Re: Building GRUB on platforms without ELF support

[Marco Gerards <mgerards@xs4all.nl>]

Robert Millan <rmh@aybabtu.com> writes:

> On Fri, Nov 16, 2007 at 11:58:14PM +0100, Christian Franke wrote:
>> Building GRUB modules requires ELF support in gas and ld. For platforms 
>> where ELF is not the native format, ld may support ELF output. If not 
>> (like on Cywin) some conversion to ELF is necessary.
>> 
>> In general, GNU objcopy allows conversion between object file formats. 
>> Unfortunately, objcopy (and BFD itself) does not include any support for 
>> the conversion of relocation formats (even conversion between ELF 
>> variants do not work). In particular, when converting PE (a COFF 
>> variant) to ELF, objcopy does not abort but silently produces bad 
>> PC-relative relocation offsets. In my first Cygwin patch, there is a 
>> hack to fix this in the GRUB ELF loader.
>> 
>> 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.

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

That would be a nice check to have.

--
Marco