The PCI bwfm(4) chips have no TX rings in the traditional sense, as on

The PCI bwfm(4) chips have no TX rings in the traditional sense, as on
the actual rings we only share messages.  Sending a TX packet means
putting a message on the ring which contains a pktid (which for us maps
to an mbuf) and the physical address of the mbuf.  On jcs@'s macbook he
seems to run out of TX pktids pretty quickly during a speedtest.  This
would mean that there are 2048 TX packets in flight that we either want
to send out or that have not been "acked" by the firmware yet.  Either
way, recover from that situation when we hit that arbitrary limit by
restarting the queue after we free'd a packet from the TX pktid list.

Tested by jcs@