Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755675Ab2FWQRY (ORCPT ); Sat, 23 Jun 2012 12:17:24 -0400 Received: from terminus.zytor.com ([198.137.202.10]:43094 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755467Ab2FWQRX (ORCPT ); Sat, 23 Jun 2012 12:17:23 -0400 References: <20120623161324.GS11413@one.firstfloor.org> User-Agent: K-9 Mail for Android In-Reply-To: <20120623161324.GS11413@one.firstfloor.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Subject: Re: PATCH] Use -mpreferred-stack-boundary=3 on x86-64 if supported From: "H. Peter Anvin" Date: Sat, 23 Jun 2012 09:17:06 -0700 To: Andi Kleen , "H.J. Lu" CC: LKML Message-ID: <24bd04a1-1702-4d57-af64-af2381992789@email.android.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 922 Lines: 29 To keep gcc from paddong the stack to maintain a nonexistent alignment. Andi Kleen wrote: >> This patch uses -mpreferred-stack-boundary=3 on x86-64 if it is >supported. >> I have been running 3.4 kernel compiled with this option for weeks. > >But why? > >All the SSE code in the kernel should adjust manually. And the other >code doesn't need it. > >Besides the entry points do not guarantee alignment. > >For the kernel it would be probably more useful to have a attribute >per function that forces alignment. > >-Andi >-- >ak@linux.intel.com -- Speaking for myself only. -- Sent from my mobile phone. Please excuse brevity and lack of formatting. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/