Re: [Qemu-devel] [PATCH for-1.6 V2 0/2] pvpanic: Separate pvpanic from machine type

[Eric Blake <eblake@redhat.com>]

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On 08/11/2013 09:10 AM, Marcel Apfelbaum wrote:
> Creating the pvpanic device as part of the machine type has the
> potential to trigger guest OS, guest firmware and driver bugs.
> The potential of such was originally viewed as minimal.
> However, since releasing 1.5 with pvpanic as part
> of the builtin machine type, several issues were observed
> in the field:
>  - Some Windows versions triggered 'New Hardware Wizard' and
>    an unidentified device appeared in Device Manager.
>  - Issue reported off list: on Linux >= 3.10
>    the pvpanic driver breaks the reset on crash option:
>    VM stops instead of being reset.
> 
> pvpanic device also changes monitor command behaviour in some cases,
> such silent incompatible changes aren't expected by management tools:
>  - Monitor command requires 'cont' before 'system_reset'
>    in order to restart the VM after kernel panic/BSOD 
> 
> Note that 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.
> 
> These issues were raised at last KVM call. The agreement reached
> there was that we were a bit too rash to make the device
> a builtin, and that for 1.6 we should drop the pvpanic device from the
> default machine type, instead teach management tools to add it by
> default using -device pvpanic.
> It's not clear whether changing 1.5 behaviour at this point
> is a sane thing, so this patchset doesn't touch 1.5 machine type.

Thanks for doing this; it makes sense to get this in for 1.6.  From the
libvirt point of view:

Series: Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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