reproduce (this is a W=1 build):
        # https://github.com/norov/linux/commit/2985d417a6ad2d864d53f69743b601ce51e36c6d
        git remote add norov https://github.com/norov/linux
        git fetch --no-tags norov fns-removal
        git checkout 2985d417a6ad2d864d53f69743b601ce51e36c6d
        # 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 prepare