[patch, binutils] Patch elf/mips.h for -mfp64 support.

[Jack Carter]

________________________________________
> From: Maciej W. Rozycki [macro@codesourcery.com]
> Sent: Tuesday, September 17, 2013 4:10 PM
> To: Jack Carter
> Cc: Richard Sandiford; Doug Gilmore; binutils@sourceware.org
> Subject: Re: [patch, binutils] Patch elf/mips.h for -mfp64 support.
> 
> [Usenet cross-posting stripped, no usable NNTP server here, sigh...]
> 
> On Tue, 17 Sep 2013, Jack Carter wrote:
> 
> >   Hehe, actually I reckon I have once raised the issue somewhere already
> > and I can surely do it again, though I think it will be wise to think
> > ahead and have an idea what the extension might look like as I'm sure the
> > need for it is bound to happen sooner rather than later.
>
> Are talking about the PT_NOTE segment and .note section? If so, that is
> described in the System V abi circa '92 and is very simple.
> 
>  Yes, we've been using these sections/segments for a while already
> although for a different purpose (see csu/abi-note.S in glibc).

Well do we want to do what SGI did and is documented in the 64-bit ELF Object
File Specification and use the Options section? I would think that the NOTE segment
would be the more generic way to go, but if it is being used for different purposes
maybe we have no choice.

SGI put this information right after the ELF header so it got pulled in with it for
quick lookups.

> 
>  The use of a note as a replacement for (or an extension of) e_flags for
> the MIPS target has been considered for at least some 10 years now, but so
> far people have only been pinching further bits from e_flags instead. ;)
> I think the MIPS target is the only one to have an issue with running out
> of these flags, other architectures seem to have been more conservative on
> creating new options and hence there has been no general rush towards
> using a note to record target ISA/ABI/etc. options.
> 
>   Maciej