reproduce (this is a W=1 build):
        # https://github.com/ceph/ceph-client/commit/a0479e90ee5778543f7bcaafd85387c2eea73126
        git remote add ceph-client https://github.com/ceph/ceph-client.git
        git fetch --no-tags ceph-client pr/29
        git checkout a0479e90ee5778543f7bcaafd85387c2eea73126

        # install powerpc cross compiling tool for clang build
        # apt-get install binutils-powerpc64-linux-gnu
        # clang-22 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=$HOME/0day COMPILER=clang-22 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=powerpc olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-22 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=powerpc SHELL=/bin/bash