Hi Rongwei, Thank you for the patch! Perhaps something to improve: [auto build test WARNING on arm64/for-next/core] [also build test WARNING on v5.10-rc6 next-20201130] [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/Rongwei-Wang/arm64-msr-Add-MSR-d... base: https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-next/core config: arm64-allyesconfig (attached as .config) compiler: aarch64-linux-gcc (GCC) 9.3.0 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/00ac9cd26a786bf9c061bc7e524f31484... git remote add linux-review https://github.com/0day-ci/linux git fetch --no-tags linux-review Rongwei-Wang/arm64-msr-Add-MSR-driver/20201201-015322 git checkout 00ac9cd26a786bf9c061bc7e524f31484408f8c1 # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=arm64 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 >>): arch/arm64/kernel/msr_arm.c: In function 'msr_open': 292 | struct cpuinfo_arm64 *c; | ^ vim +/c +292 arch/arm64/kernel/msr_arm.c 287 288 static int msr_open(struct inode *inode, struct file *file) 289 { 290 unsigned int cpu = iminor(file_inode(file)); 291 /* TODO */ 293 294 if (!capable(CAP_SYS_RAWIO)) 295 return -EPERM; 296 297 if (cpu >= nr_cpu_ids || !cpu_online(cpu)) 298 return -ENXIO; /* No such CPU */ 299 300 c = &per_cpu(cpu_data, cpu); 301 return 0; 302 } 303 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org