IOMMU Group - GRUB modifications

User Support
1

https://forum.qubes-os.org/t/create-a-gaming-hvm/19000
states that I need to:

  • Boot a live linux distribution - Fedora on another disk

  • In the grub, enable iommu: Add the parameters iommu=1 iommu_amd=on to the linux commandline
    iommu=1 intel_iommu=on for Intel, but done

  • Once you logged in your live linux distribution, you need to retrieve the folder structure of /sys/kernel/iommu_group.
    I have no iommu_group file or folder. I have an iommu_groups folder, but it’s empty

Please can y’all let me know how to get the IOMMU group of my GPU from here?

2

Weird… Do you have iommu enabled in BIOS?

1 Like
3

Intel Virtualization Tech → [Enabled]

Intel VT-D Tech → [Enabled]

Is there something else? Happy to be corrected!

4

It looks okay, but who knows with these manufacturers…

Maybe there have been a typo in kernel parameters? You can get them on a running system in /proc/cmdline

Also try to find fedora documentation on the topic. What if they’ve changed something and it is more involved than just two parameters?

5

Did you also tried the helper script shared here:
https://iommu.info/

(keep in mind that it will immediately upload and contribute the result to the online database)

1 Like
6

“You can’t see your IOMMU Group when you are using Xen (the information is hidden from dom0).”
says the guide

However…these look like IOMMU groups? Output from qvm_pci
dom0:00_00.0
dom0:00_01.0
dom0:00_01.1

Am I missing something? :confused:

7

Nope, these are device ids

For example, here’s an entry from iommu.info: PRIME X570-PRO

If you look closely you can see that device ids don’t correspond to groups at all.

1 Like
8

Thank you :slight_smile: