[Qemu-devel] Re: [PATCH v2] make windows notice media change

[Juan Quintela <quintela@redhat.com>]

Anthony Liguori <anthony@codemonkey.ws> wrote:
> Filip Navara wrote:
>> On Wed, Jul 29, 2009 at 3:50 PM, Gleb Natapov<gleb@redhat.com> wrote:
>> [snip]
>>   
>>> @@ -2898,6 +2901,7 @@ static void ide_load(QEMUFile* f, IDEState *s)
>>>
>>>     qemu_get_8s(f, &s->sense_key);
>>>     qemu_get_8s(f, &s->asc);
>>> +    qemu_get_8s(f, &s->cdrom_changed);
>>>     /* XXX: if a transfer is pending, we do not save it yet */
>>>  }
>>>
>>> @@ -3219,7 +3223,7 @@ static int pci_ide_load(QEMUFile* f, void *opaque, int version_id)
>>>     PCIIDEState *d = opaque;
>>>     int ret, i;
>>>
>>> -    if (version_id != 2)
>>> +    if (version_id != 3)
>>>         return -EINVAL;
>>>     ret = pci_device_load(&d->dev, f);
>>>     if (ret < 0)
>>>     
>>
>> Why shouldn't we support loading version 2 snapshots? Afterall that's
>> why we had the versioning in the first place.
>>   
>
> What value do you give cdrom_changed?
>
> If you give it zero, and you happened to be in a state where the cdrom
> was in the process of being changed when you migrated, this bug would
> surface again.
>
> In this case, it's better to refuse the old (broken) version.

You didn't lost anything from the old version, it already have the bug.
Value that you give it: zero.  If it was in the middle of the operation,
it will give the same bug that when it was in the older host, and when
it tells "retry", it will see the new behaviour from this on.

Later, Juan.


> Regards,
>
> Anthony Liguori