Re: [gentoo-user] Re: How to compile for less bits :)

Grant Edwards <grant.b.edwards@×××××.com> [10-09-27 21:16]:
> On 2010-09-27, meino.cramer@×××.de <meino.cramer@×××.de> wrote:
>
> >  For my microcontroller board (ATMEL AT81RM920, linux based)
>
> Do you mean AT91RM9200?
>
> >  I want to crosscompile kernels and applications on my 64bit Gentoo
> >  linux.
>
> That's easy enough.
>
> >  The source of a gcc (prepared on a 32bit system I fear) for
> >  the purpose of crosscompiling from a 32bit system-- target is the
> >  above mentioned processor -- is available.
> >
> >  Is it possible to compile this gcc as a 32bit-application on my 64bit
> >  system to ensure the same behaviour as it would if to was built on a
> >  "original 32bit Gentoo Linux"?
>
> You want to compile gcc on an AMD64 machine and end up with a
> cross-compiler that runs as an IA32 app and generates code for an ARM9
> target?
>
> That's called a "Canadian Cross", and is rather tricky, since it
> involves three different architectures: building a compiler on
> architecture A (AMD64) to be run on architecture B (IA32) and generate
> code for architecture C (ARM9).
>
> Can you explain why you want that rather than a normal cross compiler?
>
> IOW, why do you want to build a gcc cross compiler that runs as a
> 32-bit application?  It's _way_ simpler to build a "normal" cross
> compiler: building a compiler one architecture (AMD64) to be run on
> that same architecture (AMD64) and generate code for a second
> architecture (ARM9).
>
> >  (And in this context: The audio application "chuck" is only as 32bit
> >  application available currently. How is it possible to compile this
> >  on a 64bit system?)
>
> You use a compiler that generates code for a the desired 32-bit
> architecture.  The "width" of the host is immaterial.
>
> The easiest way to build such a compiler is using crosstool-ng
>
>   http://ymorin.is-a-geek.org/projects/crosstool
>
> Crosstool-NG does have some support for doing a Canadian-cross, but I
> don't see why you would want to do that.
>
> --
> Grant Edwards               grant.b.edwards        Yow! Gibble, Gobble, we
>                                   at               ACCEPT YOU ...
>                               gmail.com
>
>

Hi Grant,

Thank you very much for your offered help!

Sorry, sorry I think my English confused a lot of infos...

I'll try it again.

Setup BEFORE I switched to 64bit Gentoo Linux.
* a "normal" system gcc as installed by emerge usually on many (all?) gentoo
  systems...
* a "crosscompiling" gcc in source form. Compiled with the "normal"
  gcc to an executable which runs on the 32bit Gentoo system and
  produces executables/kernel to run on the ATMEL AT91RM9200 (yes,
  you're right - this typo was mine ;) ) .
* Additional "chuck" audio application only available for 32bit
  Linux, also compiled with the "normal" gcc

Wanted setup on my shiny new 64bit Gentoo Linux:
* a "normal" system gcc as installed by emerge usually on many (all?) gentoo
  systems... (==> already there and living quite well)
* a "crosscompiling" gcc in source form. To be Compiled with the "normal"
  gcc to an executable which runs on the 64bit Gentoo system and
  produces executables/kernel to run on the ATMEL AT91RM9200 (yes,
  you're right - this typo was mine ;) ) .
  OR: compiled to be an 32bit gcc-executable which generate executable
  binaries for my ATMEL cookie.
  As long a 64bit-executable of gcc can do the job I would prefer that
  solution of course.
* Additional "chuck" audio application only available for 32bit
  Linux, to be compiled with the "normal" gcc to be a 32 bit
  executable since not 64bit-ready.

I hope not to have made too much knots into that above...

Best regards
mcc