license (GPL) will require all applications using this kernel be GPL'ed

[bogen85]

Is that what you intend? For every application that uses this kernel be GPL'ed?

A unikernel is statically linked to all applications using. If the unikernel is GPL'ed, that requires the same kind of license for the applications.

There is no "at a distance" relationship with the kernel here.

If this is what you intend (that everyone using this unikernel GPL what they would write with it, if they distribute any of what they write) than that is fine, as it is your choice obviously.

But if that is not what you intend, you might want to add a linking exception, or use a different license.

Since you chose a strict GPL license in the first place, a linking exception might make the most sense. Changes to and source for the unikernel in the distributed apps would still be required to be distributed, but the source to the applications would not.