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

[Grant Edwards]

On 2010-09-29, meino.cramer@×××.de <meino.cramer@×××.de> wrote:

>> >  (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.

> Thank you very much for your offered help!
>
> Sorry, sorry I think my English confused a lot of infos...

Cross-building stuff is just plain confusing.

> 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 ;) ) .

All you need to do is build a cross compiler for the ARM9 target the
same way you did before.  The width of the host where you're building
things doesn't matter (if it does, that's a bug in gcc or binutils).

I've had excellent results using the crosstool-ng makefile:

   http://ymorin.is-a-geek.org/projects/crosstool
   
Crosstool is used by a lot of embedded developers. If there were
problems building an ARM comiler on an AMD64 host, Yann Morin et al.
are your best bet for a solution.  You may want to take a look at the
crossgcc mailing list:

   http://news.gmane.org/gmane.comp.gcc.cross-compiling
   http://sourceware.org/ml/crossgcc/

From a brief search of the mailing list, it appears that building an
ARM compiler on an AMD64 machines works just fine.   
    
or,

It's quite likely that you can install IA32 libraries on your AMD64
host OS and then use the exact same compiler executable you used
before.  

>   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.

You really don't want to do that.  It's rather tricky, and it
shouldn't be required.

> * 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.

Just use the arm-linux-gcc compiler and you should be fine regardless
of the width of the host on which you built the arm-linux-gcc
compiler.

-- 
Grant Edwards               grant.b.edwards        Yow! It's the RINSE CYCLE!!
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