Xen devel - Jun 2013 - Re: [Qemu-devel] [PATCH] Add Xen platform PCI device version 2.

--On 19 June 2013 10:13:17 +0000 Paul Durrant <Paul.Durrant@citrix.com> 
wrote:
>> We obviously can''t say to users "Are you running Windows
and are you
>> running PV drivers >= X.Y, if so set lever A to position B,
otherwise if
>> you are running some other OS or an earlier version of the Windows PV
>> driver set it to position A".
>
> Why not? The device can be chosen on a per-VM basis.
Not everyone knows what guest some random user will be running
(consider cloud platforms).

Expecting an admin to introspect the guest is not a good plan.
Having the same set of levers that work at least reasonably with
everything is the way to go.

-- 
Alex Bligh