Re: [PATCH bpf-next v2] bpftool: fix profiler build on systems without /usr/include/asm symlink

[Alexei Starovoitov <alexei.starovoitov@gmail.com>]

On Wed, Mar 11, 2020 at 05:14:59PM +0100, Tobias Klauser wrote:
> When compiling bpftool on a system where the /usr/include/asm symlink
> doesn't exist (e.g. on an Ubuntu system without gcc-multilib installed),
> the build fails with:
> 
>     CLANG    skeleton/profiler.bpf.o
>   In file included from skeleton/profiler.bpf.c:4:
>   In file included from /usr/include/linux/bpf.h:11:
>   /usr/include/linux/types.h:5:10: fatal error: 'asm/types.h' file not found
>   #include <asm/types.h>
>            ^~~~~~~~~~~~~
>   1 error generated.

I think the issue is different.
profiler.bpf.c should have picked up
tools/include/uapi/linux/bpf.h (instead of global from /usr/inclde)
which should have included
tools/include/linux/types.h (instead of /usr/include/linux/types.h)

we also have a workaround for some cases:
./tools/testing/selftests/bpf/include/uapi/linux/types.h

>   make: *** [Makefile:123: skeleton/profiler.bpf.o] Error 1
> 
> In certain cases (e.g. for container builds), installing gcc-multilib
> and all its dependencies - which are otherwise not needed to build
> bpftool - unnecessarily increases the image size.
> 
> Thus, fix this by adding /usr/include/$(uname -m)-linux-gnu to the
> clang search path so <asm/types.h> can be found.

In general perf builds fine on all sorts of distros and configs.
I think bpftool should use the same includes from tools/
and skeleton too.