From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933002Ab3HNQ66 (ORCPT ); Wed, 14 Aug 2013 12:58:58 -0400 Received: from terminus.zytor.com ([198.137.202.10]:47045 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932885Ab3HNQ64 (ORCPT ); Wed, 14 Aug 2013 12:58:56 -0400 Message-ID: <520BB71F.6000701@zytor.com> Date: Wed, 14 Aug 2013 09:58:07 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130625 Thunderbird/17.0.7 MIME-Version: 1.0 To: Peter Zijlstra CC: Mike Galbraith , Linus Torvalds , Ingo Molnar , Andi Kleen , Thomas Gleixner , Arjan van de Ven , linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org Subject: Re: [RFC][PATCH 0/5] preempt_count rework References: <20130814131539.790947874@chello.nl> <520B8A81.1080405@zytor.com> <1376494751.7355.28.camel@marge.simpson.net> <20130814160632.GJ24092@twins.programming.kicks-ass.net> <520BACEA.50604@zytor.com> <20130814165227.GA21191@laptop.programming.kicks-ass.net> In-Reply-To: <20130814165227.GA21191@laptop.programming.kicks-ass.net> X-Enigmail-Version: 1.5.2 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/14/2013 09:52 AM, Peter Zijlstra wrote: > > Oh curses, this is because lea can't do segment offsets? So there's no > sane way to get addresses of per-cpu variables. > > Because ideally we'd have something like: > > lea %gs:__percpu_runqueues,%rax > > So in this case it makes sense to also store the actual pointer; how > unfortunate. > Correct; the segment offset is not part of the effective address, even in 64-bit mode. -hpa