Re: Perf not able to cross compile

[James Clark]

On 01/02/2024 11:32, Anders Roxell wrote:
> Hey,
> 
> I'm trying to cross compile perf ARCH=arm64 on my x86_64 host from
> linus tree [1], branch master.
> 
> 
> This is the failue I see, full log [2]:
> 
> ...
>   CC      /home/tuxbuild/.cache/tuxmake/builds/1/build/libbpf/staticobjs/elf.o
>   CC      /home/tuxbuild/.cache/tuxmake/builds/1/build/libbpf/staticobjs/features.o
> cc1: error: ‘-fcf-protection=full’ is not supported for this target
> error: command '/usr/local/bin/sccache' failed with exit code 1
> cp: cannot stat
> '/home/tuxbuild/.cache/tuxmake/builds/1/build/python_ext_build/lib/perf*.so':
> No such file or directory
> make[2]: *** [Makefile.perf:678:
> /home/tuxbuild/.cache/tuxmake/builds/1/build/python/perf.cpython-311-x86_64-linux-gnu.so]
> Error 1
> make[2]: *** Waiting for unfinished jobs....
>   LD      /home/tuxbuild/.cache/tuxmake/builds/1/build/libbpf/staticobjs/libbpf-in.o
>   LINK    /home/tuxbuild/.cache/tuxmake/builds/1/build/libbpf/libbpf.a
> make[1]: *** [Makefile.perf:261: sub-make] Error 2
> make: *** [Makefile:70: all] Error 2
> 
> Running 'x86_64-linux-gnu-python3-config --cflags' I see
> '-fcf-protection' in the output and this happens when I'm building
> cross compile arm64 on my x86_64 host machine. Building on an arm64
> host works. cross compile x86_64 on my x86_64 host works too.
> 
> I have 'aarch64-linux-gnu-python3-config' installed but that isn't used.
> 
> $ x86_64-linux-gnu-python3-config --cflags
> -I/usr/include/python3.11 -I/usr/include/python3.11  -Wsign-compare -g
>   -fstack-protector-strong -fstack-clash-protection -Wformat
> -Werror=format-security -fcf-protection  -DNDEBUG -g -fwrapv -O2 -Wall
> $ aarch64-linux-gnu-python3-config --cflags
> -I/usr/include/python3.11 -I/usr/include/python3.11  -Wsign-compare -g
>   -fstack-protector-strong -fstack-clash-protection -Wformat
> -Werror=format-security -mbranch-protection=standard  -DNDEBUG -g
> -fwrapv -O2 -Wall
> 
> I tried to set PYTHON and PYTHON_CONFIG too, but didn't work.
> 
> It doesn't try to use $(CROSS_COMPILE)python3-config, any idea how to
> use the correct config?
> 
> Cheers,
> Anders
> [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
> [2]  https://storage.tuxsuite.com/public/linaro/lkft/builds/2bc6x6cISHzG9Jgo0oAVv2OgLOG/build.log


Hi Anders,

I see something similar but in the end it works. Despite the name, I
also get perf.cpython-311-x86_64-linux-gnu.so generated in my build, but
it's actually an arm binary.

For me I'm using python3.10, and the x86 config options don't include
-fcf-protection which is probably why it can compile successfully with
the arm compiler.

It looks like your assumption is correct and it's not using
$(CROSS_COMPILE)python3-config but just python3-config. The answer to
how to fix it is probably to start hacking at the makefiles, if PYTHON
and PYTHON_CONFIG don't work either.

James