reproduce (this is a W=1 build):
        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests
        # install riscv cross compiling tool for clang build
        # apt-get install binutils-riscv-linux-gnu
        # https://github.com/alobakin/linux/commit/ad64ef5bd3f5573b788559ba8599613ef80b3794
        git remote add alobakin https://github.com/alobakin/linux
        git fetch --no-tags alobakin libeth
        git checkout ad64ef5bd3f5573b788559ba8599613ef80b3794
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-21 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=riscv olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-21 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=riscv SHELL=/bin/bash drivers/net/