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Subject: Re: [Qemu-devel] [Xen-devel] [PATCH] Remove hardcoded xen-platform
	device initialization
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To: Ian Campbell <Ian.Campbell@citrix.com>
Cc: Paul Durrant <paul.durrant@citrix.com>, xen-devel@lists.xen.org, qemu-devel@nongnu.org, Stefano Stabellini <stefano.stabellini@eu.citrix.com>

Il 13/06/2013 13:44, Ian Campbell ha scritto:
> On Thu, 2013-06-13 at 18:33 +0100, Stefano Stabellini wrote:
>> On Thu, 13 Jun 2013, Paul Durrant wrote:
>>> The xen-platform device should be initialized by the Xen toolstack by
>>> passing the appropriate -device argument on the command line.
>>>
>>> Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
>>
>> This patch is problematic because we can't know for sure the version of
>> upstream QEMU that is going to be used with Xen.
>> If we apply this patch and QEMU 1.5 is going to be used with Xen 4.2,
>> guests won't be able to use PV drivers.
> 
> Is the right answer a lever to disable, rather than enable, it?
> 
> A workaround for the situation you envisage is to use the
> device_model_args config option, not ideal though.

I think the right solution for this is to move towards using the normal
"-M pc" machine.  libxl can simply use "-M pc -machine accel=xen -device
xen-platform-pv"; older versions that use the xenfv machine will still work.

And if you do this, you will also get the benefit of versioned machine
types.

Paolo