<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> <style type="text/css" style="display:none;"></style> </head> <body dir="ltr"> <div id="divtagdefaultwrapper" style="font-size:12pt;color:#000000;font-family:Calibri,Helvetica,sans-serif;" dir="ltr"> You are not telling enough info. Things that would be useful: Your Motherboard and Processor If the FireWire card is a Motherboard onboard Device or a discrete card, and which it is Full lspci -nn and -tvnn and IOMMU Groups, for completion sake Full VM launch settings. What else is in that pve-q35.cfg? How you invoke QEMU or libvirt? At first glance, the FireWire Controller is a PCI Device behind a PCIe-to-PCI Bridge which is attached to a PCIe Root Port from the Chipset, which could be either a Device on the Motherboard itself or a card plugged into a PCIe Slot. You don't need to Passthrough Bridges, they can be ignored even if they are in the same IOMMU Group that the Device that you want to pass. The pxb-pcie Device is a secondary PCIe Root Complex (The Q35 Chipset has its own) and is totally unnecessary for your use case. Something that you may want to try is to create a virtual Intel 82801 PCIe-to-PCI Bridge and attach your FireWire Controller there. Using a proper PCI Topology in your VM may fix obscure issues. -device i82801b11-bridge,bus=pcie.0,addr=1e.0,id=pci.0 -device vfio-pci,bus=pci.0,addr=00.0,id=firewire,host=04:00.0 </div> </body> </html>