Hi Andi,
When you add new interfaces like this you should add them to the packet (7)
manpage too.
Currently, There is nothing in the manpage of packet(7) about RX_RING.
However I can start to write a summary that describes processes,
headers and statuses of both feature (RX_RING and TX_RING).
I think "Socket Options" section of packet(7) is appropriate.
Johann