tree: https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86/entry head: 095b7a3e7745e6fb7cf0a1c09967c4f43e76f8f4 commit: fad1940a6a856f59b073e8650e02052ce531154c [4/80] x86/xen: Split HVM vector callback setup and interrupt gate allocation config: arm-randconfig-r013-20200519 (attached as .config) compiler: arm-linux-gnueabi-gcc (GCC) 9.3.0 reproduce: wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross git checkout fad1940a6a856f59b073e8650e02052ce531154c # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=arm 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 <<): >> drivers/xen/events/events_base.c:1664:6: warning: no previous prototype for 'xen_setup_callback_vector' [-Wmissing-prototypes] 1664 | void xen_setup_callback_vector(void) {} | ^~~~~~~~~~~~~~~~~~~~~~~~~ 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 > 1664 void xen_setup_callback_vector(void) {}

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