reproduce (this is a W=1 build):
        # https://github.com/zen-kernel/zen-kernel/commit/46ef77681e026cafee56306f59871ab4760809af
        git remote add zen https://github.com/zen-kernel/zen-kernel
        git fetch --no-tags zen 7.2/prjc
        git checkout 46ef77681e026cafee56306f59871ab4760809af

        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=um olddefconfig
        make W=1 O=build_dir ARCH=um SHELL=/bin/bash kernel/