Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261156AbUKMTqi (ORCPT ); Sat, 13 Nov 2004 14:46:38 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261157AbUKMTqi (ORCPT ); Sat, 13 Nov 2004 14:46:38 -0500 Received: from colo.lackof.org ([198.49.126.79]:7115 "EHLO colo.lackof.org") by vger.kernel.org with ESMTP id S261156AbUKMTqg (ORCPT ); Sat, 13 Nov 2004 14:46:36 -0500 Date: Sat, 13 Nov 2004 12:46:34 -0700 From: Grant Grundler To: Michael Chan Cc: Andi Kleen , Grant Grundler , linux-kernel@vger.kernel.org, linux-pci@atrey.karlin.mff.cuni.cz, akpm@osdl.org, greg@kroah.com, "Durairaj, Sundarapandian" Subject: Re: [PATCH] pci-mmconfig fix for 2.6.9 Message-ID: <20041113194634.GC3023@colo.lackof.org> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.3.28i X-Home-Page: http://www.parisc-linux.org/ Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1626 Lines: 35 On Sat, Nov 13, 2004 at 08:22:50AM -0800, Michael Chan wrote: > > If I got the discussion so far correctly then the PCI-SGI spec does not > > guarantee that there is no posting, but you know that the chipset > > you are using right now doesn't do it. > > Yes, that's my understanding of the spec. Grant Grundler does not agree > and thinks that non-posting is the only compliant implementation. That's not what I said. I think we do agree. I'll rephrase. The code currently in arch/i386 and arch/x86_64 support a chipset that is compliant with the part of the spec that requires non-postable config writes. Other chipsets can implement postable config space. To be compliant with the ECN, the architecture must define a method to guarantee the posted writes have reached the target device. I think the ECN we've been talking about assumes that method will be implemented in firmware somehow and NOT as a direct access method in the OS. > I wish he was right as it would be the easiest to deal with. > We contacted Intel about the out-of-spec readl when writing to > the PMCSR to change power state as they were the original author > of the mmconfig code. Their solution was to remove the readl after > confirming that mmconfig was non-posted on their chipsets. That means someone has to introduce a new method to access mmconfig if they implement postable writes. hth, grant - 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/