Other than enabling the IOMMU (which any system with Thunderbolt should have on by default), what does the motherboard firmware actually need to do for SR-IOV?

Other than enabling the IOMMU (which any system with Thunderbolt should have on by default), what does the motherboard firmware actually need to do for SR-IOV? I can't see any reason why it would need to be concerned with enumerating Virtual Functions or anything like that, but I don't actually have the SR-IOV spec on hand to dig through. EDIT: Looking through an old Intel whitepaper, it looks like the system firmware at most has to reserve some extra config space for SR-IOV devices when enumerating the PFs, so that the OS can enumerate VFs after creating them. But Linux includes an option to re-allocate this stuff if the BIOS doesn't reserve space, so this apparently isn't a hard requirement.