tree: https://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git bleeding-edge head: 506a524e05e240d2878cf86a56c47e72e09d329f commit: bc5706eaeae0b51385d3859b0fdf17a2c8fdc134 [46/47] ACPI: processor: Fix CPU0 wakeup in acpi_idle_play_dead() config: x86_64-randconfig-a012-20210330 (attached as .config) compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project 482283042f795ecc27838a3b2f76b5494991401c) 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 # https://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git/commi... git remote add pm https://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git git fetch --no-tags pm bleeding-edge git checkout bc5706eaeae0b51385d3859b0fdf17a2c8fdc134 # 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 >>): #ifdef defined(CONFIG_X86) && defined(CONFIG_HOTPLUG_CPU) ^ // drivers/acpi/processor_idle.c:1103:12: warning: no previous prototype for function 'acpi_processor_ffh_lpi_probe' [-Wmissing-prototypes] int __weak acpi_processor_ffh_lpi_probe(unsigned int cpu) ^ drivers/acpi/processor_idle.c:1103:1: note: declare 'static' if the function is not intended to be used outside of this translation unit int __weak acpi_processor_ffh_lpi_probe(unsigned int cpu) ^ static drivers/acpi/processor_idle.c:1108:12: warning: no previous prototype for function 'acpi_processor_ffh_lpi_enter' [-Wmissing-prototypes] int __weak acpi_processor_ffh_lpi_enter(struct acpi_lpi_state *lpi) ^ drivers/acpi/processor_idle.c:1108:1: note: declare 'static' if the function is not intended to be used outside of this translation unit int __weak acpi_processor_ffh_lpi_enter(struct acpi_lpi_state *lpi) ^ static 3 warnings generated. vim +546 drivers/acpi/processor_idle.c 524 525 /** 526 * acpi_idle_play_dead - enters an ACPI state for long-term idle (i.e. off-lining) 527 * @dev: the target CPU 528 * @index: the index of suggested state 529 */ 530 static int acpi_idle_play_dead(struct cpuidle_device *dev, int index) 531 { 532 struct acpi_processor_cx *cx = per_cpu(acpi_cstate[index], dev->cpu); 533 534 ACPI_FLUSH_CPU_CACHE(); 535 536 while (1) { 537 538 if (cx->entry_method == ACPI_CSTATE_HALT) 539 safe_halt(); 540 else if (cx->entry_method == ACPI_CSTATE_SYSTEMIO) { 541 inb(cx->address); 542 wait_for_freeze(); 543 } else 544 return -ENODEV; 545 547 /* If NMI wants to wake up CPU0, start CPU0. */ 548 if (wakeup_cpu0()) 549 start_cpu0(); 550 #endif 551 } 552 553 /* Never reached */ 554 return 0; 555 } 556 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org