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: Mon, 15 Jun 2009 18:15:44 +0300 Message-ID: <4A3665A0.7000702@redhat.com> References: <4A364381.401@redhat.com> <4A364401.6010500@codemonkey.ws> <4A3647FB.9010808@redhat.com> <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> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: "Daniel P. Berrange" , Anthony Liguori , "Michael S. Tsirkin" , Carsten Otte , Rusty Russell , kvm@vger.kernel.org, Mark McLoughlin , Glauber Costa , qemu-devel@nongnu.org, virtualization@lists.linux-foundation.org, Blue Swirl , Christian Borntraeger , Paul Brook To: dlaor@redhat.com Return-path: Received: from mx2.redhat.com ([66.187.237.31]:57701 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1762023AbZFOPST (ORCPT ); Mon, 15 Jun 2009 11:18:19 -0400 In-Reply-To: <4A3664EE.30207@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 06/15/2009 06:12 PM, Dor Laor wrote: >> It doesn't want to. As Mark said, libvirt just wants to be able to >> ensure >> a stable guest ABI, of which stable PCI addresses is one aspect. This >> does >> not imply libvirt wants to allocate the PCI addresses, just that it >> wants >> a way to keep them stable. All else being equal I'd rather libvirt >> wasn't >> in the PCI address allocation business. > > > It's not about what libvirt wants. It's about what will serve the end > user the most. > Apart for stable guest ABI, end users need to have the option to > control the slot for > their devices. Just like them have for physical machines. It's not > theoretical discussion, > limiting issues with shared irq is one real life example. > 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. -- error compiling committee.c: too many arguments to function