From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id AB45AC54EBD for ; Mon, 9 Jan 2023 22:32:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235571AbjAIWch (ORCPT ); Mon, 9 Jan 2023 17:32:37 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52816 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237777AbjAIWcg (ORCPT ); Mon, 9 Jan 2023 17:32:36 -0500 Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 5CEF01021 for ; Mon, 9 Jan 2023 14:32:32 -0800 (PST) Received: from gate.crashing.org (localhost.localdomain [127.0.0.1]) by gate.crashing.org (8.14.1/8.14.1) with ESMTP id 309MNfL3025747; Mon, 9 Jan 2023 16:23:41 -0600 Received: (from segher@localhost) by gate.crashing.org (8.14.1/8.14.1/Submit) id 309MNcFl025746; Mon, 9 Jan 2023 16:23:38 -0600 X-Authentication-Warning: gate.crashing.org: segher set sender to segher@kernel.crashing.org using -f Date: Mon, 9 Jan 2023 16:23:37 -0600 From: Segher Boessenkool To: Nick Desaulniers Cc: Nathan Chancellor , kernel test robot , linux-kbuild@vger.kernel.org, trix@redhat.com, masahiroy@kernel.org, llvm@lists.linux.dev, npiggin@gmail.com, linuxppc-dev@lists.ozlabs.org, nicolas@fjasle.eu Subject: Re: [PATCH 06/14] powerpc/vdso: Remove unused '-s' flag from ASFLAGS Message-ID: <20230109222337.GM25951@gate.crashing.org> References: <20221228-drop-qunused-arguments-v1-0-658cbc8fc592@kernel.org> <20221228-drop-qunused-arguments-v1-6-658cbc8fc592@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.2.3i Precedence: bulk List-ID: X-Mailing-List: linux-kbuild@vger.kernel.org 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 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 Reviewed-by: Segher Boessenkool Segher