How to generate a cross gcc toolchain that accepts both -m32 and -m64 compiler option?

How to generate a cross gcc toolchain that accepts both -m32 and -m64 compiler option?

[Jimm Chen]

Using crosstool-ng 1.20, I've managed to build a gcc 4.8.3 cross
compiler on openSUSE 12.3(32-bit) that is targeted at x86_64(x64)
linux. The CT-NG tool is a life saver. However, I have a question. the
generated compiler x86_64-pc-linux-gnu-gcc can only produce x64
executables. When I try to do

  x86_64-pc-linux-gnu-gcc -m32 hello.c

I got error message like:

/home/chj/x-tools/.../sysroot/usr/include/gnu/stubs.h:7:27: fatal
error: gnu/stubs-32.h: No such file or directory
 # include <gnu/stubs-32.h>
                           ^
compilation terminated.

You know, on an openSUSE Linux 64-bit distribution, we can use -m64 to
produce 64-bit image and -m32 to produce 32-bit image. Can someone
tell me how to achieve that functionality with CT-NG generated
toolchain?

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Re: How to generate a cross gcc toolchain that accepts both -m32 and -m64 compiler option?

[Thomas Petazzoni]

Dear Jimm Chen,

On Thu, 20 Nov 2014 00:47:37 +0800, Jimm Chen wrote:
> Using crosstool-ng 1.20, I've managed to build a gcc 4.8.3 cross
> compiler on openSUSE 12.3(32-bit) that is targeted at x86_64(x64)
> linux. The CT-NG tool is a life saver. However, I have a question. the
> generated compiler x86_64-pc-linux-gnu-gcc can only produce x64
> executables. When I try to do
> 
>   x86_64-pc-linux-gnu-gcc -m32 hello.c
> 
> I got error message like:
> 
> /home/chj/x-tools/.../sysroot/usr/include/gnu/stubs.h:7:27: fatal
> error: gnu/stubs-32.h: No such file or directory
>  # include <gnu/stubs-32.h>
>                            ^
> compilation terminated.
> 
> You know, on an openSUSE Linux 64-bit distribution, we can use -m64 to
> produce 64-bit image and -m32 to produce 32-bit image. Can someone
> tell me how to achieve that functionality with CT-NG generated
> toolchain?

You need to look at something called "multilib support". I don't
remember if Crosstool-NG has added multilib support. Last time I
looked, it didn't had multilib support, but maybe it has changed since
then.

Best regards,

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

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Re: How to generate a cross gcc toolchain that accepts both -m32 and -m64 compiler option?

[Bryan Hundven]

Jimm, Thomas,

On Sat, Nov 22, 2014 at 12:45 PM, Thomas Petazzoni
<thomas.petazzoni@free-electrons.com> wrote:
> Dear Jimm Chen,
>
> On Thu, 20 Nov 2014 00:47:37 +0800, Jimm Chen wrote:
>> Using crosstool-ng 1.20, I've managed to build a gcc 4.8.3 cross
>> compiler on openSUSE 12.3(32-bit) that is targeted at x86_64(x64)
>> linux. The CT-NG tool is a life saver. However, I have a question. the
>> generated compiler x86_64-pc-linux-gnu-gcc can only produce x64
>> executables. When I try to do
>>
>>   x86_64-pc-linux-gnu-gcc -m32 hello.c
>>
>> I got error message like:
>>
>> /home/chj/x-tools/.../sysroot/usr/include/gnu/stubs.h:7:27: fatal
>> error: gnu/stubs-32.h: No such file or directory
>>  # include <gnu/stubs-32.h>
>>                            ^
>> compilation terminated.
>>
>> You know, on an openSUSE Linux 64-bit distribution, we can use -m64 to
>> produce 64-bit image and -m32 to produce 32-bit image. Can someone
>> tell me how to achieve that functionality with CT-NG generated
>> toolchain?
>
> You need to look at something called "multilib support". I don't
> remember if Crosstool-NG has added multilib support. Last time I
> looked, it didn't had multilib support, but maybe it has changed since
> then.

Correct. Crosstool-NG currently does not have multilib support.
Last commit to Yann's repository was back in September:
http://crosstool-ng.org/git/crosstool-ng/log/

There are a lot of patches waiting to be applied:
https://patchwork.ozlabs.org/project/crosstool-ng/list/

Ray Donnelly and I started to work on multilib support, but I stopped
sending patches when Yann stopped applying them. Some of the patches
in the patchwork list no longer apply correctly and need to be resent.

I hope Crosstool-NG keeps going.

-Bryan

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