DESC_RING_WRAP
(entry == TX_RING_SIZE-1) ? cpu_to_le32(DESC_RING_WRAP) : 0;
tx_flags |= DESC_RING_WRAP; /* Wrap ring. */
tp->rx_ring[i-1].length = cpu_to_le32(PKT_BUF_SZ | DESC_RING_WRAP);
flag = 0xe0000000 | DESC_RING_WRAP;