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

["Michael S. Tsirkin" <mst@redhat.com>]

On Sun, Aug 11, 2013 at 04:45:03PM +0200, Andreas Färber wrote:
> 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.

We also mentioned an option to patch 1.5 stable to change it there,
but I'm fine with not doing it.

> Can you submit a v2 for rc3 tomorrow?
> 
> Andreas


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