Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1765295AbXFESta (ORCPT ); Tue, 5 Jun 2007 14:49:30 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1759850AbXFEStV (ORCPT ); Tue, 5 Jun 2007 14:49:21 -0400 Received: from mail-in-05.arcor-online.net ([151.189.21.45]:37400 "EHLO mail-in-05.arcor-online.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759489AbXFEStU (ORCPT ); Tue, 5 Jun 2007 14:49:20 -0400 In-Reply-To: <1181058836.16089.23.camel@hades.cambridge.redhat.com> References: <20070603183845.GA8952@lazybastard.org> <20070603184205.GE8952@lazybastard.org> <200706032342.27252.arnd@arndb.de> <20070604091245.GF14823@lazybastard.org> <1180964303.25232.358.camel@pmac.infradead.org> <18f622d94e9273fe6c93ef091fcec87c@kernel.crashing.org> <1181058836.16089.23.camel@hades.cambridge.redhat.com> Mime-Version: 1.0 (Apple Message framework v623) Content-Type: text/plain; charset=US-ASCII; format=flowed Message-Id: Content-Transfer-Encoding: 7bit Cc: Kyle Moffett , John Stoffel , Willy Tarreau , Evgeniy Polyakov , CaT , Ondrej Zajicek , linux-kernel@vger.kernel.org, Bill Davidsen , Jan Engelhardt , Thomas Gleixner , Dongjun Shin , Pekka Enberg , Arnd Bergmann , Albert Cahalan , linux-fsdevel@vger.kernel.org, linux-mtd@lists.infradead.org, Artem Bityutskiy , Sam Ravnborg , Jamie Lokier , Roland Dreier , =?ISO-8859-1?Q?J=F6rn_Engel?= , Pavel Machek , Ulisses Furquim , akpm@osdl.org, David Weinehall From: Segher Boessenkool Subject: Re: [Patch 04/18] include/linux/logfs.h Date: Tue, 5 Jun 2007 20:49:09 +0200 To: David Woodhouse X-Mailer: Apple Mail (2.623) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1027 Lines: 30 >>> It would be better if GCC had a 'nopadding' attribute which gave us >>> what we need without the _extra_ implications about alignment. >> >> That's impossible; removing the padding from a struct >> _will_ make accesses to its members unaligned (think >> about arrays of that struct). > > It _might_ make accesses to _some_ of its members unaligned. It _will_ make accesses to _at least one_ of the members unaligned, in the second array element. > That's why I said 'without the __EXTRA__ implications about alignment'. > > Obviously the lack of padding has its own implications, but we don't > necessarily need to assume that the struct may be at arbitrary > locations. The compiler does though, if it can't prove otherwise. What would "nopadding" buy us, anyway? Segher - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/