From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?iso-8859-1?Q?M=E5ns_Rullg=E5rd?= Subject: Re: alignment faults in 3.6 Date: Thu, 11 Oct 2012 10:45:25 +0100 Message-ID: References: <506E1762.3010601@gmail.com> <506E3E58.80703@gmail.com> <20121005071216.GD4625@n2100.arm.linux.org.uk> <20121005082439.GF4625@n2100.arm.linux.org.uk> <506ED18C.3010009@gmail.com> <20121005140556.GQ4625@n2100.arm.linux.org.uk> <506EEFBB.3060705@gmail.com> <507619FA.6080001@jonmasters.org> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: =?iso-8859-1?Q?M=E5ns_Rullg=E5rd?= , "Jon Masters" , , To: "David Laight" Return-path: Received: from unicorn.mansr.com ([78.86.181.103]:59421 "EHLO unicorn.mansr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755638Ab2JKJp1 convert rfc822-to-8bit (ORCPT ); Thu, 11 Oct 2012 05:45:27 -0400 In-Reply-To: (David Laight's message of "Thu, 11 Oct 2012 09:21:35 +0100") Sender: netdev-owner@vger.kernel.org List-ID: "David Laight" writes: >> -----Original Message----- >> From: netdev-owner@vger.kernel.org [mailto:netdev-owner@vger.kernel.= org] On Behalf Of M=E5ns Rullg=E5rd >> Sent: 11 October 2012 03:27 >> To: Jon Masters >> Cc: linux-arm-kernel@lists.infradead.org; netdev@vger.kernel.org >> Subject: Re: alignment faults in 3.6 >>=20 >> Jon Masters writes: >>=20 >> > Hi everyone, >> > >> > On 10/05/2012 10:33 AM, Rob Herring wrote: >> >> On 10/05/2012 09:05 AM, Russell King - ARM Linux wrote: >> >>> On Fri, Oct 05, 2012 at 07:24:44AM -0500, Rob Herring wrote: >> >>>> On 10/05/2012 03:24 AM, Russell King - ARM Linux wrote: >> >>>>> Does it matter? I'm just relaying the argument against adding= __packed >> >>>>> which was used before we were forced (by the networking folk) = to implement >> >>>>> the alignment fault handler. >> >>>> >> >>>> It doesn't really matter what will be accepted or not as adding= __packed >> >>>> to struct iphdr doesn't fix the problem anyway.=20 > ... >> There are exactly two possible solutions: >>=20 >> 1. Change the networking code so those structs are always aligned. = This >> might not be (easily) possible. >> 2. Mark the structs __packed and fix any typecasts like the ones see= n in >> this thread. This will have an adverse effect in cases where the >> structs are in fact aligned. >>=20 >> Both solutions lie squarely in the networking code. It's time to >> involve that list, or we'll never get anywhere. > > It might be enough to use __attribute__((aligned(2))) on some structu= re > members (actually does 'ldm' need 8 byte alignment?? - in which case > aligned(4) is enough). The aligned attribute can only increase alignment. --=20 M=E5ns Rullg=E5rd mans@mansr.com