How to build liboqs for Arm Cortex-M4?

[tarun14110]

How to build liboqs for Arm Cortex-M4 processor on MacOS? I am trying to build using
cmake -GNinja .. -DCMAKE_TOOLCHAIN_FILE=../.CMake/toolchain_armel.cmake. I have added set(CMAKE_C_COMPILER arm-none-eabi-gcc) and set(CMAKE_CROSSCOMPILING_EMULATOR "qemu-system-arm;-L;/opt/homebrew/bin/") in toolchain_armel.cmake

Here is the output of the command.

-- The C compiler identification is GNU 10.3.1
-- The ASM compiler identification is GNU
-- Found assembler: /Applications/ARM/bin/arm-none-eabi-gcc
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - failed
-- Check for working C compiler: /Applications/ARM/bin/arm-none-eabi-gcc
-- Check for working C compiler: /Applications/ARM/bin/arm-none-eabi-gcc - broken
CMake Error at /opt/homebrew/Cellar/cmake/3.26.3/share/cmake/Modules/CMakeTestCCompiler.cmake:67 (message):
The C compiler

"/Applications/ARM/bin/arm-none-eabi-gcc"

is not able to compile a simple test program.

It fails with the following output:

Change Dir: /Users/.../liboqs/build/CMakeFiles/CMakeScratch/TryCompile-airKbw

Run Build Command(s):/opt/homebrew/bin/ninja -v cmTC_bcc40 && [1/2] /Applications/ARM/bin/arm-none-eabi-gcc    -o CMakeFiles/cmTC_bcc40.dir/testCCompiler.c.o -c /Users/.../liboqs/build/CMakeFiles/CMakeScratch/TryCompile-airKbw/testCCompiler.c
[2/2] : && /Applications/ARM/bin/arm-none-eabi-gcc   CMakeFiles/cmTC_bcc40.dir/testCCompiler.c.o -o cmTC_bcc40   && :
FAILED: cmTC_bcc40 
: && /Applications/ARM/bin/arm-none-eabi-gcc   CMakeFiles/cmTC_bcc40.dir/testCCompiler.c.o -o cmTC_bcc40   && :
/Applications/ARM/bin/../lib/gcc/arm-none-eabi/10.3.1/../../../../arm-none-eabi/bin/ld: /Applications/ARM/bin/../lib/gcc/arm-none-eabi/10.3.1/../../../../arm-none-eabi/lib/libc.a(lib_a-exit.o): in function `exit':
exit.c:(.text.exit+0x2c): undefined reference to `_exit'
collect2: error: ld returned 1 exit status
ninja: build stopped: subcommand failed.

CMake will not be able to correctly generate this project.
Call Stack (most recent call first):
CMakeLists.txt:22 (project)

[baentsch]

I personally have no experience with cross-compiling (let alone on MacOS) but this error message seems like a standard/non-OQS-specific installation/setup problem (just looking at stackoverflow.com...).

Also, have you tried with the armhf toolchain file instead? Maybe that crosscompiler works better ...

Final suggestion: Don't use an OSX crosscompile environment, but one that we know works, namely a Linux image (via docker). See for example

liboqs/.github/workflows/linux.yml

Lines 133 to 142 in 9f912c9

	docker run --rm \
	-v `pwd`:`pwd` \
	-w `pwd` \
	openquantumsafe/ci-debian-buster-amd64:latest /bin/bash \
	-c "mkdir build && \
	(cd build && \
	cmake .. -GNinja ${{ matrix.CMAKE_ARGS }} \
	-DCMAKE_TOOLCHAIN_FILE=../.CMake/toolchain_${{ matrix.ARCH }}.cmake && \
	cmake -LA .. && \
	ninja)"