Re: [PATCH bpf-next v3 1/3] selftests/bpf: Allow building with extra flags

["Toke Høiland-Jørgensen" <toke@redhat.com>]

Andrii Nakryiko <andrii.nakryiko@gmail.com> writes:

> On Fri, Nov 1, 2024 at 1:29 AM Viktor Malik <vmalik@redhat.com> wrote:
>>
>> In order to specify extra compilation or linking flags to BPF selftests,
>> it is possible to set EXTRA_CFLAGS and EXTRA_LDFLAGS from the command
>> line. The problem is that they are not propagated to sub-make calls
>> (runqslower, bpftool, libbpf) and in the better case are not applied, in
>> the worse case cause the entire build fail.
>>
>> Propagate EXTRA_CFLAGS and EXTRA_LDFLAGS to the sub-makes.
>>
>> This, for instance, allows to build selftests as PIE with
>>
>>     $ make EXTRA_CFLAGS='-fPIE' EXTRA_LDFLAGS='-pie'
>>
>> Without this change, the command would fail because libbpf.a would not
>> be built with -fPIE and other PIE binaries would not link against it.
>>
>> The only problem is that we have to explicitly provide empty
>> EXTRA_CFLAGS='' and EXTRA_LDFLAGS='' to the builds of kernel modules as
>> we don't want to build modules with flags used for userspace (the above
>> example would fail as kernel doesn't support PIE).
>>
>> Signed-off-by: Viktor Malik <vmalik@redhat.com>
>> ---
>>  tools/testing/selftests/bpf/Makefile | 34 +++++++++++++++++++---------
>>  1 file changed, 23 insertions(+), 11 deletions(-)
>>
>
> Ok, so this will conflict with Toke's [0]. Who should go first? :)

I'm OK with rebasing on top of Viktor's patch :)
>
> And given you guys touch these more obscure parts of BPF selftests
> Makefile, I'd really appreciate it if you can help reviewing them for
> each other :)

Sure, can do!

-Toke