[RFC 2.0] Implementing hwcap2

[David Miller]

From: Roland McGrath <roland@hack.frob.com>
Date: Mon,  8 Apr 2013 16:29:52 -0700 (PDT)

>> The issue is that the API exists on the ELF level rather than that
>> of a traditional C interface.
> 
> Indeed.  We have dealt with other such cases more or less adequately
> (DT_GNU_HASH, STB_GNU_UNIQUE, etc.).  But even those were not as
> graceful as one would have liked (except perhaps for --hash-style=both,
> which is pretty thoroughly fine).  And none of those past cases involved
> an ELF ABI element that had an old-version-ABI to new-version-ABI
> transition rather than the simpler introduction of a wholly new ABI
> element.  That's essentially why I am inclined toward the position that
> STT_GNU_IFUNC is still not really ready for prime time.

I suppose we should look at setting a bit in the ELF header or
somesuch.  Something that would be rejected by current libc but which
we could make the newer libc accept.