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-riscv64-linux-gnu
        # https://github.com/zen-kernel/zen-kernel/commit/d423eb552e8d9ccb6577937f3cf762b783679f8e
        git remote add zen https://github.com/zen-kernel/zen-kernel
        git fetch --no-tags zen 6.10/main
        git checkout d423eb552e8d9ccb6577937f3cf762b783679f8e
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-20 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=riscv olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-20 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=riscv SHELL=/bin/bash kernel/