reproduce (this is a W=1 build):
        # https://github.com/jimc/linux/commit/c3746eba32683abe010272527c9ef1aede38c68b
        git remote add jimc https://github.com/jimc/linux.git
        git fetch --no-tags jimc dd-shrink-4d
        git checkout c3746eba32683abe010272527c9ef1aede38c68b
        # 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 lib/