Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755057AbYFFJ5d (ORCPT ); Fri, 6 Jun 2008 05:57:33 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753200AbYFFJ5Z (ORCPT ); Fri, 6 Jun 2008 05:57:25 -0400 Received: from vpn.id2.novell.com ([195.33.99.129]:21165 "EHLO vpn.id2.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752962AbYFFJ5Y convert rfc822-to-8bit (ORCPT ); Fri, 6 Jun 2008 05:57:24 -0400 Message-Id: <4849264D.76E4.0078.0@novell.com> X-Mailer: Novell GroupWise Internet Agent 7.0.3 Date: Fri, 06 Jun 2008 10:58:05 +0100 From: "Jan Beulich" To: "Jeremy Fitzhardinge" Cc: "Ingo Molnar" , "Stable Kernel" , , "Linux Kernel Mailing List" Subject: Re: [PATCH UPDATED] x86: set PAE PHYSICAL_MASK_SHIFT to 44 bits. References: <4848046A.5060006@goop.org> <484823BD.76E4.0078.0@novell.com> <484901A3.3040401@goop.org> In-Reply-To: <484901A3.3040401@goop.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8BIT Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1462 Lines: 42 Ah, yes! Acked-By: Jan Beulich >>> Jeremy Fitzhardinge 06.06.08 11:21 >>> 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. Signed-off-by: Jeremy Fitzhardinge Cc: Jan Beulich --- include/asm-x86/page_32.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) =================================================================== --- a/include/asm-x86/page_32.h +++ b/include/asm-x86/page_32.h @@ -22,7 +22,8 @@ #ifdef CONFIG_X86_PAE -#define __PHYSICAL_MASK_SHIFT 36 +/* 44=32+12, the limit we can fit into an unsigned long pfn */ +#define __PHYSICAL_MASK_SHIFT 44 #define __VIRTUAL_MASK_SHIFT 32 #define PAGETABLE_LEVELS 3 -- 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/