diff mbox series

[1/1] selftests: timers: use LDLIBS instead of LDFLAGS to link against libpthread

Message ID 20170628091810.30484-1-fathi.boudra@linaro.org
State Superseded
Headers show
Series [1/1] selftests: timers: use LDLIBS instead of LDFLAGS to link against libpthread | expand

Commit Message

Fathi Boudra June 28, 2017, 9:18 a.m. UTC
timers test fails to build due to undefined reference:

 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

Use LDLIBS instead of LDFLAGS to properly link against libpthread and fix
this build issue.

Signed-off-by: Denys Dmytriyenko <denys@ti.com>

Signed-off-by: Fathi Boudra <fathi.boudra@linaro.org>

---
 tools/testing/selftests/timers/Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

-- 
2.13.0

Comments

shuah June 28, 2017, 2:20 p.m. UTC | #1
On 06/28/2017 03:18 AM, Fathi Boudra wrote:
> timers test fails to build due to undefined reference:

> 

>  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

> 

> Use LDLIBS instead of LDFLAGS to properly link against libpthread and fix

> this build issue.

> 

> Signed-off-by: Denys Dmytriyenko <denys@ti.com>

> Signed-off-by: Fathi Boudra <fathi.boudra@linaro.org>


I can't reproduce this on linux-kselftest next on x86_64. Is this arm64 speocific
problem? Please try this on linux-kselftest latest.

thanks,
-- Shuah

> ---

>  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 5fa1d7e9a915..f48d7ca9d9b1 100644

> --- a/tools/testing/selftests/timers/Makefile

> +++ b/tools/testing/selftests/timers/Makefile

> @@ -1,6 +1,6 @@

>  BUILD_FLAGS = -DKTEST

>  CFLAGS += -O3 -Wl,-no-as-needed -Wall $(BUILD_FLAGS)

> -LDFLAGS += -lrt -lpthread

> +LDLIBS += -lrt -lpthread

>  

>  # these are all "safe" tests that don't modify

>  # system time or require escalated privileges

>
Fathi Boudra June 28, 2017, 2:37 p.m. UTC | #2
On 28 June 2017 at 17:20, Shuah Khan <shuah@kernel.org> wrote:
> On 06/28/2017 03:18 AM, Fathi Boudra wrote:

>> timers test fails to build due to undefined reference:

>>

>>  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

>>

>> Use LDLIBS instead of LDFLAGS to properly link against libpthread and fix

>> this build issue.

>>

>> Signed-off-by: Denys Dmytriyenko <denys@ti.com>

>> Signed-off-by: Fathi Boudra <fathi.boudra@linaro.org>

>

> I can't reproduce this on linux-kselftest next on x86_64. Is this arm64 speocific

> problem? Please try this on linux-kselftest latest.


yes, I tried linux-kselftest next and can reproduce.
Maybe related to native build vs cross-build?
I don't think it's arm64 specific.

> thanks,

> -- Shuah

>

>> ---

>>  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 5fa1d7e9a915..f48d7ca9d9b1 100644

>> --- a/tools/testing/selftests/timers/Makefile

>> +++ b/tools/testing/selftests/timers/Makefile

>> @@ -1,6 +1,6 @@

>>  BUILD_FLAGS = -DKTEST

>>  CFLAGS += -O3 -Wl,-no-as-needed -Wall $(BUILD_FLAGS)

>> -LDFLAGS += -lrt -lpthread

>> +LDLIBS += -lrt -lpthread

>>

>>  # these are all "safe" tests that don't modify

>>  # system time or require escalated privileges

>>

>
shuah June 28, 2017, 2:41 p.m. UTC | #3
On 06/28/2017 08:37 AM, Fathi Boudra wrote:
> On 28 June 2017 at 17:20, Shuah Khan <shuah@kernel.org> wrote:

>> On 06/28/2017 03:18 AM, Fathi Boudra wrote:

>>> timers test fails to build due to undefined reference:

>>>

>>>  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

>>>

>>> Use LDLIBS instead of LDFLAGS to properly link against libpthread and fix

>>> this build issue.

>>>

>>> Signed-off-by: Denys Dmytriyenko <denys@ti.com>

>>> Signed-off-by: Fathi Boudra <fathi.boudra@linaro.org>

>>

>> I can't reproduce this on linux-kselftest next on x86_64. Is this arm64 speocific

>> problem? Please try this on linux-kselftest latest.

> 

> yes, I tried linux-kselftest next and can reproduce.

> Maybe related to native build vs cross-build?

> I don't think it's arm64 specific.

> 


Can you confirm that this change doesn't cause problems in native
build environments.

thanks,
-- Shuah
Fathi Boudra June 28, 2017, 3 p.m. UTC | #4
On 28 June 2017 at 17:41, Shuah Khan <shuah@kernel.org> wrote:
> On 06/28/2017 08:37 AM, Fathi Boudra wrote:

>> On 28 June 2017 at 17:20, Shuah Khan <shuah@kernel.org> wrote:

>>> On 06/28/2017 03:18 AM, Fathi Boudra wrote:

>>>> timers test fails to build due to undefined reference:

>>>>

>>>>  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

>>>>

>>>> Use LDLIBS instead of LDFLAGS to properly link against libpthread and fix

>>>> this build issue.

