reproduce (this is a W=1 build):
        # https://github.com/alexshi/linux/commit/5f1e1e6fa5c4f220ae98b166aed05ca99ae7411d
        git remote add alexshi https://github.com/alexshi/linux.git
        git fetch --no-tags alexshi isolation
        git checkout 5f1e1e6fa5c4f220ae98b166aed05ca99ae7411d
        # 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