RCR_RXEN
smc->b0.rcr = RCR_FILT_CAR | RCR_STRIP_CRC | RCR_RXEN | RCR_ALLMUL;
CSR_WRITE_1(l, RCR, RCR_RXEN | RCR_WTDIS | RCR_DIS_LONG | RCR_DIS_CRC);