From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754647Ab3LCRKz (ORCPT ); Tue, 3 Dec 2013 12:10:55 -0500 Received: from smtp02.citrix.com ([66.165.176.63]:63677 "EHLO SMTP02.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754061Ab3LCRKx (ORCPT ); Tue, 3 Dec 2013 12:10:53 -0500 X-IronPort-AV: E=Sophos;i="4.93,819,1378857600"; d="scan'208";a="77823826" Message-ID: <529E109A.7050700@citrix.com> Date: Tue, 3 Dec 2013 17:10:50 +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: Julien Grall CC: , , , , Roger Pau Monne , Konrad Rzeszutek Wilk , Boris Ostrovsky , Ian Campbell , Stefano Stabellini Subject: Re: [PATCH v2] xen/block: Correctly define structures in public headers on ARM32 and ARM64 References: <1386085237-8334-1-git-send-email-julien.grall@linaro.org> In-Reply-To: <1386085237-8334-1-git-send-email-julien.grall@linaro.org> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.80.2.76] X-DLP: MIA1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/12/13 15:40, Julien Grall wrote: > On ARM (32 bits and 64 bits), the double-word is 8-bytes aligned. This will > result on different structure from Xen and Linux repositories. > > As Linux is using __packed__ attribute, it must have a 4-bytes padding before > each "id" field. > > This change breaks guest block support with older kernel. IMHO, it's acceptable > because Xen on ARM is still on Tech Preview and the hypercall ABI is not yet > freezed. > > Only one architecture (x86_32) doesn't have 64-bit ABI for the block interface. > Don't add padding if Linux is compiled for this architecture. I'm now satisfied that this is the right thing to do. Acked-by: David Vrabel David