reproduce (this is a W=1 build):
        # https://github.com/jcmvbkbc/linux-xtensa/commit/0c125b4fcef40ea2c876496f0e3b9b6e74dcebde
        git remote add jcmvbkbc-xtensa https://github.com/jcmvbkbc/linux-xtensa
        git fetch --no-tags jcmvbkbc-xtensa pr/26
        git checkout 0c125b4fcef40ea2c876496f0e3b9b6e74dcebde

        # 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