reproduce:
        git checkout 47ac09b91befbb6a235ab620c32af719f8208399
        b4 shazam https://lore.kernel.org/r/20240829064508.3706672-2-jammy_huang@aspeedtech.com
        make menuconfig
        # enable CONFIG_COMPILE_TEST, CONFIG_WARN_MISSING_DOCUMENTS, CONFIG_WARN_ABI_ERRORS
        # install Sphinx 2.4.4
        make htmldocs