From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932622AbbEHShI (ORCPT ); Fri, 8 May 2015 14:37:08 -0400 Received: from terminus.zytor.com ([198.137.202.10]:52353 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932122AbbEHShH (ORCPT ); Fri, 8 May 2015 14:37:07 -0400 Message-ID: <554D022E.6090503@zytor.com> Date: Fri, 08 May 2015 11:36:30 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.5.0 MIME-Version: 1.0 To: Borislav Petkov CC: Rasmus Villemoes , Thomas Gleixner , Ingo Molnar , x86@kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] x86: tell the world boot_params is 16-byte aligned References: <1431092553-12914-1-git-send-email-linux@rasmusvillemoes.dk> <20150508142453.GC4137@pd.tnic> <87mw1fkpgn.fsf@rasmusvillemoes.dk> <853B4FF2-FAC4-4FE3-90F5-D1CFD18B10F7@zytor.com> <20150508174054.GD3904@pd.tnic> In-Reply-To: <20150508174054.GD3904@pd.tnic> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/08/2015 10:40 AM, Borislav Petkov wrote: > On Fri, May 08, 2015 at 09:26:49AM -0700, H. Peter Anvin wrote: >> NAK. This could break in the case of careless bootloaders... > > Please elaborate. You mean, they'll go with the max alignment too and > search boot_params there? > A careless bootloader may not align this data structure to any particular alignment. Of course, for x86 it doesn't matter too much, as it just hurts performance. -hpa