cortex-m-rt

v0.7.6 - 2022-08-12

• Added critical-section-single-core feature which provides an implementation for the critical-section crate for single-core systems, based on disabling all interrupts. (#448)

What's Changed

• cortex-m-rt: fix off-by-one in .text in FLASH section assert by @9names in #573
• Fix _stack_end usage and doc by @tlevora in #577
• cortex-m-rt: Add optional MSPLIM initialization, fix vector table size on armv8m by @decaday in #580
• cortex-m-rt: Add alignment check for the .vector_table by @korken89 in #582
• Fix stack end placement by @tlevora in #578
• fix(coretex-m-rt-macros): Allow #[unsafe(link_section = )] for Rust 2024 edition by @yutannihilation in #596
• Mark pre_init as deprecated by @romancardenas in #598
• Fix __pre_init example by @eulerdisk in #600
• cortex-m-rt: Fix build command in docs by @mfil in #611
• Add skip-data-copy feature for when the .data LMA isn't initialized after boot. by @BenChung in #615
• Rename Cortex-M Team to Arm Team by @thejpster in #622
• Update remaining crates to edition 2021. by @wt in #621
• doc: add missing ; in _stext example by @ericu07 in #624
• Update msrv by @wt in #628
• Remove deprecated Cargo.toml authors. by @wt in #631
• Add cortex-m-rt/macros to the workspace members. by @wt in #635
• docs(msrv): unify rust-version to 1.85 across workspace by @reubenueben in #669
• Remove cortex-m deps by @thejpster in #667
• Update to checkout action v7 by @thejpster in #668
• Release cortex-m-rt by @jonathanpallant in #675

New Contributors

• @9names made their first contribution in #573
• @tlevora made their first contribution in #577
• @decaday made their first contribution in #580
• @jonathanpallant made their first contribution in #588
• @yutannihilation made their first contribution in #596
• @romancardenas made their first contribution in #598
• @eulerdisk made their first contribution in #600
• @mfil made their first contribution in #611
• @BenChung made their first contribution in #615
• @wt made their first contribution in #621
• @ericu07 made their first contribution in #624
• @jakobjung10 made their first contribution in #664
• @robamu made their first contribution in #657
• @leftger made their first contribution in #647
• @reubenueben made their first contribution in #669

Full Changelog: c-m-rt-v0.7.5...c-m-rt-v0.7.6

Fixed

• Backport: Mark .bss as NOLOAD (#265)
• Backport: Fix possible overflow of .data region (#286)
• Backport: Perform volatile reads of ICSR in DefaultHandler (#315)

Other

• Backport: Use links in Cargo.toml to prevent multiple linking of cortex-m-rt (#276)
• Backport: Use same verison for macros crate as for cortex-m-rt itself (#245)

Fixed

• Backport: Allow building the crate for macOS targets (#306, #310).

Fixed

• (ARMv6-M) Set LR value to a known value on reset (as the ARM spec requires)
• Added CFI and size info to external assembly subroutines (HardFaultTrampoline)

Fixed

• Fixed lint warnings getting emitted on macro-generated code.

Changed

• Macros now generate a second trampoline function instead of randomizing the function's symbol name. This makes the build deterministic.
• [breaking-change] static mut resources no longer have 'static lifetime except in the #[entry] function (this is a soundness fix; see #212).

Fixed

• Linker template now takes and discard *(.ARM.exidx)

Added

• Input .uninit.* sections are now collected into an output .uninit section. Uninitialized static variables are meant to be placed in these sections. The output .uninit section is not initialized by the runtime.

Fixed

• Correct stack-pointer is selected on HardFault
• Linker template now takes and discard *(.ARM.extab.*)
• Misc. documentation fixes

Changed

• Architecture added: armv8-m.main
• Cortex-M team added to authors
• The nightly build is allowed to fail in CI

Fixed

• entry / exception / interrupt: #[cfg] attributes used on static mut variables are now properly handled.

Changed

• Misuse of attributes now produce compiler errors with proper spans instead of panicking messages.

• The HardFault symbol has been renamed to HardFaultTrampoline; likewise the UserHardFault symbol has been renamed to HardFault. If you were using breakpoints on UserHardFault to detect hard fault you should now put those breakpoints on the HardFault symbol.