>>>>

>>>> Signed-off-by: Denys Dmytriyenko <denys@ti.com>

>>>> Signed-off-by: Fathi Boudra <fathi.boudra@linaro.org>

>>>

>>> I can't reproduce this on linux-kselftest next on x86_64. Is this arm64 speocific

>>> problem? Please try this on linux-kselftest latest.

>>

>> yes, I tried linux-kselftest next and can reproduce.

>> Maybe related to native build vs cross-build?

>> I don't think it's arm64 specific.

>>

>

> Can you confirm that this change doesn't cause problems in native

> build environments.


yes, I tested on x86 in native build environment as well. It builds
and run fine.

I noticed my patchset for LDFLAGS vs LDLIBS changes don't apply
cleanly on linux-kselftest next branch. I'm happy to respin the serie
on top of next branch if you're willing to take them.

> thanks,

> -- Shuah


Cheers,
Fathi
shuah June 28, 2017, 3:11 p.m. UTC | #5
On 06/28/2017 09:00 AM, Fathi Boudra wrote:
> On 28 June 2017 at 17:41, Shuah Khan <shuah@kernel.org> wrote:

>> On 06/28/2017 08:37 AM, Fathi Boudra wrote:

>>> On 28 June 2017 at 17:20, Shuah Khan <shuah@kernel.org> wrote:

>>>> On 06/28/2017 03:18 AM, Fathi Boudra wrote:

>>>>> timers test fails to build due to undefined reference:

>>>>>

>>>>>  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

>>>>>

>>>>> Use LDLIBS instead of LDFLAGS to properly link against libpthread and fix

>>>>> this build issue.

>>>>>

>>>>> Signed-off-by: Denys Dmytriyenko <denys@ti.com>

>>>>> Signed-off-by: Fathi Boudra <fathi.boudra@linaro.org>

>>>>

>>>> I can't reproduce this on linux-kselftest next on x86_64. Is this arm64 speocific

>>>> problem? Please try this on linux-kselftest latest.

>>>

>>> yes, I tried linux-kselftest next and can reproduce.

>>> Maybe related to native build vs cross-build?

>>> I don't think it's arm64 specific.

>>>

>>

>> Can you confirm that this change doesn't cause problems in native

>> build environments.

> 

> yes, I tested on x86 in native build environment as well. It builds

> and run fine.

> 

> I noticed my patchset for LDFLAGS vs LDLIBS changes don't apply

> cleanly on linux-kselftest next branch. I'm happy to respin the serie

> on top of next branch if you're willing to take them.

> 


Yeah. I knew your series won't apply on top of linux-kselftest next just
looking at that patches. Hence the question whether or not these problems
have been reproduced on linux-kselftest.

Please redo the patches. The net patch needs to be done on top of

SeongJae Park's fix

selftest/net/Makefile: Specify output with $(OUTPUT)

btw - with the the above fix, I don't see any failures on x86_64.
I am curious why it fails in cross-build? Could you figure out if
your cross-build environment is good.

thanks,
-- Shuah

thanks,
-- Shuah
Fathi Boudra June 28, 2017, 3:56 p.m. UTC | #6
On 28 June 2017 at 18:11, Shuah Khan <shuah@kernel.org> wrote:
> On 06/28/2017 09:00 AM, Fathi Boudra wrote:

>> On 28 June 2017 at 17:41, Shuah Khan <shuah@kernel.org> wrote:

>>> On 06/28/2017 08:37 AM, Fathi Boudra wrote:

>>>> On 28 June 2017 at 17:20, Shuah Khan <shuah@kernel.org> wrote:

>>>>> On 06/28/2017 03:18 AM, Fathi Boudra wrote:

>>>>>> timers test fails to build due to undefined reference:

>>>>>>

>>>>>>  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

>>>>>>

>>>>>> Use LDLIBS instead of LDFLAGS to properly link against libpthread and fix

>>>>>> this build issue.

>>>>>>

>>>>>> Signed-off-by: Denys Dmytriyenko <denys@ti.com>

>>>>>> Signed-off-by: Fathi Boudra <fathi.boudra@linaro.org>

>>>>>

>>>>> I can't reproduce this on linux-kselftest next on x86_64. Is this arm64 speocific

>>>>> problem? Please try this on linux-kselftest latest.

>>>>

>>>> yes, I tried linux-kselftest next and can reproduce.

>>>> Maybe related to native build vs cross-build?

>>>> I don't think it's arm64 specific.

>>>>

>>>

>>> Can you confirm that this change doesn't cause problems in native

>>> build environments.

>>

>> yes, I tested on x86 in native build environment as well. It builds

>> and run fine.

>>

>> I noticed my patchset for LDFLAGS vs LDLIBS changes don't apply

>> cleanly on linux-kselftest next branch. I'm happy to respin the serie

>> on top of next branch if you're willing to take them.

