From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755971Ab1ISDw4 (ORCPT ); Sun, 18 Sep 2011 23:52:56 -0400 Received: from out3.smtp.messagingengine.com ([66.111.4.27]:41170 "EHLO out3.smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753945Ab1ISDwy (ORCPT ); Sun, 18 Sep 2011 23:52:54 -0400 X-Sasl-enc: nWDfCZkFg1IVbwzEuW+TrbJ50X2AULW0FpSbsf5Qurz3 1316404373 Subject: Re: [PATCH] Force same size of struct autofs_v5_packet on x86 and x86_64 From: Ian Kent To: Thomas Meyer Cc: Al Viro , Linux Kernel Mailing List , dhowells@redhat.com In-Reply-To: <1316332908.5814.22.camel@localhost.localdomain> References: <1316167604.6545.84.camel@localhost.localdomain> <20110916101903.GI2203@ZenIV.linux.org.uk> <1316169496.8502.6.camel@perseus.themaw.net> <1316332908.5814.22.camel@localhost.localdomain> Content-Type: text/plain; charset="UTF-8" Date: Mon, 19 Sep 2011 11:52:48 +0800 Message-ID: <1316404368.3206.21.camel@perseus.themaw.net> Mime-Version: 1.0 X-Mailer: Evolution 2.32.3 (2.32.3-1.fc14) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 2011-09-18 at 10:01 +0200, Thomas Meyer wrote: > Am Freitag, den 16.09.2011, 18:38 +0800 schrieb Ian Kent: > > On Fri, 2011-09-16 at 11:19 +0100, Al Viro wrote: > > > On Fri, Sep 16, 2011 at 12:06:38PM +0200, Thomas Meyer wrote: > > > > autofs_v5_packet is 300 bytes on x86 and 304 bytes on x86_64. > > > > This difference is wrong and leads to a hang in systemd when running > > > > a x86 userspace on an x86_64 kernel. > > > > > > NAK. > > > > > > You are talking about the userland ABI. With existing users. Changing > > > it might help systemd (what the hell is it doing with autofs, anyway?), > > > but breaking existing binaries (you know, ones that *do* have some business > > > dealing with autofs) is not acceptable. > > > > That's right. > > > > Certainly my mistake (made a long time ago) and when I realized it I > > decided I would need to handle it in user space for the same reasons Al > > has mentioned. > > > > btw. where are the padding bytes are added? how to tell gcc to display > this? It's also been a long time since I looked into this so I don't remember the processor alignment details. Not sure if there is a compiler option that would report this, sorry, anyone else? Ian