reproduce (this is a W=1 build):
        # https://github.com/gourryinverse/linux/commit/bffbc25036a9d12170b0fac9418be694af8622b5
        git remote add gourryinverse https://github.com/gourryinverse/linux
        git fetch --no-tags gourryinverse scratch/gourry/managed_nodes/rfc6-complete
        git checkout bffbc25036a9d12170b0fac9418be694af8622b5

        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests

        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-8.5.0 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=xtensa olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-8.5.0 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=xtensa SHELL=/bin/bash mm/