GPU passthrough

GPU attach on a Linux Device in the Home needs IOMMU groups, the vfio-pci module, KVM, and a GPU in an IOMMU group. BarkVisor does not turn IOMMU on, load modules, or edit boot config. macOS has no VFIO path.

After the host is ready, attach from Workload detail like USB. Device detail reports Host ready or the missing piece.

Firmware

Enable Intel VT-d or AMD-Vi in the firmware. Menus call it VT-d, AMD-Vi, IOMMU, or SVM. Then boot Ubuntu or Debian.

Intel or AMD kernel flags

Edit /etc/default/grub. Keep flags you already have. Add one IOMMU pair.

Intel:

GRUB_CMDLINE_LINUX_DEFAULT="quiet intel_iommu=on iommu=pt"

AMD:

GRUB_CMDLINE_LINUX_DEFAULT="quiet amd_iommu=on iommu=pt"

Then:

sudo update-grub
sudo reboot

Device detail says why if IOMMU is still off: enable intel_iommu=on or amd_iommu=on, then reboot.

vfio-pci

sudo modprobe vfio-pci
ls /sys/bus/pci/drivers/vfio-pci
ls /sys/module/vfio_pci
ls /dev/vfio/vfio
ls /dev/kvm

Persist across reboot:

echo vfio-pci | sudo tee /etc/modules-load.d/vfio-pci.conf

Do not bind vendor:device ids yourself. BarkVisor binds vfio-pci when the Workload starts, and unbinds on detach, stop, and delete.

If /dev/kvm is missing, install qemu-kvm, add the service user to group kvm, or enable nested virtualization.

The package installs a udev rule so dropped QEMU (group kvm) can open /dev/vfio/*.

Verify groups

ls /sys/kernel/iommu_groups
find /sys/kernel/iommu_groups -type l | sort
lspci -nnk

Zero groups means IOMMU is still off. After a reboot, Workload detail lists each GPU with its group. Other PCI addresses in that group are group mates. They pass through with the GPU. The boot disk and the last remaining host uplink stay excluded from the PCI picker.

Host GPU occupancy

If this Device lists one GPU, passing it through can blank the host display. The UI says so. That warning does not block Attach.

In use by host means the host GPU driver still owns the card. Occupancy is information, not a blocker. Attach still works. The same card cannot stay host and guest after the Workload starts.

Attach

On a Linux Device, open a Workload → GPU passthrough → Attach GPU. Fail closed if IOMMU, vfio-pci, or KVM is missing. The UI states why. macOS always says GPU passthrough is unavailable.