tree: https://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git bleeding-edge head: a70fdf61936ab0200d31bebea4b44bb67454ce07 commit: 5f5e49e999acd8556e694e841d63226d21e409d9 [47/48] ACPI: processor: Fix CPU0 wakeup in acpi_idle_play_dead() config: i386-randconfig-a014-20210329 (attached as .config) compiler: gcc-9 (Debian 9.3.0-22) 9.3.0 reproduce (this is a W=1 build): # 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 5f5e49e999acd8556e694e841d63226d21e409d9 # save the attached .config to linux build tree make W=1 ARCH=i386 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 >>): drivers/acpi/processor_idle.c: In function 'acpi_idle_play_dead': 548 | if (wakeup_cpu0()) | ^~~~~~~~~~~ 549 | start_cpu0(); | ^~~~~~~~~~ | task_cpu drivers/acpi/processor_idle.c: At top level: drivers/acpi/processor_idle.c:1103:12: warning: no previous prototype for 'acpi_processor_ffh_lpi_probe' [-Wmissing-prototypes] 1103 | int __weak acpi_processor_ffh_lpi_probe(unsigned int cpu) | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~ drivers/acpi/processor_idle.c:1108:12: warning: no previous prototype for 'acpi_processor_ffh_lpi_enter' [-Wmissing-prototypes] 1108 | int __weak acpi_processor_ffh_lpi_enter(struct acpi_lpi_state *lpi) | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~ cc1: some warnings being treated as errors vim +/wakeup_cpu0 +548 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; 545 546 #ifdef CONFIG_X86 547 /* If NMI wants to wake up CPU0, 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