
+function ci_qemu_build_arm_prepare {
     make ${MAKEOPTS} -C mpy-cross
     make ${MAKEOPTS} -C ports/qemu submodules
+}
+
+function ci_qemu_build_arm_bigendian {
+    ci_qemu_build_arm_prepare
     make ${MAKEOPTS} -C ports/qemu CFLAGS_EXTRA=-DMP_ENDIANNESS_BIG=1
-    make ${MAKEOPTS} -C ports/qemu clean
-    make ${MAKEOPTS} -C ports/qemu test_full
+}
+
+function ci_qemu_build_arm_sabrelite {
+    ci_qemu_build_arm_prepare
     make ${MAKEOPTS} -C ports/qemu BOARD=SABRELITE test_full
+}
 
-    # Test building and running native .mpy with armv7m architecture.
+function ci_qemu_build_arm_thumb_softfp {
+    ci_qemu_build_arm_prepare
+    make BOARD=MPS2_AN385 ${MAKEOPTS} -C ports/qemu test_full
+
+    # Test building native .mpy with ARM-M softfp architectures.
+    ci_native_mpy_modules_build armv6m
     ci_native_mpy_modules_build armv7m
-    make ${MAKEOPTS} -C ports/qemu test_natmod
+
+    # Test running native .mpy with all ARM-M architectures.
+    make BOARD=MPS2_AN385 ${MAKEOPTS} -C ports/qemu test_natmod RUN_TESTS_EXTRA="--arch armv6m"
+    make BOARD=MPS2_AN385 ${MAKEOPTS} -C ports/qemu test_natmod RUN_TESTS_EXTRA="--arch armv7m"
+}
+
+function ci_qemu_build_arm_thumb_hardfp {
+    ci_qemu_build_arm_prepare
+    make BOARD=MPS2_AN500 ${MAKEOPTS} -C ports/qemu test_full
+
+    # Test building native .mpy with all ARM-M hardfp architectures.
+    ci_native_mpy_modules_build armv7emsp
+    ci_native_mpy_modules_build armv7emdp
+
+    # Test running native .mpy with all ARM-M hardfp architectures.
+    make BOARD=MPS2_AN500 ${MAKEOPTS} -C ports/qemu test_natmod RUN_TESTS_EXTRA="--arch armv7emsp"
+    make BOARD=MPS2_AN500 ${MAKEOPTS} -C ports/qemu test_natmod RUN_TESTS_EXTRA="--arch armv7emdp"
 }
 
 function ci_qemu_build_rv32 {
@@ -340,6 +432,12 @@ function ci_qemu_build_rv32 {
     make ${MAKEOPTS} -C ports/qemu BOARD=VIRT_RV32 test_natmod
 }
 
+function ci_qemu_build_rv64 {
+    make ${MAKEOPTS} -C mpy-cross
+    make ${MAKEOPTS} -C ports/qemu BOARD=VIRT_RV64 submodules
+    make ${MAKEOPTS} -C ports/qemu BOARD=VIRT_RV64 test
+}
+
 ########################################################################################
 # ports/renesas-ra
 
@@ -403,13 +501,22 @@ function ci_samd_build {
 # ports/stm32
 
 function ci_stm32_setup {
-    ci_gcc_arm_setup
+    # Use a recent version of the ARM toolchain, to work with Cortex-M55.
+    wget https://developer.arm.com/-/media/Files/downloads/gnu/14.3.rel1/binrel/arm-gnu-toolchain-14.3.rel1-x86_64-arm-none-eabi.tar.xz
+    xzcat arm-gnu-toolchain-14.3.rel1-x86_64-arm-none-eabi.tar.xz | tar x
+
     pip3 install pyelftools
     pip3 install ar
     pip3 install pyhy
 }
 
+function ci_stm32_path {
+    echo $(pwd)/arm-gnu-toolchain-14.3.rel1-x86_64-arm-none-eabi/bin
+}
+
 function ci_stm32_pyb_build {
+    # This function builds the following MCU families: F4, F7.
+
     make ${MAKEOPTS} -C mpy-cross
     make ${MAKEOPTS} -C ports/stm32 MICROPY_PY_NETWORK_WIZNET5K=5200 submodules
     make ${MAKEOPTS} -C ports/stm32 BOARD=PYBD_SF2 submodules
@@ -421,20 +528,18 @@ function ci_stm32_pyb_build {
     make ${MAKEOPTS} -C ports/stm32/mboot BOARD=PYBV10 CFLAGS_EXTRA='-DMBOOT_FSLOAD=1 -DMBOOT_VFS_LFS2=1'
     make ${MAKEOPTS} -C ports/stm32/mboot BOARD=PYBD_SF6
     make ${MAKEOPTS} -C ports/stm32/mboot BOARD=STM32F769DISC CFLAGS_EXTRA='-DMBOOT_ADDRESS_SPACE_64BIT=1 -DMBOOT_SDCARD_ADDR=0x100000000ULL -DMBOOT_SDCARD_BYTE_SIZE=0x400000000ULL -DMBOOT_FSLOAD=1 -DMBOOT_VFS_FAT=1'
-
-    # Test building native .mpy with armv7emsp architecture.
-    git submodule update --init lib/berkeley-db-1.xx
-    ci_native_mpy_modules_build armv7emsp
 }
 
 function ci_stm32_nucleo_build {
+    # This function builds the following MCU families: F0, H5, H7, L0, L4, WB.
+
     make ${MAKEOPTS} -C mpy-cross
     make ${MAKEOPTS} -C ports/stm32 BOARD=NUCLEO_H743ZI submodules
     git submodule update --init lib/mynewt-nimble
 
     # Test building various MCU families, some with additional options.
     make ${MAKEOPTS} -C ports/stm32 BOARD=NUCLEO_F091RC
-    make ${MAKEOPTS} -C ports/stm32 BOARD=STM32H573I_DK
+    make ${MAKEOPTS} -C ports/stm32 BOARD=STM32H573I_DK CFLAGS_EXTRA='-DMICROPY_HW_TINYUSB_STACK=1'
     make ${MAKEOPTS} -C ports/stm32 BOARD=NUCLEO_H743ZI COPT=-O2 CFLAGS_EXTRA='-DMICROPY_PY_THREAD=1'
     make ${MAKEOPTS} -C ports/stm32 BOARD=NUCLEO_L073RZ
     make ${MAKEOPTS} -C ports/stm32 BOARD=NUCLEO_L476RG DEBUG=1
@@ -454,21 +559,22 @@ function ci_stm32_nucleo_build {
 }
 
 function ci_stm32_misc_build {
+    # This function builds the following MCU families: G0, G4, H7, L1, N6, U5, WL.
+
     make ${MAKEOPTS} -C mpy-cross
     make ${MAKEOPTS} -C ports/stm32 BOARD=ARDUINO_GIGA submodules
     make ${MAKEOPTS} -C ports/stm32 BOARD=ARDUINO_GIGA
+    make ${MAKEOPTS} -C ports/stm32 BOARD=NUCLEO_G0B1RE
+    make ${MAKEOPTS} -C ports/stm32 BOARD=NUCLEO_G474RE
+    make ${MAKEOPTS} -C ports/stm32 BOARD=NUCLEO_L152RE
+    make ${MAKEOPTS} -C ports/stm32 BOARD=NUCLEO_N657X0
+    make ${MAKEOPTS} -C ports/stm32 BOARD=NUCLEO_U5A5ZJ_Q
+    make ${MAKEOPTS} -C ports/stm32 BOARD=NUCLEO_WL55
 }
 
 ########################################################################################
 # ports/unix
 
-CI_UNIX_OPTS_SYS_SETTRACE=(
-    MICROPY_PY_BTREE=0
-    MICROPY_PY_FFI=0
-    MICROPY_PY_SSL=0
-    CFLAGS_EXTRA="-DMICROPY_PY_SYS_SETTRACE=1"
-)
-
 CI_UNIX_OPTS_SYS_SETTRACE_STACKLESS=(
     MICROPY_PY_BTREE=0
     MICROPY_PY_FFI=0
@@ -494,6 +600,26 @@ CI_UNIX_OPTS_QEMU_RISCV64=(
     MICROPY_STANDALONE=1
 )
 
+CI_UNIX_OPTS_SANITIZE_ADDRESS=(
+    # Macro MP_ASAN allows detecting ASan on gcc<=13
+    CFLAGS_EXTRA="-fsanitize=address --param asan-use-after-return=0 -DMP_ASAN=1"
+    LDFLAGS_EXTRA="-fsanitize=address --param asan-use-after-return=0"
+)
+
+CI_UNIX_OPTS_SANITIZE_UNDEFINED=(
+    # Macro MP_UBSAN allows detecting UBSan on gcc<=13
+    CFLAGS_EXTRA="-fsanitize=undefined -fno-sanitize=nonnull-attribute -DMP_UBSAN=1"
+    LDFLAGS_EXTRA="-fsanitize=undefined -fno-sanitize=nonnull-attribute"
+)
+
+CI_UNIX_OPTS_REPR_B=(
+    VARIANT=standard
+    CFLAGS_EXTRA="-DMICROPY_OBJ_REPR=MICROPY_OBJ_REPR_B -DMICROPY_PY_UCTYPES=0 -Dmp_int_t=int32_t -Dmp_uint_t=uint32_t"
+    MICROPY_FORCE_32BIT=1
+    RUN_TESTS_MPY_CROSS_FLAGS="--mpy-cross-flags=\"-march=x86 -msmall-int-bits=30\""
+
+)
+
 function ci_unix_build_helper {
     make ${MAKEOPTS} -C mpy-cross
     make ${MAKEOPTS} -C ports/unix "$@" submodules
@@ -509,13 +635,26 @@ function ci_unix_run_tests_helper {
     make -C ports/unix "$@" test
 }
 
