RTL_TX_HEADER_SIZE
hw->extra_tx_headroom = RTL_TX_HEADER_SIZE;
txdesc8 = skb_push(skb, RTL_TX_HEADER_SIZE);
memset(txdesc, 0, RTL_TX_HEADER_SIZE);
set_tx_desc_offset(txdesc, RTL_TX_HEADER_SIZE);
memset((void *)pdesc, 0, RTL_TX_HEADER_SIZE);
set_tx_desc_offset(pdesc, RTL_TX_HEADER_SIZE);
txdesc = (__le32 *)skb_push(skb, RTL_TX_HEADER_SIZE);
memset(txdesc, 0, RTL_TX_HEADER_SIZE);
set_tx_desc_offset(txdesc, RTL_TX_HEADER_SIZE);
skb_pull(skb, RTL_TX_HEADER_SIZE);