On Wed, 2024-10-16 at 13:37 -0700, Andrii Nakryiko wrote: > On Mon, Oct 14, 2024 at 11:55 PM Viktor Malik <vmalik@xxxxxxxxxx> wrote: > > > > There exist compiler flags supported by GCC but not supported by Clang > > (e.g. -specs=...). Currently, these cannot be passed to BPF selftests > > builds, even when building with GCC, as some binaries (urandom_read and > > liburandom_read.so) are always built with Clang and the unsupported > > flags make the compilation fail (as -Werror is turned on). > > > > Add new Makefile variable CLANG_FILTEROUT_FLAGS which can be used by > > users to specify which flags (from the user-provided CFLAGS or LDFLAGS) > > should be filtered out for Clang invocations. > > > > This allows to do things like: > > > > $ CFLAGS="-specs=/usr/lib/rpm/redhat/redhat-hardened-cc1" \ > > CLANG_FILTEROUT_FLAGS="-specs=%" \ > > make -C tools/testing/selftests/bpf > > > > Without this patch, the compilation would fail with: > > > > [...] > > clang: error: argument unused during compilation: '-specs=/usr/lib/rpm/redhat/redhat-hardened-cc1' [-Werror,-Wunused-command-line-argument] > > maybe we should just not error out (i.e., enable > -Wno-unused-command-line-argument)? I agree with Andrii, grepping for FILTEROUT in kernel source code does not show anything similar to this. Are such filter-out variables some kind of convention? Another option might be to remove `-Werror` and add it on CI via EXTRA_CFLAGS. [...]
