[SeaBIOS] [PATCH] don't expose pvpanic device in the UI

[Gerd Hoffmann]

On 08/05/13 10:16, Gleb Natapov wrote:
> On Mon, Aug 05, 2013 at 11:10:55AM +0300, Michael S. Tsirkin wrote:
>> On Mon, Aug 05, 2013 at 03:47:23PM +0800, Hu Tao wrote:
>>> pvpanic device is an internal default device in qemu. It may cause
>>> problem when upgrading qemu from a version without pvpanic.
>>>
>>> for example: in Windows(let's say XP) the Device manager will open a
>>> "new device" wizard and the device will appear as an unrecognized
>>> device.  On a cluster with hundreds of such VMs, If that cluster has
>>> a health monitoring service it may show all the VMs in a "not healthy"
>>> state.
>>>
>>> This patch is a workaround to not show pvpanic in UI to avoid the
>>> problem in Windows.
>>>
>>> Cc: Marcel Apfelbaum <marcel.a at redhat.com>
>>> Cc: "Michael S. Tsirkin" <mst at redhat.com>
>>> Cc: Paolo Bonzini <pbonzini at redhat.com>
>>> Cc: Gerd Hoffmann <kraxel at redhat.com>
>>> Cc: Eric Blake <eblake at redhat.com>
>>> Cc: "Daniel P. Berrange" <berrange at redhat.com>
>>> Cc: Andreas Färber <afaerber at suse.de>
>>> Signed-off-by: Hu Tao <hutao at cn.fujitsu.com>
>>
>> Quoting from this discussion:
>> 	>That may "fix" the issue of a windows guest showing the yellow ! mark,
>> 	>but what if, down the road, someone writes an actual windows driver that
>> 	>is aware of that port and how to make a windows BSOD write a panic
>> 	>notification to the port?  How does a user go about installing such a
>> 	>driver if the device is not exposed in the user interface list of
>> 	>devices?
>>
>> I think the correct way to address this is:
>> - don't create the device by default, only when -device pvpanic is
>>   present
>> - teach management to supply said -device pvpanic for guests which
>>   support the pvpanic device
>>
> That's just pushing the problem elsewhere. How management suppose to know if
> guest support pvpanic device?

The problem isn't new and management already does that when figuring
whenever the guest should get ide/ahci/virtio-blk/virtio-scsi storage,
ac97 or intel-hda sound, rtl8139/e1000/virtio nic, ...

> What if initially guest did not have a
> driver, but the it was installed?

Update the machine config then?  What is so special about the pvpanic
device that it should be treated differently from everything else?

cheers,
  Gerd