Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752164AbYAMMoN (ORCPT ); Sun, 13 Jan 2008 07:44:13 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751343AbYAMMoB (ORCPT ); Sun, 13 Jan 2008 07:44:01 -0500 Received: from mx1.redhat.com ([66.187.233.31]:36302 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751234AbYAMMoA (ORCPT ); Sun, 13 Jan 2008 07:44:00 -0500 Message-ID: <478A075F.7010503@redhat.com> Date: Sun, 13 Jan 2008 07:43:11 -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: Ivan Kokshaysky , Greg KH , Matthew Wilcox , Linus Torvalds , Greg KH , linux-kernel@vger.kernel.org, Jeff Garzik , linux-pci@atrey.karlin.mff.cuni.cz, Benjamin Herrenschmidt , Martin Mares , Loic Prylli , Prarit Bhargava , "Chumbalkar, Nagananda" , "Schoeller, Patrick (Linux - Houston, TX)" , Bhavana Nagendra Subject: Re: [Patch v2] Make PCI extended config space (MMCONFIG) a driver opt-in References: <20080111204228.GP18741@parisc-linux.org> <20080111211753.GR18741@parisc-linux.org> <20080111213803.GS18741@parisc-linux.org> <20080111235856.GA16079@jurassic.park.msu.ru> <20080112002638.GA18710@kroah.com> <20080112144030.GA19279@jurassic.park.msu.ru> <20080112094557.71f5382a@laptopd505.fenrus.org> <20080112214911.GA20102@jurassic.park.msu.ru> <20080112150120.05f93768@laptopd505.fenrus.org> <47895767.3090503@redhat.com> <20080112164006.6f6f7bc2@laptopd505.fenrus.org> <47896B3B.2000108@redhat.com> <20080112204248.29abb1dd@laptopd505.fenrus.org> In-Reply-To: <20080112204248.29abb1dd@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: 2183 Lines: 55 Arjan van de Ven wrote: > On Sat, 12 Jan 2008 20:36:59 -0500 > Tony Camuso wrote: > > > Just about NOBODY has devices that need the extended config space. At all. The PCI express spec requires the platform to provide access to this space for express-compliance. More devices will be using this space as express becomes the dominant IO bus technology. >> As far as the device is concerned, after the Northbridge translates >> the config access into PCI bus cycles, the device has no idea what >> mechanism drove the Northbridge to the translation. > > Wanne bet there'll be devices that screw this up? THere's devices that even screwed > up the 64-256 region after all. > There may have been devices that incorrectly applied the PCI spec to various fields in the header, I'll grant you that. However, there is no way a device can determine electrically whether the Northbridge received Port IO or MMCONFIG cycles. This is between the CPU and the Northbridge and is utterly opaque to the devices on the bus. >> The patch I devised concerned itself with Northbridges and separated >> MMCONFIG-compliant buses from those that could not handle MMCONFIG. > > THis kind of patchup has been going on for the better part of a year (well 2 years) > by now and it's STILL NOT ENOUGH, as you can see by the more patchups that have > been proposed as "alternative" to my approach. > Which is why Loic's proposal and Ivan's implementation of it is so elegant. It solves all these problems in one sweep, and eliminates the code rendered cruft by Ivan's patch. A two-fer, by my reckoning. >> In other words, for x86, I don't think we need to worry about Port >> IO config access ever going away at all. > > You're wrong there. Sad to say, but you're wrong there. > The PCI spec provides for conf1 as an architected solution. It's not going away, and especially not in x86 land where Port IO is built-in to the CPU. -- 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/