From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932483AbWFQG6n (ORCPT ); Sat, 17 Jun 2006 02:58:43 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932485AbWFQG6n (ORCPT ); Sat, 17 Jun 2006 02:58:43 -0400 Received: from cantor.suse.de ([195.135.220.2]:6853 "EHLO mx1.suse.de") by vger.kernel.org with ESMTP id S932483AbWFQG6m (ORCPT ); Sat, 17 Jun 2006 02:58:42 -0400 From: Andi Kleen To: Brent Casavant Subject: Re: FOR REVIEW: New x86-64 vsyscall vgetcpu() Date: Sat, 17 Jun 2006 08:58:39 +0200 User-Agent: KMail/1.8 Cc: Chase Venters , Zoltan Menyhart , Jes Sorensen , Tony Luck , discuss@x86-64.org, linux-kernel@vger.kernel.org, libc-alpha@sourceware.org, vojtech@suse.cz, linux-ia64@vger.kernel.org References: <200606140942.31150.ak@suse.de> <20060616181940.S91827@pkunk.americas.sgi.com> In-Reply-To: <20060616181940.S91827@pkunk.americas.sgi.com> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200606170858.39656.ak@suse.de> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org > That work could form the basis for a low-impact method of exporting > the current CPU to user space via a read-only mapped page. I'll admit > to having zero knowledge of whether this would be workable on anything > other than ia64. On x86 per CPU mappings are not really feasible. That is because the CPU uses the Linux page tables directly and to change them per CPU you would need to fork them per CPU. That would add so much complications that I don't even want to think them all through ... -andi