Hi Fathi, On Wed, 28 Jun 2017, Fathi Boudra wrote: > seccomp_bpf fails to build due to undefined reference errors: > > aarch64-linaro-linux-gcc --sysroot=/build/tmp-rpb-glibc/sysroots/hikey > -O2 -pipe -g -feliminate-unused-debug-types -Wl,-no-as-needed -Wall > -Wl,-O1 -Wl,--hash-style=gnu -Wl,--as-needed -lpthread seccomp_bpf.c -o > /build/tmp-rpb-glibc/work/hikey-linaro-linux/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf > /tmp/ccrlR3MW.o: In function `tsync_sibling': > /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:1920: undefined reference to `sem_post' > /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:1920: undefined reference to `sem_post' > /tmp/ccrlR3MW.o: In function `TSYNC_setup': > /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:1863: undefined reference to `sem_init' > /tmp/ccrlR3MW.o: In function `TSYNC_teardown': > /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:1904: undefined reference to `sem_destroy' > /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:1897: undefined reference to `pthread_kill' > /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:1898: undefined reference to `pthread_cancel' > /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:1899: undefined reference to `pthread_join' > /tmp/ccrlR3MW.o: In function `tsync_start_sibling': > /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:1941: undefined reference to `pthread_create' > /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:1941: undefined reference to `pthread_create' > /tmp/ccrlR3MW.o: In function `TSYNC_siblings_fail_prctl': > /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:1978: undefined reference to `sem_wait' > /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:1990: undefined reference to `pthread_join' > /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:1992: undefined reference to `pthread_join' > /tmp/ccrlR3MW.o: In function `tsync_start_sibling': > /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:1941: undefined reference to `pthread_create' > /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:1941: undefined reference to `pthread_create' > /tmp/ccrlR3MW.o: In function `TSYNC_two_siblings_with_ancestor': > /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:2016: undefined reference to `sem_wait' > /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:2032: undefined reference to `pthread_join' > /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:2034: undefined reference to `pthread_join' > /tmp/ccrlR3MW.o: In function `tsync_start_sibling': > /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:1941: undefined reference to `pthread_create' > /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:1941: undefined reference to `pthread_create' > /tmp/ccrlR3MW.o: In function `TSYNC_two_sibling_want_nnp': > /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:2046: undefined reference to `sem_wait' > /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:2058: undefined reference to `pthread_join' > /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:2060: undefined reference to `pthread_join' > /tmp/ccrlR3MW.o: In function `tsync_start_sibling': > /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:1941: undefined reference to `pthread_create' > /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:1941: undefined reference to `pthread_create' > /tmp/ccrlR3MW.o: In function `TSYNC_two_siblings_with_no_filter': > /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:2073: undefined reference to `sem_wait' > /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:2098: undefined reference to `pthread_join' > /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:2100: undefined reference to `pthread_join' > /tmp/ccrlR3MW.o: In function `tsync_start_sibling': > /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:1941: undefined reference to `pthread_create' > /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:1941: undefined reference to `pthread_create' > /tmp/ccrlR3MW.o: In function `TSYNC_two_siblings_with_one_divergence': > /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:2125: undefined reference to `sem_wait' > /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:2143: undefined reference to `pthread_join' > /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:2145: undefined reference to `pthread_join' > /tmp/ccrlR3MW.o: In function `tsync_start_sibling': > /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:1941: undefined reference to `pthread_create' > /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:1941: undefined reference to `pthread_create' > /tmp/ccrlR3MW.o: In function `TSYNC_two_siblings_not_under_filter': > /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:2169: undefined reference to `sem_wait' > /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:2202: undefined reference to `pthread_join' > /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:2227: undefined reference to `pthread_join' > /tmp/ccrlR3MW.o: In function `tsync_start_sibling': > /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/seccomp/seccomp_bpf.c:1941: undefined reference to `pthread_create' > > It's GNU Make and linker specific. > > The default Makefile rule looks like: > > $(CC) $(CFLAGS) $(LDFLAGS) $@ $^ $(LDLIBS) > > When linking is done by gcc itself, no issue, but when it needs to be passed > to proper ld, only LDLIBS follows and then ld cannot know what libs to link > with. > > More detail: > https://www.gnu.org/software/make/manual/html_node/Implicit-Variables.html > > LDFLAGS > Extra flags to give to compilers when they are supposed to invoke the linker, > ‘ld’, such as -L. Libraries (-lfoo) should be added to the LDLIBS variable > instead. > > LDLIBS > Library flags or names given to compilers when they are supposed to invoke the > linker, ‘ld’. LOADLIBES is a deprecated (but still supported) alternative to > LDLIBS. Non-library linker flags, such as -L, should go in the LDFLAGS > variable. > > https://lkml.org/lkml/2010/2/10/362 > > tools/perf: libraries must come after objects > > Link order matters, use LDLIBS instead of LDFLAGS to properly link against > libpthread. > > Signed-off-by: Fathi Boudra <fathi.boudra@xxxxxxxxxx> > --- > tools/testing/selftests/seccomp/Makefile | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/tools/testing/selftests/seccomp/Makefile b/tools/testing/selftests/seccomp/Makefile > index aeb0c805f3ca..d1c74ce70f08 100644 > --- a/tools/testing/selftests/seccomp/Makefile > +++ b/tools/testing/selftests/seccomp/Makefile > @@ -1,8 +1,8 @@ > TEST_GEN_PROGS := seccomp_bpf > CFLAGS += -Wl,-no-as-needed -Wall > -LDFLAGS += -lpthread > +LDLIBS += -lpthread > > include ../lib.mk > > $(TEST_GEN_PROGS): seccomp_bpf.c ../kselftest_harness.h > - $(CC) $(CFLAGS) $(LDFLAGS) $< -o $@ > + $(CC) $(CFLAGS) $(LDLIBS) $< -o $@ Shouldn't $(LDLIBS) follow $< ? Thanks, SeongJae Park > -- > 2.13.0 > >
