Hi Andrew,

It's probably a bug fix that unveils the link errors.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   28e68154c5e2793123b248d38cf17b34dcb16d87
commit: c60f169202c7643991a8b4bfeea60e06843d5b5a arch/mn10300/kernel/fpu-nofpu.c: needs asm/elf.h
date:   6 months ago
config: mn10300-allnoconfig (attached as .config)
compiler: am33_2.0-linux-gcc (GCC) 4.9.0
reproduce:
        wget https://git.kernel.org/cgit/linux/kernel/git/wfg/lkp-tests.git/plain/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        git checkout c60f169202c7643991a8b4bfeea60e06843d5b5a
        # save the attached .config to linux build tree
        make.cross ARCH=mn10300 

All errors (new ones prefixed by >>):

   kernel/built-in.o: In function `.L412':
>> core.c:(.sched.text+0x257): undefined reference to `fpu_save'

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