[petsc-users] Warning while compiling Fortran with PETSc

[Bojan Niceno]

To whom it may concern,


I am working on a Fortran (2003) computational fluid dynamics solver, which
is actually quite mature, was parallelized with MPI from the very beginning
and it comes with its own suite of Krylov solvers.  Although the code is
self-sustained, I am inclined to believe that it would be better to use
PETSc instead of my own home-grown solvers.

In the attempt to do so, I have installed PETSc 3.16.4 with following
options:

./configure --with-debugging=yes --download-openmpi=yes
--download-fblaslapack=yes --download-metis=yes --download-parmetis=yes
--download-cmake=yes

on a workstation running Ubuntu 20.04 LTS.  The mpif90 command which I use
to compile the code, wraps gfortran with OpenMPI, hence the option
"--download-openmpi=yes" when configuring PETSc.

Anyhow, installation of PETSc went fine, I managed to link and run it with
my code, but I am getting the following messages during compilation:

Petsc_Mod.f90:18:6:

   18 |   use PetscMat, only: tMat, MAT_FINAL_ASSEMBLY
      |      1
Warning: Named COMMON block ‘mpi_fortran_bottom’ at (1) shall be of the
same size as elsewhere (4 vs 8 bytes)

Petsc_Mod.f90 is a module I wrote for interfacing PETSc.  All works, but
these messages give me a reason to worry.

Can you tell what causes this warnings?  I would guess they might appear if
one mixes OpenMPI with MPICH, but I don't think I even have MPICH on my
system.

Please let me know what you think about it?

    Cheers,

    Bojan
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20220209/d37eec53/attachment.html>