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
        git remote add horms-ipvs https://git.kernel.org/pub/scm/linux/kernel/git/horms/ipvs.git
        git fetch horms-ipvs master
        git checkout horms-ipvs/master
        b4 shazam https://lore.kernel.org/r/20240502091847.65181-13-justinlai0215@realtek.com
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-19 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=s390 olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-19 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=s390 SHELL=/bin/bash drivers/net/ethernet/realtek/rtase/