From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933506AbXCaCyn (ORCPT ); Fri, 30 Mar 2007 22:54:43 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S933535AbXCaCyn (ORCPT ); Fri, 30 Mar 2007 22:54:43 -0400 Received: from ozlabs.org ([203.10.76.45]:52876 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933506AbXCaCym (ORCPT ); Fri, 30 Mar 2007 22:54:42 -0400 Subject: Re: [patch 4/6] Convert PDA into the percpu section From: Rusty Russell To: Andi Kleen Cc: Jeremy Fitzhardinge , Andrew Morton , virtualization@lists.osdl.org, lkml In-Reply-To: <200703310435.59298.ak@suse.de> References: <20070331020042.003398870@goop.org> <20070331020055.075978807@goop.org> <200703310435.59298.ak@suse.de> Content-Type: text/plain Date: Sat, 31 Mar 2007 12:54:17 +1000 Message-Id: <1175309657.12230.420.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.8.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 2007-03-31 at 04:35 +0200, Andi Kleen wrote: > On Saturday 31 March 2007 04:00, Jeremy Fitzhardinge wrote: > > Currently x86 (similar to x84-64) has a special per-cpu structure > > called "i386_pda" which can be easily and efficiently referenced via > > the %fs register. An ELF section is more flexible than a structure, > > allowing any piece of code to use this area. Indeed, such a section > > already exists: the per-cpu area. > > Hmm, I'm a little reluctant. This moves i386 more away from x86-64 > again. If we ever merge them it would mean more work. Do you really need it? Well, I think the merge should go the other way in this case: this really does simplify things. The only thing stopping x86-64 from doing the same as i386 is the stack-protector stuff. And that can be fixed (unfortunately requires a gcc patch to change the %gs:40 to %gs:__gcc_stack_protector_offset and emit a weak absolute symbol __gss_stack_protector_offset = 40). I shall prepare a patch for that next week; I've been busy Kleening up lguest 8) Rusty.