Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761767AbYFMHY7 (ORCPT ); Fri, 13 Jun 2008 03:24:59 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1761218AbYFMHYk (ORCPT ); Fri, 13 Jun 2008 03:24:40 -0400 Received: from mx3.mail.elte.hu ([157.181.1.138]:47178 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761092AbYFMHYj (ORCPT ); Fri, 13 Jun 2008 03:24:39 -0400 Date: Fri, 13 Jun 2008 09:24:24 +0200 From: Ingo Molnar To: Jeremy Fitzhardinge Cc: Jan Beulich , Stable Kernel , x86@kernel.org, Linux Kernel Mailing List Subject: Re: [PATCH UPDATED] x86: set PAE PHYSICAL_MASK_SHIFT to 44 bits. Message-ID: <20080613072424.GB11976@elte.hu> References: <4848046A.5060006@goop.org> <484823BD.76E4.0078.0@novell.com> <484901A3.3040401@goop.org> <20080610103151.GG19136@elte.hu> <484E7C5D.50701@goop.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <484E7C5D.50701@goop.org> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1544 Lines: 42 * Jeremy Fitzhardinge wrote: > Ingo Molnar wrote: >>> When a 64-bit x86 processor runs in 32-bit PAE mode, a pte can >>> potentially have the same number of physical address bits as the >>> 64-bit host ("Enhanced Legacy PAE Paging"). This means, in theory, >>> we could have up to 52 bits of physical address in a pte. >>> >>> The 32-bit kernel uses a 32-bit unsigned long to represent a pfn. >>> This means that it can only represent physical addresses up to >>> 32+12=44 bits wide. Rather than widening pfns everywhere, just set >>> 2^44 as the Linux x86_32-PAE architectural limit for physical address >>> size. >>> >> >> applied to tip/x86/cleanups - thanks Jeremy. No urgency for v2.6.26, >> right? > > Not urgent, but it would be nice to have. ok, cherry-picked it into x86/urgent. This aspect makes it eligible for v2.6.26: | This is a bugfix for two cases: | 1. running a 32-bit PAE kernel on a machine with | more than 64GB RAM. | 2. running a 32-bit PAE Xen guest on a host machine with | more than 64GB RAM | | In both cases, a pte could need to have more than 36 bits of physical, | and masking it to 36-bits will cause fairly severe havoc. also added a stable@kernel.org Cc: to the commit, so it will be picked up in stable as well. Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/