From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S265986AbUHFOtQ (ORCPT ); Fri, 6 Aug 2004 10:49:16 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S268074AbUHFOtQ (ORCPT ); Fri, 6 Aug 2004 10:49:16 -0400 Received: from dci.doncaster.on.ca ([66.11.168.194]:27595 "EHLO smtp.istop.com") by vger.kernel.org with ESMTP id S265986AbUHFOtK (ORCPT ); Fri, 6 Aug 2004 10:49:10 -0400 From: Daniel Phillips To: "David S. Miller" Subject: Re: block layer sg, bsg Date: Fri, 6 Aug 2004 03:03:40 -0400 User-Agent: KMail/1.6.2 Cc: yoshfuji@linux-ipv6.org, ak@muc.de, jgarzik@pobox.com, axboe@suse.de, linux-kernel@vger.kernel.org References: <20040804191850.GA19224@havoc.gtf.org> <20040804.165113.06226042.yoshfuji@linux-ipv6.org> <20040804205837.6fda9a50.davem@redhat.com> In-Reply-To: <20040804205837.6fda9a50.davem@redhat.com> MIME-Version: 1.0 Content-Disposition: inline Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <200408060303.40261.phillips@arcor.de> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi Dave, On Wednesday 04 August 2004 23:58, David S. Miller wrote: > On Wed, 04 Aug 2004 16:51:13 -0700 (PDT) > > YOSHIFUJI Hideaki / 吉藤英明 wrote: > > > Well, 32bit ipsec on x86-64/ia64 is a NOP because of that. > > > > Hmm, I don't get the point. > > What part (or which structore) is broken? > > On x86-64 and ia64 they have a large issue because the ia32 > emulation layer has to handle the fact that "long long" types > do not require 8-byte alignment, whereas 64-bit natively > they do. I'm making heavy use of struct read/writes in the cluster snapshot block device, so I need to get this sorted out. Somewhere I got the idea that if a structure is declared with attribute PACKED, gcc will generate alignment-independent code (e.g., access each field byte by byte) on alignment-restricted architectures. So if what I imagine about gcc is true, what issues remain? These structs have to be declared packed anyway and with fixed field sizes, or the layout will vary across architectures. Regards, Daniel