The kernel-alt is there for debugging purposes and should not be used during normal operation, especially if you want to maintain optimal performance.
Alternative driver versions may be offered instead of driver updates. This is the case for the Intel i40e. The default version is 2.25.11-2, and its alternative (-alt) version is 2.26.8-1. This is simply a more up-to-date version of the driver.
You can therefore try this version (which is independent of the kernel-alt). It installs over the default XCP-ng installation and therefore over the standard kernel:
yum install intel-i40e-alt
Hopefully this more up-to-date version will help you.
