On 10/17/24 00:18, Eduard Zingerman wrote: > 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. Enabling -Wno-unused-command-line-argument is the simplest way here, let's do that. Thank you both for suggestions! > > [...] >
