(1) Please consider adding something like this for the default syslinux config:

label Unraid OS without GPUs
  kernel /bzimage
  append initrd=/bzroot earlymodules=vfio-pci video=efifb:off,vesafb:off gfxpayload=text

WARNING: This will mean you don't have a functioning video device for TTY/terminal access to the physical machine.

 

Why? 

 

On my machine (specs later)...

• the primary GPU cannot be selected in the BIOS settings; it is chosen by the proprietary MSI BIOS;
• the primary GPU (being the one that Unraid itself boots to) cannot be used for VMs
  • vfio-pci BIND "succeeds"
  • launching the VM gets a black screen
  • after 2-3 launches, "qemu error.... var/log is full"
    • syslog almost fills the 128 MB RAM drive, qemu logs are indeed overfull
  • Dumping VBIOS and using a ROM file does not help
  • None of the various tips/tricks help

 

These options contribute to the fix:

• earlymodules=vfio-pci
  • This might? load vfio-pci a bit earlier in the chain, helping it to grab the devices before anything else can
• video=efifb:off,vesafb:off
  • This disables the framebuffer device drivers, which can hook into the GPU connected to the primary display
• gfxpayload=text
  • I don't actually know, but it came with the others in the post I read (which I can't find). I suspect it tells the Linux kernel that the graphics subsystem will only take text, no real graphics, but when I find myself reading Linux kernel documentation, I get scared.

 

(2) GPU passthrough documentation

Please mention the above.

 

(3) VM options: add "kvm hidden mode"

This solution fixed my final issue (the "alternative for recent libvirt-qemu", the actual page is about patching the NVIDIA drivers to un-break them, please dear PTBs don't ever make me have to do that):

https://github.com/sk1080/nvidia-kvm-patcher#preferred-alternative-for-recent-libvirt--qemu

It would be really handy if the UNRAID GUI for VM creation had a checkbox for "kvm hidden mode"

<domain>
    ...
        <features>
            ...
            <kvm>
                <hidden state='on'/>
            </kvm>
            ...
            <hyperv>
                ...
                <vendor_id state='on' value='whatever'/>
            </hyperv>
            ...
        </features>
    ...
</domain>

 

Key system specs (I am happy to send a full diagnostic download directly but not post it):

•  MSI Z390 Gaming Pro Carbon AC
• Intel i7-9700KF
• GPUs, all BINDed to vfio-pci in WebGUI -> Tools -> System Devices
  • Gigabyte NVIDIA RTX 2070 Super
  • Gigabyte NVIDIA RTX 2070 Super (yes, another)
  • Quadro K600
• 1x SATA HDD (sole drive of the array)
• 2x NVMe, 2x SATA SSD (each in their own pool)
• VMs:
  • GPU Passthrough (all cards working)
  • 4-8 cores assigned
  • Hyper-V selected
  • Custom XML as above for kvm hidden

 

 

Oh, a note:

Due to my desire to be running Win 11 VMs, I'm using the "Next" Unraid version: Version: 6.10.0-rc2

I'm trying to understand if I can passthrough my 5600G to a VM...and I found your post.

 

I added the "no GPU" lines to my config file but i still get a video out of Unraid loading...what can i be missing?