Re: [Qemu-devel] [PATCH] usb-ohci: add vmstate descriptor

[Alexey Kardashevskiy <aik@ozlabs.ru>]

On 03/23/2014 08:04 AM, Andreas Färber wrote:
> Am 22.03.2014 21:54, schrieb Peter Maydell:
>> On 22 March 2014 20:18, Andreas Färber <afaerber@suse.de> wrote:
>>> Because AFAIU
>>> migration is possible without VMSD, just not with VMSD that sets
>>> .unmigratable = 1.
>>
>> Well, the migration won't fail with an error, but on the destination
>> end you'll end up with a device in its reset state but a guest which
>> may think the device is in some other state. If the device was
>> quiescent and doesn't need complex setup it might cope, but
>> more likely is that that guest driver will fall over in a heap next
>> time you try to use it...
> 
> Well, there is no OHCI state being added, only PCI state. So I'd be
> curious to know what in there is the problem because a general review of
> PCI devices might be due then - and ideally before we do the release.

Without the patch, if to migrate a machine while it is in SLOF between
BARs assigned and USB driver started working, the BAR memory regions were
not enabled and BAR accesses were ending up in unassigned_mem_ops.


-- 
Alexey