RSTAT
etsec_write(sc, RSTAT, RSTAT_QHLT | RSTAT_RXF);
uint32_t qhlt = etsec_read(sc, RSTAT) & RSTAT_QHLT;
etsec_write(sc, RSTAT, RSTAT_QHLT & rxq->rxq_qmask);
etsec_write(sc, RSTAT, RSTAT_RXF & rxq->rxq_qmask);