reproduce (this is a W=1 build):
        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests
        # https://github.com/congwang/linux/commit/d98266a1c1626a662b9712500b687adfdfef9bda
        git remote add congwang https://github.com/congwang/linux.git
        git fetch --no-tags congwang tcp_bpf
        git checkout d98266a1c1626a662b9712500b687adfdfef9bda
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-14.2.0 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=sparc64 olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-14.2.0 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=sparc64 SHELL=/bin/bash net/ipv4/