reproduce (this is a W=1 build):
        git remote add mptcp https://github.com/multipath-tcp/mptcp_net-next.git
        git fetch mptcp export
        git checkout mptcp/export
        b4 shazam https://lore.kernel.org/r/32da8f2876b30d35602232e9021d312bd105b2de.1762485513.git.tanggeliang@kylinos.cn

        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=$HOME/0day COMPILER=gcc-12.5.0 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=riscv olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.5.0 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=riscv SHELL=/bin/bash net/core/