XGBE_TX_DESC_CNT
sc->prv.tx_desc_count = XGBE_TX_DESC_CNT;
MPASS(powerof2(XGBE_TX_DESC_CNT));
pdata->tx_desc_count = XGBE_TX_DESC_CNT;
#define XGBE_TX_DESC_MIN_FREE (XGBE_TX_DESC_CNT >> 3)
#define XGBE_TX_DESC_MAX_PROC (XGBE_TX_DESC_CNT >> 1)