On Fri, 2018-02-16 at 21:28 +0100, Arnd Bergmann wrote:
> On Fri, Feb 16, 2018 at 7:21 PM, kbuild test robot
> <fengguang.wu@intel.com> wrote:
[...]
> > All errors (new ones prefixed by >>):
> > 
> >    arch/x86/kernel/head64.o: In function `_GLOBAL__sub_D_00100_1_early_pmd_flags':
> > > > head64.c:(.text.exit+0x5): undefined reference to `__gcov_exit'
> >    arch/x86/kernel/head.o: In function `_GLOBAL__sub_D_00100_1_reserve_ebda_region':
> >    head.c:(.text.exit+0x5): undefined reference to `__gcov_exit'
> >    init/built-in.o: In function `_GLOBAL__sub_D_00100_1___ksymtab_system_state':
> >    main.c:(.text.exit+0x5): undefined reference to `__gcov_exit'
> >    init/built-in.o: In function `_GLOBAL__sub_D_00100_1_root_mountflags':
> >    do_mounts.c:(.text.exit+0x10): undefined reference to `__gcov_exit'
> >    init/built-in.o: In function `_GLOBAL__sub_D_00100_1_initrd_load':
> >    do_mounts_initrd.c:(.text.exit+0x1b): undefined reference to `__gcov_exit'
> >    init/built-in.o:initramfs.c:(.text.exit+0x26): more undefined references to `__gcov_exit' follow
> 
> I think this is a result of using a too new compiler with the old 3.16
> kernel. In order
> to build with gcc-7.3, you need to backport
> 
> 05384213436a ("gcov: support GCC 7.1")
> 
> It's already part of stable-3.18 and later, but not 3.2 and 3.16.

Thanks.  I've queued up the following for 3.16:

3e44c471a2da gcov: add support for GCC 5.1
d02038f97253 gcov: add support for gcc version >= 6
05384213436a gcov: support GCC 7.1

Ben.

-- 
Ben Hutchings
Reality is just a crutch for people who can't handle science fiction.