Document and build system updates for the RPi.

[ebo]

I made a number of minor changes to the documentation and build system to get it to work. I am sending in the changes for a PR now, as it is likely going to be days before I can finish working on the CMakeLists.txt to handle setting the -march robustly.

[cerna]

Hmm, the Github Actions CI needs an approval for first time contributors. That's new.

[cerna]

I don't think it can work as it is right now. I hard sets some compile flags in main CMakeLists.txt file which are only valid for arm64 architecture (I think):

set(CMAKE_C_FLAGS "-O0 -march=armv8-a -mfloat-abi=hard -mfpu=neon-fp-armv8 ${COMMON_FLAGS}")

The architecture specific settings (and settings specific to a platform, i.e. operating system vendor) should be in a toolchain file. (Toolchain files are passed to cmake as cmake $PATH --toolchain=$TOOLCHAIN_FILE, more info can be acquired in documentation.) Machinekit-HAL's toolchain for Debian is in debianMultiarchToolchain.cmake. (But there could be more.)

I presume that when compiling directly on Raspberry PI, it works, right? And these flags can be used for all armv8 arm64 devices, right? So maybe adding an if/switch construct to that Toolchain file would be the best solution.

Now, the configuration step fails on

Run Build Command(s):/usr/bin/gmake -f Makefile cmTC_3f9e7/fast && /usr/bin/gmake  -f CMakeFiles/cmTC_3f9e7.dir/build.make CMakeFiles/cmTC_3f9e7.dir/build
gmake[1]: Entering directory '/home/mars/Documents/Programming/machinekit/cmk-hal2/build/CMakeFiles/CMakeTmp'
Building C object CMakeFiles/cmTC_3f9e7.dir/CheckIncludeFile.c.o
/usr/bin/cc   -O0 -march=armv8-a -mfloat-abi=hard -mfpu=neon-fp-armv8   -std=gnu11 -o CMakeFiles/cmTC_3f9e7.dir/CheckIncludeFile.c.o -c /home/mars/Documents/Programming/machinekit/cmk-hal2/build/CMakeFiles/CMakeTmp/CheckIncludeFile.c
cc: error: unrecognized command-line option ‘-mfloat-abi=hard’
cc: error: unrecognized command-line option ‘-mfpu=neon-fp-armv8’
gmake[1]: *** [CMakeFiles/cmTC_3f9e7.dir/build.make:78: CMakeFiles/cmTC_3f9e7.dir/CheckIncludeFile.c.o] Error 1
gmake[1]: Leaving directory '/home/mars/Documents/Programming/machinekit/cmk-hal2/build/CMakeFiles/CMakeTmp'
gmake: *** [Makefile:127: cmTC_3f9e7/fast] Error 2

[ebo]

As I said the CMakeList.txt file was not ready, but if I did not turn in the rest of it now it might be a while before I got to finish it.

…

On Jan 21 2022 12:35 PM, cerna wrote: I don't think it can work as it is right now. I hard sets some compile flags in main `CMakeLists.txt` file which are only valid for `arm64` architecture (I think): ``` set(CMAKE_C_FLAGS "-O0 -march=armv8-a -mfloat-abi=hard -mfpu=neon-fp-armv8 ${COMMON_FLAGS}") ``` The architecture specific settings (and settings specific to a platform, i.e. operating system vendor) should be in a toolchain file. (Toolchain files are passed to cmake as `cmake $PATH --toolchain=$TOOLCHAIN_FILE`, more info can be acquired in [documentation](https://cmake.org/cmake/help/latest/manual/cmake-toolchains.7.html).) Machinekit-HAL's toolchain for Debian is in [debianMultiarchToolchain.cmake](https://github.com/machinekit/machinekit-hal/blob/eca0570d9d827dc7b4fcaa029eb8407db0b6e0e1/debian/debianMultiarchToolchain.cmake). (But there could be more.) I presume that when compiling directly on Raspberry PI, it works, right? And these flags can be used for all `armv8` `arm64` devices, right? So maybe adding an if/switch construct to that Toolchain file would be the best solution. Now, the configuration step fails on ``` Run Build Command(s):/usr/bin/gmake -f Makefile cmTC_3f9e7/fast && /usr/bin/gmake -f CMakeFiles/cmTC_3f9e7.dir/build.make CMakeFiles/cmTC_3f9e7.dir/build gmake[1]: Entering directory '/home/mars/Documents/Programming/machinekit/cmk-hal2/build/CMakeFiles/CMakeTmp' Building C object CMakeFiles/cmTC_3f9e7.dir/CheckIncludeFile.c.o /usr/bin/cc -O0 -march=armv8-a -mfloat-abi=hard -mfpu=neon-fp-armv8 -std=gnu11 -o CMakeFiles/cmTC_3f9e7.dir/CheckIncludeFile.c.o -c /home/mars/Documents/Programming/machinekit/cmk-hal2/build/CMakeFiles/CMakeTmp/CheckIncludeFile.c cc: error: unrecognized command-line option ‘-mfloat-abi=hard’ cc: error: unrecognized command-line option ‘-mfpu=neon-fp-armv8’ gmake[1]: *** [CMakeFiles/cmTC_3f9e7.dir/build.make:78: CMakeFiles/cmTC_3f9e7.dir/CheckIncludeFile.c.o] Error 1 gmake[1]: Leaving directory '/home/mars/Documents/Programming/machinekit/cmk-hal2/build/CMakeFiles/CMakeTmp' gmake: *** [Makefile:127: cmTC_3f9e7/fast] Error 2 ```

[cerna]

As I said the CMakeList.txt file was not ready, but if I did not turn in
the rest of it now it might be a while before I got to finish it.

Ah, OK, got it!

[ebo]

I'll try to get back to CMakeList.txt again ASAP, but I spent quite some time trying to track down how to pull the march, mcpu and other bits from the build system to get it right. I have not seen any exemplar, but I was sent some reference documents which will help -- when supporting things like the RPi1, Nano, ...

…

On Jan 21 2022 12:53 PM, cerna wrote: > As I said the CMakeList.txt file was not ready, but if I did not turn > in the rest of it now it might be a while before I got to finish it. Ah, OK, got it!

[ebo]

@cerna I broke out the documentation edits from the work to get the build system to work as described, and sent another pull request. I am closing this one.