On "legacy enumeration" systems, such as this one the BIOS SMI handler enumerates the PCI bridges before handing off to the OS. The bridges here are the TBT host router bridges so no need for any authorization.
On "legacy enumeration" systems, such as this one the BIOS SMI handler enumerates the PCI bridges before handing off to the OS. The bridges here are the TBT host router bridges so no need for any authorization.