Re: [Gcl-devel] Re: gcc-3.2 problems in compiling GCL
Greetings!
Richard Zidlicky <rz@linux-m68k.org> writes:
> On Tue, Feb 18, 2003 at 04:46:46PM -0500, Camm Maguire wrote:
> > Greetings, and thanks for the insight. GCL does a subbuild of part of
> > GMP. With the default configure script canonical host of
> > m68k-unknown-linux-gnu, gmp3 adds -m68000 to the command line.
>
> this is slightly broken - there has never been 68000 support
> in Linux.
>
> > Perhaps the autobuilders should use m68020-unknown-linux-gnu as the
> > lowest common denominator?
>
> this would work but not very well on 68060 models though.. here
> are the options:
> a) use m68k-*linux WITHOUT -m68000 flag. Will loose some
> performance on 68020-40 models, nearly optimal for 68060
> b) m68020-linux will loose *lots* of performance on 68060 models.
> c) compile 2 versions of the library/program for 20-40 or 60
> models.
>
> (a) is pretty acceptable, (b) would be probably the worst alternative.
> (c) would be nice and I think it is time to use multilibs for m68k-linux.
>
OK, this won't get done before the next release, but what I'd like to
do is 1) benchmark the bignum code and see if these issues make a big
difference, and 2) assuming yes to 1), implement a dynamic library
alternative system as is done in atlas/lapack/blas on Debian
GNU/Linux, say by building a libgcl_gmp.so. I don't know if you are
familiar with how this works, but I'd like your feedback if you are
interested. Basically, one can install several binary-compatible
versions of the same library, and have the running cpu select the best
one for its capabilities at run time via ld.so.conf. I've made a
policy proposal, but thus far it has not received much interest:
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=120418
In any case, this works great right now for blas and lapack API's on
Debian, and quite a few packages rely on it. I feel this is the way
to go for performance critical pieces of code in a generic
distribution like Debian.
Take care,
> Richard
>
>
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>
>
--
Camm Maguire camm@enhanced.com
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