Re: cross-compiling on 64 to 32-bit Linuxlocalhost/

[John Calcote]

Hi Gregory,

On 3/2/2010 4:14 PM, Grégory Pakosz wrote:
> >   ./configure --host=i686-pc-linux-gnu \
> >                --prefix=/arch/x86-linux/gnu \
> >                CC="gcc -m32 -march=i586" \
> >                CXX="g++ -m32 -march=i586" \
> >                LDFLAGS="-m32"
> >      
> I'm curious about why setting "--host=i686-pc-linux-gnu" is not enough
> to achieve cross compiling and why in that case it's not up to
> autoconf to add "-m32" to CC.
>    

You don't need to specify -m32 if you have a tool set prefixed with the 
cross tag. The reason for using -m32 is because the user wants to use 
his 64-bit gcc to compile 32-bit code, so he has to tell the compiler to 
switch to 32-bit mode also. (Incidentally, if you're running on Linux, 
might also be a good idea to tell the compiler you're running in a 
32-bit environment by executing gcc with linux32).

Another way to use your 64-bit gcc without special compiler flags is to 
create scripts, named with the cross prefix, in your bin directory that 
execute the compiler in 32-bit mode (and perhaps also executed by 
linux32). Then these tools will be preferred by Autoconf when you use 
--host=.

Regards,
John