Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755996AbYCZWdR (ORCPT ); Wed, 26 Mar 2008 18:33:17 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753654AbYCZWdD (ORCPT ); Wed, 26 Mar 2008 18:33:03 -0400 Received: from outpipe-village-512-1.bc.nu ([81.2.110.250]:56392 "EHLO lxorguk.ukuu.org.uk" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1752978AbYCZWdB (ORCPT ); Wed, 26 Mar 2008 18:33:01 -0400 Date: Wed, 26 Mar 2008 22:07:38 +0000 From: Alan Cox To: benh@kernel.crashing.org Cc: Linus Torvalds , Ivan Kokshaysky , Gary Hade , Ingo Molnar , Thomas Meyer , Stefan Richter , Thomas Gleixner , "Rafael J. Wysocki" , LKML , Adrian Bunk , Andrew Morton , Natalie Protasevich , pm@debian.org Subject: Re: [patch] pci: revert "PCI: remove transparent bridge sizing" Message-ID: <20080326220738.060d00ef@core> In-Reply-To: <1206568675.6926.7.camel@pasglop> References: <20080325201125.GD15330@elte.hu> <20080325202954.GA22007@elte.hu> <47E969E1.6080608@m3y3r.de> <20080326101450.GA9060@jurassic.park.msu.ru> <20080326135458.GA27621@elte.hu> <20080326180701.GA6249@us.ibm.com> <20080326203012.GB6249@us.ibm.com> <20080326205828.GA15225@jurassic.park.msu.ru> <1206568675.6926.7.camel@pasglop> X-Mailer: Claws Mail 3.3.1 (GTK+ 2.12.5; x86_64-redhat-linux-gnu) Organization: Red Hat UK Cyf., Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SL4 1TE, Y Deyrnas Gyfunol. Cofrestrwyd yng Nghymru a Lloegr o'r rhif cofrestru 3798903 Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1124 Lines: 22 > PCI bridges at zero is perfectly valid indeed and I'm sure we have that > around at least for IO space. In fact, I'm surprised you don't have that > on x86. Typically, things like an HT segment with a P2P bridge and > behind that bridge an ISA bridge could well have the P2P bridge with a > resource forwarding 0...0x1000 IO downstream for example even on x86 > no ? (I'm not -that- familiar with the crazyness of legacy ISA on x86 > but I've definitely seen such setup on other archs). On a PC system 0x00-0xFF are motherboard resources (sometimes chipset, some even swallowed by the CPU in certain cases) so 0 as disabled is sort of safe but as shown by the pci_enable_device_bars replacement code - not a good idea neccessarily. A lot of driver code does assume 0 == unavailable/off/disabled including large chunks of serial, ata, ide and probably other subsystems. Alan -- 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/