[petsc-users] Warning while compiling Fortran with PETSc

[Balay, Satish]

Are you using the same MPI to build both PETSc and your appliation?

Satish

On Wed, 2022-02-09 at 05:21 +0100, Bojan Niceno wrote:
> 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
> 
> 
> 
>