Fixed

• Attributes on local static mut variables (declared at the beginning of entry / interrupt / exception) are now respected.

• The "GDB can now unwind HardFault callstacks" fix from the previous release broke HardFault's' &ExceptionFrame argument (the pointer was off by 8 bytes). This release fixes that problem without compromising GDB's ability to unwind HardFaults.

Changed

• We now keep .stack_sizes by default, for use with external tooling.
• (macros) New #[interrupt] attribute added, similar to #[exception] for use with device-specific interrupt handlers.

Fixed

• GDB can now unwind HardFault callstacks

Changed

• (macros) Improved the error message when any of the attribute is used on the wrong kind of item.

Fixed

• (macros) The expansion of the exception attribute now uses the extern "C" ABI which is what the hardware expects.

• (macros) entry and exception now respect the declared unsafety. That is #[entry] unsafe main() -> ! won't require unsafe blocks to use unsafe API.

Fixed

• Fixed the rand problem for real.

Fixed

• Worked around a Cargo limitation that broke builds that depend on rand.

• Updated the documentation link in the README to point to working docs.

Changed

• Produce a better error message if two (or more) copies of cortex-m-rt are going to be linked into a binary.

Changed

• [breaking-change] the entry!, pre_init! and exception! macros have been replaced with attributes: #[entry], #[pre_init] and #[exception], respectively. This also changes the toolchain requirement to 1.30-beta or newer.

Changed

• This crate no longer depends on arm-none-eabi-gcc.

Added

• A pre_init! macro and related functionality to run a function immediately after reset, before memory initialisation

Changed

• The entry! and exception! macros now also accept a closure instead of a path.

• DefaultHandler and UserHardFault now default to an infinite loop if left undefined.

Fixed

• Linked script modified to correctly detect FLASH overflow caused by .data

Fixed

• A recompilation problem where this cortex-m-rt would be recompiled every time cargo build is invoked.

Added

• An entry! macro to set the entry point of the program.

• A heap_start function that returns a pointer into the start of the heap region.

• A device feature. When disabled this crate provides the interrupt vectors; when enabled the interrupt vectors are expected to be provided by another crate. Read the documentation for details.

Changed

• This crate now compiles on the beta and stable channels.

• [breaking-change] this crate now requires arm-none-eabi-gcc to be installed and available in $PATH to compile.

• [breaking-change] the start lang item has been removed. The standard main interface won't work. Instead use #![no_main] and the entry! macro. See documentation for details.

• [breaking-change] the default_handler! macro has been merged into the exception! macro. Use exception!(*, ..) to set the default exception handler.

• [breaking-change] there's no weak default handler so a default handler must be defined by the application, or one of its dependencies.

• [breaking-change] the syntax of the third argument of the exception! handler has changed. See the documentation of the macro for details.

• [breaking-change] the exception names that the exception! macro accepts has changed to match the CMSIS specification. See the documentation of the macro for the list of names it accepts.

• [breaking-change] The number of symbol interfaces has been reduced. Check the advanced section of the documentation for details.

Added

• LLD support. The linker script provided by this crate has been tweaked to support both LLD and GNU LD. To use LLD as a linker change .cargo/config to look like this:

 [target.thumbv7m-none-eabi]
 rustflags = [
   "-C", "link-arg=-Tlink.x",
-  "-C", "linker=arm-none-eabi-ld",
-  "-Z", "linker-flavor=ld",
+  "-C", "linker=lld",
+  "-Z", "linker-flavor=ld.lld",
 ]

Removed

• [breaking-change] Stack overflow protection has been removed. Unfortunately, supporting this feature produces totally wrong arm-none-eabi-size reports when LLD is used to link the program. If you need the stack overflow protection feature you can continue to use version v0.3.13+.

• [breaking-change] The "abort-on-panic" Cargo feature, which provided a panic_fmt implementation, has been removed. If you were using this feature you can instead use a panic implementation crate.

Fixed

• Support the newest nightly

Fixed

• dev channel support

Added

• Fictitious .stack and .heap linker sections that represent the locations of the stack and the heap in RAM. You can visualize these linker sections by running arm-none-eabi-size -Ax over your binary.

• Zero cost stack overflow protection when you use the cortex-m-rt-ld linker. Check documentation for details.

