reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext.git/commit/?id=49668b4d8b790ac182e57d3bab3ac65b5f561192
        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-bandwidth-control
        git checkout 49668b4d8b790ac182e57d3bab3ac65b5f561192
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=i386 olddefconfig
        make W=1 O=build_dir ARCH=i386 SHELL=/bin/bash kernel/