Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754121AbYAMB4S (ORCPT ); Sat, 12 Jan 2008 20:56:18 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752987AbYAMB4H (ORCPT ); Sat, 12 Jan 2008 20:56:07 -0500 Received: from idcmail-mo1so.shaw.ca ([24.71.223.10]:51252 "EHLO pd2mo3so.prod.shaw.ca" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752926AbYAMB4F (ORCPT ); Sat, 12 Jan 2008 20:56:05 -0500 Date: Sat, 12 Jan 2008 19:56:01 -0600 From: Robert Hancock Subject: Re: [Patch v2] Make PCI extended config space (MMCONFIG) a driver opt-in In-reply-to: To: Linus Torvalds Cc: Matthew Wilcox , Greg KH , Arjan van de Ven , Greg KH , linux-kernel@vger.kernel.org, Jeff Garzik , linux-pci@atrey.karlin.mff.cuni.cz, Benjamin Herrenschmidt , Martin Mares Message-id: <47896FB1.2070707@shaw.ca> MIME-version: 1.0 Content-type: text/plain; charset=ISO-8859-1; format=flowed Content-transfer-encoding: 7bit References: User-Agent: Thunderbird 2.0.0.9 (Windows/20071031) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2346 Lines: 53 Linus Torvalds wrote: > > On Fri, 11 Jan 2008, Matthew Wilcox wrote: >> Did I miss a bug report? The only problems I'm currently aware of are >> the ones where using MMCONFIG during BAR probing causes a hard lockup on >> some Intel machines, and the ones where we get bad config data on some >> AMD machines due to the configuration retry status being mishandled. > > Hmm. Were all those reports root-caused to just that BAR probing? If so, > we may be in better shape than I worried. As far as I'm aware, the known MMCONFIG-related issues that I'm aware of are or have been: -Some devices built into the AMD K8 integrated northbridge can't be reached by MMCONFIG - already handled -Overlap of device BAR and MMCONFIG aperature during BAR sizing causing lockup - can be avoided by disabling device decode during BAR sizing. -PCI Express CRS-related issues - already handled by disabling CRS by default -Devices behind certain host bridges (some AMD HT to PCI-X bridges, others?) can't be reached by MMCONFIG - can be handled by Tony Camuso's patch or something similar (note that this is really a BIOS bug, it should not list those buses in the MCFG table if MMCONFIG cannot access them, and if it didn't I think we could already handle that) -Some issue with some AMD CPUs needing MMCONFIG accesses to use a certain register I believe? already handled? Of these, I think the PCI BAR/MMCONFIG overlap problem is responsible for by far the most cases of machines thought to have "broken MMCONFIG", when in fact they were nothing of the sort. I don't recall hearing of a single machine where MMCONFIG really just didn't work at all. As I've mentioned before, all of these issues (well, I suppose not the BAR overlap one) need to be resolved whether we have Arjan's patch or not, otherwise if a driver does opt in and tries to use extended config space it will still break. And if they are resolved, the patch seems quite pointless. -- Robert Hancock Saskatoon, SK, Canada To email, remove "nospam" from hancockr@nospamshaw.ca Home Page: http://www.roberthancock.com/ -- 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/