IOMMU Group

What is IOMMU Group

TBD...

Common Issues

Sometimes there is problem that the expected iommu_group directories are missing from the respective bus directory.

• Check whether the machine supports Vt-d, and whether it is enbaled in the BIOS settings.
• Check whether intel_iommu=on is passed to the systemd-boot options.

To enable VT-d and ensure functionality, we need to edit /etc/default/grub. Look for the line that says GRUB_CMDLINE_DEFAULT="" and append intel_iommu=on to what is inside of that line. Mine looks like this

GRUB_CMDLINE_LINUX_DEFAULT="resume=UUID=79f7cf0c-05d3-45a0-8c0f-965cb4924300 intel_iommu=on"

Once you've done that we need to rebuild our grub.cfg file. Run this to do so

sudo grub-mkconfig -o /boot/grub/grub.cfg

The corresponding snippet in the grub.cfg looks like this

linux /boot/vmlinux-4.4.0-31-generic root=UUID=79f7cf0c-05d3-45a0-8c0f-965cb4924300 ro quiet splash intel_iommu=on $vt_handoff

• Reboot and check kernel ring messages with dmesg | grep IOMMU and check whether the output contains DMAR: IOMMU enabled.