cpu_to_dma
np->rx_ring[i].rxaddr = cpu_to_dma(np->rx_info[i].mapping | RxDescValid);
np->rx_ring[RX_RING_SIZE - 1].rxaddr |= cpu_to_dma(RxDescEndRing);
np->tx_ring[entry].addr = cpu_to_dma(np->tx_info[entry].mapping);
cpu_to_dma(np->rx_info[entry].mapping | RxDescValid);
np->rx_ring[entry].rxaddr |= cpu_to_dma(RxDescEndRing);
np->rx_ring[i].rxaddr = cpu_to_dma(0xBADF00D0); /* An invalid address. */