From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762454AbXKTCOk (ORCPT ); Mon, 19 Nov 2007 21:14:40 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1760908AbXKTCEF (ORCPT ); Mon, 19 Nov 2007 21:04:05 -0500 Received: from netops-testserver-3-out.sgi.com ([192.48.171.28]:39456 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1761077AbXKTCED (ORCPT ); Mon, 19 Nov 2007 21:04:03 -0500 Date: Mon, 19 Nov 2007 18:03:56 -0800 (PST) From: Christoph Lameter X-X-Sender: clameter@schroedinger.engr.sgi.com To: "H. Peter Anvin" cc: ak@suse.de, akpm@linux-foundation.org, travis@sgi.com, Mathieu Desnoyers , linux-kernel@vger.kernel.org Subject: Re: [rfc 37/45] x86_64: Support for fast per cpu operations In-Reply-To: <47423FB7.20800@zytor.com> Message-ID: References: <20071120011132.143632442@sgi.com> <20071120011340.569486037@sgi.com> <47423FB7.20800@zytor.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 19 Nov 2007, H. Peter Anvin wrote: > There was, at some point, discussion about using the gcc TLS mechanism, which > should permit even better code to be generated. Unfortunately, it would How would that be possible? Oh. You mean the discussion where I mentioned using the thread attribute? > require gcc to be able to reference %gs instead of %fs (and vice versa for > i386), which I don't think is available in anything except maybe the most > cutting-edge version of gcc. Right. That is why we do it in ASM here. > However, if we're doing a masssive revampt it would be good to get an idea of > how to migrate to that model eventually, or why it doesn't make sense at all. If you can tell me what the difference would be then we can discuss it. AFAICT there is no difference. Both use a segment register.