From: Segher Boessenkool <segher@kernel.crashing.org>
To: Nick Desaulniers <ndesaulniers@google.com>
Cc: kernel test robot <lkp@intel.com>,
linux-kbuild@vger.kernel.org, trix@redhat.com,
masahiroy@kernel.org, llvm@lists.linux.dev, npiggin@gmail.com,
Nathan Chancellor <nathan@kernel.org>,
linuxppc-dev@lists.ozlabs.org, nicolas@fjasle.eu
Subject: Re: [PATCH 06/14] powerpc/vdso: Remove unused '-s' flag from ASFLAGS
Date: Mon, 9 Jan 2023 16:23:37 -0600 [thread overview]
Message-ID: <20230109222337.GM25951@gate.crashing.org> (raw)
In-Reply-To: <CAKwvOdknEE7DyUG0s43GNGf27QeMgW2fUTXcCzKLbjH1g318vQ@mail.gmail.com>
Hi! Happy new year all.
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
It is required by POSIX (for the c99 command, anyway). It *also* is
required to be supported when producing object files (so when no linking
is done).
It is a GCC flag, and documented just fine:
https://gcc.gnu.org/onlinedocs/gcc/Link-Options.html#index-s
(Yes, that says it is for linking; but the option is allowed without
error of any kind always).
(ASFLAGS sounds like it is for assembler commands, but it really is
for compiler commands that just happen to get .S input files).
> 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)
Yeah, good question. This compiler flag does the moral equivalent of
strip -s (aka --strip-all). Maybe this was needed at some point, or
the symbol or debug info was just annoying (during bringup or similar)?
> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Segher Boessenkool <segher@kernel.crashing.org>
Segher
next prev parent reply other threads:[~2023-01-09 22:32 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-04 19:54 [PATCH 00/14] Remove clang's -Qunused-arguments from KBUILD_CPPFLAGS Nathan Chancellor
2023-01-04 19:54 ` [PATCH 05/14] powerpc: Remove linker flag from KBUILD_AFLAGS Nathan Chancellor
2023-01-09 21:24 ` Nick Desaulniers
2023-01-04 19:54 ` [PATCH 06/14] powerpc/vdso: Remove unused '-s' flag from ASFLAGS Nathan Chancellor
2023-01-09 21:58 ` Nick Desaulniers
2023-01-09 22:15 ` Nathan Chancellor
2023-01-09 22:21 ` Nick Desaulniers
2023-01-09 22:23 ` Segher Boessenkool [this message]
2023-01-09 22:37 ` Nathan Chancellor
2023-01-09 22:47 ` Segher Boessenkool
2023-01-09 23:14 ` Nick Desaulniers
2023-01-10 0:51 ` Nathan Chancellor
2023-01-10 11:45 ` Segher Boessenkool
2023-01-10 15:02 ` Nathan Chancellor
[not found] ` <20230109222337.GM25951__25255.3859770828$1673303520$gmane$org@gate.crashing.org>
2023-01-10 0:22 ` Andreas Schwab
2023-01-10 0:43 ` Segher Boessenkool
2023-01-04 19:54 ` [PATCH 07/14] powerpc/vdso: Improve linker flags Nathan Chancellor
2023-01-09 22:08 ` Nick Desaulniers
2023-01-09 22:15 ` Nathan Chancellor
2023-01-04 19:54 ` [PATCH 08/14] powerpc/vdso: Remove an unsupported flag from vgettimeofday-32.o with clang Nathan Chancellor
2023-01-09 22:12 ` Nick Desaulniers
2023-01-09 22:38 ` Nathan Chancellor
2023-01-09 23:16 ` Nick Desaulniers
2023-01-05 8:00 ` [PATCH 00/14] Remove clang's -Qunused-arguments from KBUILD_CPPFLAGS Heiko Carstens
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