RCVDESCUF
sc->sc_intmask |= RCVINT | RCVFIFOOF | RCVDESCUF;
if (intstatus & RCVDESCUF) {
intmask &= ~RCVDESCUF;
intmask |= RCVDESCUF;
sc->sc_intmask |= RCVINT | RCVDESCUF | RCVFIFOOF;