+function ci_unix_run_tests_full_extra {
+    micropython=$1
+    (cd tests && MICROPY_CPYTHON3=python3 MICROPY_MICROPYTHON=$micropython ./run-multitests.py multi_net/*.py)
+    (cd tests && MICROPY_CPYTHON3=python3 MICROPY_MICROPYTHON=$micropython ./run-perfbench.py --average 1 1000 1000)
+}
+
+function ci_unix_run_tests_full_no_native_helper {
+    variant=$1
+    shift
+    micropython=../ports/unix/build-$variant/micropython
+    make -C ports/unix VARIANT=$variant "$@" test_full_no_native
+    ci_unix_run_tests_full_extra $micropython
+}
+
 function ci_unix_run_tests_full_helper {
     variant=$1
     shift
     micropython=../ports/unix/build-$variant/micropython
     make -C ports/unix VARIANT=$variant "$@" test_full
-    (cd tests && MICROPY_CPYTHON3=python3 MICROPY_MICROPYTHON=$micropython ./run-multitests.py multi_net/*.py)
-    (cd tests && MICROPY_CPYTHON3=python3 MICROPY_MICROPYTHON=$micropython ./run-perfbench.py 1000 1000)
+    ci_unix_run_tests_full_extra $micropython
 }
 
 function ci_native_mpy_modules_build {
@@ -524,40 +663,19 @@ function ci_native_mpy_modules_build {
     else
         arch=$1
     fi
-    for natmod in features1 features3 features4 heapq re
+    for natmod in btree deflate features1 features3 features4 framebuf heapq random re
     do
-        make -C examples/natmod/$natmod clean
+        make -C examples/natmod/$natmod ARCH=$arch clean
         make -C examples/natmod/$natmod ARCH=$arch
     done
 
-    # deflate, framebuf, and random currently cannot build on xtensa due to
-    # some symbols that have been removed from the compiler's runtime, in
-    # favour of being provided from ROM.
-    if [ $arch != "xtensa" ]; then
-        for natmod in deflate framebuf random
-        do
-            make -C examples/natmod/$natmod clean
-            make -C examples/natmod/$natmod ARCH=$arch
-        done
-    fi
-
-    # features2 requires soft-float on armv7m, rv32imc, and xtensa.  On armv6m
-    # the compiler generates absolute relocations in the object file
-    # referencing soft-float functions, which is not supported at the moment.
-    make -C examples/natmod/features2 clean
-    if [ $arch = "rv32imc" ] || [ $arch = "armv7m" ] || [ $arch = "xtensa" ]; then
+    # features2 requires soft-float on rv32imc and xtensa.
+    make -C examples/natmod/features2 ARCH=$arch clean
+    if [ $arch = "rv32imc" ] || [ $arch = "xtensa" ]; then
         make -C examples/natmod/features2 ARCH=$arch MICROPY_FLOAT_IMPL=float
-    elif [ $arch != "armv6m" ]; then
+    else
         make -C examples/natmod/features2 ARCH=$arch
     fi
-
-    # btree requires thread local storage support on rv32imc, whilst on xtensa
-    # it relies on symbols that are provided from ROM but not exposed to
-    # natmods at the moment.
-    if [ $arch != "rv32imc" ] && [ $arch != "xtensa" ]; then
-        make -C examples/natmod/btree clean
-        make -C examples/natmod/btree ARCH=$arch
-    fi
 }
 
 function ci_native_mpy_modules_32bit_build {
@@ -569,7 +687,7 @@ function ci_unix_minimal_build {
 }
 
 function ci_unix_minimal_run_tests {
-    (cd tests && MICROPY_CPYTHON3=python3 MICROPY_MICROPYTHON=../ports/unix/build-minimal/micropython ./run-tests.py -e exception_chain -e self_type_check -e subclass_native_init -d basics)
+    make -C ports/unix VARIANT=minimal test
 }
 
 function ci_unix_standard_build {
@@ -591,9 +709,9 @@ function ci_unix_standard_v2_run_tests {
 }
 
 function ci_unix_coverage_setup {
-    sudo pip3 install setuptools
-    sudo pip3 install pyelftools
-    sudo pip3 install ar
+    pip3 install setuptools
+    pip3 install pyelftools
+    pip3 install ar
     gcc --version
     python3 --version
 }
@@ -604,7 +722,7 @@ function ci_unix_coverage_build {
 }
 
 function ci_unix_coverage_run_tests {
-    ci_unix_run_tests_full_helper coverage
+    MICROPY_TEST_TIMEOUT=60 ci_unix_run_tests_full_helper coverage
 }
 
 function ci_unix_coverage_run_mpy_merge_tests {
@@ -639,12 +757,11 @@ function ci_unix_coverage_run_native_mpy_tests {
 function ci_unix_32bit_setup {
     sudo dpkg --add-architecture i386
     sudo apt-get update
-    sudo apt-get install gcc-multilib g++-multilib libffi-dev:i386 python2.7
+    sudo apt-get install gcc-multilib g++-multilib libffi-dev:i386
     sudo pip3 install setuptools
     sudo pip3 install pyelftools
     sudo pip3 install ar
     gcc --version
-    python2.7 --version
     python3 --version
 }
 
@@ -662,13 +779,20 @@ function ci_unix_coverage_32bit_run_native_mpy_tests {
 }
 
 function ci_unix_nanbox_build {
-    # Use Python 2 to check that it can run the build scripts
-    ci_unix_build_helper PYTHON=python2.7 VARIANT=nanbox CFLAGS_EXTRA="-DMICROPY_PY_MATH_CONSTANTS=1"
+    ci_unix_build_helper VARIANT=nanbox CFLAGS_EXTRA="-DMICROPY_PY_MATH_CONSTANTS=1"
     ci_unix_build_ffi_lib_helper gcc -m32
 }
 
 function ci_unix_nanbox_run_tests {
-    ci_unix_run_tests_full_helper nanbox PYTHON=python2.7
+    ci_unix_run_tests_full_no_native_helper nanbox
+}
+
+function ci_unix_longlong_build {
+    ci_unix_build_helper VARIANT=longlong "${CI_UNIX_OPTS_SANITIZE_UNDEFINED[@]}"
+}
+
+function ci_unix_longlong_run_tests {
+    ci_unix_run_tests_full_helper longlong
 }
 
 function ci_unix_float_build {
@@ -681,7 +805,17 @@ function ci_unix_float_run_tests {
     ci_unix_run_tests_helper CFLAGS_EXTRA="-DMICROPY_FLOAT_IMPL=MICROPY_FLOAT_IMPL_FLOAT"
 }
 
+function ci_unix_gil_enabled_build {
+    ci_unix_build_helper VARIANT=standard MICROPY_PY_THREAD_GIL=1
+    ci_unix_build_ffi_lib_helper gcc
+}
+
+function ci_unix_gil_enabled_run_tests {
+    ci_unix_run_tests_full_helper standard MICROPY_PY_THREAD_GIL=1
+}
+
 function ci_unix_clang_setup {
+    sudo apt-get update
     sudo apt-get install clang
     clang --version
 }
@@ -693,7 +827,8 @@ function ci_unix_stackless_clang_build {
 }
 
 function ci_unix_stackless_clang_run_tests {
-    ci_unix_run_tests_helper CC=clang
+    # Timeout needs to be increased for thread/stress_aes.py test.
+    MICROPY_TEST_TIMEOUT=90 ci_unix_run_tests_helper CC=clang
 }
 
 function ci_unix_float_clang_build {
@@ -706,24 +841,36 @@ function ci_unix_float_clang_run_tests {
     ci_unix_run_tests_helper CC=clang
 }
 
-function ci_unix_settrace_build {
+function ci_unix_settrace_stackless_build {
+    make ${MAKEOPTS} -C mpy-cross
+    make ${MAKEOPTS} -C ports/unix submodules
+    make ${MAKEOPTS} -C ports/unix "${CI_UNIX_OPTS_SYS_SETTRACE_STACKLESS[@]}"
+}
+
+function ci_unix_settrace_stackless_run_tests {
+    ci_unix_run_tests_full_helper standard "${CI_UNIX_OPTS_SYS_SETTRACE_STACKLESS[@]}"
+}
+
+function ci_unix_sanitize_undefined_build {
     make ${MAKEOPTS} -C mpy-cross
     make ${MAKEOPTS} -C ports/unix submodules
-    make ${MAKEOPTS} -C ports/unix "${CI_UNIX_OPTS_SYS_SETTRACE[@]}"
+    make ${MAKEOPTS} -C ports/unix VARIANT=coverage "${CI_UNIX_OPTS_SANITIZE_UNDEFINED[@]}"
+    ci_unix_build_ffi_lib_helper gcc
 }
 
-function ci_unix_settrace_run_tests {
-    ci_unix_run_tests_full_helper standard "${CI_UNIX_OPTS_SYS_SETTRACE[@]}"
+function ci_unix_sanitize_undefined_run_tests {
+    MICROPY_TEST_TIMEOUT=60 ci_unix_run_tests_full_helper coverage VARIANT=coverage "${CI_UNIX_OPTS_SANITIZE_UNDEFINED[@]}"
 }
 
-function ci_unix_settrace_stackless_build {
+function ci_unix_sanitize_address_build {
     make ${MAKEOPTS} -C mpy-cross
     make ${MAKEOPTS} -C ports/unix submodules
-    make ${MAKEOPTS} -C ports/unix "${CI_UNIX_OPTS_SYS_SETTRACE_STACKLESS[@]}"
+    make ${MAKEOPTS} -C ports/unix VARIANT=coverage "${CI_UNIX_OPTS_SANITIZE_ADDRESS[@]}"
+    ci_unix_build_ffi_lib_helper gcc
 }
 
