tree: https://git.kernel.org/pub/scm/linux/kernel/git/djbw/nvdimm.git libnvdimm-pending head: 17c5211450a8fb964757f9f51cae1dc9f973e5ee commit: 084a33058b0518760f04823e55fa17fd813f51fc [4/22] ACPI: HMAT: Refactor hmat_register_target_device to hmem_register_device config: x86_64-allyesconfig (attached as .config) compiler: clang version 11.0.0 (https://github.com/llvm/llvm-project 02946de3802d3bc65bc9f2eb9b8d4969b5a7add8) reproduce (this is a W=1 build): wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross # install x86_64 cross compiling tool for clang build # apt-get install binutils-x86-64-linux-gnu git checkout 084a33058b0518760f04823e55fa17fd813f51fc # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=x86_64 If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All warnings (new ones prefixed by >>): void hmem_register_device(int target_nid, struct resource *r) ^ drivers/dax/hmem/device.c:7:1: note: declare 'static' if the function is not intended to be used outside of this translation unit void hmem_register_device(int target_nid, struct resource *r) ^ static 1 warning generated. vim +/hmem_register_device +7 drivers/dax/hmem/device.c 6 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org