Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S267387AbUIFBl3 (ORCPT ); Sun, 5 Sep 2004 21:41:29 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S267393AbUIFBl3 (ORCPT ); Sun, 5 Sep 2004 21:41:29 -0400 Received: from parcelfarce.linux.theplanet.co.uk ([195.92.249.252]:51690 "EHLO www.linux.org.uk") by vger.kernel.org with ESMTP id S267387AbUIFBk7 (ORCPT ); Sun, 5 Sep 2004 21:40:59 -0400 Date: Mon, 6 Sep 2004 02:40:58 +0100 From: Matthew Wilcox To: Jon Smirl Cc: Matthew Wilcox , Jesse Barnes , lkml Subject: Re: multi-domain PCI and sysfs Message-ID: <20040906014058.GV642@parcelfarce.linux.theplanet.co.uk> References: <9e4733910409041300139dabe0@mail.gmail.com> <200409041527.50136.jbarnes@engr.sgi.com> <9e47339104090415451c1f454f@mail.gmail.com> <200409041603.56324.jbarnes@engr.sgi.com> <20040905230425.GU642@parcelfarce.linux.theplanet.co.uk> <9e473391040905165048798741@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <9e473391040905165048798741@mail.gmail.com> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2023 Lines: 51 On Sun, Sep 05, 2004 at 07:50:04PM -0400, Jon Smirl wrote: > So how do multiple root buses work? Since they are all in the same > domain it seems like a single IO operation would go to all of the root > bridges simultaneously. Then each root bridge matches to the address > and decides to send the IO operation on if there is a match. Not exactly -- each rope (the line that connects the memory & I/O controller to the I/O adapter) has a limited bandwidth, so the memory & I/O controller makes the decision which rope each transaction is destined for. > When implementing the VGA control I'm running into the problem that > there is no root node in sysfs for the top of a domain. I need a > domain node to attach an attribute disabling all VGA devices in the > domain. In the zx1 diagram I could have vga devices on any of the > PCI-X or AGP buses. Why would it be a problem if the attribute is per-bus, as it is right now? see bus->bridge_ctl (PCI_BRIDGE_CTL_VGA) > With the xz1 sysfs would look like this: > /sys/devices/pci0000:00 > /sys/devices/pci0000:01 > /sys/devices/pci0000:02 > /sys/devices/pci0000:03 > /sys/devices/pci0000:04 > /sys/devices/pci0000:05 Actually, they're sparsely numbered to allow for people plugging in pci-pci bridges on cards, so: $ ls -1 /sys/devices/ pci0000:00 pci0000:80 pci0000:a0 pci0000:c0 platform system -- "Next the statesmen will invent cheap lies, putting the blame upon the nation that is attacked, and every man will be glad of those conscience-soothing falsities, and will diligently study them, and refuse to examine any refutations of them; and thus he will by and by convince himself that the war is just, and will thank God for the better sleep he enjoys after this process of grotesque self-deception." -- Mark Twain - 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/