Re: [Qemu-devel] [PATCH] xhci: child detach fix

[Gonglei (Arei)]

> -----Original Message-----
> From: Gerd Hoffmann [mailto:address@hidden
> Sent: Tuesday, May 13, 2014 2:56 PM
> 
> > BTW, in usb_release_port(), the detached port should be insert
> > the head of bus->free list table. Because of the save/restore will
> > cause qemu crash, after hot plug/hot unplug multi times. For example,
> > save the port '2' to memory file, but when we restore it, the port will
> > be assign to '1' over again, which not match with the memory file,
> > and then crash qemu.
> 
> If you want hotplug and live migration play well you have to explicitly
> assign devices ports, i.e.
> 
>   -device usb-host,port=2,$args
> 
> Otherwise it will simply not work reliable.
> 
Yep, I have noticed that case, which pass-through two USB devices, and
then hot-unplug the first one, then save/restore, which will also crash qemu.

So maybe assign ports ahead was the exclusive method. Thanks,

Best regards,
-Gonglei