BMAC_TXBUFS
sc->sc_txdbdma = dbdma_alloc(sc->sc_dmat, BMAC_TXBUFS);
sc->sc_rxbuf = sc->sc_txbuf + BMAC_BUFLEN * BMAC_TXBUFS;
sc->sc_rxbuf_pa = sc->sc_txbuf_pa + BMAC_BUFLEN * BMAC_TXBUFS;
bzero(sc->sc_txcmd, BMAC_TXBUFS * sizeof(dbdma_command_t));
#define BMAC_BUFSZ ((BMAC_RXBUFS + BMAC_TXBUFS + 2) * BMAC_BUFLEN)