Hi Douglas, I love your patch! Yet something to improve: [auto build test ERROR on arm64/for-next/core] [also build test ERROR on tty/tty-testing v5.6 next-20200410] [cannot apply to kgdb/kgdb-next] [if your patch is applied to the wrong git tree, please drop us a note to help improve the system. BTW, we also suggest to use '--base' option to specify the base tree in git format-patch, please see https://stackoverflow.com/a/37406982] url: https://github.com/0day-ci/linux/commits/Douglas-Anderson/kgdb-Support-la... base: https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-next/core config: microblaze-mmu_defconfig (attached as .config) compiler: microblaze-linux-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 # save the attached .config to linux build tree GCC_VERSION=9.3.0 make.cross ARCH=microblaze If you fix the issue, kindly add following tag as appropriate Reported-by: kbuild test robot <lkp(a)intel.com&gt; All errors (new ones prefixed by >>): drivers/misc/kgdbts.c: In function 'configure_kgdbts': 1080 | err = kgdb_register_io_module(&kgdbts_io_ops); | ^~~~~~~~~~~~~~~~~~~~~~~ In file included from drivers/misc/kgdbts.c:86: include/linux/kgdb.h:326:12: note: declared here 326 | extern int kgdb_register_io_module(struct kgdb_io *new_dbg_io_ops, | ^~~~~~~~~~~~~~~~~~~~~~~ vim +/kgdb_register_io_module +1080 drivers/misc/kgdbts.c e8d31c204e36e0 Jason Wessel 2008-03-07 1069 e8d31c204e36e0 Jason Wessel 2008-03-07 1070 static int configure_kgdbts(void) e8d31c204e36e0 Jason Wessel 2008-03-07 1071 { e8d31c204e36e0 Jason Wessel 2008-03-07 1072 int err = 0; e8d31c204e36e0 Jason Wessel 2008-03-07 1073 e8d31c204e36e0 Jason Wessel 2008-03-07 1074 if (!strlen(config) || isspace(config[0])) e8d31c204e36e0 Jason Wessel 2008-03-07 1075 goto noconfig; e8d31c204e36e0 Jason Wessel 2008-03-07 1076 e8d31c204e36e0 Jason Wessel 2008-03-07 1077 final_ack = 0; e8d31c204e36e0 Jason Wessel 2008-03-07 1078 run_plant_and_detach_test(1); e8d31c204e36e0 Jason Wessel 2008-03-07 1079 e8d31c204e36e0 Jason Wessel 2008-03-07 @1080 err = kgdb_register_io_module(&kgdbts_io_ops); e8d31c204e36e0 Jason Wessel 2008-03-07 1081 if (err) { e8d31c204e36e0 Jason Wessel 2008-03-07 1082 configured = 0; e8d31c204e36e0 Jason Wessel 2008-03-07 1083 return err; e8d31c204e36e0 Jason Wessel 2008-03-07 1084 } e8d31c204e36e0 Jason Wessel 2008-03-07 1085 configured = 1; e8d31c204e36e0 Jason Wessel 2008-03-07 1086 kgdbts_run_tests(); e8d31c204e36e0 Jason Wessel 2008-03-07 1087 e8d31c204e36e0 Jason Wessel 2008-03-07 1088 return err; e8d31c204e36e0 Jason Wessel 2008-03-07 1089 e8d31c204e36e0 Jason Wessel 2008-03-07 1090 noconfig: e8d31c204e36e0 Jason Wessel 2008-03-07 1091 config[0] = 0; e8d31c204e36e0 Jason Wessel 2008-03-07 1092 configured = 0; e8d31c204e36e0 Jason Wessel 2008-03-07 1093 e8d31c204e36e0 Jason Wessel 2008-03-07 1094 return err; e8d31c204e36e0 Jason Wessel 2008-03-07 1095 } e8d31c204e36e0 Jason Wessel 2008-03-07 1096 :::::: The code at line 1080 was first introduced by commit :::::: e8d31c204e36e019b9134f2a11926cac0fcf9b19 kgdb: add kgdb internal test suite :::::: TO: Jason Wessel <jason.wessel(a)windriver.com&gt; :::::: CC: Ingo Molnar <mingo(a)elte.hu&gt; --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org