reproduce (this is a W=1 build):
        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests
        # https://git.kernel.org/pub/scm/linux/kernel/git/palmer/linux.git/commit/?id=3db02a78faf494fd44a2a9a29d3b159704ab00d0
        git remote add palmer https://git.kernel.org/pub/scm/linux/kernel/git/palmer/linux.git
        git fetch --no-tags palmer wip-hwprobe
        git checkout 3db02a78faf494fd44a2a9a29d3b159704ab00d0
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-10.5.0 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=riscv olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-10.5.0 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=riscv SHELL=/bin/bash arch/riscv/