reproduce (this is a W=1 build):
        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests
        git remote add spacemit https://github.com/spacemit-com/linux
        git fetch spacemit for-next
        git checkout spacemit/for-next
        b4 shazam https://lore.kernel.org/r/20250903145334.425633-1-hendrik.hamerlinck@hammernet.be
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.5.0 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=riscv olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.5.0 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=riscv SHELL=/bin/bash dtbs_check