--enable-fat option doesn't work on Mac OS X / PowerPC

Vincent Lefevre vincent at vinc17.org
Fri Aug 17 13:56:39 CEST 2007

On 2007-08-17 13:36:35 +0200, Michael Abshoff wrote:
> Hello Vincent,

Hi Michael, thanks for the quick reply.

> Vincent Lefevre wrote:
> > "./configure --help" says:
> >
> >   --enable-fat            build a fat binary on systems that support it
> >                           [default=no]
> >
> > I've tried it under Mac OS X, as Mac OS X supports fat binaries,
> Technically fat binaries on Mac OS9 and maybe earlier are binaries with an
> 68k and a PowerPC personality. MacOSX has universal binaries which combine
> 32 or 64 bit and PowerPC or x86 (a total of 4 combinations) executables.

In fact, "fat binaries" and "universal binaries" seem to be the same
notion. "man otool" says "-f     Display the universal headers.", but
"otool -fv" output uses the word "fat":

Fat headers
fat_magic FAT_MAGIC
nfat_arch 2

> If you want to build a universal version of the gmp build them
> individually and use lipo to combine the output. For more details
> see man lipo.

Thanks for the information. I'll try that (I want to have a library
with ppc and ppc64 code). I suppose that concerning gmp.h, the best
solution is to rename both versions, and create my own gmp.h, which
includes the right header file with "#if __ppc64__ ... #else ...".

> > but it doesn't seem to work: no dynamic library is generated.
> The same happens on Opterons, but as it is stated in the help this
> only works on x86.

OK, so the problem is with configure, which gives incorrect

Vincent Lefèvre <vincent at vinc17.org> - Web: <http://www.vinc17.org/>
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Work: CR INRIA - computer arithmetic / Arenaire project (LIP, ENS-Lyon)

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