[vfio-users] Skylake IGD + Windows 10 VM = 4.3Gb of non paged memory

[Alex Williamson]

On Sat, 7 Oct 2017 15:37:32 -0400
<mathieu at lesperance.cloud> wrote:

> Hi folks,
> 
>  
> 
> I have a Windows 10 VM running on unRAID 6.3.5 which as KVM/QEMU built-in
> (QEMU 2.7.1 / libvirt 2.4.0), which I passthrough a Skylake IGD in legacy
> mode. The video output works fine, however, the issue is that the intel
> video driver memory manager stole 4.3GB and put it in a non-paged memory
> pool. That mean that on my 8GB of ram in my VM, only 3.7GB is available to
> the user. If I assign less than 4GB, the intel IGD wont work at all.
> 
>  
> 
> I've read about the fw_cfg that need some configuration for IGD, but I
> didn't find any prebuild file for an IGD nor the source files to build the
> binaries.
> 
>  
> 
> I have open threads in two other forum but no success so far: 
> 
>  
> 
> https://forums.lime-technology.com/topic/60107-635-passing-through-intel-igd
> -with-win10-abnormally-high-mem-usage/
> 
>  
> 
> https://communities.intel.com/thread/118393
> 
>  
> 
> Thanks for your help, Mathieu.

There are versions of the IGD Windows driver that freak out when they
find zero stolen memory reserved, the workaround is to add the
parameter x-igd-gms=1 to the parameter list for the device.  Intel has
indicated that they intend to fix this in the Windows driver, so
updating to the latest Intel driver release may also be enough to
resolve it.  See:

https://lists.gnu.org/archive/html/qemu-devel/2017-07/msg08092.html

Thanks,
Alex