From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753872Ab1AJMuu (ORCPT ); Mon, 10 Jan 2011 07:50:50 -0500 Received: from mx1.redhat.com ([209.132.183.28]:25125 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753710Ab1AJMut (ORCPT ); Mon, 10 Jan 2011 07:50:49 -0500 Date: Mon, 10 Jan 2011 14:50:11 +0200 From: Gleb Natapov To: "Michael S. Tsirkin" Cc: Milton Miller , Rusty Russell , Anthony Liguori , Jamie Lokier , Thomas Weber , virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] virtio: remove virtio-pci root device Message-ID: <20110110125011.GI2202@redhat.com> References: <20110105191711.GA27489@redhat.com> <20110109151821.GA9063@redhat.com> <20110110111859.GC2202@redhat.com> <20110110112205.GC12065@redhat.com> <20110110112739.GD2202@redhat.com> <20110110114219.GE2202@redhat.com> <20110110120808.GA15554@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110110120808.GA15554@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jan 10, 2011 at 02:08:08PM +0200, Michael S. Tsirkin wrote: > On Mon, Jan 10, 2011 at 01:42:19PM +0200, Gleb Natapov wrote: > > On Mon, Jan 10, 2011 at 01:27:39PM +0200, Gleb Natapov wrote: > > > On Mon, Jan 10, 2011 at 01:22:05PM +0200, Michael S. Tsirkin wrote: > > > > On Mon, Jan 10, 2011 at 01:18:59PM +0200, Gleb Natapov wrote: > > > > > On Sun, Jan 09, 2011 at 05:18:21PM +0200, Michael S. Tsirkin wrote: > > > > > > On Fri, Jan 07, 2011 at 02:55:06AM -0600, Milton Miller wrote: > > > > > > > We sometimes need to map between the virtio device and > > > > > > > the given pci device. One such use is OS installer that > > > > > > > gets the boot pci device from BIOS and needs to > > > > > > > find the relevant block device. Since it can't, > > > > > > > installation fails. > > > > > > > > > > > > > > Instead of creating a top-level devices/virtio-pci > > > > > > > directory, create each device under the corresponding > > > > > > > pci device node. Symlinks to all virtio-pci > > > > > > > devices can be found under the pci driver link in > > > > > > > bus/pci/drivers/virtio-pci/devices, and all virtio > > > > > > > devices under drivers/bus/virtio/devices. > > > > > > > > > > > > > > Signed-off-by: Milton Miller > > > > > > > > > > > > OK, this works fine for me. I played with options to add compat > > > > > > softlinks under devices/virtio-pci but we still don't get exactly the > > > > > > same layout and since I don't think anyone actually uses them, it's > > > > > > probably ok to just to the simple thing. > > > > > > > > > > > > Tested/Acked-by: Michael S. Tsirkin > > > > > > > > > > > > Rusty, since this help fix at least one user, any chance this can be put > > > > > > in 2.6.38? OK to backport to -stable? > > > > > > > > > > > > Gleb, could you try this out too? > > > > > > > > > > > With this patch if I have 3 virtio disks for a VM I get: > > > > > /sys/devices/pci0000:00/0000:00:04.0/virtio0/block/vda > > > > > /sys/devices/pci0000:00/0000:00:05.0/virtio1/block/vdb > > > > > /sys/devices/pci0000:00/0000:00:06.0/virtio2/block/vdc > > > > > > > > > > Number after virtio has no much sense. It either should be dropped at all > > > > > or be always zero in case we will support more then one virtio controller > > > > > per pci card. In that case each virtio controller will have directories > > > > > virtio0/virtio1/virtio2... under same pci device directory. > > > > > > > > Yes. But this is the bus name. It must be unique - all devices > > > > also appear under /sys/bus/virtio/devices. > > > > > > > It is very strange king of bus that is spread over several PCI devices :) > > > It doesn't make much sense IMHO, but I can leave with it. > > > > > I can't "leave" with it, but I can "live" with it. > > The virtio bus is an attempt to make as many applications as > possible work transparently on any virtio system, > be it lguest, s390 or pci. Arbitrary IDs is just a hint to the > applications 'don't rely on the name at all'. > Shouldn't sysfs directory reflect real device topology? There are other buses AFAIK that connected differently on different HW. How virtio is special? What applications this allow to work transparently? -- Gleb.