reproduce:
        git remote add drm-xe https://gitlab.freedesktop.org/drm/xe/kernel.git
        git fetch --no-tags drm-xe drm-xe-next
        git checkout cc2a6cbd6823678fe70ba76f88623827a6e06a87
        make menuconfig
        # enable CONFIG_COMPILE_TEST, CONFIG_WARN_MISSING_DOCUMENTS, CONFIG_WARN_ABI_ERRORS
        # pip install -r Documentation/sphinx/requirements.txt
        make htmldocs