[SOLVED] No boot when using GPU passthrough settings PVE6

[GarrettB]

Regarding problems with GPU passthrough, would the setting of pc-q35-3.1 on a VM affect the booting of the host, when the VM is not set to boot?

I could not get the host system to boot, and ended up commenting out all of the "modules" files entry, the modprobe.d conf files regarding video settings, and reverted the grub command line to original. With these changes, it still hung saying something about vga change...

Then I tried disabling IOMMU in the BIOS, and it booted.

I have left it this way for now to get things up and running. Trying to troubleshoot.

With the files commented out, but BIOS with IOMMU enabled, I must have missed one (even though this was commented out...actually, I didn't update initramfs so maybe that's why it reports a failure to find module?):

Jul 20 23:05:33 pve systemd-modules-load[464]: Failed to find module 'options vfio_pci ids=1002:6779,1002:aa98 disable_vga=1'
Jul 20 23:19:14 pve kernel: [    0.489149] pci 0000:01:00.0: vgaarb: setting as boot VGA device
Jul 20 23:19:14 pve kernel: [    0.489149] pci 0000:01:00.0: vgaarb: VGA device added: decodes=io+mem,owns=io+mem,locks=none
Jul 20 23:19:14 pve kernel: [    0.489149] pci 0000:01:00.0: vgaarb: bridge control possible
Jul 20 23:19:14 pve kernel: [    0.489149] vgaarb: loaded
Jul 20 23:19:14 pve kernel: [    3.594439] vfio-pci 0000:01:00.0: vgaarb: changed VGA decodes: olddecodes=io+mem,decodes=none:owns=io+mem

With IOMMU disabled in the BIOS:

Jul 20 23:22:14 pve kernel: [    0.449131] pci 0000:01:00.0: vgaarb: setting as boot VGA device
Jul 20 23:22:14 pve kernel: [    0.449131] pci 0000:01:00.0: vgaarb: VGA device added: decodes=io+mem,owns=io+mem,locks=none
Jul 20 23:22:14 pve kernel: [    0.449131] pci 0000:01:00.0: vgaarb: bridge control possible
Jul 20 23:22:14 pve kernel: [    0.449131] vgaarb: loaded
Jul 20 23:22:14 pve kernel: [    7.099894] snd_hda_intel 0000:01:00.1: Handle vga_switcheroo audio client

With nothing commented out, and IOMMU enabled in the BIOS, it hung on the message "vgaarb: changed VGA decodes: olddecodes=io+mem,decodes=none: owns=io+mem" but I don't understand this.

Grub command line was:

GRUB_CMDLINE_LINUX_DEFAULT="quiet iommu=pt amd_iommu=pt video=efifb:off"

 

[dcsapak]

I could not get the host system to boot, and ended up commenting out all of the "modules" files entry, the modprobe.d conf files regarding video settings, and reverted the grub command line to original. With these changes, it still hung saying something about vga change...

did you update your initramfs after?

 

[GarrettB]

No. I'm certain I did not update initramfs because I had only at first modified the files through a live CD to get it to boot at all.

But what broke passthrough? The hardware has not changed. The card is in same slot and is being recognized with the same number and Ids. I double checked the setup and it should work.

But after the upgrade to 6 it wouldn't boot. And, of course, I then regretted having the passthrough turned on as I couldn't see why.

I will have to find something else in my logs to post. But shouldn't it work? Thus my question about q35-3.1...I have not read anything indication there are other changes regarding passthrough.

 

[GarrettB]

When I looked back through the logs, I could only find the one error about not being able to find the module with a note of the "options vfio-pci" line in vfio.conf.

I attempted it again with passthrough options, and it worked.

I cannot determine the source of the problem, and am guessing it must have been the network connection somehow being down. Sorry for the trouble, and thanks for the response! Proxmox provides good service.