RFC: Add 32bit x86-64 support to binutils

[Jan Beulich]

>>> On 05.01.11 at 09:01, "H. Peter Anvin" <hpa@zytor.com> wrote:
> On 01/04/2011 11:46 PM, Jan Beulich wrote:
>>>>
>>>> Oh god, please, no.
>>>>
>>>> I have to say I'm highly questioning to Jan's statement in the first
>>>> place.  Crossing 32- and 64-bit ELF like that sounds like a kernel
>>>> security hole waiting to happen.
>> 
>> A particular OS/kernel has the freedom to not implement support for
>> other than the default format. But having the ABI disallow it
>> altogether certainly isn't the right choice. And yes, we had been
>> allowing cross-bitness ELF in an experimental (long canceled) OS
>> of ours.
>> 
>>> Yeah, and there are other targets where the elf class determines ABI
>>> too (e.g. EM_S390 is used for both 31-bit and 64-bit binaries and
>>> the ELF class determines which).
>> 
>> So the usual thing is going to happen - someone made a mistake (I'm
>> convinced the ELF class was never meant to affect anything but the
>> file format), and this gets taken as an excuse to let the mistake
>> spread.
>> 
> 
> I don't think it's all that unreasonable to say the ELF class affects
> the ABI.  After all, there are lots of things about the ABI that is
> related to the ELF class -- the format of the GOT and PLT, for one thing.

That's in executables and dynamic objects only. I'm not aware of
anything in relocatable objects, and I'd question it for core files.
The ABI, however, has to cover all of them.

Jan