AGE_TX_RING_SZ
bzero(rd->age_tx_ring, AGE_TX_RING_SZ);
error = bus_dmamap_create(sc->sc_dmat, AGE_TX_RING_SZ, 1,
AGE_TX_RING_SZ, 0, BUS_DMA_NOWAIT, &sc->age_cdata.age_tx_ring_map);
error = bus_dmamem_alloc(sc->sc_dmat, AGE_TX_RING_SZ,
nsegs, AGE_TX_RING_SZ, (caddr_t *)&sc->age_rdata.age_tx_ring,
sc->age_rdata.age_tx_ring, AGE_TX_RING_SZ, NULL, BUS_DMA_WAITOK);