-function ci_unix_settrace_stackless_run_tests {
-    ci_unix_run_tests_full_helper standard "${CI_UNIX_OPTS_SYS_SETTRACE_STACKLESS[@]}"
+function ci_unix_sanitize_address_run_tests {
+    MICROPY_TEST_TIMEOUT=60 ci_unix_run_tests_full_helper coverage VARIANT=coverage "${CI_UNIX_OPTS_SANITIZE_ADDRESS[@]}"
 }
 
 function ci_unix_macos_build {
@@ -740,7 +887,9 @@ function ci_unix_macos_run_tests {
     # Issues with macOS tests:
     # - float_parse and float_parse_doubleprec parse/print floats out by a few mantissa bits
     # - ffi_callback crashes for an unknown reason
-    (cd tests && MICROPY_MICROPYTHON=../ports/unix/build-standard/micropython ./run-tests.py --exclude '(float_parse|float_parse_doubleprec|ffi_callback).py')
+    # - thread/stress_heap.py is flaky
+    # - thread/thread_gc1.py is flaky
+    (cd tests && MICROPY_MICROPYTHON=../ports/unix/build-standard/micropython ./run-tests.py --exclude '(float_parse|float_parse_doubleprec|ffi_callback|thread/stress_heap|thread/thread_gc1).py')
 }
 
 function ci_unix_qemu_mips_setup {
@@ -758,8 +907,12 @@ function ci_unix_qemu_mips_build {
 }
 
 function ci_unix_qemu_mips_run_tests {
+    # Issues with MIPS tests:
+    # - thread/stress_aes.py takes around 50 seconds
+    # - thread/stress_recurse.py is flaky
+    # - thread/thread_gc1.py is flaky
     file ./ports/unix/build-coverage/micropython
-    (cd tests && MICROPY_MICROPYTHON=../ports/unix/build-coverage/micropython ./run-tests.py)
+    (cd tests && MICROPY_MICROPYTHON=../ports/unix/build-coverage/micropython MICROPY_TEST_TIMEOUT=90 ./run-tests.py --exclude 'thread/stress_recurse.py|thread/thread_gc1.py')
 }
 
 function ci_unix_qemu_arm_setup {
@@ -779,8 +932,11 @@ function ci_unix_qemu_arm_build {
 function ci_unix_qemu_arm_run_tests {
     # Issues with ARM tests:
     # - (i)listdir does not work, it always returns the empty list (it's an issue with the underlying C call)
+    # - thread/stress_aes.py takes around 70 seconds
+    # - thread/stress_recurse.py is flaky
+    # - thread/thread_gc1.py is flaky
     file ./ports/unix/build-coverage/micropython
-    (cd tests && MICROPY_MICROPYTHON=../ports/unix/build-coverage/micropython ./run-tests.py --exclude 'vfs_posix.*\.py')
+    (cd tests && MICROPY_MICROPYTHON=../ports/unix/build-coverage/micropython MICROPY_TEST_TIMEOUT=90 ./run-tests.py --exclude 'vfs_posix.*\.py|thread/stress_recurse.py|thread/thread_gc1.py')
 }
 
 function ci_unix_qemu_riscv64_setup {
@@ -798,14 +954,30 @@ function ci_unix_qemu_riscv64_build {
 }
 
 function ci_unix_qemu_riscv64_run_tests {
+    # Issues with RISCV-64 tests:
+    # - thread/stress_aes.py takes around 140 seconds
+    # - thread/stress_recurse.py is flaky
+    # - thread/thread_gc1.py is flaky
     file ./ports/unix/build-coverage/micropython
-    (cd tests && MICROPY_MICROPYTHON=../ports/unix/build-coverage/micropython ./run-tests.py)
+    (cd tests && MICROPY_MICROPYTHON=../ports/unix/build-coverage/micropython MICROPY_TEST_TIMEOUT=180 ./run-tests.py --exclude 'thread/stress_recurse.py|thread/thread_gc1.py')
+}
+
+function ci_unix_repr_b_build {
+    ci_unix_build_helper "${CI_UNIX_OPTS_REPR_B[@]}"
+    ci_unix_build_ffi_lib_helper gcc -m32
+}
+
+function ci_unix_repr_b_run_tests {
+    # ci_unix_run_tests_full_no_native_helper is not used due to
+    # https://github.com/micropython/micropython/issues/18105
+    ci_unix_run_tests_helper "${CI_UNIX_OPTS_REPR_B[@]}"
 }
 
 ########################################################################################
 # ports/windows
 
 function ci_windows_setup {
+    sudo apt-get update
     sudo apt-get install gcc-mingw-w64
 }
 
@@ -813,14 +985,15 @@ function ci_windows_build {
     make ${MAKEOPTS} -C mpy-cross
     make ${MAKEOPTS} -C ports/windows submodules
     make ${MAKEOPTS} -C ports/windows CROSS_COMPILE=i686-w64-mingw32-
+    make ${MAKEOPTS} -C ports/windows CROSS_COMPILE=x86_64-w64-mingw32- BUILD=build-standard-w64
 }
 
 ########################################################################################
 # ports/zephyr
 
-ZEPHYR_DOCKER_VERSION=v0.26.13
-ZEPHYR_SDK_VERSION=0.16.8
-ZEPHYR_VERSION=v3.7.0
+ZEPHYR_DOCKER_VERSION=v0.28.1
+ZEPHYR_SDK_VERSION=0.17.2
+ZEPHYR_VERSION=v4.2.0
 
 function ci_zephyr_setup {
     IMAGE=ghcr.io/zephyrproject-rtos/ci:${ZEPHYR_DOCKER_VERSION}
@@ -859,6 +1032,7 @@ function ci_zephyr_install {
 }
 
 function ci_zephyr_build {
+    git submodule update --init lib/micropython-lib
     docker exec zephyr-ci west build -p auto -b qemu_x86 -- -DCONF_FILE=prj_minimal.conf
     docker exec zephyr-ci west build -p auto -b frdm_k64f
     docker exec zephyr-ci west build -p auto -b mimxrt1050_evk
@@ -867,9 +1041,7 @@ function ci_zephyr_build {
 
 function ci_zephyr_run_tests {
     docker exec zephyr-ci west build -p auto -b qemu_cortex_m3 -- -DCONF_FILE=prj_minimal.conf
-    # Issues with zephyr tests:
-    # - inf_nan_arith fails pow(-1, nan) test
-    (cd tests && ./run-tests.py -t execpty:"qemu-system-arm -cpu cortex-m3 -machine lm3s6965evb -nographic -monitor null -serial pty -kernel ../ports/zephyr/build/zephyr/zephyr.elf" -d basics float --exclude inf_nan_arith)
+    (cd tests && ./run-tests.py -t execpty:"qemu-system-arm -cpu cortex-m3 -machine lm3s6965evb -nographic -monitor null -serial pty -kernel ../ports/zephyr/build/zephyr/zephyr.elf")
 }
 
 ########################################################################################
@@ -886,3 +1058,86 @@ function ci_alif_ae3_build {
     make ${MAKEOPTS} -C ports/alif BOARD=OPENMV_AE3 MCU_CORE=M55_DUAL
     make ${MAKEOPTS} -C ports/alif BOARD=ALIF_ENSEMBLE MCU_CORE=M55_DUAL
 }
+
+function _ci_help {
+    # Note: these lines must be indented with tab characters (required by bash <<-EOF)
+    cat <<-EOF
+	ci.sh: Script fragments used during CI
+
+	When invoked as a script, runs a sequence of ci steps,
+	stopping after the first error.
+
+	Usage:
+	    ${BASH_SOURCE} step1 step2...
+
+	Steps:
+	EOF
+    if type -path column > /dev/null 2>&1; then
+        grep '^function ci_' $0 | awk '{print $2}' | sed 's/^ci_//' | column
+    else
+        grep '^function ci_' $0 | awk '{print $2}' | sed 's/^ci_//'
+    fi
+    exit
+}
+
+function _ci_bash_completion {
+    echo "alias ci=\"$(readlink -f "$0")\"; complete -W '$(grep '^function ci_' $0 | awk '{print $2}' | sed 's/^ci_//')' ci"
+}
+
+function _ci_zsh_completion {
+    echo "alias ci=\"$(readlink -f "$0"\"); _complete_mpy_ci_zsh() { compadd $(grep '^function ci_' $0 | awk '{sub(/^ci_/,"",$2); print $2}' | tr '\n' ' ') }; autoload -Uz compinit; compinit; compdef _complete_mpy_ci_zsh $(readlink -f "$0")"
+}
+
+function _ci_fish_completion {
+    echo "alias ci=\"$(readlink -f "$0"\"); complete -c ci -p $(readlink -f "$0") -f -a '$(grep '^function ci_' $(readlink -f "$0") | awk '{sub(/^ci_/,"",$2); print $2}' | tr '\n' ' ')'"
+}
+
+function _ci_main {
+    case "$1" in
+        (-h|-?|--help)
+            _ci_help
+        ;;
+        (--bash-completion)
+            _ci_bash_completion
+        ;;
+        (--zsh-completion)
+            _ci_zsh_completion
+        ;;
+        (--fish-completion)
+            _ci_fish_completion
+        ;;
+        (-*)
+            echo "Unknown option: $1" 1>&2
+            exit 1
+        ;;
+        (*)
+            set -e
+            cd $(dirname "$0")/..
+            while [ $# -ne 0 ]; do
+                ci_$1
+                shift
+            done
+        ;;
+    esac
+}
+
+# https://stackoverflow.com/questions/2683279/how-to-detect-if-a-script-is-being-sourced
+sourced=0
+if [ -n "$ZSH_VERSION" ]; then
+  case $ZSH_EVAL_CONTEXT in *:file) sourced=1;; esac
+elif [ -n "$KSH_VERSION" ]; then
+  [ "$(cd -- "$(dirname -- "$0")" && pwd -P)/$(basename -- "$0")" != "$(cd -- "$(dirname -- "${.sh.file}")" && pwd -P)/$(basename -- "${.sh.file}")" ] && sourced=1
+elif [ -n "$BASH_VERSION" ]; then
+  (return 0 2>/dev/null) && sourced=1
+else # All other shells: examine $0 for known shell binary filenames.
+     # Detects `sh` and `dash`; add additional shell filenames as needed.
+  case ${0##*/} in sh|-sh|dash|-dash) sourced=1;; esac
+fi
+
+if [ $sourced -eq 0 ]; then
+    # invoked as a command
+    if [ "$#" -eq 0 ]; then
+        set -- --help
+    fi
+    _ci_main "$@"
+fi
diff --git a/tools/codeformat.py b/tools/codeformat.py
index a648d401ec312..cf91049a73162 100644
--- a/tools/codeformat.py
+++ b/tools/codeformat.py
@@ -231,7 +231,7 @@ def batch(cmd, files, N=200, check=False):
             command = ["python3", "tools/ruff_bindings.py"]
             batch(command, bindings_files(), check=True)
 
