Cross toolchain support for SPUs on Cell / ppc64

[Ralf Corsepius]

On Fri, 2008-06-20 at 20:55 +0200, Jochen Roth wrote:

> Before we start opening Review Requests in Bugzilla we want to start the 
> discussion what the best approach for supporting cross compiling 
> toolchains like the SPU toolchain in Fedora is. As far as I know there 
> is only one example for cross compiler support in Fedora which is Atmels 
> AVR.
> 
> Our suggestion would be to build spu-binutils from the same source as 
> the system gcc for ppc is build.
Theoretically, this would be one possibility, however, practice tells
this doesn't work, because there always will be situations when you will
want to patch/apply hacks to your cross-binutils, or when
target-specific bugs force your cross-binutils to use a different
version of binutils than of the native binutils.

>  Here we'd have to change the ppc 
> binutils package and add --enable-target=spu . A separate spu-binutils 
> package including the spu assembly is needed anyhow.
The latter is what I have learned to be the only viable approach.

> It would also be good to be able to build the spu-gcc from the same 
> sources as the system gcc is build.
IMO, this doesn't work for the same rationales as above.

>  It would be even better if the 
> spu-gcc is build from the same .spec file. Of course this needs a lot of 
> configuration and adjustments.
Yes, building cross-toolchain packages is tedious.

> For spu-newlib we'd have to create a separate package as we'd have for 
> spu-gdb.
This is one option, but it raises problems with bootstrapping GCC.

The alternative is building newlib+gcc one-tree-style (building newlib
and gcc at the same time). It's what I do for my cross-toolchains.

Ralf