Re: Gnat cross compiler

["Yannick Duchêne (Hibou57)" <yannick_duchene@yahoo.fr>]

Le Fri, 21 May 2010 09:31:25 +0200, Alexis  
<jose_alexis_paez_thurgood@hotmail.com> a écrit:
> Thanks for your reply. I have decided to stop trying to compile libada
> and have managed to get the cross compiler to work by setting the RTS
> option to \cygwin\lib\gcc\i686-pc-cygwin\4.3.4, which is where the
> adainclude and adalib for the ada compiler bundled with Cygwin.
>
> So far so good, but this makes me wonder, what is the RTS used for? Is
> this now a real cross compiler as I'm using the RTS for the i686-pc-
> cygwin target?
>
> My guess is I should be using a proper i696-elf Ada RTS, right?
>
> Best regards, Alexis.
RTS stands for RunTime System. This is the GNAT runtime library (exception  
handling, package elaboration, dispatching, and etc).

GNAT for Windows, is shipped with an RTS for Windows only. To target  
Linux, you need an RTS for Linux... for Linux and the target architecture,  
as Linux runs on multiple architectures (well, you've said the  
architecture is Intel, so there should not be any trouble there).

The RTS is not the sole thing to be related to target OS and target  
architecture : the Ada standard packages also have dependencies to that,  
at least, the package named Standard.

So, even if you have a copy of the RTS for the target OS and architecture,  
you will also need the standard packages for that OS and architecture.

You will also need a linker which can handle the OS target binary  
application format.

GNAT on Windows is shipped with an LD which can only handle Windows binary  
applications format.

You may find LD specific builds which can handle both Windows and ELF for  
Intel architecture, however, this would not work. I know this would not  
work, because I tried it in the past (that was the reason why I finally  
decided to build my own cross-compiler).

All of that, to say if you want to cross-compile, you *really need* a  
cross-compile tool chain : a gcc-ada cross-compiler with target RTS and  
packages, some binutils for the target and an LD for the target.

I you are really in troubles with that, or fail to build a cross-compiler,  
I would agree to send you mine via e-mail. But I would not provide support  
for it (or may be if... well let me know), and I must say this is a MinGW  
based cross-compiler, not Cygwin. It was also built to target i386, not  
i686. By the way, I'm not sure I built it with C++ enabled (will have to  
check).

Note: I could not really help you with building a cross-compiler with  
Cygwin, as I suspect the related issues to be not the same as with MinGW.  
The only thing I'm pretty sure about, reading your initial post, is that  
your sysroot is not properly setup.

-- 
There is even better than a pragma Assert: a SPARK --# check.