Hi Kuppuswamy,

[FYI, it's a private test report for your RFC patch.]
[auto build test ERROR on tip/x86/core]
[also build test ERROR on tip/master linux/master linus/master v5.13-rc2 next-20210521]
[cannot apply to luto/next]
[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/Kuppuswamy-Sathyanarayanan/x86-boot-Add-a-trampoline-for-APs-booting-in-64-bit-mode/20210522-211940
base:   https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git 2c88d45edbb89029c1190bb3b136d2602f057c98
config: x86_64-randconfig-a013-20210522 (attached as .config)
compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project e84a9b9bb3051c35dea993cdad7b3d2575638f85)
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/290ddae8f6cfa354bd4b518bfa86823478e53f5e
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Kuppuswamy-Sathyanarayanan/x86-boot-Add-a-trampoline-for-APs-booting-in-64-bit-mode/20210522-211940
        git checkout 290ddae8f6cfa354bd4b518bfa86823478e53f5e
        # 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@intel.com>

All errors (new ones prefixed by >>):

   In file included from arch/x86/realmode/init.c:9:
>> arch/x86/include/asm/realmode.h:96:6: error: implicit declaration of function 'is_tdx_guest' [-Werror,-Wimplicit-function-declaration]
           if (is_tdx_guest())
               ^
   1 error generated.


vim +/is_tdx_guest +96 arch/x86/include/asm/realmode.h

    91	
    92	/* Common helper function to get start IP address */
    93	static inline unsigned long get_trampoline_start_ip(struct real_mode_header *rmh)
    94	{
    95	#ifdef CONFIG_X86_64
  > 96		if (is_tdx_guest())
    97			return rmh->trampoline_start64;
    98	#endif
    99		return rmh->trampoline_start;
   100	}
   101	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all(a)lists.01.org