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 870F8C433EF for ; Fri, 25 Feb 2022 22:38:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238496AbiBYWjH (ORCPT ); Fri, 25 Feb 2022 17:39:07 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34488 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236215AbiBYWjF (ORCPT ); Fri, 25 Feb 2022 17:39:05 -0500 Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id E6E5C140C5; Fri, 25 Feb 2022 14:38:31 -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 21PMXKWJ022487; Fri, 25 Feb 2022 16:33:20 -0600 Received: (from segher@localhost) by gate.crashing.org (8.14.1/8.14.1/Submit) id 21PMXJBw022486; Fri, 25 Feb 2022 16:33:19 -0600 X-Authentication-Warning: gate.crashing.org: segher set sender to segher@kernel.crashing.org using -f Date: Fri, 25 Feb 2022 16:33:19 -0600 From: Segher Boessenkool To: Nicholas Piggin Cc: Anders Roxell , Arnd Bergmann , linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, mpe@ellerman.id.au, stable@vger.kernel.org Subject: Re: [PATCH 2/3] powerpc: fix build errors Message-ID: <20220225223319.GT614@gate.crashing.org> References: <20220223135820.2252470-1-anders.roxell@linaro.org> <20220223135820.2252470-2-anders.roxell@linaro.org> <1645670923.t0z533n7uu.astroid@bobo.none> <1645678884.dsm10mudmp.astroid@bobo.none> <20220224171207.GM614@gate.crashing.org> <1645748601.idp48wexp9.astroid@bobo.none> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1645748601.idp48wexp9.astroid@bobo.none> User-Agent: Mutt/1.4.2.3i Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Feb 25, 2022 at 10:32:02AM +1000, Nicholas Piggin wrote: > Excerpts from Segher Boessenkool's message of February 25, 2022 3:12 am: > > On Thu, Feb 24, 2022 at 03:05:28PM +1000, Nicholas Piggin wrote: > >> + * gcc 10 started to emit a .machine directive at the beginning of generated > >> + * .s files, which overrides assembler -Wa,-m options passed down. > >> + * Unclear if this behaviour will be reverted. > > > > It will not be reverted. If you need a certain .machine for some asm > > code, you should write just that! > > It should be reverted because it breaks old binutils which did not have > the workaround patch for this broken gcc behaviour. And it is just > unnecessary because -m option can already be used to do the same thing. > > Not that I expect gcc to revert it. Nothing will happen if you do not file a bug report. And do read the bug reporting instructions first please. > >> +#ifdef CONFIG_CC_IS_GCC > >> +#if (GCC_VERSION >= 100000) > >> +#if (CONFIG_AS_VERSION == 23800) > >> +asm(".machine any"); > >> +#endif > >> +#endif > >> +#endif > >> +#endif /* __ASSEMBLY__ */ > > > > Abusing toplevel asm like this is broken and you *will* end up with > > unhappiness all around. > > It actually unbreaks things and reduces my unhappiness. It is broken. You will need -fno-toplevel-reorder, and you really do not want that, if you *can* use it in the kernel even. > It's only done > for broken compiler versions and only where as does not have the > workaround for the breakage. What compiler versions? Please file a PR. Segher