reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/soc/soc.git/commit/?id=061991b5690f233fb8a0248fa1ccb1172443e5c5
        git remote add soc https://git.kernel.org/pub/scm/linux/kernel/git/soc/soc.git
        git fetch --no-tags soc board-remove
        git checkout 061991b5690f233fb8a0248fa1ccb1172443e5c5

        # install arm cross compiling tool for clang build
        # apt-get install binutils-arm-linux-gnueabi
        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=$HOME/0day COMPILER=clang-21 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=arm olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-21 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=arm SHELL=/bin/bash