reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/jfern/linux.git/commit/?id=bac6d97ec2be6650f81c945564fcb76669ef4251
        git remote add jfern https://git.kernel.org/pub/scm/linux/kernel/git/jfern/linux.git
        git fetch --no-tags jfern sched/scx-dlserver-boost
        git checkout bac6d97ec2be6650f81c945564fcb76669ef4251
        # 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