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From: Marcel Apfelbaum <marcel.a@redhat.com>
Date: Thu, 01 Aug 2013 19:39:44 +0300
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Subject: Re: [Qemu-devel] pvpanic device should not be automatically
 included as an internal device
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To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Hu Tao <hutao@cn.fujitsu.com>, Anthony Liguori <aliguori@us.ibm.com>, qemu-devel@nongnu.org, Markus Armbruster <armbru@redhat.com>

On Thu, 2013-08-01 at 16:32 +0300, Michael S. Tsirkin wrote:
> On Thu, Aug 01, 2013 at 04:08:57PM +0300, Marcel Apfelbaum wrote:
> > Hi,
> > 
> > The problem with pvpanic being an internal device is that VMs running
> > operating systems without a driver for this device will have problems
> > when qemu will be upgraded (from qemu without this pvpanic).
> > 
> > The outcome may be, 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.
> > Now what will happen 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.
> > 
> > My point is that a device that requires a driver that is not "inbox", should not
> > be present by default.
> > One possible solution is to add it manually with -device from command line.
> > 
> > Any thoughts?
> > Marcel
> 
> Interesting. You are basically saying we should have a rule
> that no new builtin devices should be added
> without an explicit request from management interface?

Basically, yes.
The only builtin devices shall be devices that the operating systems
know how to handle with the default drivers.
Marcel

> 
>