reproduce:
        # https://github.com/Xilinx/linux-xlnx/commit/16a2a853f1bd633c9a7c8c9721d9f31bf9aaf505
        git remote add xilinx-xlnx https://github.com/Xilinx/linux-xlnx
        git fetch --no-tags xilinx-xlnx master
        git checkout 16a2a853f1bd633c9a7c8c9721d9f31bf9aaf505
        make menuconfig
        # enable CONFIG_COMPILE_TEST, CONFIG_WARN_MISSING_DOCUMENTS, CONFIG_WARN_ABI_ERRORS
        # pip install -r Documentation/sphinx/requirements.txt
        make htmldocs