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

[Gleb Natapov]

On Mon, Aug 05, 2013 at 11:03:53AM +0200, Gerd Hoffmann wrote:
> 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, ...
> 
All of those are multiple choses and some of then expect you to install
drivers actually since they also do not work out of the box with all guests.

> > 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
You cannot change HW after machine is installed without risking Windows
reactivation.
 
> device that it should be treated differently from everything else?
> 
It is simple, it does not have alternative, there is not reason to not
have it. So your options are: having the device and installing driver if
functionality is needed, or never have it.

--
			Gleb.