On Tue, Apr 13, 2021 at 3:08 PM Andrii Nakryiko <andrii.nakryiko@xxxxxxxxx> wrote: > > On Tue, Apr 13, 2021 at 8:34 AM Yonghong Song <yhs@xxxxxx> wrote: > > > > With clang compiler: > > make -j60 LLVM=1 LLVM_IAS=1 <=== compile kernel > > make -j60 -C tools/testing/selftests/bpf LLVM=1 LLVM_IAS=1 > > Some linker flags are not used/effective for some binaries and > > we have warnings like: > > warning: -lelf: 'linker' input unused [-Wunused-command-line-argument] > > > > We also have warnings like: > > .../selftests/bpf/prog_tests/ns_current_pid_tgid.c:74:57: note: treat the string as an argument to avoid this > > if (CHECK(waitpid(cpid, &wstatus, 0) == -1, "waitpid", strerror(errno))) > > ^ > > "%s", > > .../selftests/bpf/test_progs.h:129:35: note: expanded from macro 'CHECK' > > _CHECK(condition, tag, duration, format) > > ^ > > .../selftests/bpf/test_progs.h:108:21: note: expanded from macro '_CHECK' > > fprintf(stdout, ##format); \ > > ^ > > The first warning can be silenced with clang option -Wno-unused-command-line-argument. > > For the second warning, source codes are modified as suggested by the compiler > > to silence the warning. Since gcc does not support the option > > -Wno-unused-command-line-argument and the warning only happens with clang > > compiler, the option -Wno-unused-command-line-argument is enabled only when > > clang compiler is used. > > > > Signed-off-by: Yonghong Song <yhs@xxxxxx> > > --- > > LGTM, please see the question below. > > Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx> > > > tools/testing/selftests/bpf/Makefile | 5 +++++ > > tools/testing/selftests/bpf/prog_tests/fexit_sleep.c | 4 ++-- > > tools/testing/selftests/bpf/prog_tests/ns_current_pid_tgid.c | 4 ++-- > > 3 files changed, 9 insertions(+), 4 deletions(-) > > > > diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile > > index dcc2dc1f2a86..c45ae13b88a0 100644 > > --- a/tools/testing/selftests/bpf/Makefile > > +++ b/tools/testing/selftests/bpf/Makefile > > @@ -28,6 +28,11 @@ CFLAGS += -g -Og -rdynamic -Wall $(GENFLAGS) $(SAN_CFLAGS) \ > > -Dbpf_load_program=bpf_test_load_program > > LDLIBS += -lcap -lelf -lz -lrt -lpthread > > > > +# Silence some warnings when compiled with clang > > +ifneq ($(LLVM),) > > This won't handle the case where someone does `make CC=clang`, right? > Do we care at all? Right; it would be better to check CC=clang and have LLVM=1 enable CC=clang from a higher level Makefile (since tools/build/Makefile seems to override the top level $CC). See the top level Makefile L448-456. Then it should work for CC=clang or LLVM=1. > > > > +CFLAGS += -Wno-unused-command-line-argument > > +endif > > + > > [...] -- Thanks, ~Nick Desaulniers
