reproduce (this is a W=1 build):
        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests
        # install powerpc cross compiling tool for clang build
        # apt-get install binutils-powerpc64-linux-gnu
        # https://github.com/alexshi/linux/commit/8ac2ea5f299444d065b292043aed0a1e94996159
        git remote add alexshi https://github.com/alexshi/linux.git
        git fetch --no-tags alexshi ptdesc
        git checkout 8ac2ea5f299444d065b292043aed0a1e94996159
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-20 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=powerpc olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-20 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=powerpc prepare