Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261555AbUKOJAW (ORCPT ); Mon, 15 Nov 2004 04:00:22 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261557AbUKOJAW (ORCPT ); Mon, 15 Nov 2004 04:00:22 -0500 Received: from mail.suse.de ([195.135.220.2]:30356 "EHLO Cantor.suse.de") by vger.kernel.org with ESMTP id S261555AbUKOJAK (ORCPT ); Mon, 15 Nov 2004 04:00:10 -0500 Date: Mon, 15 Nov 2004 09:33:05 +0100 From: Andi Kleen To: Grant Grundler Cc: Andi Kleen , Michael Chan , 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: <20041115083305.GA1662@wotan.suse.de> References: <20041113194634.GC3023@colo.lackof.org> <20041114085831.GF16795@wotan.suse.de> <20041115060021.GA3302@colo.lackof.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20041115060021.GA3302@colo.lackof.org> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1770 Lines: 49 On Sun, Nov 14, 2004 at 11:00:21PM -0700, Grant Grundler wrote: > > writes to handle Michael's power management issue properly. > > That would be definitely the safer approach. > > hrm...are you suggesting another entry point in the struct raw_pci_ops? Yes. > > There are two tests in arch/i386/pci/mmconfig.c:pci_mmcfg_init() before > the raw_pci_ops is set to &pci_mmcfg. Perhaps some additional crude tests > could select a different set of pci_raw_ops to deal with posted writes > to mmconfig space. Someone more familiar with those chipsets might > find a more elegant solution. I cannot think of a generic good way to detect posting from the software side. > > > > That means someone has to introduce a new method to access > > > mmconfig if they implement postable writes. > > > > > > Problem is that it adds silently a very subtle bug and there > > is no way I know of for ACPI to tell the firmware it shouldn't use > > posting. > > Uhm, ACPI needs to tell the firmware? > I would expect firmware to be platform/chip specific and "just know". x86-64 always uses direct hardware access, x86 can use the 32bit PCI BIOS, but it's now discouraged. > > If you meant OS, we already embed knowledge about specific chipsets > for bug workarounds (e.g. tg3 driver). I think that's an option here too. > I mean tweaking mmconfig.c to install a (possibly) chip specific > method (raw_pci_ops) to flush posted mmconfig writes. Possibly yes. One issue is that we have a subtle bug until we notice though. -Andi - 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/