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

[Laurent Vivier <laurent@vivier.eu>]

Le 07/11/2015 00:12, Benjamin Herrenschmidt a écrit :
> 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.

Yes, Segher has given me the commit id. It is just what I need.

Laurent