IXGBE_FCTRL_UPE
rctl &= (~IXGBE_FCTRL_UPE);
rctl |= (IXGBE_FCTRL_UPE | IXGBE_FCTRL_MPE);
rctl &= ~IXGBE_FCTRL_UPE;
fctrl |= (IXGBE_FCTRL_UPE | IXGBE_FCTRL_MPE);
fctrl &= ~IXGBE_FCTRL_UPE;
fctrl &= ~(IXGBE_FCTRL_UPE | IXGBE_FCTRL_MPE);
fctrl |= IXGBE_FCTRL_UPE;
fctrl &= ~IXGBE_FCTRL_UPE;