linux/tools/testing/selftests/timers/Makefile
Fathi Boudra 7d4e591bc0 selftests: timers: use LDLIBS instead of LDFLAGS
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>
2019-01-28 08:02:12 -07:00

24 lines
773 B
Makefile

# SPDX-License-Identifier: GPL-2.0
CFLAGS += -O3 -Wl,-no-as-needed -Wall
LDLIBS += -lrt -lpthread -lm
# these are all "safe" tests that don't modify
# system time or require escalated privileges
TEST_GEN_PROGS = posix_timers nanosleep nsleep-lat set-timer-lat mqueue-lat \
inconsistency-check raw_skew threadtest rtcpie
DESTRUCTIVE_TESTS = alarmtimer-suspend valid-adjtimex adjtick change_skew \
skew_consistency clocksource-switch freq-step leap-a-day \
leapcrash set-tai set-2038 set-tz
TEST_GEN_PROGS_EXTENDED = $(DESTRUCTIVE_TESTS)
include ../lib.mk
# these tests require escalated privileges
# and may modify the system time or trigger
# other behavior like suspend
run_destructive_tests: run_tests
$(call RUN_TESTS, $(DESTRUCTIVE_TESTS))