Hi Bert, FYI, the error/warning still remains. tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master head: d9403d307dba1a71ee6462b22300c2d3be773b1c commit: 4042147a0cc6af5a400b5e12a7855e893dec01b4 MIPS: Add Realtek RTL838x/RTL839x support as generic MIPS system date: 5 months ago config: mips-randconfig-r014-20210620 (attached as .config) compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project d1baf2895467735ab14f4b3415fce204c0cc8e7f) 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 mips cross compiling tool for clang build # apt-get install binutils-mips-linux-gnu # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit... git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git git fetch --no-tags linus master git checkout 4042147a0cc6af5a400b5e12a7855e893dec01b4 # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=mips 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 >>): void *vpe_alloc(void) ^ arch/mips/kernel/vpe-mt.c:178:1: note: declare 'static' if the function is not intended to be used outside of this translation unit void *vpe_alloc(void) ^ static int vpe_start(void *vpe, unsigned long start) ^ arch/mips/kernel/vpe-mt.c:196:1: note: declare 'static' if the function is not intended to be used outside of this translation unit int vpe_start(void *vpe, unsigned long start) ^ static int vpe_stop(void *vpe) ^ arch/mips/kernel/vpe-mt.c:206:1: note: declare 'static' if the function is not intended to be used outside of this translation unit int vpe_stop(void *vpe) ^ static int vpe_free(void *vpe) ^ arch/mips/kernel/vpe-mt.c:227:1: note: declare 'static' if the function is not intended to be used outside of this translation unit int vpe_free(void *vpe) ^ static 4 warnings generated. vim +/vpe_alloc +178 arch/mips/kernel/vpe-mt.c 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 175 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 176 /* module wrapper entry points */ 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 177 /* give me a vpe */ 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 @178 void *vpe_alloc(void) 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 179 { 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 180 int i; 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 181 struct vpe *v; 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 182 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 183 /* find a vpe */ 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 184 for (i = 1; i < MAX_VPES; i++) { 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 185 v = get_vpe(i); 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 186 if (v != NULL) { 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 187 v->state = VPE_STATE_INUSE; 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 188 return v; 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 189 } 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 190 } 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 191 return NULL; 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 192 } 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 193 EXPORT_SYMBOL(vpe_alloc); 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 194 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 195 /* start running from here */ 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 @196 int vpe_start(void *vpe, unsigned long start) 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 197 { 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 198 struct vpe *v = vpe; 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 199 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 200 v->__start = start; 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 201 return vpe_run(v); 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 202 } 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 203 EXPORT_SYMBOL(vpe_start); 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 204 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 205 /* halt it for now */ 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 @206 int vpe_stop(void *vpe) 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 207 { 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 208 struct vpe *v = vpe; 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 209 struct tc *t; 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 210 unsigned int evpe_flags; 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 211 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 212 evpe_flags = dvpe(); 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 213 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 214 t = list_entry(v->tc.next, struct tc, tc); 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 215 if (t != NULL) { 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 216 settc(t->index); 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 217 write_vpe_c0_vpeconf0(read_vpe_c0_vpeconf0() & ~VPECONF0_VPA); 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 218 } 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 219 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 220 evpe(evpe_flags); 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 221 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 222 return 0; 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 223 } 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 224 EXPORT_SYMBOL(vpe_stop); 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 225 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 226 /* I've done with it thank you */ 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 @227 int vpe_free(void *vpe) 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 228 { 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 229 struct vpe *v = vpe; 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 230 struct tc *t; 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 231 unsigned int evpe_flags; 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 232 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 233 t = list_entry(v->tc.next, struct tc, tc); 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 234 if (t == NULL) 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 235 return -ENOEXEC; 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 236 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 237 evpe_flags = dvpe(); 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 238 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 239 /* Put MVPE's into 'configuration state' */ 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 240 set_c0_mvpcontrol(MVPCONTROL_VPC); 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 241 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 242 settc(t->index); 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 243 write_vpe_c0_vpeconf0(read_vpe_c0_vpeconf0() & ~VPECONF0_VPA); 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 244 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 245 /* halt the TC */ 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 246 write_tc_c0_tchalt(TCHALT_H); 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 247 mips_ihb(); 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 248 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 249 /* mark the TC unallocated */ 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 250 write_tc_c0_tcstatus(read_tc_c0_tcstatus() & ~TCSTATUS_A); 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 251 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 252 v->state = VPE_STATE_UNUSED; 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 253 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 254 clear_c0_mvpcontrol(MVPCONTROL_VPC); 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 255 evpe(evpe_flags); 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 256 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 257 return 0; 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 258 } 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 259 EXPORT_SYMBOL(vpe_free); 1a2a6d7e8816ed Dengcheng Zhu 2013-10-30 260 :::::: The code at line 178 was first introduced by commit :::::: 1a2a6d7e8816ed2b2679a0c4f7ba4019cd31dd62 MIPS: APRP: Split VPE loader into separate files. :::::: TO: Deng-Cheng Zhu <dengcheng.zhu(a)imgtec.com&gt; :::::: CC: Ralf Baechle <ralf(a)linux-mips.org&gt; --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org