From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753403Ab3LCLBd (ORCPT ); Tue, 3 Dec 2013 06:01:33 -0500 Received: from smtp02.citrix.com ([66.165.176.63]:12699 "EHLO SMTP02.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752790Ab3LCLBa (ORCPT ); Tue, 3 Dec 2013 06:01:30 -0500 X-IronPort-AV: E=Sophos;i="4.93,817,1378857600"; d="scan'208";a="77667445" Message-ID: <529DBA07.6090108@citrix.com> Date: Tue, 3 Dec 2013 11:01:27 +0000 From: David Vrabel User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.16) Gecko/20121215 Iceowl/1.0b1 Icedove/3.0.11 MIME-Version: 1.0 To: Roger Pau Monne CC: , , Julien Grall , Konrad Rzeszutek Wilk , Boris Ostrovsky , Stefano Stabellini Subject: Re: [PATCH RFC] xen-block: correctly define structures in public headers References: <1386068254-1413-1-git-send-email-roger.pau@citrix.com> In-Reply-To: <1386068254-1413-1-git-send-email-roger.pau@citrix.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.80.2.76] X-DLP: MIA2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/12/13 10:57, Roger Pau Monne wrote: > Using __packed__ on the public interface is not correct, this > structures should be compiled using the native ABI, and __packed__ > should only be used in the backend counterpart of those structures > (which needs to handle different ABIs). > > This was even worse in the ARM case, where the Linux kernel was > incorrectly using the X86_32 protocol ABI. This patch fixes it, but > also breaks compatibility, so an ARM DomU kernel compiled with > this patch will fail to communicate with PV disk devices unless the > Dom0 also has this patch. This ABI change needs to be justified. Why do you think it is acceptable to break existing Linux guests? Because I don't think it is. David