reproduce:
        # https://github.com/Xilinx/linux-xlnx/commit/4740565c61cdf6bfaa87e268e934fdb24511becc
        git remote add xilinx-xlnx https://github.com/Xilinx/linux-xlnx
        git fetch --no-tags xilinx-xlnx master
        git checkout 4740565c61cdf6bfaa87e268e934fdb24511becc
        make menuconfig
        # enable CONFIG_COMPILE_TEST, CONFIG_WARN_MISSING_DOCUMENTS, CONFIG_WARN_ABI_ERRORS
        # pip install -r Documentation/sphinx/requirements.txt
        make htmldocs