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CMake validates a compiler by building and linking a test program. For a bare metal cross toolchain that link cannot succeed on its own terms, and the flags NuttX supplies for it assume a toolchain shipped with newlib: gcc.cmake sets set(CMAKE_EXE_LINKER_FLAGS_INIT "--specs=nosys.specs") A perfectly usable arm-none-eabi-gcc built without those specs therefore fails configuration before a single NuttX source file is considered: arm-none-eabi-gcc: fatal error: cannot read spec file 'nosys.specs': No such file or directory CMake Error: ... CMake will not be able to correctly generate this project. Setting CMAKE_TRY_COMPILE_TARGET_TYPE to STATIC_LIBRARY makes the detection step compile without linking, which is the documented approach for cross compiling to a bare metal target. Toolchains that do ship nosys.specs are unaffected: the flag only applies to CMake's own detection, not to the NuttX link. This is not arch specific, so it is set once in the top level CMakeLists.txt alongside the toolchain-file selection, before project() triggers detection. sim is excluded: it is hosted and links real host executables, so it keeps the usual executable-based detection. try_compile() reads the variable from the calling scope, so it takes effect without living in a toolchain file; tools/toolchain.cmake.export already sets the same for the exported build. Assisted-by: Claude Code:claude-opus-4-8 Assisted-by: Claude Code:claude-fable-5 Signed-off-by: Marco Casaroli <marco.casaroli@gmail.com> |
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| .github | ||
| arch | ||
| audio | ||
| binfmt | ||
| boards | ||
| cmake | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| dummy | ||
| fs | ||
| graphics | ||
| include | ||
| libs | ||
| mm | ||
| net | ||
| openamp | ||
| pass1 | ||
| sched | ||
| syscall | ||
| tools | ||
| video | ||
| wireless | ||
| .asf.yaml | ||
| .codespell-ignore-lines | ||
| .codespellrc | ||
| .editorconfig | ||
| .gitignore | ||
| .gitmessage | ||
| .pre-commit-config.yaml | ||
| .yamllint | ||
| AUTHORS | ||
| CMakeLists.txt | ||
| CONTRIBUTING.md | ||
| INVIOLABLES.md | ||
| Kconfig | ||
| LICENSE | ||
| Makefile | ||
| NOTICE | ||
| README.md | ||
| ReleaseNotes | ||
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.