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#1 2019-08-30 15:42:46

Mindstormscreator
Member
Registered: 2012-07-01
Posts: 185

Integrated graphics PCI passthrough attempt: monitor won't wake up

Hello,

I've set up a libvirt VM (with virt-manager) to use the passed-through integrated graphics on my i7 9700K. My primary GPU is the Radeon RX 570. Here is a list of all of the parts in my build.

Here are my IOMMU groups, and here is evidence that the VFIO module seems to be loaded correctly. I followed the ArchWiki's instructions all the way up through creating the Windows VM, passing through the PCI device, all that stuff. Windows seems to recognize the device and detects an additional display.

But alas, nothing is showing up on the monitor I've plugged into my motherboard. I'm using a DVI cable if it matters, but I've tried DisplayPort as well.

I've also tried running Looking Glass for the heck of it, and while I was able to install the shared memory driver in Windows fine and launch the Looking Glass host, when launching the Looking Glass client on Linux, it can't connect to the host and fails to show the Windows display.

As an additional thing to note, my discrete graphics card appears to be identified as a VGA-compatible controller, but the integrated graphics just appears as a "Display Controller". I don't know whether this is a problem or not.

I feel completely stumped. Is there some hardware limitation I'm bumping into but not realizing?

Last edited by Mindstormscreator (2019-08-30 16:41:24)

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#2 2019-08-30 16:33:53

loqs
Member
Registered: 2014-03-06
Posts: 8,435

Re: Integrated graphics PCI passthrough attempt: monitor won't wake up

What if you test using arch as the guest?

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#3 2019-08-31 16:54:32

Mindstormscreator
Member
Registered: 2012-07-01
Posts: 185

Re: Integrated graphics PCI passthrough attempt: monitor won't wake up

That's a good idea.

I installed Arch and it boots fine, and when I add the integrated graphics display controller PCI device to the Arch VM, two things happen:

1. The VM's default virtual display shows this mangled mess.
2. The display connected to my motherboard / integrated graphics turns on, but shows a blank screen.

For the heck of it I also tried installing Xubuntu 18.04 in a separate VM. Interestingly, it shows the Xubuntu splash screen upon booting both in the VM's default emulated display, as well as on my separate monitor. But after booting, the desktop isn't shown on the other monitor, and the other monitor doesn't appear at all in Display settings. In this VM, the integrated graphics device is also described by lspci as "Display controller: Intel Corporation UHD Graphics 630", like on my host. The splash screen is still shown on the external monitor even after installation, but the desktop is still not aware of the monitor.

EDIT: A couple more things I tried:

* I tried booting the Xubuntu without any spice channel / virtual display hardware connected, with just the PCI device. It seems to fully boot to the desktop while showing on the external monitor. So that's cool, I guess!
* Unfortunately I can't say the same for Windows. I tried removing all the virtual display hardware, and Windows still won't show anything on my separate monitor. This is even the case when booting a fresh Windows install ISO with only the PCI graphics device attached; nothing is shown.

Last edited by Mindstormscreator (2019-08-31 18:14:17)

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#4 2019-09-01 20:37:29

Mindstormscreator
Member
Registered: 2012-07-01
Posts: 185

Re: Integrated graphics PCI passthrough attempt: monitor won't wake up

Just a quick update for any future Googlers.

Passing through the discrete card while using the integrated card for Linux definitely works for a Windows guest. So I guess an easy solution for this would be to buy a second discrete card, so both Windows and Linux can have a discrete card.

I'm also going to look into Intel GVT-g / GVT-d to see if that helps.

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#5 2019-09-10 22:07:48

Mindstormscreator
Member
Registered: 2012-07-01
Posts: 185

Re: Integrated graphics PCI passthrough attempt: monitor won't wake up

Just to give some closure to this from my perspective: apparently, passing through the integrated GPU to a Windows VM is not supported (by Windows? not sure), at least for my CPU. I can still either pass the AMD GPU through and use Intel graphics on Linux, or I might eventually buy a second discrete graphics card as well.

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