From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754524AbZELO7G (ORCPT ); Tue, 12 May 2009 10:59:06 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752229AbZELO6w (ORCPT ); Tue, 12 May 2009 10:58:52 -0400 Received: from one.firstfloor.org ([213.235.205.2]:35770 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752156AbZELO6w (ORCPT ); Tue, 12 May 2009 10:58:52 -0400 Date: Tue, 12 May 2009 17:04:08 +0200 From: Andi Kleen To: Ulrich Drepper Cc: Andi Kleen , Tobias Doerffel , LKML Subject: Re: Specific support for Intel Atom architecture Message-ID: <20090512150408.GH19296@one.firstfloor.org> References: <200904301408.09370.tobias.doerffel@gmail.com> <877i0xib7d.fsf@basil.nowhere.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 12, 2009 at 07:20:14AM -0700, Ulrich Drepper wrote: > On Mon, May 4, 2009 at 12:22 AM, Andi Kleen wrote: > > This should be obsolete anyways, you can just uses CORE2. They have compatible ISAs. > > Only correct if you don't plan to use the movbe instruction. The > kernel would be the one place where I can imagine this to make sense. The problem is that you can't express the situations where movbe is better than bswap (you need both and the old and the new value) in inline assembler in a way that gcc decides automatically. I also doubt there are many (any?) situations in the kernel where the destruction of the old register is a problem in the kernel; e.g. the network stack normally doesn't care. My understanding is that movbe is really mainly useful for some special situations where you run a emulator/jit for a BE ISA, but that's not something the kernel does. -Andi -- ak@linux.intel.com -- Speaking for myself only.