reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/commit/?id=8375dadb8d4c6de0dc916ea50b376d9d946ce544
        git remote add tip https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git
        git fetch --no-tags tip master
        git checkout 8375dadb8d4c6de0dc916ea50b376d9d946ce544

        # 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