Hi Vitaly, FYI, the error/warning still remains. tree: https://git.kernel.org/pub/scm/linux/kernel/git/tglx/devel.git x86/entry head: 7f5a4e54ac5fab86776ca040aa9b998e35bf7a86 commit: fad1940a6a856f59b073e8650e02052ce531154c [4/119] x86/xen: Split HVM vector callback setup and interrupt gate allocation config: x86_64-randconfig-a001-20200524 (attached as .config) compiler: clang version 11.0.0 (https://github.com/llvm/llvm-project 3393cc4cebf9969db94dc424b7a2b6195589c33b) 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 fad1940a6a856f59b073e8650e02052ce531154c # 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: kbuild test robot <lkp(a)intel.com&gt; All warnings (new ones prefixed by >>, old ones prefixed by <<): void xen_setup_callback_vector(void) {} ^ drivers/xen/events/events_base.c:1664:1: note: declare 'static' if the function is not intended to be used outside of this translation unit void xen_setup_callback_vector(void) {} ^ static 1 warning generated. vim +/xen_setup_callback_vector +1664 drivers/xen/events/events_base.c 1654 1655 static __init void xen_alloc_callback_vector(void) 1656 { 1657 if (!xen_have_vector_callback) 1658 return; 1659 1660 pr_info("Xen HVM callback vector for event delivery is enabled\n"); 1661 alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR, xen_hvm_callback_vector); 1662 } 1663 #else 1665 static inline void xen_alloc_callback_vector(void) {} 1666 #endif 1667 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org