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Kerogit eb41209a07 sched/clock/clock_delay: added config flag to remove weak up_udelay
While attempting to create architecture-specific implementation
of up_udelay, it was discovered that the overriding function is not
included in the final binary, the weak implementation was used instead.

Further investigation and experimentation showed that the linker
only overrides the weak implementation with the custom one if
the custom one is present in a .c source file that contains at least
one other function that is called from somewhere. Some additional
testing revealed that at least one other already present up_udelay
override (rv32m1-vega:nsh) is affected by this.

In a short mailing list discussion it was determined that this
is a likely result of using static libraries during the build process
and it was suggested to introduce configuration option that will
exclude weak implementations of the function from the build altogether.
This patch does that.

This patch does not enable this configuration option for any existing
board/chip because doing so would change its behaviour and needs
to be tested by users of the hardware.

Also changed is the static assertion in sched/clock/clock_delay.c
to not prevent building the code when architecture declares that
it does not use BOARD_LOOPSPERMSEC to determine required loop count.
BOARD_LOOPSPERMSEC is made undefined in such case.

Patch was tested by building breadxavr:nsh (identical binary by SHA256),
rv32m1-vega:nsh (identical text section) and rv-virt:nsh (text section
differs because of different ordering of functions in the binary, ostest
passed though.)

Signed-off-by: Kerogit <kr.git@kerogit.eu>
2026-06-17 17:10:02 +08:00
.github workflows/build.yml: Fix Skipping sim\windows in the MSVC job 2026-06-10 22:40:52 +08:00
arch sched/clock/clock_delay: added config flag to remove weak up_udelay 2026-06-17 17:10:02 +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 boards/avr/avrdx/breadxavr: provide board_late_initialize 2026-06-17 17:10:02 +08:00
cmake build/fix: remove nonexistent target in cmake 2026-06-11 03:23:04 +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 Documentation/components/boards.rst: fix typo 2026-06-10 08:54:17 -03:00
drivers sched/clock/clock_delay: added config flag to remove weak up_udelay 2026-06-17 17:10:02 +08:00
dummy build: add initial cmake build system 2023-07-08 13:50:48 +08:00
fs fs/vfs: validate chmod and chown callers in inode_chstat() 2026-05-28 09:36:51 +08:00
graphics include/debug.h: Move to include/nuttx/debug.h 2026-04-07 07:50:06 -03:00
include !sensors/bme680: allow sensor configuration during registration 2026-06-10 20:45:31 +02:00
libs libs/libc/dirent: preserve errno on readdir() end-of-directory 2026-06-10 22:04:00 +08:00
mm mm/kasan: Fix compile options applied to wrong target in SPLIT build 2026-06-11 03:23:04 +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 sched/clock/clock_delay: added config flag to remove weak up_udelay 2026-06-17 17:10:02 +08:00
syscall syscall: fcntl param3 type to uintptr_t 2026-04-27 12:01:55 -03:00
tools tools/nxstyle: Whitelist Micro XRCE-DDS uxrCustomTransport prefix. 2026-06-01 09:56:23 +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 arch/sim: replace macOS C++ constructor runtime hack with post-link patch 2026-05-19 07:08:55 -03:00
.editorconfig .editorconfig: fix character encoding property specification 2025-11-28 19:12:13 +08:00
.gitignore git: Specify multiple build directories in .gitignore. 2026-05-20 03:06:58 +08:00
.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 feat: add a GitHub action to lint the YAML files 2020-12-15 09:52:04 -06:00
AUTHORS AUTHORS: add Eren Terzioglu 2026-05-20 15:17:00 +08:00
CMakeLists.txt tools/rust: Fix aarch64 NuttX Rust target specs 2026-05-29 10:25:10 +02:00
CONTRIBUTING.md docs: Fix typos, formatting, and numbering in README.md and CONTRIBUTING.md. 2026-03-23 12:05:24 +01:00
INVIOLABLES.md INVIOLABLES.md: Fix a simple alignment and change occurrences of Nuttx 2020-09-03 01:33:05 +08:00
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 Remove the double blank line from source files 2022-02-20 20:10:14 +01:00
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.