From: Paul Brook Subject: Re: [Qemu-devel] [PATCH 05/11] qemu: MSI-X support functions Date: Wed, 10 Jun 2009 17:46:03 +0100 Message-ID: <200906101746.06740.paul@codesourcery.com> References: <200906101708.27815.paul@codesourcery.com> <20090610162644.GJ28601@redhat.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit 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: "Michael S. Tsirkin" Return-path: Received: from mail.codesourcery.com ([65.74.133.4]:55931 "EHLO mail.codesourcery.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752570AbZFJQqG (ORCPT ); Wed, 10 Jun 2009 12:46:06 -0400 In-Reply-To: <20090610162644.GJ28601@redhat.com> Content-Disposition: inline Sender: kvm-owner@vger.kernel.org List-ID: > > If you can't create an identical machine from scratch then I don't > > consider snapshot/migration to be a useful feature. i.e. as soon as you > > shutdown and restart the guest it is liable to break anyway. > > Why is liable to break? A VM booted on an old version of qemu and migrated to a new version will behave differently to a the same VM booted on a new version of qemu. I hope I don't need to explain why this is bad. As previously discussed, any guest visible changes are liable to break a guest OS, particularly guests like Windows which deliberately break when run on "different" hardware. Personally I don't particularly care, but if we support live migration we also need to support "cold" migration - i.e. shutdown and restart. >So once you load and image with MSIX capability off, >it will stay off across guest restarts. I'm assuming guest restart includes restarting qemu. Paul