tree: https://git.kernel.org/pub/scm/linux/kernel/git/joro/linux.git sev-es-client-tip head: 57349dbe54433697c5b96bd5d8b5bd7499754d2b commit: c12cc81e6b52de5e4c779e29d7ec903eff341cbc [29/76] x86/head/64: Install startup GDT config: x86_64-allyesconfig (attached as .config) compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project ed6b578040a85977026c93bf4188f996148f3218) 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 c12cc81e6b52de5e4c779e29d7ec903eff341cbc # 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 >>): void __head startup_64_setup_env(unsigned long physbase) ^ arch/x86/kernel/head64.c:514:1: note: declare 'static' if the function is not intended to be used outside of this translation unit void __head startup_64_setup_env(unsigned long physbase) ^ static 1 warning generated. vim +/startup_64_setup_env +514 arch/x86/kernel/head64.c 510 511 /* 512 * Setup boot CPU state needed before kernel switches to virtual addresses. 513 */ --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org