How to enable IOMMU on the board?

I am trying to connect PCI board to the virtual machine yet I am getting:

No IOMMU detected, please activate it.See Documentation for further information.

Thank you!


Since no one has answered this and I ran into the same issue, I’ll add my solution here.

I ran into a similar problem where I needed VMs to share PCI slots. I reached out to seeed tech support, and there is support in the BIOS under Advanced → CPU Configuration → VT-d (reference). Enabling the VT-d setting and saving the BIOS config enables IOMMU.

Since I already had that enabled, I went searching on the proxmox side, and found this Proxmox forum post, which after following the steps to update the GRUB configuration listed therein by leesteken and reboot, I was able to share single PCI devices into VMs:

Specifically, I:

  1. In /etc/default/grub, to GRUB_CMDLINE_LINUX I appended intel_iommu=on to any other options (there were none).
  2. Ran sudo update-grub
  3. Rebooted
  4. Ran cat /proc/cmdline to confirm that intel_iommu=on was amongst the other options.
  5. Loaded the Proxmox GUI, no longer received the IOMMU warning, and was able to add map PCI devices into VM configurations using Raw Device mode.