From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Hogan Subject: Re: [PATCH v2 03/44] Add CONFIG_HAVE_64BIT_ALIGNED_STRUCT for taskstats Date: Mon, 10 Dec 2012 10:22:27 +0000 Message-ID: <50C5B7E3.2080909@imgtec.com> References: <1354723742-6195-1-git-send-email-james.hogan@imgtec.com> <1354723742-6195-4-git-send-email-james.hogan@imgtec.com> <50C2B751.5000507@zytor.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: Received: from multi.imgtec.com ([194.200.65.239]:52713 "EHLO multi.imgtec.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754726Ab2LJKWd (ORCPT ); Mon, 10 Dec 2012 05:22:33 -0500 In-Reply-To: <50C2B751.5000507@zytor.com> Sender: linux-arch-owner@vger.kernel.org List-ID: To: "H. Peter Anvin" Cc: linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, Arnd Bergmann , Balbir Singh , Ingo Molnar , Andrew Morton , Eric Paris , Will Drewry , James Morris On 08/12/12 03:43, H. Peter Anvin wrote: > On 12/05/2012 08:08 AM, James Hogan wrote: >> On 64 bit architectures with no efficient unaligned access, taskstats >> has to add some padding to a reply to prevent unaligned access warnings. >> However this also needs to apply to 32 bit architectures with 64 bit >> struct alignment such as metag (which has 64 bit memory accesses). > > Wait... 64-bit struct alignment on structures with only 32-bit members? > That might be... interesting... in a number of places... Hi, I'll rewrite the description as it's a bit misleading. On metag 64bit struct alignment is required when it contains 64bit members, not if it only contains 32bit members. Although metag is a 32bit arch, it can do 64bit memory accesses which must be aligned. Thanks for taking a look. James