reproduce (this is a W=1 build):
        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests
        # https://git.kernel.org/pub/scm/linux/kernel/git/robh/linux.git/commit/?id=2146bfc43e891f1ee2c62e3be5d536b64cb66ae9
        git remote add robh https://git.kernel.org/pub/scm/linux/kernel/git/robh/linux.git
        git fetch --no-tags robh ethos-v2
        git checkout 2146bfc43e891f1ee2c62e3be5d536b64cb66ae9
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=mips olddefconfig
        ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=mips SHELL=/bin/bash drivers/accel/ethos/