Hi Arnd, First bad commit (maybe != root cause): tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master head: 0aa78d17099b04fd9d36fe338af48ad6fe2d7fca commit: 71b9114d2c13a648fbe6523dd859e611c316ad90 ARM: s3c: move into a common directory date: 12 months ago config: arm-randconfig-r023-20210815 (attached as .config) compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project 1f7b25ea76a925aca690da28de9d78db7ca99d0c) 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://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit... git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git git fetch --no-tags linus master git checkout 71b9114d2c13a648fbe6523dd859e611c316ad90 # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=arm 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 >>): unsigned long tmp = 0; ^ 1 warning generated. -- unsigned int s3c2410_modify_misccr(unsigned int clear, unsigned int change) ^ arch/arm/mach-s3c/gpio-samsung.c:1309:1: note: declare 'static' if the function is not intended to be used outside of this translation unit unsigned int s3c2410_modify_misccr(unsigned int clear, unsigned int change) ^ static 1 warning generated. vim +/tmp +177 arch/arm/mach-s3c/s3c24xx.c 68d9ab394f06f9 arch/arm/mach-s3c2410/cpu.c Ben Dooks 2006-06-24 174 92311272c1a514 arch/arm/plat-s3c24xx/cpu.c Nicolas Pitre 2011-08-03 175 static void s3c24xx_default_idle(void) 92311272c1a514 arch/arm/plat-s3c24xx/cpu.c Nicolas Pitre 2011-08-03 176 { 813f13e7d6ad23 arch/arm/mach-s3c24xx/common.c Cong Ding 2013-01-18 @177 unsigned long tmp = 0; 92311272c1a514 arch/arm/plat-s3c24xx/cpu.c Nicolas Pitre 2011-08-03 178 int i; 92311272c1a514 arch/arm/plat-s3c24xx/cpu.c Nicolas Pitre 2011-08-03 179 92311272c1a514 arch/arm/plat-s3c24xx/cpu.c Nicolas Pitre 2011-08-03 180 /* idle the system by using the idle mode which will wait for an 92311272c1a514 arch/arm/plat-s3c24xx/cpu.c Nicolas Pitre 2011-08-03 181 * interrupt to happen before restarting the system. 92311272c1a514 arch/arm/plat-s3c24xx/cpu.c Nicolas Pitre 2011-08-03 182 */ 92311272c1a514 arch/arm/plat-s3c24xx/cpu.c Nicolas Pitre 2011-08-03 183 92311272c1a514 arch/arm/plat-s3c24xx/cpu.c Nicolas Pitre 2011-08-03 184 /* Warning: going into idle state upsets jtag scanning */ 92311272c1a514 arch/arm/plat-s3c24xx/cpu.c Nicolas Pitre 2011-08-03 185 92311272c1a514 arch/arm/plat-s3c24xx/cpu.c Nicolas Pitre 2011-08-03 186 __raw_writel(__raw_readl(S3C2410_CLKCON) | S3C2410_CLKCON_IDLE, 92311272c1a514 arch/arm/plat-s3c24xx/cpu.c Nicolas Pitre 2011-08-03 187 S3C2410_CLKCON); 92311272c1a514 arch/arm/plat-s3c24xx/cpu.c Nicolas Pitre 2011-08-03 188 92311272c1a514 arch/arm/plat-s3c24xx/cpu.c Nicolas Pitre 2011-08-03 189 /* the samsung port seems to do a loop and then unset idle.. */ 92311272c1a514 arch/arm/plat-s3c24xx/cpu.c Nicolas Pitre 2011-08-03 190 for (i = 0; i < 50; i++) 92311272c1a514 arch/arm/plat-s3c24xx/cpu.c Nicolas Pitre 2011-08-03 191 tmp += __raw_readl(S3C2410_CLKCON); /* ensure loop not optimised out */ 92311272c1a514 arch/arm/plat-s3c24xx/cpu.c Nicolas Pitre 2011-08-03 192 92311272c1a514 arch/arm/plat-s3c24xx/cpu.c Nicolas Pitre 2011-08-03 193 /* this bit is not cleared on re-start... */ 92311272c1a514 arch/arm/plat-s3c24xx/cpu.c Nicolas Pitre 2011-08-03 194 92311272c1a514 arch/arm/plat-s3c24xx/cpu.c Nicolas Pitre 2011-08-03 195 __raw_writel(__raw_readl(S3C2410_CLKCON) & ~S3C2410_CLKCON_IDLE, 92311272c1a514 arch/arm/plat-s3c24xx/cpu.c Nicolas Pitre 2011-08-03 196 S3C2410_CLKCON); 92311272c1a514 arch/arm/plat-s3c24xx/cpu.c Nicolas Pitre 2011-08-03 197 } 92311272c1a514 arch/arm/plat-s3c24xx/cpu.c Nicolas Pitre 2011-08-03 198 :::::: The code at line 177 was first introduced by commit :::::: 813f13e7d6ad239bb1003041f4cfae13ae27b14d ARM: S3C24XX: fix uninitialized variable warning :::::: TO: Cong Ding <dinggnu(a)gmail.com&gt; :::::: CC: Kukjin Kim <kgene.kim(a)samsung.com&gt; --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org