reproduce (this is a W=1 build):
        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests
        # install powerpc cross compiling tool for clang build
        # apt-get install binutils-powerpc-linux-gnu
        # clang-21 might not be officially released. Try a lower version if installation fails.
        # https://github.com/krzk/linux/commit/b2c87200aae5db99ba86065d020ac14a22d22a03
        git remote add krzk-github https://github.com/krzk/linux
        git fetch --no-tags krzk-github pending/dt-bindings-qcom-new-and-fixes-for-warnings-linux-next
        git checkout b2c87200aae5db99ba86065d020ac14a22d22a03
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-21 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=powerpc olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-21 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=powerpc SHELL=/bin/bash crypto/ drivers/ kernel/