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    Subject[PATCH 4.14 065/135] selftests: timers: use LDLIBS instead of LDFLAGS
    Date
    4.14-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    [ Upstream commit 7d4e591bc051d3382c45caaa2530969fb42ed23d ]

    posix_timers 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 -O3 -Wl,-no-as-needed -Wall
    -DKTEST -Wl,-O1 -Wl,--hash-style=gnu -Wl,--as-needed -lrt -lpthread
    posix_timers.c
    -o /build/tmp-rpb-glibc/work/hikey-linaro-linux/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/timers/posix_timers
    /tmp/cc1FTZzT.o: In function `check_timer_create':
    /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/timers/posix_timers.c:157:
    undefined reference to `timer_create'
    /usr/src/debug/kselftests/4.12-r0/linux-4.12-rc7/tools/testing/selftests/timers/posix_timers.c:170:
    undefined reference to `timer_settime'
    collect2: error: ld returned 1 exit status

    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: Denys Dmytriyenko <denys@ti.com>
    Signed-off-by: Fathi Boudra <fathi.boudra@linaro.org>
    Signed-off-by: Shuah Khan <shuah@kernel.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    tools/testing/selftests/timers/Makefile | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    diff --git a/tools/testing/selftests/timers/Makefile b/tools/testing/selftests/timers/Makefile
    index 3496680981f2..d937e45532d8 100644
    --- a/tools/testing/selftests/timers/Makefile
    +++ b/tools/testing/selftests/timers/Makefile
    @@ -1,6 +1,6 @@
    # SPDX-License-Identifier: GPL-2.0
    CFLAGS += -O3 -Wl,-no-as-needed -Wall
    -LDFLAGS += -lrt -lpthread -lm
    +LDLIBS += -lrt -lpthread -lm

    # these are all "safe" tests that don't modify
    # system time or require escalated privileges
    --
    2.19.1


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