IXGBE_TDH
val = IXGBE_READ_REG(&sc->hw, IXGBE_TDH(txr->me));
IXGBE_WRITE_REG(hw, IXGBE_TDH(j), 0);
nic_i = IXGBE_READ_REG(&sc->hw, IXGBE_TDH(kring->ring_id));