-    # Format Python files with black.
+    # Format Python files with "ruff format" (using config in pyproject.toml).
     if format_py:
         command = ["ruff", "format"]
         if args.v:
diff --git a/tools/file2h.py b/tools/file2h.py
index df9cc02fdabba..2707d4a16e5cf 100644
--- a/tools/file2h.py
+++ b/tools/file2h.py
@@ -9,8 +9,6 @@
 #    ;
 # This script simply prints the escaped string straight to stdout
 
-from __future__ import print_function
-
 import sys
 
 # Can either be set explicitly, or left blank to auto-detect
diff --git a/tools/insert-usb-ids.py b/tools/insert-usb-ids.py
index 4691d5a710c1e..1b043e1fef04f 100644
--- a/tools/insert-usb-ids.py
+++ b/tools/insert-usb-ids.py
@@ -6,8 +6,6 @@
 # inserts those values into the template file specified by sys.argv[2],
 # printing the result to stdout
 
-from __future__ import print_function
-
 import sys
 import re
 import string
diff --git a/tools/makemanifest.py b/tools/makemanifest.py
index e076a03e0be3c..860935397af14 100644
--- a/tools/makemanifest.py
+++ b/tools/makemanifest.py
@@ -24,7 +24,6 @@
 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 # THE SOFTWARE.
 
-from __future__ import print_function
 import sys
 import os
 import subprocess
diff --git a/tools/manifestfile.py b/tools/manifestfile.py
index beaa36d0f5fc2..9c7a6e140f968 100644
--- a/tools/manifestfile.py
+++ b/tools/manifestfile.py
@@ -25,7 +25,6 @@
 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 # THE SOFTWARE.
 
-from __future__ import print_function
 import contextlib
 import os
 import sys
diff --git a/tools/metrics.py b/tools/metrics.py
index f6189e65abb4d..8bb96ba119a23 100755
--- a/tools/metrics.py
+++ b/tools/metrics.py
@@ -43,20 +43,23 @@
 
 """
 
-import collections, sys, re, subprocess
+import collections, os, sys, re, shlex, subprocess, multiprocessing
 
-MAKE_FLAGS = ["-j3", "CFLAGS_EXTRA=-DNDEBUG"]
+MAKE_FLAGS = ["-j{}".format(multiprocessing.cpu_count()), "CFLAGS_EXTRA=-DNDEBUG"]
 
 
 class PortData:
-    def __init__(self, name, dir, output, make_flags=None):
+    def __init__(self, name, dir, output, make_flags=None, pre_cmd=None):
         self.name = name
         self.dir = dir
         self.output = output
         self.make_flags = make_flags
         self.needs_mpy_cross = dir not in ("bare-arm", "minimal")
+        self.pre_cmd = pre_cmd
 
 
+mpy_cross_output = "mpy-cross/build/mpy-cross"
+
 port_data = {
     "b": PortData("bare-arm", "bare-arm", "build/firmware.elf"),
     "m": PortData("minimal x86", "minimal", "build/firmware.elf"),
@@ -65,7 +68,12 @@ def __init__(self, name, dir, output, make_flags=None):
     "s": PortData("stm32", "stm32", "build-PYBV10/firmware.elf", "BOARD=PYBV10"),
     "c": PortData("cc3200", "cc3200", "build/WIPY/release/application.axf", "BTARGET=application"),
     "8": PortData("esp8266", "esp8266", "build-ESP8266_GENERIC/firmware.elf"),
-    "3": PortData("esp32", "esp32", "build-ESP32_GENERIC/micropython.elf"),
+    "3": PortData(
+        "esp32",
+        "esp32",
+        "build-ESP32_GENERIC/micropython.elf",
+        pre_cmd=". esp-idf/export.sh",
+    ),
     "x": PortData("mimxrt", "mimxrt", "build-TEENSY40/firmware.elf"),
     "e": PortData("renesas-ra", "renesas-ra", "build-EK_RA6M2/firmware.elf"),
     "r": PortData("nrf", "nrf", "build-PCA10040/firmware.elf"),
@@ -74,8 +82,15 @@ def __init__(self, name, dir, output, make_flags=None):
     "v": PortData("qemu rv32", "qemu", "build-VIRT_RV32/firmware.elf", "BOARD=VIRT_RV32"),
 }
 
+for port_letter, port in port_data.items():
+    port.pre_cmd = os.environ.get(f"PRE_CMD_{port_letter}", port.pre_cmd)
+
+
+def quoted(args):
+    return " ".join(shlex.quote(word) for word in args)
 
-def syscmd(*args):
+
+def syscmd(*args, pre_cmd=None):
     sys.stdout.flush()
     a2 = []
     for a in args:
@@ -83,6 +98,10 @@ def syscmd(*args):
             a2.append(a)
         elif a:
             a2.extend(a)
+    if pre_cmd is not None:
+        a2_quoted = quoted(a2)
+        a2 = ["bash", "-c", "{} && {}".format(pre_cmd, a2_quoted)]
+        print(a2)
     subprocess.check_call(a2)
 
 
@@ -108,6 +127,8 @@ def read_build_log(filename):
     with open(filename) as f:
         for line in f:
             line = line.strip()
+            if line.startswith("BUILDING ") and "_ref" not in data:
+                data["_ref"] = line.removeprefix("BUILDING ")
             if line.strip() == "COMPUTING SIZES":
                 found_sizes = True
             elif found_sizes:
@@ -139,9 +160,15 @@ def do_diff(args):
     data1 = read_build_log(args[0])
     data2 = read_build_log(args[1])
 
+    ref1 = data1.pop("_ref", "(unknown ref)")
+    ref2 = data2.pop("_ref", "(unknown ref)")
+    print(f"Reference:  {ref1}")
+    print(f"Comparison: {ref2}")
     max_delta = None
     for key, value1 in data1.items():
         value2 = data2[key]
+        if key == mpy_cross_output:
+            name = "mpy-cross"
         for port in port_data.values():
             if key == "ports/{}/{}".format(port.dir, port.output):
                 name = port.name
@@ -181,8 +208,19 @@ def do_clean(args):
     ports = parse_port_list(args)
 
     print("CLEANING")
+
+    if any(port.needs_mpy_cross for port in ports):
+        syscmd("make", "-C", "mpy-cross", "clean")
+
     for port in ports:
-        syscmd("make", "-C", "ports/{}".format(port.dir), port.make_flags, "clean")
+        syscmd(
+            "make",
+            "-C",
+            "ports/{}".format(port.dir),
+            port.make_flags,
+            "clean",
+            pre_cmd=port.pre_cmd,
+        )
 
 
 def do_build(args):
@@ -196,7 +234,14 @@ def do_build(args):
 
     print("BUILDING PORTS")
     for port in ports:
-        syscmd("make", "-C", "ports/{}".format(port.dir), MAKE_FLAGS, port.make_flags)
+        syscmd(
+            "make",
+            "-C",
+            "ports/{}".format(port.dir),
+            MAKE_FLAGS,
+            port.make_flags,
+            pre_cmd=port.pre_cmd,
+        )
 
     do_sizes(args)
 
@@ -207,6 +252,10 @@ def do_sizes(args):
     ports = parse_port_list(args)
 
     print("COMPUTING SIZES")
+
+    if any(port.needs_mpy_cross for port in ports):
+        syscmd("size", mpy_cross_output)
+
     for port in ports:
         syscmd("size", "ports/{}/{}".format(port.dir, port.output))
 
diff --git a/tools/mpy-tool.py b/tools/mpy-tool.py
index 8849f2f1e5956..bf0b89018e4e7 100755
--- a/tools/mpy-tool.py
+++ b/tools/mpy-tool.py
@@ -24,40 +24,21 @@
 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 # THE SOFTWARE.
 
