Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755580Ab0FNPLk (ORCPT ); Mon, 14 Jun 2010 11:11:40 -0400 Received: from terminus.zytor.com ([198.137.202.10]:50791 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755526Ab0FNPLh (ORCPT ); Mon, 14 Jun 2010 11:11:37 -0400 Message-ID: <4C164688.2030107@zytor.com> Date: Mon, 14 Jun 2010 08:11:04 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.9) Gecko/20100430 Fedora/3.0.4-3.fc13 Thunderbird/3.0.4 MIME-Version: 1.0 To: "Maciej W. Rozycki" CC: Kenji Kaneshige , Thomas Gleixner , Ingo Molnar , linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, jbarnes@virtuousgeek.org Subject: Re: [PATCH 2/4] x86: ioremap: fix physical address check References: <4C11FF10.4060203@jp.fujitsu.com> <4C11FFC0.1030006@jp.fujitsu.com> <4C1275BF.3070605@zytor.com> <4C158BCF.6000303@jp.fujitsu.com> In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1156 Lines: 30 On 06/13/2010 11:38 PM, Maciej W. Rozycki wrote: > On Mon, 14 Jun 2010, Kenji Kaneshige wrote: > >> - Architectural limit of physical address in x86 32-bit mode is 40-bit >> (depnds on processor version). > > According to documentation I happen to have handy this limit is actually > 52 bits (and space is currently available in the data structures used for > a possible future extension up to 63 bits). > Yes. There are, however, very likely bugs in several classes due to incorrect bitmasks as well as 32-bit PFNs. We have made the decision based on data structure limitations (and just usability) to not support more than 2^36 bytes of RAM on 32 bits, but those data structures should not affect I/O. I;d like to track down and fix the bugs instead of papering over the problem... -hpa -- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf. -- 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/