How to prevent multilib builds if OS support missing?

[Ulrich Weigand]

Richard Henderson wrote:

>--disable-multilib?

Well, yes, but then gcc tries to find the 64-bit system libraries
in /usr/lib, where they aren't ...

What I need to build gcc on, say, SuSE SLES-7 for zSeries is a
setup where the 64-bit system libraries are taken from /usr/lib64
(just like the multi-lib setup with MULTILIB_OSDIRNAMES does),
but no attempt to build the 31-bit libraries is made (because in
/usr/lib there is just enough to support *running* 31-bit binaries,
but not *building* them.)

I had been looking to achieve that by running with --enable-multilib,
but removing the -m31 variant from the list of multilibs.  However,
this doesn't work for libgcc_s, it appears.

(Actually, besides the full multilib scenario as in SLES-8 and 
the just mentioned /usr/lib64 64-bit only scenario as in SLES-7,
there is a third variant: the 64-bit only scenario with system
libraries in /usr/lib, like in e.g. Red Hat 7.1 for zSeries.
*This* can be handled via --disable-multilib just fine, but the
ideal solution would be to automatically discover that during
configure, so that everything just works on all distributions
currently in use on our platform ;-))

Bye,
Ulrich

-- 
  Dr. Ulrich Weigand
  weigand@informatik.uni-erlangen.de