bge_tx_bd
sizeof(struct bge_tx_bd));
struct bge_tx_bd *cur_tx;
struct bge_tx_bd *d;
((ringno * sizeof(struct bge_tx_bd) * size) / 4)
struct bge_tx_bd *bge_tx_ring;
(sizeof(struct bge_tx_bd) * BGE_TX_RING_CNT)