[ppc64] newer gcc breaks kernel build?

[Jakub Jelinek]

On Thu, Sep 17, 2009 at 01:44:42PM -0400, Kyle McMartin wrote:
> - fix ppc/ppc64 -mmultiple and out of line gpr/fpr saving bugs
>   (#519409, PR target/40677, PR target/41175)
> 
> My guess is this has broken the kernel build on powerpc64:
> init/built-in.o: In function `arch_disable_smp_support':
> /builddir/build/BUILD/kernel-2.6.31/linux-2.6.31.ppc64/init/main.c:139: undefined reference to `._savegpr0_31'
> /builddir/build/BUILD/kernel-2.6.31/linux-2.6.31.ppc64/init/main.c:139: undefined reference to `._restgpr0_31'
> 
> by generating calls to out of line handlers, which are only supplied for
> PPC32 in arch/powerpc/lib/.
> 
> Any thoughts? If it's not this, it must have been something hitting rawhide
> between:
> 2009-09-16 22:06:38	and
> 2009-09-17 15:25:47

For 64-bit code it is ld that is supposed to synthetize those symbols on the
fly.  gcc uses them (newly, starting with gcc 4.5 as of a few days ago
upstream and gcc-4.4.1-14 in rawhide) even for 64-bit code when -Os, as the
out of line savers/restorers are smaller than inline register
saving/restoring.

	Jakub