From mboxrd@z Thu Jan 1 00:00:00 1970 From: arnd@arndb.de (Arnd Bergmann) Date: Fri, 19 Feb 2016 15:23:16 +0100 Subject: [PATCH 1/3] [RESEND] ARM: pass -march=armv7-a when building NEON files with clang In-Reply-To: References: <1455815113-2562966-1-git-send-email-arnd@arndb.de> <1455815113-2562966-2-git-send-email-arnd@arndb.de> Message-ID: <3205167.CfekeqRXnt@wuerfel> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Thursday 18 February 2016 12:31:35 Nicolas Pitre wrote: > On Thu, 18 Feb 2016, Arnd Bergmann wrote: > > > clang ignores the -mfpu=neon flag when building with -march=armv6: > > > > In file included from lib/raid6/neon1.c:27: > > clang/3.8.0/include/arm_neon.h:28:2: error: "NEON support not enabled" > > > > There is no real need to build the file with -march=armv6 in a > > multi-CPU enabled kernel, as nothing in here will ever get called > > on an ARMv6 CPU. Adding -march=armv7 doesn't hurt and can only > > improve the code quality. > > Is this enough to override a previous -mfpu for gcc? I did not see any build failures on gcc with this, so I assume it has no effect. I could move the -march=armv7-a in front of -mfpu=neon if you think that would be safer though. Arnd From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1948532AbcBSOXs (ORCPT ); Fri, 19 Feb 2016 09:23:48 -0500 Received: from mout.kundenserver.de ([217.72.192.74]:58364 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1947941AbcBSOXq (ORCPT ); Fri, 19 Feb 2016 09:23:46 -0500 From: Arnd Bergmann To: Nicolas Pitre Cc: Russell King , linux-arm-kernel@lists.infradead.org, Ard Biesheuvel , Jon Medhurst , Marc Zyngier , linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/3] [RESEND] ARM: pass -march=armv7-a when building NEON files with clang Date: Fri, 19 Feb 2016 15:23:16 +0100 Message-ID: <3205167.CfekeqRXnt@wuerfel> User-Agent: KMail/4.11.5 (Linux/3.16.0-10-generic; KDE/4.11.5; x86_64; ; ) In-Reply-To: References: <1455815113-2562966-1-git-send-email-arnd@arndb.de> <1455815113-2562966-2-git-send-email-arnd@arndb.de> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" X-Provags-ID: V03:K0:kRn8eAhEW1hKbZmsPiOnrPfXBkBDUI9R/sa3Kbo8CsYLjaqcERj Y7kBy4GjKIAdWhiGxS51GYkWm+1GLBPCjLBWl7Pgj7HPyMHTk+oZ673/2pkJ2uLppkS1/9J 3aJHxD/7Vbjp+Bg3eQ3r9IWWkxwFnhYN5cQoiZbcUhcfjR7AOX3E9X5lVHebigVEMeZT2Ny cL7XNWMmMvV15imCczjqA== X-UI-Out-Filterresults: notjunk:1;V01:K0:fM/ThhjoEP8=:nq4k/YIPh1H3Ffoms0xTs2 Eu/bQ1sxyWdaEtIO22ZcEPBAYFUd+e7xxteNkqwHt1EsLHlewUCMjDgoSk4YTOaubtAMqjbpg e0/UchCfuWgoOqZIqEai/0Z4EEM58Fq5hkk2T23xXLbxS20kTbBcMTm68MZfkkiY5UKJxXR94 fzzeLE+dYd/6Ii/4B0T3SXS3iwPr6setsluDZBi0WcbcaB+j9sEMXbbUlNrA1YnF2kVVaJYoN SXN98p8FmLiOZmHcj/6n2F+A30OOzMK8IHSWvUEOmXYZJYhbJbxQBKA156ot0I1530Z395d7c +SVqqGdkRx9CyyB/xWyND8DlWYysEgEJa/NV4avfD0QGw959Wdto4dmMRWbqBl517X5UEPHs+ FTTmGyDztdOzdVy7eydB4uwIia/G/GDaariHOasI1Vsv8L4LXjmbxOBgrGTiuLZpzcmLNZjnD c5N4egeiYZQ6oKiBV9jOPAHhZQJYastrRvWP1Cu6c77fLqwZwSG66StVBEeNtxJ3Nav1MbpxE xMXnFvhXnwp/ZY2gAO+UOge7yfEXLgekT6PkRglsKFnmiXfSlkr9sGo8vgFdFxRCwJdHIRI56 4UGYfce5D5fnPFZgPf5TFf4EF+vQicCxRd+FY0rSazFVEc7JtL1sKY5zNs796ASidH1iCssL1 pouN6PJRM0UYcNl+qA7dgS6cJ0CVnWYzCLWqqXGa0lC3BquAUjukR1z7WLMapjItRKa7OPqUP wiTkLrgrkERYpgUs Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thursday 18 February 2016 12:31:35 Nicolas Pitre wrote: > On Thu, 18 Feb 2016, Arnd Bergmann wrote: > > > clang ignores the -mfpu=neon flag when building with -march=armv6: > > > > In file included from lib/raid6/neon1.c:27: > > clang/3.8.0/include/arm_neon.h:28:2: error: "NEON support not enabled" > > > > There is no real need to build the file with -march=armv6 in a > > multi-CPU enabled kernel, as nothing in here will ever get called > > on an ARMv6 CPU. Adding -march=armv7 doesn't hurt and can only > > improve the code quality. > > Is this enough to override a previous -mfpu for gcc? I did not see any build failures on gcc with this, so I assume it has no effect. I could move the -march=armv7-a in front of -mfpu=neon if you think that would be safer though. Arnd