-# Python 2/3/MicroPython compatibility code
-from __future__ import print_function
+import io
+import struct
 import sys
+from binascii import hexlify
 
-if sys.version_info[0] == 2:
-    from binascii import hexlify as hexlify_py2
-
-    str_cons = lambda val, enc=None: str(val)
-    bytes_cons = lambda val, enc=None: bytearray(val)
-    is_str_type = lambda o: isinstance(o, str)
-    is_bytes_type = lambda o: type(o) is bytearray
-    is_int_type = lambda o: isinstance(o, int) or isinstance(o, long)  # noqa: F821
-
-    def hexlify_to_str(b):
-        x = hexlify_py2(b)
-        return ":".join(x[i : i + 2] for i in range(0, len(x), 2))
-
-elif sys.version_info[0] == 3:  # Also handles MicroPython
-    from binascii import hexlify
-
-    str_cons = str
-    bytes_cons = bytes
-    is_str_type = lambda o: isinstance(o, str)
-    is_bytes_type = lambda o: isinstance(o, bytes)
-    is_int_type = lambda o: isinstance(o, int)
-
-    def hexlify_to_str(b):
-        return str(hexlify(b, ":"), "ascii")
+str_cons = str
+bytes_cons = bytes
+is_str_type = lambda o: isinstance(o, str)
+is_bytes_type = lambda o: isinstance(o, bytes)
+is_int_type = lambda o: isinstance(o, int)
 
 
-# end compatibility code
+def hexlify_to_str(b):
+    return str(hexlify(b, ":"), "ascii")
 
-import sys
-import struct
 
 sys.path.append(sys.path[0] + "/../py")
 import makeqstrdata as qstrutil
@@ -114,6 +95,23 @@ class Config:
 MP_NATIVE_ARCH_XTENSA = 9
 MP_NATIVE_ARCH_XTENSAWIN = 10
 MP_NATIVE_ARCH_RV32IMC = 11
+MP_NATIVE_ARCH_RV64IMC = 12
+
+MP_NATIVE_ARCH_NAMES = [
+    "NONE",
+    "X86",
+    "X64",
+    "ARMV6",
+    "ARMV6M",
+    "ARMV7M",
+    "ARMV7EM",
+    "ARMV7EMSP",
+    "ARMV7EMDP",
+    "XTENSA",
+    "XTENSAWIN",
+    "RV32IMC",
+    "RV64IMC",
+]
 
 MP_PERSISTENT_OBJ_FUN_TABLE = 0
 MP_PERSISTENT_OBJ_NONE = 1
@@ -142,6 +140,8 @@ class Config:
 MP_BC_FORMAT_VAR_UINT = 2
 MP_BC_FORMAT_OFFSET = 3
 
+MP_NATIVE_ARCH_FLAGS_PRESENT = 0x40
+
 mp_unary_op_method_name = (
     "__pos__",
     "__neg__",
@@ -306,6 +306,25 @@ class Opcode:
         MP_BC_POP_JUMP_IF_TRUE,
         MP_BC_POP_JUMP_IF_FALSE,
     )
+    ALL_OFFSET = (
+        MP_BC_UNWIND_JUMP,
+        MP_BC_JUMP,
+        MP_BC_POP_JUMP_IF_TRUE,
+        MP_BC_POP_JUMP_IF_FALSE,
+        MP_BC_JUMP_IF_TRUE_OR_POP,
+        MP_BC_JUMP_IF_FALSE_OR_POP,
+        MP_BC_SETUP_WITH,
+        MP_BC_SETUP_EXCEPT,
+        MP_BC_SETUP_FINALLY,
+        MP_BC_POP_EXCEPT_JUMP,
+        MP_BC_FOR_ITER,
+    )
+    ALL_WITH_CHILD = (
+        MP_BC_MAKE_FUNCTION,
+        MP_BC_MAKE_FUNCTION_DEFARGS,
+        MP_BC_MAKE_CLOSURE,
+        MP_BC_MAKE_CLOSURE_DEFARGS,
+    )
 
     # Create a dict mapping opcode value to opcode name.
     mapping = ["unknown" for _ in range(256)]
@@ -562,6 +581,7 @@ def __init__(
         mpy_source_file,
         mpy_segments,
         header,
+        arch_flags,
         qstr_table,
         obj_table,
         raw_code,
@@ -574,6 +594,7 @@ def __init__(
         self.mpy_segments = mpy_segments
         self.source_file = qstr_table[0]
         self.header = header
+        self.arch_flags = arch_flags
         self.qstr_table = qstr_table
         self.obj_table = obj_table
         self.raw_code = raw_code
@@ -651,6 +672,14 @@ def disassemble(self):
         print("mpy_source_file:", self.mpy_source_file)
         print("source_file:", self.source_file.str)
         print("header:", hexlify_to_str(self.header))
+        arch_index = (self.header[2] >> 2) & 0x2F
+        if arch_index >= len(MP_NATIVE_ARCH_NAMES):
+            arch_name = "UNKNOWN"
+        else:
+            arch_name = MP_NATIVE_ARCH_NAMES[arch_index]
+        print("arch:", arch_name)
+        if self.header[2] & MP_NATIVE_ARCH_FLAGS_PRESENT != 0:
+            print("arch_flags:", hex(self.arch_flags))
         print("qstr_table[%u]:" % len(self.qstr_table))
         for q in self.qstr_table:
             print("    %s" % q.str)
@@ -888,7 +917,7 @@ def __init__(self, parent_name, qstr_table, fun_data, prelude_offset, code_kind)
         self.escaped_name = unique_escaped_name
 
     def disassemble_children(self):
-        print("  children:", [rc.simple_name.str for rc in self.children])
+        self.print_children_annotated()
         for rc in self.children:
             rc.disassemble()
 
@@ -980,6 +1009,75 @@ def freeze_raw_code(self, prelude_ptr=None, type_sig=0):
         raw_code_count += 1
         raw_code_content += 4 * 4
 
+    @staticmethod
+    def decode_lineinfo(line_info: memoryview) -> "tuple[int, int, memoryview]":
+        c = line_info[0]
+        if (c & 0x80) == 0:
+            # 0b0LLBBBBB encoding
+            return (c & 0x1F), (c >> 5), line_info[1:]
+        else:
+            # 0b1LLLBBBB 0bLLLLLLLL encoding (l's LSB in second byte)
+            return (c & 0xF), (((c << 4) & 0x700) | line_info[1]), line_info[2:]
+
+    def get_source_annotation(self, ip: int, file=None) -> dict:
+        bc_offset = ip - self.offset_opcodes
+        try:
+            line_info = memoryview(self.fun_data)[self.offset_line_info : self.offset_opcodes]
+        except AttributeError:
+            return {"file": file, "line": None}
+
+        source_line = 1
+        while line_info:
+            bc_increment, line_increment, line_info = self.decode_lineinfo(line_info)
+            if bc_offset >= bc_increment:
+                bc_offset -= bc_increment
+                source_line += line_increment
+            else:
+                break
+
+        return {"file": file, "line": source_line}
+
+    def get_label(self, ip: "int | None" = None, child_num: "int | None" = None) -> str:
+        if ip is not None:
+            assert child_num is None
+            return "%s.%d" % (self.escaped_name, ip)
+        elif child_num is not None:
+            return "%s.child%d" % (self.escaped_name, child_num)
+        else:
+            return "%s" % self.escaped_name
+
+    def print_children_annotated(self) -> None:
+        """
+        Equivalent to `print("  children:", [child.simple_name.str for child in self.children])`,
+        but also includes json markers for the start and end of each one's name in that line.
+        """
+
+        labels = ["%s.children" % self.escaped_name]
+        annotation_labels = []
+        output = io.StringIO()
+        output.write("  children: [")
+        sep = ", "
+        for i, child in enumerate(self.children):
+            if i != 0:
+                output.write(sep)
+            start_col = output.tell() + 1
+            output.write(child.simple_name.str)
+            end_col = output.tell() + 1
+            labels.append(self.get_label(child_num=i))
+            annotation_labels.append(
+                {
+                    "name": self.get_label(child_num=i),
+                    "target": child.get_label(),
+                    "range": {
+                        "startCol": start_col,
+                        "endCol": end_col,
+                    },
+                },
+            )
+        output.write("]")
+
+        print(output.getvalue(), annotations={"labels": annotation_labels}, labels=labels)
+
 
 class RawCodeBytecode(RawCode):
     def __init__(self, parent_name, qstr_table, obj_table, fun_data):
@@ -988,9 +1086,58 @@ def __init__(self, parent_name, qstr_table, obj_table, fun_data):
             parent_name, qstr_table, fun_data, 0, MP_CODE_BYTECODE
         )
 
+    def get_opcode_annotations_labels(
+        self, opcode: int, ip: int, arg: int, sz: int, arg_pos: int, arg_len: int
+    ) -> "tuple[dict, list[str]]":
+        annotations = {
+            "source": self.get_source_annotation(ip),
+            "disassembly": Opcode.mapping[opcode],
+        }
+        labels = [self.get_label(ip)]
+
+        if opcode in Opcode.ALL_OFFSET:
+            annotations["link"] = {
+                "offset": arg_pos,
+                "length": arg_len,
+                "to": ip + arg + sz,
+            }
+            annotations["labels"] = [
+                {
+                    "name": self.get_label(ip),
+                    "target": self.get_label(ip + arg + sz),
+                    "range": {
+                        "startCol": arg_pos + 1,
+                        "endCol": arg_pos + arg_len + 1,
+                    },
+                },
+            ]
+
+        elif opcode in Opcode.ALL_WITH_CHILD:
+            try:
+                child = self.children[arg]
+            except IndexError:
+                # link out-of-range child to the child array itself
+                target = "%s.children" % self.escaped_name
+            else:
+                # link resolvable child to the actual child
+                target = child.get_label()
+
+            annotations["labels"] = [
+                {
+                    "name": self.get_label(ip),
+                    "target": target,
+                    "range": {
+                        "startCol": arg_pos + 1,
+                        "endCol": arg_pos + arg_len + 1,
+                    },
+                },
+            ]
+
+        return annotations, labels
+
     def disassemble(self):
         bc = self.fun_data
-        print("simple_name:", self.simple_name.str)
+        print("simple_name:", self.simple_name.str, labels=[self.get_label()])
         print("  raw bytecode:", len(bc), hexlify_to_str(bc))
         print("  prelude:", self.prelude_signature)
         print("  args:", [self.qstr_table[i].str for i in self.names[1:]])
@@ -1006,9 +1153,22 @@ def disassemble(self):
                 pass
             else:
                 arg = ""
-            print(
-                "  %-11s %s %s" % (hexlify_to_str(bc[ip : ip + sz]), Opcode.mapping[bc[ip]], arg)
+
+            pre_arg_part = "  %-11s %s" % (
+                hexlify_to_str(bc[ip : ip + sz]),
+                Opcode.mapping[bc[ip]],
+            )
+            arg_part = "%s" % arg
+            annotations, labels = self.get_opcode_annotations_labels(
+                opcode=bc[ip],
+                ip=ip,
+                arg=arg,
+                sz=sz,
+                arg_pos=len(pre_arg_part) + 1,
+                arg_len=len(arg_part),
             )
+
+            print(pre_arg_part, arg_part, annotations=annotations, labels=labels)
             ip += sz
         self.disassemble_children()
 
