From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S271860AbTGRP6d (ORCPT ); Fri, 18 Jul 2003 11:58:33 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S269950AbTGRP4k (ORCPT ); Fri, 18 Jul 2003 11:56:40 -0400 Received: from pub237.cambridge.redhat.com ([213.86.99.237]:13820 "EHLO passion.cambridge.redhat.com") by vger.kernel.org with ESMTP id S271815AbTGRPzy (ORCPT ); Fri, 18 Jul 2003 11:55:54 -0400 Subject: Re: NFS structure allocation alignment patch From: David Woodhouse To: Richard Curnow Cc: Trond Myklebust , Marcelo Tosatti , Linux Kernel Mailing List , Paul Mundt , Ben Gaster , Sean McGoogan , Boyd Moffat In-Reply-To: <20030716150326.GA320@malvern.uk.w2k.superh.com> References: <20030630135233.GN5586@malvern.uk.w2k.superh.com> <1057835121.21073.208.camel@passion.cambridge.redhat.com> <20030716150326.GA320@malvern.uk.w2k.superh.com> Content-Type: text/plain Message-Id: <1058544639.29924.15.camel@passion.cambridge.redhat.com> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.4.1 (dwmw2) Date: Fri, 18 Jul 2003 17:10:39 +0100 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2003-07-16 at 16:03, Richard Curnow wrote: > Apart from this issue, we haven't seen any code- or compiler-related > problems due to misaligned loads and stores occurring. That doesn't mean they don't exist. Various parts of the network code _require_ alignment fixups -- the common case is that it'll be aligned, and we take the hit only in the _rare_ case of misalignment rather than using get_unaligned() in the fast path. Also the flash code does the same in places too. It _did_ use get_unaligned() for a while but it was removed since it's never valid for an architecture to _not_ fix up unaligned in-kernel accesses. > I bet someone will wonder how the misalignment hadn't shown up before. Because all other architectures implement alignment fixups. -- dwmw2