reproduce:
        # https://github.com/cornelisnetworks/linux/commit/bce4b75564c769741d87d441093328ee3463694e
        git remote add cornelisnetworks https://github.com/cornelisnetworks/linux.git
        git fetch --no-tags cornelisnetworks for-upstream-20250627-1
        git checkout bce4b75564c769741d87d441093328ee3463694e
        make menuconfig
        # enable CONFIG_COMPILE_TEST, CONFIG_WARN_MISSING_DOCUMENTS, CONFIG_WARN_ABI_ERRORS
        # install Sphinx 3.4.3
        make htmldocs