Re: [Xen-devel] [v5][PATCH 0/5] xen: add Intel IGD passthrough support

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Mon, 30 Jun 2014, Michael S. Tsirkin wrote:
> On Mon, Jun 30, 2014 at 03:24:58PM +0800, Chen, Tiejun wrote:
> > On 2014/6/30 14:48, Michael S. Tsirkin wrote:
> > >On Mon, Jun 30, 2014 at 10:51:49AM +0800, Chen, Tiejun wrote:
> > >>On 2014/6/26 18:03, Paolo Bonzini wrote:
> > >>>Il 26/06/2014 11:18, Chen, Tiejun ha scritto:
> > >>>>
> > >>>>>
> > >>>>>- offsets 0x0000..0x0fff map to configuration space of the host MCH
> > >>>>>
> > >>>>
> > >>>>Are you saying the config space in the video device?
> > >>>
> > >>>No, I am saying in a new BAR, or at some magic offset of an existing
> > >>>MMIO BAR.
> > >>>
> > >>
> > >>As I mentioned previously, the IGD guy told me we have no any unused a
> > >>offset or BAR in the config space.
> > >>
> > >>And guy who are responsible for the native driver seems not be accept to
> > >>extend some magic offset of an existing MMIO BAR.
> > >>
> > >>In addition I think in a short time its not possible to migrate i440fx to
> > >>q35 as a PCIe machine of xen.
> > >
> > >That seems like a weak motivation.  I don't see a need to get something
> > >merged upstream in a short time: this seems sure to miss 2.1,
> > >so you have the time to make it architecturally sound.
> > >"Making existing guests work" would be a better motivation.
> > 
> > Yes.
> 
> So focus on this then. Existing guests will probably work
> fine on a newer chipset - likely better than on i440fx.
> xen management tools need to do some work to support this?

Unfortunately existing Windows guests don't take well chipset changes.
Windows might request a new activation.

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