Some kernel drivers are not able to handle the link status correctly after DPDK
application sets the PHY to link down.

Implication:
The link status can’t be set to “up” after the NIC is rebound to the kernel
driver. Before a DPDK application quits it will invoke the function
i40e_dev_stop() which will sets the PHY to link down. Some kernel drivers may
not be able to handle the link status correctly after it retakes control of the
device. This is a known PHY link configuration issue in the i40e kernel driver.
The fix has been addressed in the 2.7.4 rc version. So if the i40e kernel
driver is < 2.7.4 and doesn’t have the fix backported it will encounter this
issue.

Resolution/Workaround:
First try to remove and reinsert the i40e kernel driver. If that fails reboot
the system.

Affected Environment/Platform:
All.

Driver/Module:
Poll Mode Driver (PMD).