From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: Configuration vs. compat hints [was Re: [Qemu-devel] [PATCHv3 03/13] qemu: add routines to manage PCI capabilities] Date: Wed, 17 Jun 2009 09:38:07 +0300 Message-ID: <4A388F4F.8000900@redhat.com> References: <4A364B53.9080007@codemonkey.ws> <4A364FE0.40204@redhat.com> <4A3651EB.3070204@codemonkey.ws> <4A36555A.4090303@redhat.com> <4A3659A0.3050108@codemonkey.ws> <20090615143737.GB14405@redhat.com> <4A3662BA.6030304@codemonkey.ws> <20090615150804.GH7233@redhat.com> <4A3664EE.30207@redhat.com> <4A3665A0.7000702@redhat.com> <20090616183222.GH11893@shareable.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: dlaor@redhat.com, Carsten Otte , kvm@vger.kernel.org, "Michael S. Tsirkin" , Glauber Costa , Rusty Russell , qemu-devel@nongnu.org, virtualization@lists.linux-foundation.org, Blue Swirl , Christian Borntraeger , Paul Brook , Mark McLoughlin To: Jamie Lokier Return-path: Received: from mx2.redhat.com ([66.187.237.31]:41786 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753900AbZFQGkm (ORCPT ); Wed, 17 Jun 2009 02:40:42 -0400 In-Reply-To: <20090616183222.GH11893@shareable.org> Sender: kvm-owner@vger.kernel.org List-ID: On 06/16/2009 09:32 PM, Jamie Lokier wrote: > Avi Kivity wrote: > >> Another issue is enumeration. Guests will present their devices in the >> order they find them on the pci bus (of course enumeration is guest >> specific). So if I have 2 virtio controllers the only way I can >> distinguish between them is using their pci slots. >> > > virtio controllers really should have a user-suppliable string or UUID > to identify them to the guest. Don't they? > virtio controllers don't exist. When they do, they may have a UUID or not, but in either case guest infrastructure is in place for reporting the PCI slot, not the UUID. virtio disks do have a UUID. I don't think older versions of Windows will use it though, so if you reorder your slots you'll see your drive letters change. Same with Linux if you don't use udev by-uuid rules. -- Do not meddle in the internals of kernels, for they are subtle and quick to panic.