reproduce (this is a W=1 build):
        git remote add jack-fs https://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs.git
        git fetch jack-fs for_next
        git checkout jack-fs/for_next
        b4 shazam https://lore.kernel.org/r/19e54c7cba1.5355cb8650862.622752146451851140@zohomail.in

        # install riscv cross compiling tool for clang build
        # apt-get install binutils-riscv64-linux-gnu
        # clang-23 might not be officially released. Try a lower version if installation fails.
        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=$HOME/0day COMPILER=clang-23 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=riscv olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-23 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=riscv SHELL=/bin/bash fs/ext2/