[mpich2-dev] shared-lib builds, MPE, and SELinux en ENFORCING mode

[Lisandro Dalcin]

Just built 1.1rc1 with shared libraries, and then tried to build
mpi4py's Python extension module (a dlpen()'able shared lib) with MPE
(by passing -mpi=mpilog to mpicc). When I try to import my extension
module, I get:

$ python
>>> from mpi4py import MPI
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: /u/dalcinl/lib/python/mpi4py/MPI.so: cannot restore
segment prot after reloc: Permission denied
>>>

This happens because I have SELinux enabled in ENFORCING and because
the MPE sources were not compiled with -fPIC

$ eu-findtextrel /u/dalcinl/lib/python/mpi4py/MPI.so
/u/dalcinl/BUILD/MPI/mpich2-1.1rc1/src/mpe2/src/wrappers/src/log_mpi_core.c
not compiled with -fpic/-fPIC
<...more-output...>

and then my "MPI.so" extension module requires relocation on loading
(and this is prohibited by SELinux in ENFORCING mode).

This could be solved (apart from asking me to use "chcon -t
texrel_shlib_t ...") by two ways:

1) Use -fPIC for compiling the MPE sources, but continue building the
MPE libs as static ones.
2) Also build shared libs for MPE.

(1) is easy and definitely works on Linux, though I do not know if
this is valid on other systems.
(2) is the definitive solution, but perhaps a bit harder to implement
because of the required modifications to MPICH2's buildsystem.



-- 
Lisandro Dalcín
---------------
Centro Internacional de Métodos Computacionales en Ingeniería (CIMEC)
Instituto de Desarrollo Tecnológico para la Industria Química (INTEC)
Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)
PTLC - Güemes 3450, (3000) Santa Fe, Argentina
Tel/Fax: +54-(0)342-451.1594