reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/niks/linux.git/commit/?id=87b502098882192d5986bcaec909f9a44a45cce4
        git remote add niks https://git.kernel.org/pub/scm/linux/kernel/git/niks/linux.git
        git fetch --no-tags niks b4/uid_slot
        git checkout 87b502098882192d5986bcaec909f9a44a45cce4
        # install loongarch cross compiling tool for clang build
        # apt-get install binutils-loongarch-linux-gnu
        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests
        # apt-get install sparse
        # sparse version: v0.6.4-66-g0196afe1
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-20 ~/lkp-tests/kbuild/make.cross W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__ -fmax-errors=unlimited -fmax-warnings=unlimited' O=build_dir ARCH=loongarch olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-20 ~/lkp-tests/kbuild/make.cross W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__ -fmax-errors=unlimited -fmax-warnings=unlimited' O=build_dir ARCH=loongarch SHELL=/bin/bash drivers/pci/ fs/ceph/