[SeaBIOS] [PATCH] don't expose pvpanic device in the UI
Gleb Natapov
gleb at redhat.com
Mon Aug 5 10:16:17 CEST 2013
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? What if initially guest did not have a
driver, but the it was installed? If device appears for old machine
models this is bug, otherwise I fail to see any problem.
--
Gleb.
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