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Re: [Xen-devel] [RFC] XenGT - An Mediated Graphics Passthrough Solution from Intel

> From: Paul Durrant [mailto:Paul.Durrant@xxxxxxxxxx]
> Sent: Tuesday, September 10, 2013 4:38 PM
> > -----Original Message-----
> >
> > XenGT implements the mediator in dom0, called vgt driver. This avoids
> > adding complex device knowledge to Xen, and also permits a more flexible
> > release model. In the meantime, we want to have a unified architecture to
> > mediate all the VMs, including dom0. Thus, We developed a ³deprivileged²
> > dom0 mode, which essentially trapped Dom0's access to selected resources
> > (graphics resources in XenGT case) and forwarded to vgt driver (which is
> > also in Dom0) for processing.
> >
> Hi,
>   Thanks for sharing the patches. From my cursory glance at the code do seem
> to have put quite a lot of it into the hypervisor itself. Are you 
> implementing your
> device model there and talking directly to the vgt driver in some way, or is
> trapped IO going via QEMU?

device model is in vgt driver in dom0. hypervisor changes are more about:
        a) trap dom0's mmio/pio accesses to gfx device and forward to vgt 
driver for
        b) hypercall support to allow vgt driver accessing gfx device to avoid 

Qemu is only involved for legacy VGA port emulation, i.e. legacy VGA (boot, 
bsod, etc.)
is still shown in the qemu window. When gfx driver is loaded, the output will be
full screen on the physical monitor.


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