MAX_TX_DESC_CNT
#define MAX_TX_AVAIL (MAX_TX_DESC_CNT * NUM_TX_RINGS - 2)
#define NEXT_TX_IDX(x) ((((x) & MAX_TX_DESC_CNT) == \
(MAX_TX_DESC_CNT - 1)) ? \
#define TX_BD_POFF(x) ((x) & MAX_TX_DESC_CNT)
(((bds) + MAX_TX_DESC_CNT - 1) / \
MAX_TX_DESC_CNT * NEXT_PAGE_TX_DESC_CNT)