From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759332AbXKTVfM (ORCPT ); Tue, 20 Nov 2007 16:35:12 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1759060AbXKTVez (ORCPT ); Tue, 20 Nov 2007 16:34:55 -0500 Received: from relay1.sgi.com ([192.48.171.29]:40687 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1760375AbXKTVey (ORCPT ); Tue, 20 Nov 2007 16:34:54 -0500 Date: Tue, 20 Nov 2007 13:34:53 -0800 (PST) From: Christoph Lameter X-X-Sender: clameter@schroedinger.engr.sgi.com To: "H. Peter Anvin" cc: Andi Kleen , akpm@linux-foundation.org, travis@sgi.com, Mathieu Desnoyers , linux-kernel@vger.kernel.org Subject: Re: [rfc 08/45] cpu alloc: x86 support In-Reply-To: <47434C46.5080301@zytor.com> Message-ID: References: <20071120011132.143632442@sgi.com> <200711201301.25373.ak@suse.de> <474346DE.5050305@zytor.com> <200711202151.58310.ak@suse.de> <47434C46.5080301@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 Tue, 20 Nov 2007, H. Peter Anvin wrote: > But you wouldn't actually *use* this address space. It's just for the linker > to know what address to tag the references with; it gets relocated by gs_base > down into proper kernel space. The linker can stash the initialized reference > copy at any address (LMA) which can be different from what it will be used at > (VMA); that is not an issue. That is already provided by this patchset. The cpu area starts at absolute 0. > To use %rip references, though, which are more efficient, you probably want to > use offsets that are just below .text (at -2 GB); presumably > -2 GB-[max size of percpu section]. Again, however, no CPU actually needs to > have its data stashed in that particular location; it's just an offset. Right. That is what we are discussion in another thread.