[Buildroot] [PATCH 1/1] package/ltp-testsuite: fix static build with lts-musl

[Thomas Petazzoni <thomas.petazzoni@bootlin.com>]

Hello Petr,

On Thu, 17 Oct 2019 00:26:25 +0200
Petr Vorel <petr.vorel@gmail.com> wrote:

> > > Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>  
> 
> > So essentially the problem here is that libcpu_set.a uses some FTS
> > functions, but -lfts appears *before* -lcpu_set in the link command
> > line.  
> But in the patch bellow -lfts is behind -lcpu_set:
> +-LDLIBS			+= -lcpu_set -lcontrollers -lltp
> ++LDLIBS			+= -lcpu_set -lcontrollers -lltp $(FTS_LIBS)

That's what my point is: without the patch from Fabrice, passing some
LDLIBS to ltp-testsuite puts those libraries listed in LDLIBS *before*
the internal ltp-testsuite libraries, which contradicts the
ltp-testsuite documentation for this LDLIBS variable.

What Fabrice's patch does is provide a way to give a list of libraries
that are *really* used after the list of objects/internal libraries.


> /br-test-pkg/br-arm-full-static/host/bin/arm-linux-gcc -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -Os -static -I/br-test-pkg/br-arm-full-static/host/bin/../arm-buildroot-linux-uclibcgnueabi/sysroot/usr/include/tirpc  -g -O2 -fno-strict-aliasing -pipe -Wall -W -Wold-style-definition -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FORTIFY_SOURCE=2 -I../../../../../include -I../../../../../include -I../../../../../include/old/ -static  -L/br-test-pkg/br-arm-full-static/build/ltp-testsuite-20190930/testcases/kernel/controllers/cpuset/cpuset_memory_test/../cpuset_lib -L/br-test-pkg/br-arm-full-static/build/ltp-testsuite-20190930/testcases/kernel/controllers/cpuset/cpuset_memory_test/../../libcontrollers -L../../../../../lib  cpuset_memory_test.c  -L/br-test-pkg/br-arm-full-static/host/bin/../arm-buildroot-linux-uclibcgnueabi/sysroot/usr/lib -ltirpc -lpthread  -lfts -lltp -lcpu_set -lcontrollers -lltp -lpthread -o cpuset_memory_test

See that -lfts is passed, but *before* -lcpu_set ? That's what causes the issue.

> > Petr: is that expected ? What do you suggest ?  
> To be honest, I don't know, it looks like a bug. There was some change related
> I need to to dig a bit more into library Makefiles.
> Cyril, do you have any idea?

An option would be in the various Makefiles to do:

LDLIBS := -lrt $(LDLIBS)

instead of:

LDLIBS += -lrt

And similarly for the specific case causing the trouble:

LDLIBS := -lcpu_set -lcontrollers -lltp $(LDLIBS)

instead of the current:

LDLIBS += -lcpu_set -lcontrollers -lltp

Another option is to decide that ltp-testsuite is not available for
static-only builds.

Best regards,

Thomas
-- 
Thomas Petazzoni, CTO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com