Use "cmake ../ -DKERNEL=ON" to build the Linux kernel driver (Experimental). Needs a recent kernel and libv4l2. Will need extra work to support Airspy and Hackrf. Needs "cp KERNEL_SOURCE/include/linux/compiler.h /usr/include/linux/" and "cp KERNEL_SOURCE/include/uapi/linux/videodev2.h /usr/include/uapi/linux/" and package "libv4l-dev".