[SeaBIOS] [PATCH] don't expose pvpanic device in the UI

[Eric Blake]

On 08/05/2013 01:04 PM, Paolo Bonzini wrote:
> 
>> Libvirt has no problem enabling -device pvpanic for all guests where
>> <on_crash> is set to a non-default value, since the use of <on_crash> is
>> a sufficient hint that the user expects the guest to be able to notify
>> of a crash in the first place.  But I definitely agree that it is more
>> conservative to ask libvirt to always provide -device pvpanic than it is
>> to blindly enable the device and hope that it never causes damage.
> 
> Changing guest ABI depending on <on_crash> is a much much worse
> cure than the disease.

I'm not sure I follow.  If the user requests <on_crash> but qemu is too
old to provide -device pvpanic, then libvirt can fail to create the
guest by telling the user their request can't be honored.  If the user
requests <on_crash> and qemu is new enough, then libvirt requests the
pvpanic device as part of starting the guest.  If the user doesn't
requst <on_crash> handling, then the presence or absence of the device
doesn't matter, and it is more conservative to omit the device.  The
only time the guest ABI would change is if the user changes XML - but
that's exactly what the user is already capable of doing in any number
of other situations.

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

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