From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from canuck.infradead.org ([209.217.80.40]:41634 "EHLO canuck.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752612AbXFOMii (ORCPT ); Fri, 15 Jun 2007 08:38:38 -0400 Subject: Re: [PATCH] Introduce compat_u64 and compat_s64 types From: David Woodhouse In-Reply-To: <20070615121133.GF8154@parisc-linux.org> References: <200706150159.l5F1xNgM000459@hera.kernel.org> <1181897905.26853.66.camel@localhost.localdomain> <200706151128.39566.arnd@arndb.de> <200706151131.38429.arnd@arndb.de> <20070615121133.GF8154@parisc-linux.org> Content-Type: text/plain Date: Fri, 15 Jun 2007 13:38:32 +0100 Message-Id: <1181911112.25228.472.camel@pmac.infradead.org> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-arch-owner@vger.kernel.org To: Matthew Wilcox Cc: Arnd Bergmann , Benjamin Herrenschmidt , Linux Kernel Mailing List , Dave Airlie , linux-arch@vger.kernel.org, Andrew Morton List-ID: On Fri, 2007-06-15 at 06:11 -0600, Matthew Wilcox wrote: > You're relying on compat_[us]64 being only used in structures which are > already packed. In which case the whole exercise is pointless, on account of the structure being already packed. It was _already_ laid out the same on 32-bit and 64-bit builds. > If someone uses them in a non-packed struct, they won't > decrease the alignment. I think it would be more effective to specify > it as: > __attribute__((aligned(4), packed)) Good point. Yes, it looks like we need the additional 'packed' in order for the aligned(4) to be anything other than a no-op. -- dwmw2