Hi Juergen, I love your patch! Perhaps something to improve: [auto build test WARNING on v5.10-rc4] [also build test WARNING on next-20201120] [cannot apply to tip/x86/core xen-tip/linux-next tip/x86/asm] [If your patch is applied to the wrong git tree, kindly drop us a note. And when submitting patch, we suggest to use '--base' as documented in https://git-scm.com/docs/git-format-patch] url: https://github.com/0day-ci/linux/commits/Juergen-Gross/x86-major-paravirt-cleanup/20201120-194934 base: 09162bc32c880a791c6c0668ce0745cf7958f576 config: x86_64-randconfig-r014-20201120 (attached as .config) compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project 3ded927cf80ac519f9f9c4664fef08787f7c537d) 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 # https://github.com/0day-ci/linux/commit/340df5e02c66ec37486a1f31e6497a22dab65059 git remote add linux-review https://github.com/0day-ci/linux git fetch --no-tags linux-review Juergen-Gross/x86-major-paravirt-cleanup/20201120-194934 git checkout 340df5e02c66ec37486a1f31e6497a22dab65059 # 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 All warnings (new ones prefixed by >>): >> arch/x86/kernel/paravirt.c:124:10: warning: no previous prototype for function 'paravirt_patch_insns' [-Wmissing-prototypes] unsigned paravirt_patch_insns(void *insn_buff, unsigned len, ^ arch/x86/kernel/paravirt.c:124:1: note: declare 'static' if the function is not intended to be used outside of this translation unit unsigned paravirt_patch_insns(void *insn_buff, unsigned len, ^ static 1 warning generated. vim +/paravirt_patch_insns +124 arch/x86/kernel/paravirt.c 63f70270ccd981c arch/i386/kernel/paravirt.c Jeremy Fitzhardinge 2007-05-02 123 1fc654cf6e04b40 arch/x86/kernel/paravirt.c Ingo Molnar 2019-04-25 @124 unsigned paravirt_patch_insns(void *insn_buff, unsigned len, 63f70270ccd981c arch/i386/kernel/paravirt.c Jeremy Fitzhardinge 2007-05-02 125 const char *start, const char *end) 63f70270ccd981c arch/i386/kernel/paravirt.c Jeremy Fitzhardinge 2007-05-02 126 { 63f70270ccd981c arch/i386/kernel/paravirt.c Jeremy Fitzhardinge 2007-05-02 127 unsigned insn_len = end - start; 63f70270ccd981c arch/i386/kernel/paravirt.c Jeremy Fitzhardinge 2007-05-02 128 2777cae2b19d4a0 arch/x86/kernel/paravirt.c Ingo Molnar 2019-04-25 129 /* Alternative instruction is too large for the patch site and we cannot continue: */ 2777cae2b19d4a0 arch/x86/kernel/paravirt.c Ingo Molnar 2019-04-25 130 BUG_ON(insn_len > len || start == NULL); 2777cae2b19d4a0 arch/x86/kernel/paravirt.c Ingo Molnar 2019-04-25 131 1fc654cf6e04b40 arch/x86/kernel/paravirt.c Ingo Molnar 2019-04-25 132 memcpy(insn_buff, start, insn_len); 139ec7c416248b9 arch/i386/kernel/paravirt.c Rusty Russell 2006-12-07 133 139ec7c416248b9 arch/i386/kernel/paravirt.c Rusty Russell 2006-12-07 134 return insn_len; 139ec7c416248b9 arch/i386/kernel/paravirt.c Rusty Russell 2006-12-07 135 } 139ec7c416248b9 arch/i386/kernel/paravirt.c Rusty Russell 2006-12-07 136 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org