tree: https://git.kernel.org/pub/scm/linux/kernel/git/joro/linux.git sev-es-client-tip-5.9 head: 7e2e0f5fb47e16dec0e6b81ce2ee36abb4c28eb9 commit: 81d96c582b1dbd5e6bd431d0dfc26fe967fdad45 [70/76] x86/smpboot: Setup TSS for starting AP config: x86_64-randconfig-r011-20200817 (attached as .config) compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project de71b46a519db014ce906a39f8a0e1b235ef1568) 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 git checkout 81d96c582b1dbd5e6bd431d0dfc26fe967fdad45 # 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 >>): arch/x86/kernel/head64.c:400:13: warning: no previous prototype for function 'do_early_exception' [-Wmissing-prototypes] void __init do_early_exception(struct pt_regs *regs, int trapnr) ^ arch/x86/kernel/head64.c:400:1: note: declare 'static' if the function is not intended to be used outside of this translation unit void __init do_early_exception(struct pt_regs *regs, int trapnr) ^ static void __head early_load_tss(void) ^ arch/x86/kernel/head64.c:549:1: note: declare 'static' if the function is not intended to be used outside of this translation unit void __head early_load_tss(void) ^ static 2 warnings generated. # https://git.kernel.org/pub/scm/linux/kernel/git/joro/linux.git/commit/?id... git remote add joro https://git.kernel.org/pub/scm/linux/kernel/git/joro/linux.git git fetch --no-tags joro sev-es-client-tip-5.9 git checkout 81d96c582b1dbd5e6bd431d0dfc26fe967fdad45 vim +/early_load_tss +549 arch/x86/kernel/head64.c 548 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org