reproduce (this is a W=1 build):
        git remote add kees https://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git
        git fetch kees for-next/kspp
        git checkout kees/for-next/kspp
        b4 shazam https://lore.kernel.org/r/20260908125155.1777895-1-qirui.001@bytedance.com

        # install riscv cross compiling tool for clang build
        # apt-get install binutils-riscv64-linux-gnu
        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests

        # 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 arch/riscv/kernel/ kernel/