reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/robh/linux.git/commit/?id=d6ee4b64651fba947d99c7567e7f008d323f61f3
        git remote add robh https://git.kernel.org/pub/scm/linux/kernel/git/robh/linux.git
        git fetch --no-tags robh ethos-v6
        git checkout d6ee4b64651fba947d99c7567e7f008d323f61f3

        # install mips cross compiling tool for clang build
        # apt-get install binutils-mips64-linux-gnuabi64
        # clang-22 might not be officially released. Try a lower version if installation fails.
        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=$HOME/0day COMPILER=clang-22 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=mips olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-22 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=mips SHELL=/bin/bash