reproduce (this is a W=1 build):
        # https://github.com/linuxppc/linux/commit/92258b5bf1ec10204c23a793793a65dc92d17014
        git remote add linuxppc https://github.com/linuxppc/linux
        git fetch --no-tags linuxppc next-test
        git checkout 92258b5bf1ec10204c23a793793a65dc92d17014

        # install powerpc cross compiling tool for clang build
        # apt-get install binutils-powerpc-linux-gnu
        # clang-23 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=$HOME/0day COMPILER=clang-23 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=powerpc olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-23 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=powerpc SHELL=/bin/bash arch/powerpc/net/