[vfio-users] about hotplug of the IGD device

[Alex Williamson]

On Fri, Mar 10, 2017 at 2:47 AM, fulaiyang <fulaiyang at 163.com> wrote:

> Hi Alex:
>     After passthrough the IGD device to the virtual machine, the linux
> host can not use the IGD device again. And the dmesg tell that i915 can not
> restart the GPU. I know  'Hotplug of the IGD device is not supported' from
> the 'VFIO tips and tricks'. Could you tell me why? and is there some ways
> to work it out?
>


Nothing in vfio specifically prevents hotplug of any GPU, including IGD.
The trouble with hotplug of GPUs is that it's generally poorly supported by
the device drivers, both host and guest.  The driver and software stack for
hotplug of a graphics device is simply not as robust as something like a
NIC device.  For instance, I think if you were to unbind and rebind IGD
with the i915 driver repeatedly, you'd hit similar errors to the case where
IGD is used by vfio and returned to the host i915 driver.  Thanks,

Alex
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