Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1764152AbYA2PQ6 (ORCPT ); Tue, 29 Jan 2008 10:16:58 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754918AbYA2PQu (ORCPT ); Tue, 29 Jan 2008 10:16:50 -0500 Received: from mx1.redhat.com ([66.187.233.31]:47690 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754841AbYA2PQt (ORCPT ); Tue, 29 Jan 2008 10:16:49 -0500 Message-ID: <479F4321.6030106@redhat.com> Date: Tue, 29 Jan 2008 10:15:45 -0500 From: Tony Camuso Reply-To: tcamuso@redhat.com User-Agent: Thunderbird 2.0.0.9 (X11/20071031) MIME-Version: 1.0 To: Arjan van de Ven CC: Greg KH , Matthew Wilcox , Grant Grundler , Loic Prylli , Adrian Bunk , Linus Torvalds , Benjamin Herrenschmidt , Ivan Kokshaysky , Greg KH , linux-kernel@vger.kernel.org, Jeff Garzik , linux-pci@atrey.karlin.mff.cuni.cz, Martin Mares Subject: Re: [Patch v2] Make PCI extended config space (MMCONFIG) a driver opt-in References: <20080114225225.GQ18741@parisc-linux.org> <20080114230448.GL9847@does.not.exist> <478CD8A5.5090608@myri.com> <20080115174643.GB28238@kroah.com> <20080115175641.GE18741@parisc-linux.org> <20080119165809.GB11553@colo.lackof.org> <479E1FA6.1030708@redhat.com> <20080128204431.GA15227@kroah.com> <20080128190505.5f5b1ccc@laptopd505.fenrus.org> <20080129031804.GF20198@parisc-linux.org> <20080129131955.GC10761@kroah.com> <479F34E6.40806@redhat.com> <20080129064724.0f7e91e5@laptopd505.fenrus.org> In-Reply-To: <20080129064724.0f7e91e5@laptopd505.fenrus.org> 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: 1841 Lines: 50 Arjan van de Ven wrote: > On Tue, 29 Jan 2008 09:15:02 -0500 > Tony Camuso wrote: > >> Greg, >> >> The problem with Arjan's patch, if I understand it correctly, is that >> it requires drivers to make a call to access extended PCI config >> space. >> >> And, IIRC, Arjan's patch encumbers drivers for all arch's, even those >> that have no MMCONFIG problems. >> >> The patches proposed by Loic, Ivan, Matthew, and myself, all address >> the problem in an x86-specific manner that is transparent to the >> drivers. > > this is not quite correct; the patches from Loic, Ivan, Matthew and you are for a different > problem statement. > > Your patch problem statement is "need to fix mmconfig", my patch problem statement is "need > to not make users who don't need it suffer". These are orthogonal problems. > > Yes, but your patch also makes users who need extended PCI config space suffer. Right now, that isn't a lot of people in x86 land, but your patch encumbers drivers for non-x86 archs with an additional call to access space that they've never had a problem with. As more PCI express drivers start to take advantage of AER and other advanced express capabilities, the extra call to address a condition specific to legacy x86 hardware is, IMNSHO, a kludge. The patches submitted by the others fix the problems with MMCONFIG without encumbering the drivers to be aware of any difference between legacy config space and extended config space. I have tested these patches on a number of systems exhibiting various MMCONFIG- related pathologies, and they work. -- 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/