[ET Trac] [Einstein Toolkit] #1667: ExternalLibraries/MPI should report error messages

[Einstein Toolkit]

#1667: ExternalLibraries/MPI should report error messages
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  Reporter:  hinder  |       Owner:                     
      Type:  defect  |      Status:  new                
  Priority:  minor   |   Milestone:                     
 Component:  Cactus  |     Version:  development version
Resolution:          |    Keywords:  MPI                
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Comment (by eschnett):

 This error message means that (a) thorn MPI was not able to find a usable
 MPI version on its own, and (b) you did not specify sufficient information
 in the option list for manual configuration.

 The old MPI thorn did not output any more information in this case either.
 But it probably would have continued, leading to build errors later.

 I see these options for Loewe:
 {{{
 MPI_DIR      = NO_BUILD
 MPI_INC_DIRS = /cm/shared/apps/slurm/current/include
 /cm/shared/apps/mvapich2/intel-14.0.3/2.0/include
 /cm/shared/apps/mvapich2/intel-14.0.3/2.0/include
 MPI_LIB_DIRS = /cm/shared/apps/mvapich2/intel-14.0.3/2.0/lib
 MPI_LIBS     = mpich opa mpl
 }}}

 Since MPI_DIR is not specified (it is set to NO_BUILD), this means you do
 not want to provide a manual configuration. A manual configuration, at the
 very least, needs to point to a directory where MPI is installed. Since
 you also say NO_BUILD, thorn MPI will not build MPI. That leaves auto-
 configuration -- but that apparently didn't work either, probably because
 no MPI modules are loaded.

 I suggest changing MPI_DIR to /cm/shared/apps/mvapich2/intel-14.0.3/2.0.
 The setting for MPI_LIB_DIRS can then be omitted.

 We could output something like my explanation above, but note that this
 does not depend on anything that thorn MPI did or found; this is just an
 explanation of how MPI_DIR works. Maybe this would be a good idea, since
 people find it confusing.

-- 
Ticket URL: <https://trac.einsteintoolkit.org/ticket/1667#comment:6>
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