reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git/commit/?id=f394a8df5bf700bb265f631664fbfb1cb42b69ad
        git remote add kees https://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git
        git fetch --no-tags kees for-next/kspp
        git checkout f394a8df5bf700bb265f631664fbfb1cb42b69ad
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=x86_64 olddefconfig
        make W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash