Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754173AbXLWVN6 (ORCPT ); Sun, 23 Dec 2007 16:13:58 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751474AbXLWVNv (ORCPT ); Sun, 23 Dec 2007 16:13:51 -0500 Received: from gate.crashing.org ([63.228.1.57]:49253 "EHLO gate.crashing.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750709AbXLWVNu (ORCPT ); Sun, 23 Dec 2007 16:13:50 -0500 Subject: Re: [patch] Make MMCONFIG space (extended PCI config space) a driver opt-in issue From: Benjamin Herrenschmidt Reply-To: benh@kernel.crashing.org To: Jeff Garzik Cc: Loic Prylli , Linus Torvalds , Arjan van de Ven , linux-kernel@vger.kernel.org, gregkh@suse.de, linux-pci@atrey.karlin.mff.cuni.cz In-Reply-To: <476DF5BE.5030004@garzik.org> References: <20071222043139.0cd59804@laptopd505.fenrus.org> <476D1D16.5090703@garzik.org> <20071222064719.73fdd9a4@laptopd505.fenrus.org> <476DB95F.3090801@garzik.org> <476DDFEE.3010009@garzik.org> <476DE98F.2010009@garzik.org> <476DF1A6.3060900@myri.com> <476DF5BE.5030004@garzik.org> Content-Type: text/plain Date: Mon, 24 Dec 2007 08:13:07 +1100 Message-Id: <1198444387.6686.20.camel@pasglop> Mime-Version: 1.0 X-Mailer: Evolution 2.12.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 828 Lines: 21 > Are you prepared to guarantee that freely mixing mmconfig and type1 > config accesses at runtime will always work, on all chipsets? I'm > talking about silicon here, not kernel software. We spinlock config space accesses. So the silicon will never see simultaneous accesses, which is what I strongly suspect would be broken in chipsets (asking for livelocks here). Now there is the question of whether the silicon implements MMCONFIG writes in some asynchronous way, in which case, there might be an issue if you go bang the port right away but I very much doubt it. Ben. -- 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/