• A _heap_size symbol that indicates how large the heap is. This symbol is only used when cortex-m-rt-ld is used as a linker.

Fixed

• Support for recent nightlies.

Changed

• Dynamically support recent nightlies, which have the termination lang item, and nightly-2017-09-22, which doesn't. That nightly version is used by the docs.rs builder. Supporting that version instead of rejecting it ensures this crate and its reverse-dependencies will get their documentation built by the docs.rs service.

Removed

• The nightly date check from build script that improved error messages for users of old, unsupported nightlies. Unfortunately the check was preventing this crate and reverse-dependencies from getting their documentation build on docs.rs

Fixed

• cargo doc warnings

Added

• Termination lang item

Changed

• The start lang item to match the new signature

Added

• Support for overriding the DEBUG_MONITOR exception handler on ARMv7-M.

Fixed

• Builds with multiple codegen units by forcing the linker to look harder for the exceptions vector table.

Fixed

• Remove duplication of default exception handlers. This saves 32 bytes of Flash memory (.text).

Changed

• Align the end of .rodata to a 4-byte boundary. With this the sections that will go into Flash memory will be 4 byte aligned at the start and at the end. Which seems to be required (?) by Cortex-M0 devices.

• .bss and .data are now padded so their sizes are multiple of 4 bytes. This improves the output of objdump; before, the output showed "Address 0x20000004 is out of bounds".

• Linking now aborts if any of the input files contains a .got section. Dynamic relocations are not supported and Rust code is not relocatable by default. This error only occurs if C code that was compiled with the -fPIC flag is linked in. The error message will tell the user how to compile their C code without -fPIC.

Changed

• Updated the documentation: it's no longer necessary to use the compiler-builtins repository since that crate landed in rust-lang/rust and it's now available in the rust-src component.

Changed

• Tweaked documentation

Fixed

• A warning when compiling for x86_64 and the "abort-on-panic" feature is enabled.

Added

• A default_handler! macro to override the default exception handler.

• An exception! macro to override the handler for a particular exception.

Changed

• The FPU will now be enabled before main if the target has FPU support.

• [breaking-change] the features "panic-over-itm" and "panic-over-semihosting" has been removed. the panic_fmt language item is now not included by default. An opt-in feature named "abort-on-panic" can be enabled to make this crate provide a panic_fmt implementation that simply aborts.

• [breaking-change] The sections .rodata.{exceptions,interrupts} have been renamed to .vector_table.{exceptions,interrupts}. This break the old mechanism for registering exceptions (static EXCEPTIONS); use the new ones: default_handler! and exception!.

• The _stack_start is now optional in the memory.x file. If unspecified its value will be set to ORIGIN(RAM) + LENGTH(RAM).

Added

• A non-allocatable .stlog section to support the stlog logging framework.

Added

• A _stext symbol which can be specified in the linker script to customize the location of the .text section. If not specified the .text section will be placed right after the .vector_table section.

Added

• A _sheap symbol where the heap can be located.

Changed

• The linker sections have renamed / reorder to make arm-none-eabi-size -A more useful. You'll now see something like this:

$ arm-none-eabi-size -A hello
hello  :
section                size        addr
.vector_table          1024   134217728
.text                   288   134218752
.rodata                  14   134219040

• cortex-m-rt::reset_handler is now the entry point of all programs that link to cortex-m-rt. This makes GDB's load command work correctly. It will now set the Program Counter to reset_handler after flashing the program so there's no need to reset the microcontroller after flashing.

• Renamed __exceptions and __interrupts symbols, which are only used internally, to _eexceptions and _einterrupts respectively for consistency.

Fixed

• Include input .text and .rodata sections (note: no suffix as in .text.foo) in the output file. (C) Code compiled without the equivalent -ffunction-sections / -fdata-sections may place stuff in those unsuffixed sections.

Fixed

• Do not load the .debug_gdb_script section in flash. It's only needed for debugging.

Changed

• [breaking-change] the _stack_start symbol is now required and must be provided in the memory.x file when using the "linker-script" feature. This symbol indicates where in memory the call stack will be allocated.

Fixed

• A rustdoc warning

Changed

• Unclutter the reset_handler function for a better debugging experience.

Changed

• Improved linker error messages

Initial release