RSS results in the possibility of multiple vDPA queues for each virtio channel. While physical functions are configured using the –vdev feature in DPDK, the SR-IOV virtual functions that are used for vDPA virtio channels are PCI probed and require additional configuration, to be able to specify the number of queues for each channel needed. This is done using the PCI allow list in DPDK, where optional parameters can be added.
There are two methods that can be used. Method 1 is to specify the PCI ID of each virtual function individually, both in the allow list and in the OVSDB configuration. See Setup Representor Ports VF auto PCI Probe, Method 1. Method 2 uses a representor base VF, where the first VF (VF#0) is used as the representor port configuration base. Since the first virtual function is always taken by the Napatech OVS-DPDK setup, it is natural to use this first virtual function (for example, 0000:3b:00.4) as the representor configuration port for all remaining virtual functions. See Setup Representor Ports VF auto PCI Probe, Method 2.
In conclusion, VF#0: <domain>:<bus>:00.4 represents a special configuration port for all virtual functions. This virtual function must always be in the allow list anyway.