[libvirt-users] [RFC] per-device metadata

[Francesco Romani]

Hi,


Currently libvirt supports metadata in the domain XML. This is very
convenient for data related to the VM, but it is a little awkward for
devices. Let's pretend I want to have extradata (say, a specific port
for a virtual switch) related to a device (say, a NIC). Nowadays I can
store that data in the metadata section, but I need some kind of mapping
to correlate this piece of information to the specific device.

I can use the device alias, but this is not available when the device is
created. This is also more complex when doing hotplug/hotunplug, because
I need to do update device and update metadata; if either fails, the
entire operation must be considered failed.

It would be nice to be able to attach metadata to the device, and this
is what I'm asking for/proposing in this mail.

Would it be possible in a future libvirt release?


If this is not possible, what's the best way to do the aforementioned
mapping? If it's alias (or device address), how can I be sure than I'm
addressing (no pun intended) the right device when I don't have them?
(e.g. hotplug new device, or just first time VM created)?


Thanks,


-- 
Francesco Romani
Red Hat Engineering Virtualization R & D
IRC: fromani