Re: Building GRUB on platforms without ELF support

[Christian Franke <Christian.Franke@t-online.de>]

Marco Gerards wrote:
> Robert Millan <rmh@aybabtu.com> writes:
>
>   
>> On Fri, Nov 16, 2007 at 11:58:14PM +0100, Christian Franke wrote:
>>     
>>> ...
>>> For specific conversions, fixing this in objcopy itself is easy. But 
>>> there is not much chance that such pragmatic patches will be accepted 
>>> upstream.
>>> (http://sourceware.org/ml/binutils/2007-10/threads.html#00302)
>>>
>>> I have prepared a reduced (~680 LoC) version of objcopy with the PE->ELF 
>>> fix added. To support build on non-ELF platforms, I would suggest to add 
>>> this to the GRUB codebase. It can be later extended for other platforms 
>>> if desired.
>>>       
>> I'm not sure what the GRUB maintainers will think, but I'm not very inclined
>> to duplicate stuff that binutils already have.
>>     
>
> So am I.
>
>   

Actually, binutils actually does not have this ("convert relocatable 
object files from format X to ELF") stuff.


>> How about building binutils with --enable-targets=i386-elf ?  Maybe the
>> Cygwin maintainers would even add it as default.  


It is not so easy:

Cygwin's libbfd, ld and objcopy support elf32-i386, gas does not.

But ld refuses to output elf32-i386 if pe-i386 is the input format. This 
restriction is hard-coded into ld because some pe-specific operations 
are hard-coded into bfd backend (This includes the hack which fixes the 
pc-relative relocation in the executable).

Enable elf32-i386 as additional output format for gas does not work. The 
compilation fails, multiple emulations are not supported on i386 platform.

But even building gas as a cross-assembler does not help. Some assembler 
directives, like symbol type specs, are output format specific. Output 
from Cygwin's gcc produces syntax errors.

Therefore, you would need also a gcc build as a cross-compiler.



Not really worth the effort, so I posted the patch for kern/i386/dl.c 
instead.


>> We could also have a
>> configure check that aborts build when -m elf_i386 is not supported (which
>> may also be a problem on pure-x86_64 environment!) and prompt user to
>> rebuild binutils.
>>     
>
>   

Better prompt "sorry", as rebuilding binutils probably won't work OOTB 
in many cases ... :-)

Christian