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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 18:12:29 -0400 (EDT)
- Subject: Re: [RFC 2.0] Implementing hwcap2
- References: <20130328234033 dot 9197A2C0A7 at topped-with-meat dot com> <20130328 dot 201048 dot 1654197573467873843 dot davem at davemloft dot net> <20130408220507 dot 5699D2C088 at topped-with-meat dot com>
From: Roland McGrath <roland@hack.frob.com>
Date: Mon, 8 Apr 2013 15:05:07 -0700 (PDT)
> The calling convention for IFUNC resolvers is machine-specific.
> Thus, it's up to each machine maintainer to decide what it should be
> for his machine. Given how rare IFUNC use still is, I'd say it's
> also up to each machine maintainer to decide whether or not an
> incompatible change to the convention is acceptable at this stage.
>
> It might be nice if these conventions were unified, but to get there
> from the status quo would require consensus among all the maintainers
> for machines that now support IFUNC at all.
>From my perspective, I'd like to say that sparc has a sufficient small
user base that changing the calling convention might be doable.
But even for a small user base, consider something like how right now
I'm about to start working on using IFUNC for sparc in libgmp. If I
tell the GMP maintainer that "by the way" the IFUNC calling convention
is libc version specific, he'll not be too pleased about that, because
he will demand that this new facility will work with all libc versions.
The existing calling convention has several glibc releases worth of
exposure, plus it's the one in use on all Linux distributions.
I frankly don't think we can safely change it for any target, and at
the same time expect any level of adoption outside of glibc
whatsoever.