reproduce (this is a W=1 build):
        # https://github.com/multipath-tcp/mptcp_net-next/commit/b03554f51454944c778c34b3d752337d805887fa
        git remote add mptcp https://github.com/multipath-tcp/mptcp_net-next.git
        git fetch --no-tags mptcp export-net
        git checkout b03554f51454944c778c34b3d752337d805887fa

        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=$HOME/0day COMPILER=gcc-15.2.0 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=openrisc olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-15.2.0 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=openrisc SHELL=/bin/bash