Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754203AbYFFJW2 (ORCPT ); Fri, 6 Jun 2008 05:22:28 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752589AbYFFJWU (ORCPT ); Fri, 6 Jun 2008 05:22:20 -0400 Received: from gw.goop.org ([64.81.55.164]:59227 "EHLO mail.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752303AbYFFJWU (ORCPT ); Fri, 6 Jun 2008 05:22:20 -0400 Message-ID: <484901A3.3040401@goop.org> Date: Fri, 06 Jun 2008 10:21:39 +0100 From: Jeremy Fitzhardinge User-Agent: Thunderbird 2.0.0.14 (X11/20080501) MIME-Version: 1.0 To: Jan Beulich CC: Ingo Molnar , Stable Kernel , x86@kernel.org, Linux Kernel Mailing List Subject: [PATCH UPDATED] x86: set PAE PHYSICAL_MASK_SHIFT to 44 bits. References: <4848046A.5060006@goop.org> <484823BD.76E4.0078.0@novell.com> In-Reply-To: <484823BD.76E4.0078.0@novell.com> X-Enigmail-Version: 0.95.6 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1345 Lines: 36 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/