reproduce (this is a W=1 build):
        # https://github.com/cilium/linux/commit/9af2f31e06cb3dd2f2d62545b4fc6ae8b94ebdaa
        git remote add cilium https://github.com/cilium/linux.git
        git fetch --no-tags cilium pr/v6fix
        git checkout 9af2f31e06cb3dd2f2d62545b4fc6ae8b94ebdaa

        # install sparc64 cross compiling tool for clang build
        # apt-get install binutils-sparc64-linux-gnu
        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=$HOME/0day COMPILER=clang-20 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=sparc64 olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-20 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=sparc64 SHELL=/bin/bash net/