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
        # https://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs.git/commit/?id=a444dfe1f8508714a93fd5e7aed69d737bc6aa5f
        git remote add viro-vfs https://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs.git
        git fetch --no-tags viro-vfs work.debugfs
        git checkout a444dfe1f8508714a93fd5e7aed69d737bc6aa5f
        # save the config file
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-20 ~/lkp-tests/kbuild/make.cross W=1 ARCH=powerpc olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-20 ~/lkp-tests/kbuild/make.cross W=1 ARCH=powerpc