Re: [PATCH] selftests/net/tcp-ao: Use LDLIBS instead of LDFLAGS

[Paolo Abeni]

On Wed, 2024-01-10 at 21:34 +0000, Dmitry Safonov wrote:
> The rules to link selftests are:
> 
> > $(OUTPUT)/%_ipv4: %.c
> > 	$(LINK.c) $^ $(LDLIBS) -o $@
> > 
> > $(OUTPUT)/%_ipv6: %.c
> > 	$(LINK.c) -DIPV6_TEST $^ $(LDLIBS) -o $@
> 
> The intel test robot uses only selftest's Makefile, not the top linux
> Makefile:
> 
> > make W=1 O=/tmp/kselftest -C tools/testing/selftests
> 
> So, $(LINK.c) is determined by environment, rather than by kernel
> Makefiles. On my machine (as well as other people that ran tcp-ao
> selftests) GNU/Make implicit definition does use $(LDFLAGS):
> 
> > [dima@Mindolluin ~]$ make -p -f/dev/null | grep '^LINK.c\>'
> > make: *** No targets.  Stop.
> > LINK.c = $(CC) $(CFLAGS) $(CPPFLAGS) $(LDFLAGS) $(TARGET_ARCH)
> 
> But, according to build robot report, it's not the case for them.
> While I could just avoid using pre-defined $(LINK.c), it's also used by
> selftests/lib.mk by default.
> 
> Anyways, according to GNU/Make documentation [1], I should have used
> $(LDLIBS) instead of $(LDFLAGS) in the first place, so let's just do it:
> 
> > 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.
> 
> [1]: https://www.gnu.org/software/make/manual/html_node/Implicit-Variables.html
> 
> Fixes: cfbab37b3da0 ("selftests/net: Add TCP-AO library")
> Reported-by: kernel test robot <lkp@xxxxxxxxx>
> Closes: https://lore.kernel.org/oe-kbuild-all/202401011151.veyYTJzq-lkp@xxxxxxxxx/
> Signed-off-by: Dmitry Safonov <dima@xxxxxxxxxx>

Acked-by: Paolo Abeni <pabeni@xxxxxxxxxx>