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[PATCH 2/3] selftests: seccomp: use LDLIBS instead of LDFLAGS

Started byFathi Boudra <fathi.boudra@linaro.org>
First post2017-06-28 20:00 +0200
Last post2017-06-29 09:10 +0200
Articles 3 — 2 participants

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  [PATCH 2/3] selftests: seccomp: use LDLIBS instead of LDFLAGS Fathi Boudra <fathi.boudra@linaro.org> - 2017-06-28 20:00 +0200
    Re: [PATCH 2/3] selftests: seccomp: use LDLIBS instead of LDFLAGS sjpark <sj38.park@gmail.com> - 2017-06-28 23:50 +0200
      Re: [PATCH 2/3] selftests: seccomp: use LDLIBS instead of LDFLAGS Fathi Boudra <fathi.boudra@linaro.org> - 2017-06-29 09:10 +0200

#1676935 — [PATCH 2/3] selftests: seccomp: use LDLIBS instead of LDFLAGS

FromFathi Boudra <fathi.boudra@linaro.org>
Date2017-06-28 20:00 +0200
Subject[PATCH 2/3] selftests: seccomp: use LDLIBS instead of LDFLAGS
Message-ID<tXppY-t5-85@gated-at.bofh.it>
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@linaro.org>
---
 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 $@
-- 
2.13.0

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#1677204

Fromsjpark <sj38.park@gmail.com>
Date2017-06-28 23:50 +0200
Message-ID<tXt0u-yk-9@gated-at.bofh.it>
In reply to#1676935

[Multipart message — attachments visible in raw view] — view raw

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@linaro.org>
> ---
>  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
>
>

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#1677452

FromFathi Boudra <fathi.boudra@linaro.org>
Date2017-06-29 09:10 +0200
Message-ID<tXBKp-4yb-11@gated-at.bofh.it>
In reply to#1677204
On 29 June 2017 at 00:40, sjpark <sj38.park@gmail.com> wrote:
> 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@linaro.org>
>> ---
>>  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 $< ?

Good catch. Thanks, will add to v3.

>
> Thanks,
> SeongJae Park
>
>> --
>> 2.13.0
>>
>>

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