reproduce (this is a W=1 build):
        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests
        # install s390 cross compiling tool for clang build
        # apt-get install binutils-s390x-linux-gnu
        # https://github.com/lunn/linux/commit/bbf56e8f7d5498f3221826f0608649ddd997afa9
        git remote add lunn https://github.com/lunn/linux.git
        git fetch --no-tags lunn v6.15-rc1-next-next-inband
        git checkout bbf56e8f7d5498f3221826f0608649ddd997afa9
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-18 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=s390 olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-18 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=s390 SHELL=/bin/bash drivers/net/dsa/qca/