[petsc-users] Warning while compiling Fortran with PETSc

[Satish Balay]

To clarify:

you are using --download-openmpi=yes with petsc. However you say:

> > The mpif90 command which
> > I use to compile the code, wraps gfortran with OpenMPI

This suggests a different install of OpenMPI is used to build your code.

One way to resolve this is - delete current build of PETSc - and rebuild it with this same MPI [that you are using with your application]

./configure --with-cc=mpicc --with-cxx=mpicxx --with-fc=mpif90  --download-fblaslapack --download-metis --download-parmetis --download-cmake

Also PETSc provides makefile format that minimizes such conflicts..

https://petsc.org/release/docs/manual/getting_started/#writing-c-c-or-fortran-applications

Satish

On Wed, 9 Feb 2022, Balay, Satish via petsc-users wrote:

> 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
> > 
> > 
> > 
> > 
> 
>