Re: [PATCH v4 3/4] selftests/vDSO: Use KHDR_INCLUDES to locate UAPI headers for vdso_test_getrandom

["Jason A. Donenfeld" <Jason@zx2c4.com>]

On Tue, Aug 27, 2024 at 04:50:59PM +0200, Christophe Leroy wrote:
> 
> 
> Le 27/08/2024 à 16:41, Xi Ruoyao a écrit :
> > On Tue, 2024-08-27 at 16:15 +0200, Jason A. Donenfeld wrote:
> > 
> > /* snip */
> > 
> >> gcc -std=gnu99 -D_GNU_SOURCE= -isystem /home/zx2c4/Projects/random-linux/tools/testing/selftests/../../../tools/include -isystem /home/zx2c4/Projects/random-linux/tools/testing/selftests/../../../usr/include    vdso_test_getrandom.c parse_vdso.c  -o /home/zx2c4/Projects/random-linux/tools/testing/selftests/vDSO/vdso_test_getrandom
> >> vdso_test_getrandom.c:43:41: error: field ‘params’ has incomplete type
> >>     43 |         struct vgetrandom_opaque_params params;
> >>        |                                         ^~~~~~
> >>
> >> $ ls /home/zx2c4/Projects/random-linux/tools/testing/selftests/../../../usr/include
> >> headers_check.pl  Makefile
> >>
> >> Since I don't build in there, this directory is empty.
> > 
> > In the toplevel Makefile:
> > 
> > kselftest-%: headers FORCE
> >      $(Q)$(MAKE) -C $(srctree)/tools/testing/selftests $*
> > 
> > So running "make kselftest-all" to build the self tests should have
> > already caused make to build the "headers" target, which puts the
> > headers into usr/include.
> > 
> > I don't think it's supported to build self tests w/o invoking the
> > toplevel Makefile: many other self tests use KHDR_INCLUDES as well, so
> > generally building with something like "make -C tools/testing/selftests"
> > just won't work.
> > 
> 
> My usr/include/ is also empty (only Makefile and headers_check.pl) and 
> building directly in tools/testing/selftests/vDSO works for me.
> 
> The command is:
> 
> ppc-linux-gcc -std=gnu99 -D_GNU_SOURCE= -isystem 
> /home/chleroy/linux-powerpc/tools/testing/selftests/../../../tools/include 
> -isystem 
> /home/chleroy/linux-powerpc/tools/testing/selftests/../../../include/uapi 
>     vdso_test_getrandom.c parse_vdso.c  -o 
> /home/chleroy/linux-powerpc/tools/testing/selftests/vDSO/vdso_test_getrandom
> 
> I believe I get the needed headers through : -isystem 
> /home/chleroy/linux-powerpc/tools/testing/selftests/../../../include/uapi

The effect of this patch is to replace include/uapi with usr/include, so
it will break for you too.

What I'm wondering is why yours and mine work like that, while Ruoyao's
breaks. He makes a good argument as to why this patch is the "right
way", even if it breaks our workflow...

> 
> Christophe
> 
> PS: By the way, did you see the -DBULID_VDSO for the chacha test ? Don't 
> know the impact though ....

Yes and https://lore.kernel.org/all/20240827145454.3317093-1-Jason@zx2c4.com/