From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754202AbYAONkK (ORCPT ); Tue, 15 Jan 2008 08:40:10 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750860AbYAONj6 (ORCPT ); Tue, 15 Jan 2008 08:39:58 -0500 Received: from mx3.mail.elte.hu ([157.181.1.138]:34667 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750901AbYAONj5 (ORCPT ); Tue, 15 Jan 2008 08:39:57 -0500 Date: Tue, 15 Jan 2008 14:39:42 +0100 From: Ingo Molnar To: "H. Peter Anvin" Cc: "Huang, Ying" , venkatesh.pallipadi@intel.com, akpm@linux-foundation.org, Thomas Gleixner , Ingo Molnar , Andi Kleen , linux-kernel@vger.kernel.org Subject: Re: [PATCH -mm 0/3] i386 boot: replace boot_ioremap with enhanced bt_ioremap Message-ID: <20080115133942.GI7025@elte.hu> References: <1200375902.3505.29.camel@caritas-dev.intel.com> <20080115084417.GA16449@elte.hu> <1200390535.3505.62.camel@caritas-dev.intel.com> <478CAC70.80309@zytor.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <478CAC70.80309@zytor.com> User-Agent: Mutt/1.5.17 (2007-11-01) 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 * H. Peter Anvin wrote: > I did a quick scan over the patchset (not quite awake yet, so I may > very well have missed something), but it looks like EFI (again!) is > the only user of ioremapping before paging_init(). This makes me > wonder if that code can't be restructured so that isn't necessary. i think that in general making access to unmapped memory a bit easier is generally a good robustness idea as ACPI could be impacted by it as well. Fundamentally, paging_init() has obvious dependency on "figuring out the memory setup" of the box, and "figuring out the memory setup" means interpreting various data structures passed in by the BIOS - some of which might be in not yet mapped areas or iommu areas (if we have to do some early quirk). So having a robust implementation of ioremap_early() sounds like a definitive plus. Ingo