@@ -1085,6 +1245,7 @@ def __init__(
             MP_NATIVE_ARCH_XTENSA,
             MP_NATIVE_ARCH_XTENSAWIN,
             MP_NATIVE_ARCH_RV32IMC,
+            MP_NATIVE_ARCH_RV64IMC,
         ):
             self.fun_data_attributes = '__attribute__((section(".text,\\"ax\\",@progbits # ")))'
         else:
@@ -1102,13 +1263,13 @@ def __init__(
             self.fun_data_attributes += " __attribute__ ((aligned (4)))"
         elif (
             MP_NATIVE_ARCH_ARMV6M <= config.native_arch <= MP_NATIVE_ARCH_ARMV7EMDP
-        ) or config.native_arch == MP_NATIVE_ARCH_RV32IMC:
-            # ARMVxxM or RV32IMC -- two byte align.
+        ) or MP_NATIVE_ARCH_RV32IMC <= config.native_arch <= MP_NATIVE_ARCH_RV64IMC:
+            # ARMVxxM or RV{32,64}IMC -- two byte align.
             self.fun_data_attributes += " __attribute__ ((aligned (2)))"
 
     def disassemble(self):
         fun_data = self.fun_data
-        print("simple_name:", self.simple_name.str)
+        print("simple_name:", self.simple_name.str, labels=[self.get_label()])
         print(
             "  raw data:",
             len(fun_data),
@@ -1362,7 +1523,7 @@ def read_mpy(filename):
         if header[1] != config.MPY_VERSION:
             raise MPYReadError(filename, "incompatible .mpy version")
         feature_byte = header[2]
-        mpy_native_arch = feature_byte >> 2
+        mpy_native_arch = (feature_byte >> 2) & 0x2F
         if mpy_native_arch != MP_NATIVE_ARCH_NONE:
             mpy_sub_version = feature_byte & 3
             if mpy_sub_version != config.MPY_SUB_VERSION:
@@ -1373,6 +1534,11 @@ def read_mpy(filename):
                 raise MPYReadError(filename, "native architecture mismatch")
         config.mp_small_int_bits = header[3]
 
+        arch_flags = 0
+        # Read the architecture-specific flag bits if present.
+        if (feature_byte & MP_NATIVE_ARCH_FLAGS_PRESENT) != 0:
+            arch_flags = reader.read_uint()
+
         # Read number of qstrs, and number of objects.
         n_qstr = reader.read_uint()
         n_obj = reader.read_uint()
@@ -1401,6 +1567,7 @@ def read_mpy(filename):
         filename,
         segments,
         header,
+        arch_flags,
         qstr_table,
         obj_table,
         raw_code,
@@ -1696,26 +1863,40 @@ def merge_mpy(compiled_modules, output_file):
             merged_mpy.extend(f.read())
     else:
         main_cm_idx = None
+        arch_flags = 0
         for idx, cm in enumerate(compiled_modules):
             feature_byte = cm.header[2]
-            mpy_native_arch = feature_byte >> 2
+            mpy_native_arch = (feature_byte >> 2) & 0x2F
             if mpy_native_arch:
                 # Must use qstr_table and obj_table from this raw_code
                 if main_cm_idx is not None:
                     raise Exception("can't merge files when more than one contains native code")
                 main_cm_idx = idx
+                arch_flags = cm.arch_flags
         if main_cm_idx is not None:
             # Shift main_cm to front of list.
             compiled_modules.insert(0, compiled_modules.pop(main_cm_idx))
 
+        if config.arch_flags is not None:
+            arch_flags = config.arch_flags
+
         header = bytearray(4)
         ## CIRCUITPY-CHANGE: "C" is used for CircuitPython
         header[0] = ord("C")
         header[1] = config.MPY_VERSION
-        header[2] = config.native_arch << 2 | config.MPY_SUB_VERSION if config.native_arch else 0
+        header[2] = (
+            (MP_NATIVE_ARCH_FLAGS_PRESENT if arch_flags != 0 else 0)
+            | config.native_arch << 2
+            | config.MPY_SUB_VERSION
+            if config.native_arch
+            else 0
+        )
         header[3] = config.mp_small_int_bits
         merged_mpy.extend(header)
 
+        if arch_flags != 0:
+            merged_mpy.extend(mp_encode_uint(arch_flags))
+
         n_qstr = 0
         n_obj = 0
         for cm in compiled_modules:
@@ -1771,6 +1952,138 @@ def copy_section(file, offset, offset2):
             f.write(merged_mpy)
 
 
+def extract_segments(compiled_modules, basename, kinds_arg):
+    import re
+
+    kind_str = ("META", "QSTR", "OBJ", "CODE")
+    kinds = set()
+    if kinds_arg is not None:
+        for kind in kinds_arg.upper().split(","):
+            if kind in kind_str:
+                kinds.add(kind)
+            else:
+                raise Exception('unknown segment kind "%s"' % (kind,))
+    segments = []
+    for module in compiled_modules:
+        for segment in module.mpy_segments:
+            if not kinds or kind_str[segment.kind] in kinds:
+                segments.append((module.mpy_source_file, module.source_file.str, segment))
+    count_len = len(str(len(segments)))
+    sanitiser = re.compile("[^a-zA-Z0-9_.-]")
+    for counter, entry in enumerate(segments):
+        file_name, source_file, segment = entry
+        output_name = (
+            basename
+            + "_"
+            + str(counter).rjust(count_len, "0")
+            + "_"
+            + sanitiser.sub("_", source_file)
+            + "_"
+            + kind_str[segment.kind]
+            + "_"
+            + sanitiser.sub("_", str(segment.name))
+            + ".bin"
+        )
+        with open(file_name, "rb") as source:
+            with open(output_name, "wb") as output:
+                source.seek(segment.start)
+                output.write(source.read(segment.end - segment.start))
+
+
+class PrintShim:
+    """Base class for interposing extra functionality onto the global `print` method."""
+
+    def __init__(self):
+        self.wrapped_print = None
+
+    def __enter__(self):
+        global print
+
+        if self.wrapped_print is not None:
+            raise RecursionError
+
+        self.wrapped_print = print
+        print = self
+
+        return self
+
+    def __exit__(self, exc_type, exc_value, traceback):
+        global print
+
+        if self.wrapped_print is None:
+            return
+
+        print = self.wrapped_print
+        self.wrapped_print = None
+
+        self.on_exit()
+
+    def on_exit(self):
+        pass
+
+    def __call__(self, *a, **k):
+        return self.wrapped_print(*a, **k)
+
+
+class PrintIgnoreExtraArgs(PrintShim):
+    """Just strip the `annotations` and `labels` kwargs and pass down to the underlying print."""
+
+    def __call__(self, *a, annotations: dict = {}, labels: "list[str]" = (), **k):
+        return super().__call__(*a, **k)
+
+
+class PrintJson(PrintShim):
+    """Output lines as godbolt-compatible JSON with extra annotation info from `annotations` and `labels`, rather than plain text."""
+
+    def __init__(self, fp=sys.stdout, language_id: str = "mpy"):
+        super().__init__()
+        self.fp = fp
+        self.asm = {
+            "asm": [],
+            "labelDefinitions": {},
+            "languageId": language_id,
+        }
+        self.line_number: int = 0
+        self.buf: "io.StringIO | None" = None
+
+    def on_exit(self):
+        import json
+
+        if self.buf is not None:
+            # flush last partial line
+            self.__call__()
+
+        json.dump(self.asm, self.fp)
+
+    def __call__(self, *a, annotations: dict = {}, labels: "list[str]" = (), **k):
+        # ignore prints directed to an explicit output
+        if "file" in k:
+            return super().__call__(*a, **k)
+
+        if self.buf is None:
+            self.buf = io.StringIO()
+
+        super().__call__(*a, file=sys.stderr, **k)
+
+        if "end" in k:
+            # buffer partial-line prints to collect into a single AsmResultLine
+            return super().__call__(*a, file=self.buf, **k)
+        else:
+            retval = super().__call__(*a, file=self.buf, end="", **k)
+            output = self.buf.getvalue()
+            self.buf = None
+
+        asm_line = {"text": output}
+        asm_line.update(annotations)
+        self.asm["asm"].append(asm_line)
+
+        self.line_number += 1
+        for label in labels:
+            self.asm["labelDefinitions"][label] = self.line_number
+
+        return retval
+
+
 def main(args=None):
     global global_qstrs
 
