IXGBE_VFTDT
regs_buff[37 + i] = IXGBE_READ_REG(hw, IXGBE_VFTDT(i));
IXGBE_WRITE_REG(hw, IXGBE_VFTDT(reg_idx), 0);
ring->tail = adapter->io_addr + IXGBE_VFTDT(reg_idx);
u32 tail = IXGBE_READ_REG(hw, IXGBE_VFTDT(ring->reg_idx));
IXGBE_READ_REG(hw, IXGBE_VFTDT(tx_ring->reg_idx)),