Re: [PATCH 06/14] powerpc/vdso: Remove unused '-s' flag from ASFLAGS

[Nathan Chancellor <nathan@kernel.org>]

On Mon, Jan 09, 2023 at 01:58:32PM -0800, Nick Desaulniers wrote:
> On Wed, Jan 4, 2023 at 11:55 AM Nathan Chancellor <nathan@kernel.org> wrote:
> >
> > When clang's -Qunused-arguments is dropped from KBUILD_CPPFLAGS, it
> > warns that ASFLAGS contains '-s', which is a linking phase option, so it
> > is unused.
> >
> >   clang-16: error: argument unused during compilation: '-s' [-Werror,-Wunused-command-line-argument]
> >
> > Looking at the GAS sources, '-s' is only useful when targeting Solaris
> > and it is ignored for the powerpc target so just drop the flag
> > altogether, as it is not needed.
> 
> Do you have any more info where you found this?  I don't see -s
> documented as an assembler flag.
> https://sourceware.org/binutils/docs/as/PowerPC_002dOpts.html
> https://sourceware.org/binutils/docs/as/Invoking.html

Sure thing, sorry I did not include it initially. See the section from
line 1284 to 1291 or search for "case 's':":

https://sourceware.org/git/?p=binutils-gdb.git;a=blob;f=gas/config/tc-ppc.c;h=9450fa74de1b61542c9a18babf8c8f621ef904fb;hb=HEAD

> The patch seems fine to me, but what was this ever supposed to be?
> FWICT it predates git history (looking at
> arch/powerpc/kernel/vdso32/Makefile at fc15351d9d63)

Right, I could not figure it out either, it has been there since the
vDSO was introduced back in 2005 (I was three days away from 10!) and
there is no comment about it so *shrug*:

https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git/commit/?id=054eb7153aeb84cc92da84210cf93b0e2a34811b

If someone else's archeological skills are better and can provide more
information, I am happy to include that.

> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>

Thanks as always for the review! I'll include this and a note about
where in binutils I found that information for v2.

> >
> > Signed-off-by: Nathan Chancellor <nathan@kernel.org>
> > ---
> > Cc: mpe@ellerman.id.au
> > Cc: npiggin@gmail.com
> > Cc: christophe.leroy@csgroup.eu
> > Cc: linuxppc-dev@lists.ozlabs.org
> > ---
> >  arch/powerpc/kernel/vdso/Makefile | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/arch/powerpc/kernel/vdso/Makefile b/arch/powerpc/kernel/vdso/Makefile
> > index 6a977b0d8ffc..45c0cc5d34b6 100644
> > --- a/arch/powerpc/kernel/vdso/Makefile
> > +++ b/arch/powerpc/kernel/vdso/Makefile
> > @@ -51,10 +51,10 @@ ccflags-y := -shared -fno-common -fno-builtin -nostdlib -Wl,--hash-style=both
> >  ccflags-$(CONFIG_LD_IS_LLD) += $(call cc-option,--ld-path=$(LD),-fuse-ld=lld)
> >
> >  CC32FLAGS := -Wl,-soname=linux-vdso32.so.1 -m32
> > -AS32FLAGS := -D__VDSO32__ -s
> > +AS32FLAGS := -D__VDSO32__
> >
> >  CC64FLAGS := -Wl,-soname=linux-vdso64.so.1
> > -AS64FLAGS := -D__VDSO64__ -s
> > +AS64FLAGS := -D__VDSO64__
> >
> >  targets += vdso32.lds
> >  CPPFLAGS_vdso32.lds += -P -C -Upowerpc
> >
> > --
> > 2.39.0
> 
> 
> 
> -- 
> Thanks,
> ~Nick Desaulniers