On Fri, Feb 15, 2013 at 2:15 PM, Kirk, Benjamin (JSC-EG311) <benjamin.kirk-1@nasa.gov> wrote:
On Feb 15, 2013, at 2:42 PM, Roy Stogner <roystgnr@ices.utexas.edu> wrote:

> "trump --enable-petsc with --disable-mpi", why?
> PETSc can be built without MPI, and in fact an enable-petsc,
> disable-mpi build is the first non-default configuration we're testing
> in BuildBot.

In case you want to --disable-mpi, of course?!

I was just running a Cygwin configuration with

$ ../configure --disable-mpi

only to find LIBMESH_HAVE_MPI defined, courtesy of petsc.m4's MPI fallback stuff.  

Is this is that old "mpiuni" thing?  So it looks like you have MPI but it only works on one processor... or is this a full MPI installation sitting in $PETSC_DIR?

In this case there is MPI on the system,

What if I don't want MPI??  Should I need to remember

$ ../configure --disable-mpi --disable-petsc?

I'd say --disable-mpi should allow a PETSc with an mpiuni implementation (if such a beast still exists) but not allow a PETSc that has a "real" MPI implementation.  No idea how we'd detect that though :P