Re: [Qemu-devel] [PATCH for-1.6 1/2] don't create pvpanic device by default.

["Andreas Färber" <afaerber@suse.de>]

Am 11.08.2013 12:33, schrieb Michael S. Tsirkin:
> On Fri, Aug 02, 2013 at 10:27:31AM +0200, Paolo Bonzini wrote:
>> On 08/02/2013 09:04 AM, Hu Tao wrote:
>>> 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. 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.
>>>
>>> Reported-by: Marcel Apfelbaum <marcel.a@redhat.com>
>>> Signed-off-by: Hu Tao <hutao@cn.fujitsu.com>
>>
>> NACK,
>>
>> this is premature.  It is fundamentally a firmware problem.
>>
>> We have time to apply an even smaller patch that doesn't set
>> has_pvpanic to true, and delay the whole feature to 1.7, if we do
>> not fix the firmware in the next two weeks.
>>
>> Paolo
> 
> I think this is not just a firmware problem.  Adding device by default
> was too rush, assumption was risk of guest bugs was 0.
> 
> We are now seeing problems with bios guest code and with linux guest
> drivers as well.  Yes they all can be fixed, but we simply shouldn't
> force this risk of broken guests on everyone.
> 
> libvirt is the main user and libvirt people
> indicated their preference to creating device with
> -device pvpanic rather than a built-in one that
> can't be removed.
> 
> So please reconsider, and here's an ack from me.
> 
> Acked-by: Michael S. Tsirkin <mst@redhat.com>

NACK for this v1: As pointed out on the KVM call, we still need to keep
the pvpanic device around by default for pc-*-1.5. Removing has_pvpanic
completely therefore seems wrong. Can you submit a v2 for rc3 tomorrow?

Andreas

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