Apache NuttX is a mature, real-time embedded operating system (RTOS) https://nuttx.apache.org/
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Xiang Xiao 2c9f91526a board: enable LTO on g431 nsh boards and fix LTO link with toolchain switch
For boards b-g431b-esc1/nsh, nucleo-g431kb/nsh and nucleo-g431rb/nsh,
the `.data` section of nuttx.elf overflows the 128 KB flash region by a
few hundred bytes on default GNU EABI builds:

    arm-none-eabi-ld: nuttx section `.data' will not fit in region `flash'
    arm-none-eabi-ld: region `flash' overflowed by 296 bytes

Enabling CONFIG_LTO_FULL=y in the corresponding defconfigs brings flash
usage back below the 128 KB limit (~93%).

Additionally, fix arch/arm/src/cmake/gcc.cmake so that when LTO is
enabled it always uses the gcc-ar / gcc-nm / gcc-ranlib wrappers, not
just when CONFIG_ARM_TOOLCHAIN_GNU_EABI is also set.  CI tooling (via
tools/testbuild.sh) configures cmake first, then flips the toolchain
choice in .config with kconfig-tweak before running `cmake --build`.
With the previous "ARM_TOOLCHAIN_GNU_EABI && !LTO_NONE" guard the
regen step would switch to plain `ar` for the .a files, even though the
linker driver picked at configure time is still arm-none-eabi-g++ and
the object files contain GCC LTO IR.  The result was a flood of
"undefined reference to `printf' / `free' / `puts' ..." link errors
when running tools/testbuild.sh -A -N -R on the *_CLANG variants.

Now that we are inside gcc.cmake the toolchain is unambiguously GCC,
so dropping the redundant CONFIG_ARM_TOOLCHAIN_GNU_EABI conjunct keeps
the LTO-aware ar wrappers in place across kconfig-tweak toolchain
switches.

Signed-off-by: Xiang Xiao <xiaoxiang@xiaomi.com>
2026-05-19 16:21:28 +08:00
.github ci: retry git clone for nuttx-ntfc-testing 2026-05-12 08:45:30 -03:00
arch arch/esp32: Fix conflicting types for '_times_r' 2026-05-19 16:21:28 +08:00
audio include/debug.h: Move to include/nuttx/debug.h 2026-04-07 07:50:06 -03:00
binfmt include/debug.h: Move to include/nuttx/debug.h 2026-04-07 07:50:06 -03:00
boards board: enable LTO on g431 nsh boards and fix LTO link with toolchain switch 2026-05-19 16:21:28 +08:00
cmake cmake: Moved the creation of the nxtmpdir folder to the root CMake file 2026-04-22 06:22:36 +08:00
crypto !nuttx: drop redundant casts on tv_sec/tv_nsec and fix printf formats 2026-05-19 16:21:28 +08:00
Documentation !sched/clock: remove CONFIG_SYSTEM_TIME64 and always use 64-bit time 2026-05-19 16:21:28 +08:00
drivers !nuttx: drop redundant casts on tv_sec/tv_nsec and fix printf formats 2026-05-19 16:21:28 +08:00
dummy build: add initial cmake build system 2023-07-08 13:50:48 +08:00
fs !nuttx: drop redundant casts on tv_sec/tv_nsec and fix printf formats 2026-05-19 16:21:28 +08:00
graphics include/debug.h: Move to include/nuttx/debug.h 2026-04-07 07:50:06 -03:00
include !sys/types.h: change time_t and clock_t to int64_t to align with other OSes 2026-05-19 16:21:28 +08:00
libs !nuttx: drop redundant casts on tv_sec/tv_nsec and fix printf formats 2026-05-19 16:21:28 +08:00
mm !nuttx: drop redundant casts on tv_sec/tv_nsec and fix printf formats 2026-05-19 16:21:28 +08:00
net !sys/types.h: change time_t and clock_t to int64_t to align with other OSes 2026-05-19 16:21:28 +08:00
openamp openamp: fix CMake dcache option 2026-05-10 15:03:24 +02:00
pass1 Makefile: Remove make depend files by make distclean 2026-02-16 16:27:57 +01:00
sched !nuttx: drop redundant casts on tv_sec/tv_nsec and fix printf formats 2026-05-19 16:21:28 +08:00
syscall syscall: fcntl param3 type to uintptr_t 2026-04-27 12:01:55 -03:00
tools board: enable LTO on g431 nsh boards and fix LTO link with toolchain switch 2026-05-19 16:21:28 +08:00
video video: ensure video library is non-empty 2026-05-08 19:51:39 +08:00
wireless include/debug.h: Move to include/nuttx/debug.h 2026-04-07 07:50:06 -03:00
.asf.yaml github: master branch protection tune. 2025-05-07 18:37:13 -05:00
.codespell-ignore-lines !boards: Remove NSH_ARCHINIT and board_app_initialize 2026-05-02 18:36:46 +08:00
.codespellrc codespellrc: add ist to ignorelist 2025-10-14 17:42:01 +08:00
.editorconfig .editorconfig: fix character encoding property specification 2025-11-28 19:12:13 +08:00
.gitignore arch/*/src/Makefile: Avoid uncessary relinking of the nuttx binary. 2026-05-18 09:33:58 +02:00
.gitmessage docs/contributing: Add a commit message template 2025-06-03 17:33:24 +08:00
.pre-commit-config.yaml pre-commit: enable codespell checks 2025-05-05 12:34:39 +08:00
.yamllint
AUTHORS AUTHORS: add Donny Jiuzhu 2026-02-25 10:17:40 +01:00
CMakeLists.txt cmake: Moved the creation of the nxtmpdir folder to the root CMake file 2026-04-22 06:22:36 +08:00
CONTRIBUTING.md docs: Fix typos, formatting, and numbering in README.md and CONTRIBUTING.md. 2026-03-23 12:05:24 +01:00
INVIOLABLES.md
Kconfig tools/stackusage.py: use toolchain binaries instead of Python libraries 2026-03-17 11:26:44 -03:00
LICENSE !boards: Remove NSH_ARCHINIT and board_app_initialize 2026-05-02 18:36:46 +08:00
Makefile tools: migrate to SPDX identifier 2024-09-10 23:11:11 +08:00
NOTICE
README.md docs: Fix typos, formatting, and numbering in README.md and CONTRIBUTING.md. 2026-03-23 12:05:24 +01:00
ReleaseNotes Documentation: move ReleaseNotes 2023-09-26 20:41:00 +08:00

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Apache NuttX is a real-time operating system (RTOS) with an emphasis on standards compliance and small footprint. Scalable from 8-bit to 64-bit microcontroller environments, the primary governing standards in NuttX are POSIX and ANSI standards. Additional standard APIs from Unix and other common RTOSs (such as VxWorks) are adopted for functionality not available under these standards, or for functionality that is not appropriate for deeply-embedded environments (such as fork()).

For brevity, many parts of the documentation will refer to Apache NuttX as simply NuttX.

Getting Started

First time on NuttX? Read the Getting Started guide! If you don't have a board available, NuttX has its own simulator that you can run on terminal.

Documentation

You can find the current NuttX documentation on the Documentation Page.

Alternatively, you can build the documentation yourself by following the Documentation Build Instructions.

The old NuttX documentation is still available in the Apache wiki.

Supported Boards

NuttX supports a wide variety of platforms. See the full list on the Supported Platforms page.

Contributing

If you wish to contribute to the NuttX project, read the Contributing guidelines for information on Git usage, coding standard, workflow and the NuttX principles.

License

The code in this repository is under either the Apache 2 license, or a license compatible with the Apache 2 license. See the License Page for more information.