@@ -1784,9 +2097,23 @@ def main(args=None):
         "-d", "--disassemble", action="store_true", help="output disassembled contents of files"
     )
     cmd_parser.add_argument("-f", "--freeze", action="store_true", help="freeze files")
+    cmd_parser.add_argument(
+        "-j",
+        "--json",
+        action="store_true",
+        help="output hexdump, disassembly, and frozen code as JSON with extra metadata",
+    )
     cmd_parser.add_argument(
         "--merge", action="store_true", help="merge multiple .mpy files into one"
     )
+    cmd_parser.add_argument(
+        "-e", "--extract", metavar="BASE", type=str, help="write segments into separate files"
+    )
+    cmd_parser.add_argument(
+        "--extract-only",
+        metavar="KIND[,...]",
+        help="extract only segments of the given type (meta, qstr, obj, code)",
+    )
     cmd_parser.add_argument("-q", "--qstr-header", help="qstr header file to freeze against")
     cmd_parser.add_argument(
         "-mlongint-impl",
@@ -1801,6 +2128,12 @@ def main(args=None):
         default=16,
         help="mpz digit size used by target (default 16)",
     )
+    cmd_parser.add_argument(
+        "-march-flags",
+        metavar="F",
+        type=int,
+        help="architecture flags value to set in the output file (strips existing flags if not present)",
+    )
     cmd_parser.add_argument("-o", "--output", default=None, help="output file")
     cmd_parser.add_argument("files", nargs="+", help="input .mpy files")
     args = cmd_parser.parse_args(args)
@@ -1813,6 +2146,7 @@ def main(args=None):
     }[args.mlongint_impl]
     config.MPZ_DIG_SIZE = args.mmpz_dig_size
     config.native_arch = MP_NATIVE_ARCH_NONE
+    config.arch_flags = args.march_flags
 
     # set config values for qstrs, and get the existing base set of qstrs
     # already in the firmware
@@ -1836,24 +2170,40 @@ def main(args=None):
         print(er, file=sys.stderr)
         sys.exit(1)
 
-    if args.hexdump:
-        hexdump_mpy(compiled_modules)
+    if args.json:
+        if args.freeze:
+            print_shim = PrintJson(sys.stdout, language_id="c")
+        elif args.hexdump:
+            print_shim = PrintJson(sys.stdout, language_id="stderr")
+        elif args.disassemble:
+            print_shim = PrintJson(sys.stdout, language_id="mpy")
+        else:
+            print_shim = PrintJson(sys.stdout)
+    else:
+        print_shim = PrintIgnoreExtraArgs()
 
-    if args.disassemble:
+    with print_shim:
         if args.hexdump:
-            print()
-        disassemble_mpy(compiled_modules)
+            hexdump_mpy(compiled_modules)
 
-    if args.freeze:
-        try:
-            freeze_mpy(firmware_qstr_idents, compiled_modules)
-        except FreezeError as er:
-            print(er, file=sys.stderr)
-            sys.exit(1)
+        if args.disassemble:
+            if args.hexdump:
+                print()
+            disassemble_mpy(compiled_modules)
+
+        if args.freeze:
+            try:
+                freeze_mpy(firmware_qstr_idents, compiled_modules)
+            except FreezeError as er:
+                print(er, file=sys.stderr)
+                sys.exit(1)
 
     if args.merge:
         merge_mpy(compiled_modules, args.output)
 
+    if args.extract:
+        extract_segments(compiled_modules, args.extract, args.extract_only)
+
 
 if __name__ == "__main__":
     main()
diff --git a/tools/mpy_ld.py b/tools/mpy_ld.py
index 219cd1a7468bc..26db07261631c 100755
--- a/tools/mpy_ld.py
+++ b/tools/mpy_ld.py
@@ -402,6 +402,7 @@ def __init__(self, arch):
         self.known_syms = {}  # dict of symbols that are defined
         self.unresolved_syms = []  # list of unresolved symbols
         self.mpy_relocs = []  # list of relocations needed in the output .mpy file
+        self.externs = {}  # dict of externally-defined symbols
 
     def check_arch(self, arch_name):
         if arch_name != self.arch.name:
@@ -491,10 +492,14 @@ def populate_got(env):
         sym = got_entry.sym
         if hasattr(sym, "resolved"):
             sym = sym.resolved
-        sec = sym.section
-        addr = sym["st_value"]
-        got_entry.sec_name = sec.name
-        got_entry.link_addr += sec.addr + addr
+        if sym.name in env.externs:
+            got_entry.sec_name = ".external.fixed_addr"
+            got_entry.link_addr = env.externs[sym.name]
+        else:
+            sec = sym.section
+            addr = sym["st_value"]
+            got_entry.sec_name = sec.name
+            got_entry.link_addr += sec.addr + addr
 
     # Get sorted GOT, sorted by external, text, rodata, bss so relocations can be combined
     got_list = sorted(
@@ -520,6 +525,9 @@ def populate_got(env):
             dest = int(got_entry.name.split("+")[1], 16) // env.arch.word_size
         elif got_entry.sec_name == ".external.mp_fun_table":
             dest = got_entry.sym.mp_fun_table_offset
+        elif got_entry.sec_name == ".external.fixed_addr":
+            # Fixed-address symbols should not be relocated.
+            continue
         elif got_entry.sec_name.startswith(".text"):
             dest = ".text"
         elif got_entry.sec_name.startswith(".rodata"):
@@ -703,8 +711,9 @@ def do_relocation_text(env, text_addr, r):
         (addr, value) = process_riscv32_relocation(env, text_addr, r)
 
     elif env.arch.name == "EM_ARM" and r_info_type == R_ARM_ABS32:
-        # happens for soft-float on armv6m
-        raise ValueError("Absolute relocations not supported on ARM")
+        # Absolute relocation, handled as a data relocation.
+        do_relocation_data(env, text_addr, r)
+        return
 
     else:
         # Unknown/unsupported relocation
@@ -773,9 +782,9 @@ def do_relocation_data(env, text_addr, r):
     ):
         # Relocation in data.rel.ro to internal/external symbol
         if env.arch.word_size == 4:
-            struct_type = "<I"
+            struct_type = "<i"
         elif env.arch.word_size == 8:
-            struct_type = "<Q"
+            struct_type = "<q"
         if hasattr(s, "resolved"):
             s = s.resolved
         sec = s.section
@@ -1131,7 +1140,7 @@ def load_object_file(env, f, felf):
         elif sym.entry["st_shndx"] == "SHN_UNDEF" and sym["st_info"]["bind"] == "STB_GLOBAL":
             # Undefined global symbol, needs resolving
             env.unresolved_syms.append(sym)
-    if len(dup_errors):
+    if dup_errors:
         raise LinkError("\n".join(dup_errors))
 
 
@@ -1207,6 +1216,9 @@ def link_objects(env, native_qstr_vals_len):
             sym.section = env.obj_table_section
         elif sym.name in env.known_syms:
             sym.resolved = env.known_syms[sym.name]
+        elif sym.name in env.externs:
+            # Fixed-address symbols do not need pre-processing.
+            continue
         else:
             if sym.name in fun_table:
                 sym.section = mp_fun_table_sec
@@ -1214,7 +1226,16 @@ def link_objects(env, native_qstr_vals_len):
             else:
                 undef_errors.append("{}: undefined symbol: {}".format(sym.filename, sym.name))
 
-    if len(undef_errors):
+    for sym in env.externs:
+        if sym in env.known_syms:
+            log(
+                LOG_LEVEL_1,
+                "Symbol {} is a fixed-address symbol at {:08x} and is also provided from an object file".format(
+                    sym, env.externs[sym]
+                ),
+            )
+
+    if undef_errors:
         raise LinkError("\n".join(undef_errors))
 
     # Align sections, assign their addresses, and create full_text
@@ -1457,6 +1478,9 @@ def do_link(args):
     log(LOG_LEVEL_2, "qstr vals: " + ", ".join(native_qstr_vals))
     env = LinkEnv(args.arch)
     try:
+        if args.externs:
+            env.externs = parse_linkerscript(args.externs)
+
         # Load object files
         for fn in args.files:
             with open(fn, "rb") as f:
@@ -1485,6 +1509,50 @@ def do_link(args):
         sys.exit(1)
 
 
+def parse_linkerscript(source):
+    # This extracts fixed-address symbol lists from linkerscripts, only parsing
+    # a small subset of all possible directives.  Right now the only
+    # linkerscript file this is really tested against is the ESP8266's builtin
+    # ROM functions list ($SDK/ld/eagle.rom.addr.v6.ld).
+    #
+    # The parser should be able to handle symbol entries inside ESP-IDF's ROM
+    # symbol lists for the ESP32 range of MCUs as well (see *.ld files in
+    # $SDK/components/esp_rom/<name>/).
+
+    symbols = {}
+
+    LINE_REGEX = re.compile(
+        r"^(?P<weak>PROVIDE\()?"  # optional weak marker start
+        r"(?P<symbol>[a-zA-Z_]\w*)"  # symbol name
+        r"=0x(?P<address>[\da-fA-F]{1,8})*"  # symbol address
+        r"(?(weak)\));$",  # optional weak marker end and line terminator
+        re.ASCII,
+    )
+
+    inside_comment = False
+    for line in (line.strip() for line in source.readlines()):
+        if line.startswith("/*") and not inside_comment:
+            if not line.endswith("*/"):
+                inside_comment = True
+            continue
+        if inside_comment:
+            if line.endswith("*/"):
+                inside_comment = False
+            continue
+        if line.startswith("//"):
+            continue
+        match = LINE_REGEX.match("".join(line.split()))
+        if not match:
+            continue
+        tokens = match.groupdict()
+        symbol = tokens["symbol"]
+        address = int(tokens["address"], 16)
+        if symbol in symbols:
+            raise ValueError(f"Symbol {symbol} already defined")
+        symbols[symbol] = address
+    return symbols
+
+
 def main():
     import argparse
 
