Hi Nicholas, I love your patch! Yet something to improve: [auto build test ERROR on powerpc/next] [also build test ERROR on v5.16-rc1 next-20211115] [If your patch is applied to the wrong git tree, kindly drop us a note. And when submitting patch, we suggest to use '--base' as documented in https://git-scm.com/docs/git-format-patch] url: https://github.com/0day-ci/linux/commits/Nicholas-Piggin/powerpc-64s-Get-... base: https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git next config: powerpc64-randconfig-c024-20211115 (attached as .config) compiler: powerpc64-linux-gcc (GCC) 11.2.0 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 # https://github.com/0day-ci/linux/commit/b8fe7181506bf3011295456a9ee471ddf... git remote add linux-review https://github.com/0day-ci/linux git fetch --no-tags linux-review Nicholas-Piggin/powerpc-64s-Get-LPID-bit-width-from-device-tree/20211110-160038 git checkout b8fe7181506bf3011295456a9ee471ddf49d694d # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross ARCH=powerpc If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All errors (new ones prefixed by >>): arch/powerpc/mm/init_64.c: In function 'mmu_early_init_devtree': 472 | int rc; | ^~ cc1: all warnings being treated as errors vim +/rc +472 arch/powerpc/mm/init_64.c 469 470 void __init mmu_early_init_devtree(void) 471 { --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org