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Re: [RFC 2.0] Implementing hwcap2
- From: David Miller <davem at davemloft dot net>
- To: roland at hack dot frob dot com
- Cc: rsa at us dot ibm dot com, libc-alpha at sourceware dot org
- Date: Mon, 08 Apr 2013 19:49:58 -0400 (EDT)
- Subject: Re: [RFC 2.0] Implementing hwcap2
- References: <20130408223743 dot 7FA9E2C088 at topped-with-meat dot com> <20130408 dot 185933 dot 1477627444584685494 dot davem at davemloft dot net> <20130408232952 dot 4898F2C080 at topped-with-meat dot com>
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.