[PATCH] powerpc: allow cross-compilation of ppc64 kernel

[Benjamin Herrenschmidt]

On Fri, 2015-11-06 at 15:09 -0600, Scott Wood wrote:
> On Thu, 2015-11-05 at 12:47 +0100, Laurent Vivier wrote:
> > When I try to cross compile a ppc64 kernel, it generally
> > fails on the VDSO stage. This is true for powerpc64 cross-
> > compiler, but also when I try to build a ppc64le kernel
> > on a ppc64 host.
> > 
> > VDSO64L fails:
> > 
> >   VDSO64L arch/powerpc/kernel/vdso64/vdso64.so.dbg
> > /usr/bin/powerpc64-linux-gnu-ld:
> > arch/powerpc/kernel/vdso64/sigtramp.o:
> > file class ELFCLASS64 incompatible with ELFCLASS32
> > /usr/bin/powerpc64-linux-gnu-ld: final link failed: File in wrong
> > format
> > 
> > This fails because gcc calls "collect2" with
> > "--oformat elf32-powerpcle" with ppc64 objects, without the
> > "--oformat" ld works well because it use the format of the
> > first object as output format.
> > 
> > As this case is correctly managed to build the other kernel
> > objects, this patch replaces $(GCC) by $(LD) to generate the
> > VDSO objects.

This is LE ? I think that's a bug in binutils or gcc ... I remember we
fought that a while ago for the openpower builds. It might have been
fixed in upstream toolchain.

Cheers,
Ben.