@@ -1501,6 +1569,13 @@ def main():
     cmd_parser.add_argument(
         "--output", "-o", default=None, help="output .mpy file (default to input with .o->.mpy)"
     )
+    cmd_parser.add_argument(
+        "--externs",
+        "-e",
+        type=argparse.FileType("rt"),
+        default=None,
+        help="linkerscript providing fixed-address symbols to augment symbol resolution",
+    )
     cmd_parser.add_argument("files", nargs="+", help="input files")
     args = cmd_parser.parse_args()
 
diff --git a/tools/pyboard.py b/tools/pyboard.py
index 20310ba7081c0..c9f65d5d873c2 100755
--- a/tools/pyboard.py
+++ b/tools/pyboard.py
@@ -248,14 +248,22 @@ def inWaiting(self):
 
 class Pyboard:
     def __init__(
-        self, device, baudrate=115200, user="micro", password="python", wait=0, exclusive=True
+        self,
+        device,
+        baudrate=115200,
+        user="micro",
+        password="python",
+        wait=0,
+        exclusive=True,
+        timeout=None,
+        write_timeout=5,
     ):
         self.in_raw_repl = False
         self.use_raw_paste = True
         if device.startswith("exec:"):
             self.serial = ProcessToSerial(device[len("exec:") :])
         elif device.startswith("execpty:"):
-            self.serial = ProcessPtyToTerminal(device[len("qemupty:") :])
+            self.serial = ProcessPtyToTerminal(device[len("execpty:") :])
         elif device and device[0].isdigit() and device[-1].isdigit() and device.count(".") == 3:
             # device looks like an IP address
             self.serial = TelnetToSerial(device, user, password, read_timeout=10)
@@ -264,7 +272,12 @@ def __init__(
             import serial.tools.list_ports
 
             # Set options, and exclusive if pyserial supports it
-            serial_kwargs = {"baudrate": baudrate, "interCharTimeout": 1}
+            serial_kwargs = {
+                "baudrate": baudrate,
+                "timeout": timeout,
+                "write_timeout": write_timeout,
+                "interCharTimeout": 1,
+            }
             if serial.__version__ >= "3.3":
                 serial_kwargs["exclusive"] = exclusive
 
@@ -304,14 +317,25 @@ def __init__(
     def close(self):
         self.serial.close()
 
-    def read_until(self, min_num_bytes, ending, timeout=10, data_consumer=None):
-        # if data_consumer is used then data is not accumulated and the ending must be 1 byte long
+    def read_until(
+        self, min_num_bytes, ending, timeout=10, data_consumer=None, timeout_overall=None
+    ):
+        """
+        min_num_bytes: Obsolete.
+        ending: Return if 'ending' matches.
+        timeout [s]: Return if timeout between characters. None: Infinite timeout.
+        timeout_overall [s]: Return not later than timeout_overall. None: Infinite timeout.
+        data_consumer: Use callback for incoming characters.
+            If data_consumer is used then data is not accumulated and the ending must be 1 byte long
+
+        It is not visible to the caller why the function returned. It could be ending or timeout.
+        """
         assert data_consumer is None or len(ending) == 1
+        assert isinstance(timeout, (type(None), int, float))
+        assert isinstance(timeout_overall, (type(None), int, float))
 
-        data = self.serial.read(min_num_bytes)
-        if data_consumer:
-            data_consumer(data)
-        timeout_count = 0
+        data = b""
+        begin_overall_s = begin_char_s = time.monotonic()
         while True:
             if data.endswith(ending):
                 break
@@ -322,15 +346,25 @@ def read_until(self, min_num_bytes, ending, timeout=10, data_consumer=None):
                     data = new_data
                 else:
                     data = data + new_data
-                timeout_count = 0
+                begin_char_s = time.monotonic()
             else:
-                timeout_count += 1
-                if timeout is not None and timeout_count >= 100 * timeout:
+                if timeout is not None and time.monotonic() >= begin_char_s + timeout:
+                    break
+                if (
+                    timeout_overall is not None
+                    and time.monotonic() >= begin_overall_s + timeout_overall
+                ):
                     break
                 time.sleep(0.01)
         return data
 
-    def enter_raw_repl(self, soft_reset=True):
+    def enter_raw_repl(self, soft_reset=True, timeout_overall=10):
+        try:
+            self._enter_raw_repl_unprotected(soft_reset, timeout_overall)
+        except OSError as er:
+            raise PyboardError("could not enter raw repl: {}".format(er))
+
+    def _enter_raw_repl_unprotected(self, soft_reset, timeout_overall):
         self.serial.write(b"\r\x03")  # ctrl-C: interrupt any running program
 
         # flush input (without relying on serial.flushInput())
@@ -342,7 +376,9 @@ def enter_raw_repl(self, soft_reset=True):
         self.serial.write(b"\r\x01")  # ctrl-A: enter raw REPL
 
         if soft_reset:
-            data = self.read_until(1, b"raw REPL; CTRL-B to exit\r\n>")
+            data = self.read_until(
+                1, b"raw REPL; CTRL-B to exit\r\n>", timeout_overall=timeout_overall
+            )
             if not data.endswith(b"raw REPL; CTRL-B to exit\r\n>"):
                 print(data)
                 raise PyboardError("could not enter raw repl")
@@ -352,12 +388,12 @@ def enter_raw_repl(self, soft_reset=True):
             # Waiting for "soft reboot" independently to "raw REPL" (done below)
             # allows boot.py to print, which will show up after "soft reboot"
             # and before "raw REPL".
-            data = self.read_until(1, b"soft reboot\r\n")
+            data = self.read_until(1, b"soft reboot\r\n", timeout_overall=timeout_overall)
             if not data.endswith(b"soft reboot\r\n"):
                 print(data)
                 raise PyboardError("could not enter raw repl")
 
-        data = self.read_until(1, b"raw REPL; CTRL-B to exit\r\n")
+        data = self.read_until(1, b"raw REPL; CTRL-B to exit\r\n", timeout_overall=timeout_overall)
         if not data.endswith(b"raw REPL; CTRL-B to exit\r\n"):
             print(data)
             raise PyboardError("could not enter raw repl")
@@ -475,8 +511,8 @@ def eval(self, expression, parse=False):
             return ret
 
     # In Python3, call as pyboard.exec(), see the setattr call below.
-    def exec_(self, command, data_consumer=None):
-        ret, ret_err = self.exec_raw(command, data_consumer=data_consumer)
+    def exec_(self, command, timeout=10, data_consumer=None):
+        ret, ret_err = self.exec_raw(command, timeout, data_consumer)
         if ret_err:
             raise PyboardError("exception", ret, ret_err)
         return ret
diff --git a/tools/pydfu.py b/tools/pydfu.py
index cd7354818cdea..376c697cbd5eb 100755
--- a/tools/pydfu.py
+++ b/tools/pydfu.py
@@ -11,8 +11,6 @@
 See document UM0391 for a description of the DFuse file.
 """
 
-from __future__ import print_function
-
 import argparse
 import collections
 import inspect
@@ -75,11 +73,7 @@
 # USB DFU interface
 __DFU_INTERFACE = 0
 
-# Python 3 deprecated getargspec in favour of getfullargspec, but
-# Python 2 doesn't have the latter, so detect which one to use
-getargspec = getattr(inspect, "getfullargspec", getattr(inspect, "getargspec", None))
-
-if "length" in getargspec(usb.util.get_string).args:
+if "length" in inspect.getfullargspec(usb.util.get_string).args:
     # PyUSB 1.0.0.b1 has the length argument
     def get_string(dev, index):
         return usb.util.get_string(dev, 255, index)
diff --git a/tools/verifygitlog.py b/tools/verifygitlog.py
index 67215d5c5d066..dba6ebd6de59a 100755
--- a/tools/verifygitlog.py
+++ b/tools/verifygitlog.py
@@ -96,20 +96,47 @@ def verify_message_body(raw_body, err):
     if len(subject_line) >= 73:
         err.error("Subject line must be 72 or fewer characters: " + subject_line)
 
+    # Do additional checks on the prefix of the subject line.
+    verify_subject_line_prefix(subject_line.split(": ")[0], err)
+
     # Second one divides subject and body.
     if len(raw_body) > 1 and raw_body[1]:
         err.error("Second message line must be empty: " + raw_body[1])
 
     # Message body lines.
     for line in raw_body[2:]:
-        # Long lines with URLs are exempt from the line length rule.
-        if len(line) >= 76 and "://" not in line:
+        # Long lines with URLs or human names are exempt from the line length rule.
+        if len(line) >= 76 and not (
+            "://" in line
+            or line.startswith("Co-authored-by: ")
+            or line.startswith("Signed-off-by: ")
+        ):
             err.error("Message lines should be 75 or less characters: " + line)
 
     if not raw_body[-1].startswith("Signed-off-by: ") or "@" not in raw_body[-1]:
         err.error('Message must be signed-off. Use "git commit -s".')
 
 
+def verify_subject_line_prefix(prefix, err):
+    ext = (".c", ".h", ".cpp", ".js", ".rst", ".md")
+
+    if prefix.startswith((".", "/")):
+        err.error('Subject prefix cannot begin with "." or "/".')
+
+    if prefix.endswith("/"):
+        err.error('Subject prefix cannot end with "/".')
+
+    if prefix.startswith("ports/"):
+        err.error(
+            'Subject prefix cannot begin with "ports/", start with the name of the port instead.'
+        )
+
+    if prefix.endswith(ext):
+        err.error(
+            "Subject prefix cannot end with a file extension, use the main part of the filename without the extension."
+        )
+
+
 def run(args):
     verbose("run", *args)