arch/mips/sgi-ip30/ip30-console.c:15:6: warning: no previous prototype for 'prom_putchar'

[kernel test robot]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   23ee3e4e5bd27bdbc0f1785eef7209ce872794c7
commit: 7505576d1c1ac0cfe85fdf90999433dd8b673012 MIPS: add support for SGI Octane (IP30)
date:   9 months ago
config: mips-randconfig-r013-20200725 (attached as .config)
compiler: mips64-linux-gcc (GCC) 9.3.0
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
        git checkout 7505576d1c1ac0cfe85fdf90999433dd8b673012
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=mips 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@xxxxxxxxx>

All error/warnings (new ones prefixed by >>):

   mips64-linux-ld: arch/mips/kernel/signal.o: in function `restore_hw_fp_context':
>> arch/mips/kernel/signal.c:141: undefined reference to `_restore_fp_context'
   mips64-linux-ld: arch/mips/kernel/signal.o: in function `save_hw_fp_context':
>> arch/mips/kernel/signal.c:132: undefined reference to `_save_fp_context'
   mips64-linux-ld: arch/mips/kernel/traps.o: in function `trap_init':
>> arch/mips/kernel/traps.c:2408: undefined reference to `handle_fpe'
>> mips64-linux-ld: arch/mips/kernel/traps.c:2412: undefined reference to `handle_fpe'
>> mips64-linux-ld: arch/mips/kernel/traps.c:2412: undefined reference to `handle_fpe'
>> mips64-linux-ld: arch/mips/kernel/traps.c:2412: undefined reference to `handle_fpe'
>> mips64-linux-ld: arch/mips/kernel/traps.c:2412: undefined reference to `handle_fpe'
--
>> arch/mips/sgi-ip30/ip30-console.c:15:6: warning: no previous prototype for 'prom_putchar' [-Wmissing-prototypes]
      15 | void prom_putchar(char c)
         |      ^~~~~~~~~~~~

vim +/prom_putchar +15 arch/mips/sgi-ip30/ip30-console.c

    14	
  > 15	void prom_putchar(char c)

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

Attachment: .config.gz
Description: application/gzip