I think of -m32 (and -m64) as really selecting a different compiler.  My practice is to put those flags in the compiler/linker environment variables.  For example:

# ./configure >configure.log 2>&1 \
   --prefix=/usr/local/openmpi --with-sge \
   CC="gcc -m32" \
   CFLAGS="-g -O3" \
   CXX="g++ -m32" \
   CXXFLAGS="-g -O3" \
   FC="gfortran -m32" \
   FCFLAGS="-g -O3" \
   F77="gfortran -m32" \
   FFLAGS="-g -O3"

Larry Baker
US Geological Survey

On 23 Nov 2011, at 10:52 AM, TERRY DONTJE wrote:

On 11/23/2011 1:45 PM, Lukas Razik wrote:
TERRY DONTJE <terry.dontje@oracle.com> wrote

Can you build OMPI as a 32 bit library and see if that works any better?
So you mean I shall leave the whole OFED stack as 64 bit and build only openmpi as 32 bit?
I believe the OFED user libraries will need to be 32 bit also or the 32 bit MPI libraries will not be able to use them.
How must I configure openmpi that it'll be definitely built as 32bit?
You need to change the CFLAGS, CXXFLAGS, FFLAGS and FCFLAGS in the configure line such that you replace "-m64" with "-m32" or just "-m32" if "-m64" is not there?

Terry D. Dontje | Principal Software Engineer
Developer Tools Engineering | +1.781.442.2631
Oracle - Performance Technologies
95 Network Drive, Burlington, MA 01803
Email terry.dontje@oracle.com

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