GMAC_FCB_LEN
struct txfcb *fcb = skb_push(skb, GMAC_FCB_LEN);
memset(fcb, 0, GMAC_FCB_LEN);
fcb_len = GMAC_FCB_LEN;
fcb_len = GMAC_FCB_LEN + GMAC_TXPAL_LEN;
__skb_pull(skb, GMAC_FCB_LEN);
lstatus |= BD_LFLAG(TXBD_CRC | TXBD_READY) | GMAC_FCB_LEN;
GMAC_FCB_LEN + GMAC_TXPAL_LEN;
skb_pull(skb, GMAC_FCB_LEN + GMAC_TXPAL_LEN);
skb_pull(skb, GMAC_FCB_LEN);
dev->needed_headroom = GMAC_FCB_LEN + GMAC_TXPAL_LEN;