[Qemu-devel] Re: [PATCH 1/8] qdev: Allow device addressing via 'driver.instance'

[Gerd Hoffmann]

  Hi,

> Agreed.  The problem here is that we sent the instance_id on the wire,
> so for "legacy" devices that used an instance_id != -1, we are stuck
> with it :(

Another way would be to fill the instance id with something useful, say 
encode the pci address there for pci devices.  That should be good 
enough to reliably identify devices even after hot-plugging them in and out.

Of course this has transition isses too.  But maybe it is easier to 
handle than replacing instance_id with something entirely different.

And it also makes the instance id less useful to address devices in a 
human-friendly way.

cheers,
  Gerd