Cross compilation

[Fernando Apesteguía]

Ok, finally I found the solution.

First I compiled the .c files into .o objects and then I needed to run
gcc to link in this way:

gcc -o prog -m32 -march=i386 -L/usr/lib -L/lib $obj -lreadline -lncurses

with obj=`ls *.o`

I don't know why I need two steps because I couldn't do this in one
single step (it seems like if gcc doesn't bypass the proper
flags/options to ld to compile agains the 32 bit libraries)

HTH to another one,

Cheers

On 12/6/06, Fernando Apesteguía <fernando.apesteguia at gmail.com> wrote:
> On 11/28/06, Steven W. Orr <steveo at syslang.net> wrote:
> > On Tuesday, Nov 28th 2006 at 18:50 +0100, quoth Fernando Apesteguía:
> >
> > =>Helo list,
> > =>
> > =>I'm using FC6 for x86_64. I need to compile a program for linux 32
> > =>bits. I tried with the -m32 flag to gcc, but I got:
> > =>
> > =>core_recv.c:(.text+0x130): undefined reference to `__umoddi3'
> > =>
> > =>and tons of ld warnings:
> > =>
> > =>/usr/bin/ld: warning: i386 architecture of input file `main.o' is
> > =>incompatible with i386:x86-64 output
> > =>
> > =>I searched in Google, but couldn't find the solution. For the
> > =>undefinded references I suppose it is because some missing i386
> > =>libraries right?
> > =>
> > =>And what about the other things? How can I compile a 32 bit
> > =>application under a 64 bit system?
> >
> > Sorry, but you need to create a seperate cross compiler. You're running on
> > a your native system and you're trying to create an executable for another
> > machine. So you need a whole different toolchain. The easiest way *might*
> > be to use buildroot (just google it please) but the point is that you need
> > a whole different setup to target a different machine. gcc, binutils,
> > libc, gdb, the whole banana, and the whole thing has to be specific to the
> > version of the kernel you're running on the target system. Just don't even
> > *try* to figgah out options for your current system. It won't work.
> >
> > --
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> > fedora-list at redhat.com
> > To unsubscribe: https://www.redhat.com/mailman/listinfo/fedora-list
> >
> >
>
> Hi again,
>
> Yes, the question is that I could make a chroot, but I would prefer
> not to do it for several reasons (hard disk space is one of them).
>
> The compiler does his work, the .o are all:
> ELF 32-bit LSB relocatable, Intel 80386, version 1 (SYSV), not stripped
>
> but then, the ld doesn't manage the situation. The supported emulations are
> elf_x86_64 elf_i386 i386linux
>
> I tried with the last two and it didn't work...
> The program uses the common standard functions like printf and strcpy
> and some other features of libreadline.
>
> I have both i386 and x86_64 (and again both, binaries and devel
> packages) installed in my system.
>
> Any more clues?
>
> Thanks in advance
>