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

["Chen, Tiejun" <tiejun.chen@xxxxxxxxx>]

On 2014/7/1 3:31, Ross Philipson wrote:
> On 06/30/2014 03:22 PM, Stefano Stabellini wrote:
> > 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.
> That is a very good point. A while back I did a bunch of work to try to
> keep Windows activated between running an instance of Windows on bare
> metal and as a VM. There were numerous bits of hardware and firmware
> that went into the calculation as to whether Windows thought it was the
> same platform for activation purposes. Changing the chipset sounds like
> a likely candidate for inspection. Somewhere out there on the webs is a
> partial list of the things that are inspected - lost the URL.
So do this mean currently we still can't go q35?

Thanks
Tiejun

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