[openadk] Skip kernel building? (rootfs only mode)

Hello there! This is a really simple one but I haven't been able to find it yet. Since there are various configurations in the tasks/ folder, I would like to know if it would be possible to make one, in which a kernel image is not built? Reason being that I am trying to construct a rootfs for a Docker container. So, a kernel is not needed - just the headers. Is that possible? Kind regards, Ingwie