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
tools/bpf/bpftool/Makefile | 6 ++++-
tools/testing/selftests/bpf/Makefile | 36 +++++++++++++++++++---------
2 files changed, 30 insertions(+), 12 deletions(-)
--
2.47.0
