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/jgunthorpe/linux/commit/e7b7ae31414a4f3db3fecb2bab0a2f101fff1bcf
        git remote add jgunthorpe https://github.com/jgunthorpe/linux
        git fetch --no-tags jgunthorpe fwctl
        git checkout e7b7ae31414a4f3db3fecb2bab0a2f101fff1bcf
        # 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