Relocatable linking on x86-64 for i386

[Valery Reznic]

--- On Mon, 4/4/11, Shachar Shemesh <shachar at shemesh.biz> wrote:

> From: Shachar Shemesh <shachar at shemesh.biz>
> Subject: Re: Relocatable linking on x86-64 for i386
> To: "Valery Reznic" <valery_reznic at yahoo.com>
> Cc: linux-il at cs.huji.ac.il
> Date: Monday, April 4, 2011, 11:13 AM
> On 04/04/11 10:15, Valery Reznic
> wrote:
> > Hello. I am trying to make relocatable linking on
> x86-64 box for objects in format i386
> > 
> > Naive
> > 
> > ld -r file1.o file2.o -o output.o
> > 
> > produce
> > ld: Relocatable linking with relocations from format
> elf32-i386 (file1.o) to format elf64-x86-64 (output.o) is
> not supported
> > 
> > But even when I add --oformat situation not improved:
> > 
> > ld --output-format elf32-i386 -r file1.o file2.o -o
> output.o
> > ld: Relocatable linking with relocations from format
> elf32-i386 (file1.o) to format elf32-i386 (output.o) is not
> supported
> > 
> > So linker correctly recognize what input and output
> format should be,
> > but for some reason don't want do it.
> > 
> > Do you have any ideas if it can be done at all and
> how?
> >    
> Can't. You're trying to link objects compiled for different
> machine codes. Tis not the linking stage that is wrong.

I am not trying to mix i386 and x86_64 code in the same object.

I have two object files for i386 and I want to combine it into one object file for i386 two.

It works perfectly well on i386 box, but on x86-64 it's not.

Valery.

> 
> While it is possible to run both machine codes on your
> computer, they must run in different processes (the kernel
> actually treats x86 and amd64 codes differently when it sets
> up the registers for the context switch), and thus you
> cannot link them into a single executable, cannot
> dynamically load one from the other, and cannot have two
> threads with different types. Your only option for
> interaction is RPC of some sort (or recompile one of them).
> 
> Shachar
> 
> -- Shachar Shemesh
> Lingnu Open Source Consulting Ltd.
> http://www.lingnu.com
> 
>