reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma.git/commit/?id=e873663e5f05f355aa40e372f516fe3949fdfc61
        git remote add rdma-rdma https://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma.git
        git fetch --no-tags rdma-rdma wip/leon-for-next
        git checkout e873663e5f05f355aa40e372f516fe3949fdfc61

        # install loongarch cross compiling tool for clang build
        # apt-get install binutils-loongarch-linux-gnu
        # clang-22 might not be officially released. Try a lower version if installation fails.
        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=$HOME/0day COMPILER=clang-22 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=loongarch olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-22 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=loongarch SHELL=/bin/bash drivers/infiniband/hw/bng_re/