From: "Michael S. Tsirkin" Subject: Re: [Qemu-devel] [PATCH 05/11] qemu: MSI-X support functions Date: Wed, 10 Jun 2009 18:52:38 +0300 Message-ID: <20090610155238.GH28601@redhat.com> References: <200906101539.12367.paul@codesourcery.com> <20090610144739.GA28601@redhat.com> <200906101615.12956.paul@codesourcery.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: qemu-devel@nongnu.org, Carsten Otte , kvm@vger.kernel.org, Rusty Russell , virtualization@lists.linux-foundation.org, Blue Swirl , Christian Borntraeger , Avi Kivity To: Paul Brook Return-path: Received: from mx2.redhat.com ([66.187.237.31]:53514 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756095AbZFJPzj (ORCPT ); Wed, 10 Jun 2009 11:55:39 -0400 Content-Disposition: inline In-Reply-To: <200906101615.12956.paul@codesourcery.com> Sender: kvm-owner@vger.kernel.org List-ID: On Wed, Jun 10, 2009 at 04:15:04PM +0100, Paul Brook wrote: > > > That's seems just plain wrong to me. > > > Loading a VM shouldn't not > > > do anything that can't happen during normal operation. > > > > At least wrt pci, we are very far from this state: load just overwrites > > all registers, readonly or not, which can never happen during normal > > operation. > > IMO that code is wrong. We should only be loading things that the guest can > change (directly or indirectly). > > Paul Making it work this way will mean that minor changes to a device can break backwards compatibility with old images, often in surprising ways. What are the advantages? -- MST