If threads are not supported but were required we will go for SERIALIZED,

otherwise whatever was required.

This commit was SVN r25653.

ompi/runtime/ompi_mpi_init.c

@@ -386,12 +386,18 @@ int ompi_mpi_init(int argc, char **argv, int requested, int *provided)
        MPI_THREAD_MULTIPLE.  Set this stuff up here early in the
        process so that other components can make decisions based on
        this value. */
-
+    /**
+     * These values are monotonic; MPI_THREAD_SINGLE < MPI_THREAD_FUNNELED
+     *                             < MPI_THREAD_SERIALIZED < MPI_THREAD_MULTIPLE.
+     * If possible, the call will return provided = required. Failing this,
+     * the call will return the least supported level such that
+     * provided > required. Finally, if the user requirement cannot be
+     * satisfied, then the call will return in provided the highest
+     * supported level.
+     */
     ompi_mpi_thread_requested = requested;
-    if (OPAL_ENABLE_MULTI_THREADS == 0) {
-        ompi_mpi_thread_provided = *provided = MPI_THREAD_SINGLE;
-        ompi_mpi_main_thread = NULL;
-    } else if (OMPI_ENABLE_THREAD_MULTIPLE == 1) {
+
+    if (OMPI_ENABLE_THREAD_MULTIPLE == 1) {
         ompi_mpi_thread_provided = *provided = requested;
         ompi_mpi_main_thread = opal_thread_get_self();
     } else {
@@ -400,21 +406,20 @@ int ompi_mpi_init(int argc, char **argv, int requested, int *provided)
         } else {
             ompi_mpi_thread_provided = *provided = requested;
         }
-        ompi_mpi_main_thread = opal_thread_get_self();
+        ompi_mpi_main_thread = (OPAL_ENABLE_MULTI_THREADS ? opal_thread_get_self() : NULL);
     }
 
     ompi_mpi_thread_multiple = (ompi_mpi_thread_provided == 
                                 MPI_THREAD_MULTIPLE);
 
-
     /* determine the bitflag belonging to the threadlevel_support provided */
     memset ( &threadlevel_bf, 0, sizeof(uint8_t));
     OMPI_THREADLEVEL_SET_BITFLAG ( ompi_mpi_thread_provided, threadlevel_bf );
 
     /* add this bitflag to the modex */
     if ( OMPI_SUCCESS != (ret = ompi_modex_send_string("MPI_THREAD_LEVEL", &threadlevel_bf, sizeof(uint8_t)))) {
-	error = "ompi_mpi_init: modex send thread level";
-	goto error;
+        error = "ompi_mpi_init: modex send thread level";
+        goto error;
     }
 
     /* Once we've joined the RTE, see if any MCA parameters were