Error "arielapi.c: MPI_Init called in arielapi.c but this file was compiled without MPI." although Ariel was compiled with MPI

[EweLo]

In the latest Version of sst-elements (15.1.0) a binary that was compiled with the Ariel API throws the following error even if sst-elements was configured with --enable-ariel-mpi:

Error: arielapi.c: MPI_Init called in arielapi.c but this file was compiled without MPI.

Details

• sst-core was configured with ./configure --prefix=$SST_CORE_HOME --disable-mpi (mpi needs to be disabled for Ariel to be able to run mpi binaries)
• sst-elements was configured with ./configure --prefix=$SST_ELEMENTS_HOME --with-sst-core=$SST_CORE_HOME --with-pin=$PIN_HOME --enable-ariel-mpi. The output of the configure command confirmed that MPI for Ariel was enabled: ariel_mpi : YES.
• My binary that gets run by Ariel gets compiled with the following Makefile target:

  mpi-test: mpi-test.c
          $(MPICC) $(CFLAGS) -Wl,-rpath,$(ARIEL_API_LIB_DIR) -o $@ $^ -I$(ARIEL_API_INCLUDE_DIR) -L$(ARIEL_API_LIB_DIR) -larielapi -fopenmp

• Ariel in my SST Configuration:

  ariel = sst.Component("ariel0", "ariel.ariel")
  ariel.addParams( {
      "verbose" : "1",
      "maxcorequeue" : "256",
      "maxissuepercycle" : "2",
      "pipetimeout" : "0",
      "corecount" : str(corecount),
      "clock" : clock,
      "executable" : "./mpi-test",
      "arielmode" : "0",
      "arielinterceptcalls" : "0", # Do not intercept malloc/free 
      "launchparamcount" : 1,
      "launchparam0" : "-ifeellucky", # For Pin2.14 on newer hardware
      "mpimode" : 1,
      "mpiranks": 4,
      "mpitracerank" : 1,
  } )

Possible Fix

I'm not familiar with Automake Makefiles, but here is how I was able to fix the issue: In src/sst/elements/ariel/api/Makefile.am I added AM_CFLAGS = $(CFLAGS_LOCAL).

--- Makefile.am.old	2026-01-16 16:49:54.434124538 +0100
+++ Makefile.am	2026-01-16 16:50:03.922150464 +0100
@@ -1,21 +1,23 @@
 if SST_USE_ARIEL_MPI
 CC_LOCAL = $(ARIEL_MPICC)
 CFLAGS_LOCAL = -fopenmp $(ARIEL_MPI_CFLAGS) -DENABLE_ARIEL_MPI=1
 else
 CC_LOCAL = $(CC)
 CFLAGS_LOCAL =
 endif
 
 AM_CPPFLAGS += \
 	$(MPI_CPPFLAGS) \
 	-I$(top_srcdir)/src
 
+AM_CFLAGS = $(CFLAGS_LOCAL)
+
 lib_LTLIBRARIES = libarielapi.la
 
 libarielapi_la_SOURCES = \
     arielapi.c \
     arielapi.h
 
 libarielapi_la_LDFLAGS = -module -avoid-version -shared
 
 include_HEADERS = arielapi.h

[plavin]

MPI support in Ariel now requires that core be built with MPI, which is a reversal of the previous requirement. It now uses MPI_Comm_spawn_multiple to spawn the traced app in a communicator separate from the one core uses. MPI apps are not supposed to fork, so this is a more robust solution.

The new sst-info arie.ariel text reflects this, but we probably should have put it in the release notes.

Could you try recompiling core with MPI enabled and see if that fixes your issue?

[plavin]

Apologies, @EweLo, it looks like the changes got merged into Core to support this but not into Ariel. I will work on merging it ASAP and let you know.