tree: git://git.infradead.org/users/hch/misc.git um-set_fs head: 62ef80add97f4b90b4435670fcd5c0a6bd424fad commit: bc1802ed3414136e0dfe2ea0a747aca59dc33b5c [1/2] x86/mtrr: don't include <asm/memtype.h> for !CONFIG_MTRR config: i386-randconfig-a001-20211214 (https://download.01.org/0day-ci/archive/20211214/202112142040.U9bqf0Ta-lk...) compiler: gcc-9 (Debian 9.3.0-22) 9.3.0 reproduce (this is a W=1 build): git remote add hch-misc git://git.infradead.org/users/hch/misc.git git fetch --no-tags hch-misc um-set_fs git checkout bc1802ed3414136e0dfe2ea0a747aca59dc33b5c # save the config file to linux build tree mkdir build_dir make W=1 O=build_dir ARCH=i386 SHELL=/bin/bash arch/x86/kernel/cpu/ arch/x86/mm/ 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 >>): In file included from arch/x86/kernel/cpu/common.c:46: arch/x86/include/asm/mtrr.h: In function 'mtrr_bp_init': arch/x86/include/asm/mtrr.h:89:2: error: implicit declaration of function 'pat_disable'; did you mean 'ptrace_disable'? [-Werror=implicit-function-declaration] 89 | pat_disable("PAT support disabled because CONFIG_MTRR is disabled in the kernel."); | ^~~~~~~~~~~ | ptrace_disable In file included from arch/x86/kernel/cpu/common.c:55: arch/x86/include/asm/memtype.h: At top level: 9 | extern void pat_disable(const char *reason); | ^~~~~~~~~~~ In file included from arch/x86/kernel/cpu/common.c:46: arch/x86/include/asm/mtrr.h:89:2: note: previous implicit declaration of 'pat_disable' was here 89 | pat_disable("PAT support disabled because CONFIG_MTRR is disabled in the kernel."); | ^~~~~~~~~~~ cc1: some warnings being treated as errors -- In file included from arch/x86/mm/pat/memtype.c:51: arch/x86/include/asm/mtrr.h: In function 'mtrr_bp_init': arch/x86/include/asm/mtrr.h:89:2: error: implicit declaration of function 'pat_disable' [-Werror=implicit-function-declaration] 89 | pat_disable("PAT support disabled because CONFIG_MTRR is disabled in the kernel."); | ^~~~~~~~~~~ In file included from arch/x86/mm/pat/memtype.c:54: arch/x86/include/asm/memtype.h: At top level: 9 | extern void pat_disable(const char *reason); | ^~~~~~~~~~~ In file included from arch/x86/mm/pat/memtype.c:51: arch/x86/include/asm/mtrr.h:89:2: note: previous implicit declaration of 'pat_disable' was here 89 | pat_disable("PAT support disabled because CONFIG_MTRR is disabled in the kernel."); | ^~~~~~~~~~~ cc1: some warnings being treated as errors vim +/pat_disable +9 arch/x86/include/asm/memtype.h 2e5d9c857d4e6c include/asm-x86/pat.h venkatesh.pallipadi(a)intel.com 2008-03-18 7 533d49b37a2b53 arch/x86/include/asm/memtype.h Ingo Molnar 2019-11-20 8 extern bool pat_enabled(void); 533d49b37a2b53 arch/x86/include/asm/memtype.h Ingo Molnar 2019-11-20 @9 extern void pat_disable(const char *reason); 2e5d9c857d4e6c include/asm-x86/pat.h venkatesh.pallipadi(a)intel.com 2008-03-18 10 extern void pat_init(void); 99c13b8c8896d7 arch/x86/include/asm/pat.h Mikulas Patocka 2017-07-04 11 extern void init_cache_modes(void); 2e5d9c857d4e6c include/asm-x86/pat.h venkatesh.pallipadi(a)intel.com 2008-03-18 12 :::::: The code at line 9 was first introduced by commit :::::: 533d49b37a2b532354d3841a142173b8321818df x86/mm/pat: Clean up <asm/memtype.h> externs :::::: TO: Ingo Molnar <mingo(a)kernel.org&gt; :::::: CC: Ingo Molnar <mingo(a)kernel.org&gt; --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org