>>

>

> Yeah. I knew your series won't apply on top of linux-kselftest next just

> looking at that patches. Hence the question whether or not these problems

> have been reproduced on linux-kselftest.

>

> Please redo the patches. The net patch needs to be done on top of

>

> SeongJae Park's fix

>

> selftest/net/Makefile: Specify output with $(OUTPUT)

>

> btw - with the the above fix, I don't see any failures on x86_64.

> I am curious why it fails in cross-build? Could you figure out if

> your cross-build environment is good.


I'm using openembedded to cross-build a full distro, not only kselftest.
I'm confident my cross-build environment is good.

The issue encountered is the same as
https://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest.git/commit/?h=next&id=dc816e5d84cbc28baf776799839a632d6002236f

Using LDFLAGS vs LDLIBS affects the ordering of the linker flags.
* with LDFLAGS
aarch64-linux-gnu-gcc -lrt -lpthread posix_timers.c -o posix_timers
* with LDLIBS
aarch64-linux-gnu-gcc posix_timers.c -lrt -lpthread -o posix_timers

> thanks,

> -- Shuah

>

> thanks,

> -- Shuah
Denys Dmytriyenko June 28, 2017, 4:04 p.m. UTC | #7
On Wed, Jun 28, 2017 at 06:56:30PM +0300, Fathi Boudra wrote:
> On 28 June 2017 at 18:11, Shuah Khan <shuah@kernel.org> wrote:

> > On 06/28/2017 09:00 AM, Fathi Boudra wrote:

> >> On 28 June 2017 at 17:41, Shuah Khan <shuah@kernel.org> wrote:

> >>> On 06/28/2017 08:37 AM, Fathi Boudra wrote:

> >>>> On 28 June 2017 at 17:20, Shuah Khan <shuah@kernel.org> wrote:

> >>>>> On 06/28/2017 03:18 AM, Fathi Boudra wrote:

> >>>>>> timers test fails to build due to undefined reference:

> >>>>>>

> >>>>>>  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

> >>>>>>

> >>>>>> Use LDLIBS instead of LDFLAGS to properly link against libpthread and fix

> >>>>>> this build issue.

> >>>>>>

> >>>>>> Signed-off-by: Denys Dmytriyenko <denys@ti.com>

> >>>>>> Signed-off-by: Fathi Boudra <fathi.boudra@linaro.org>

> >>>>>

> >>>>> I can't reproduce this on linux-kselftest next on x86_64. Is this arm64 speocific

> >>>>> problem? Please try this on linux-kselftest latest.

> >>>>

> >>>> yes, I tried linux-kselftest next and can reproduce.

> >>>> Maybe related to native build vs cross-build?

> >>>> I don't think it's arm64 specific.

> >>>>

> >>>

> >>> Can you confirm that this change doesn't cause problems in native

> >>> build environments.

> >>

> >> yes, I tested on x86 in native build environment as well. It builds

> >> and run fine.

> >>

> >> I noticed my patchset for LDFLAGS vs LDLIBS changes don't apply

> >> cleanly on linux-kselftest next branch. I'm happy to respin the serie

> >> on top of next branch if you're willing to take them.

> >>

> >

> > Yeah. I knew your series won't apply on top of linux-kselftest next just

> > looking at that patches. Hence the question whether or not these problems

> > have been reproduced on linux-kselftest.

> >

> > Please redo the patches. The net patch needs to be done on top of

> >

> > SeongJae Park's fix

> >

> > selftest/net/Makefile: Specify output with $(OUTPUT)

> >

> > btw - with the the above fix, I don't see any failures on x86_64.

> > I am curious why it fails in cross-build? Could you figure out if

> > your cross-build environment is good.

> 

> I'm using openembedded to cross-build a full distro, not only kselftest.

> I'm confident my cross-build environment is good.

> 

> The issue encountered is the same as

> https://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest.git/commit/?h=next&id=dc816e5d84cbc28baf776799839a632d6002236f

> 

> Using LDFLAGS vs LDLIBS affects the ordering of the linker flags.

> * with LDFLAGS

> aarch64-linux-gnu-gcc -lrt -lpthread posix_timers.c -o posix_timers

> * with LDLIBS

> aarch64-linux-gnu-gcc posix_timers.c -lrt -lpthread -o posix_timers


It's GNU Make and linker specific, not cross vs. native.

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, especially now since distributions are
using -Wl,--as-needed.

-- 
Denys
diff mbox series

Patch

diff --git a/tools/testing/selftests/timers/Makefile b/tools/testing/selftests/timers/Makefile
index 5fa1d7e9a915..f48d7ca9d9b1 100644
--- a/tools/testing/selftests/timers/Makefile
+++ b/tools/testing/selftests/timers/Makefile
@@ -1,6 +1,6 @@ 
 BUILD_FLAGS = -DKTEST
 CFLAGS += -O3 -Wl,-no-as-needed -Wall $(BUILD_FLAGS)
-LDFLAGS += -lrt -lpthread
+LDLIBS += -lrt -lpthread
 
 # these are all "safe" tests that don't modify
 # system time or require escalated privileges