Re: [Qemu-devel] [RfC PATCH] usb/vmstate: add parent dev path

[Gerd Hoffmann]

On 08/26/11 12:25, Daniel P. Berrange wrote:
> On Fri, Aug 26, 2011 at 12:11:20PM +0200, Gerd Hoffmann wrote:
> > ... to make vmstate id string truely unique with multiple host
> > controllers, i.e. move from "1/usb-ptr" to "0000:00:01.3/1/usb-ptr"
> > (usb tabled connected to piix3 uhci).
> >
> > Obvious problem with that is that it breaks migration from and to older
> > versions, thats why it is RfC.  I don't see any way to fix the issue
> > without breaking though.  So the question is how to deal with that best?
>
> How about keeping the original naming *only* for devices on the first
> USB controller. Since it was impossible to start a QEMU process with
> 2 USB controllers,

Now it is, and we have a release (0.15) in the wild which supports it.

> migration compatibility does not matter for the
> naming of devices on the 2nd, 3rd, 4th.... controller.

That would still break users which use usb 2.0 with qemu 0.15 today.

cheers,
  Gerd