reproduce:
        git remote add robh https://git.kernel.org/pub/scm/linux/kernel/git/robh/linux.git
        git fetch robh for-next
        git checkout robh/for-next
        b4 shazam https://lore.kernel.org/r/20250612221630.45198-1-matthew.gerlach@altera.com
        make menuconfig
        # enable CONFIG_COMPILE_TEST, CONFIG_WARN_MISSING_DOCUMENTS, CONFIG_WARN_ABI_ERRORS
        # install Sphinx 3.4.3
        make htmldocs