reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext.git/commit/?id=2a52ca7c98960aafb0eca9ef96b2d0c932171357
        git remote add tj-sched-ext https://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext.git
        git fetch --no-tags tj-sched-ext scx-cpuperf
        git checkout 2a52ca7c98960aafb0eca9ef96b2d0c932171357
        # 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 distclean