On 11/1/24 20:46, Andrii Nakryiko wrote:
> On Fri, Nov 1, 2024 at 1:38 AM Viktor Malik <vmalik@xxxxxxxxxx> wrote:
>>
>> When trying to build BPF selftests with additional compiler and linker
>> flags, we're running into multiple problems. This series addresses all
>> of them:
>>
>> - CFLAGS are not passed to sub-makes of bpftool and libbpf. This is a
>> problem when compiling with PIE as libbpf.a ends up being non-PIE and
>> cannot be linked with other binaries (patch #1).
>>
>> - bpftool Makefile runs `llvm-config --cflags` and appends the result to
>> CFLAGS. The result typically contains `-D_GNU_SOURCE` which may be
>> already set in CFLAGS. That causes a compilation error (patch #2).
>>
>> - Some GCC flags are not supported by Clang but there are binaries which
>> are always built with Clang but reuse user-defined CFLAGS. When CFLAGS
>> contain such flags, compilation fails (patch #3).
>>
>> Changelog:
>> ----------
>> v2 -> v3:
>> - resolve conflicts between patch #1 and 4192bb294f80 ("selftests/bpf:
>> Provide a generic [un]load_module helper")
>> - add Quentin's and Jiri's acks for patches #2 and #3
>>
>> v1 -> v2:
>> - cover forgotten case in patch#1 (noted by Eduard)
>> - remove -D_GNU_SOURCE unconditionally in patch#2 (suggested by Andrii)
>> - rewrite patch#3 to just add -Wno-unused-command-line-argument
>> (suggested by Andrii)
>>
>> Viktor Malik (3):
>> selftests/bpf: Allow building with extra flags
>> bpftool: Prevent setting duplicate _GNU_SOURCE in Makefile
>> selftests/bpf: Disable warnings on unused flags for Clang builds
>>
>
> I've applied the last two patches, they seem to be independent from
> the first, right?
Yes, they are independent, thanks. I'll sync with Toke on the first one.
Viktor
>
>
>> tools/bpf/bpftool/Makefile | 6 ++++-
>> tools/testing/selftests/bpf/Makefile | 36 +++++++++++++++++++---------
>> 2 files changed, 30 insertions(+), 12 deletions(-)
>>
>> --
>> 2.47.0
>>
>>
>
