[libvirt] Upgrade-problems from qemu-0.14.1 + libvirt-0.8.4 to qemu-0.15.1 + libvirt-0.9.6: Why I think multifunction=on is a bad idea...

Hello, this mail is something between a bug report and a warning to other users of libvirt, before they also experience the problem I encountered today: I just hat the painful experience of trying to install some newer versions of qemu(-kvm) and libvirt on a system with many managedsave-states and many snapshots. They are now all broken because 1. Newer qemu(-kvm) uses iPXE instead of etherboot, which have different ROM file sizes, which aborts loading the old VM state. So be careful to not delete your old PXE-ROM images. 2. libvirt defaults to add ',multifuntion=on' to the (in my case) rtl8139 network card and balloon-driver, which produces the "really helpful" message of qemu: warning: error while loading state for instance 0x0 of device '0000:00:03.0/rtl8139' or qemu: warning: error while loading state for instance 0x0 of device 'ram' Nothing you can't fix with installing the old etherboot-qemu package and some dirty "dd"-hackery on your saved files and snapshot xml files to add an explicit 'multifunction=off', but hard to diagnose and annoying enough. So even if the qemu people try to be backward compatible with their VMState format, libvirt doesn't seem to handle backward compatibility taht good at the moment. Perhaps it would help to not (only) store the XML domain configuration for snapshots and managedsave-files, but the exact qemu-argv string to at least get libvirt out of any backward incompatible changes when re-constructing the qemu command line from the XML data. Sincerely Philipp PS: I hope that info helps other people when getting those messages. -- Philipp Hahn Open Source Software Engineer hahn(a)univention.de Univention GmbH Linux for Your Business fon: +49 421 22 232- 0 Mary-Somerville-Str.1 D-28359 Bremen fax: +49 421 22 232-99 http://www.univention.de/