Index: ompi/runtime/ompi_mpi_init.c
===================================================================
--- ompi/runtime/ompi_mpi_init.c	(revision 26313)
+++ ompi/runtime/ompi_mpi_init.c	(working copy)
@@ -388,6 +388,7 @@
         gettimeofday(&ompistart, NULL);
     }

+    opal_output(0, "Pre orte_init -- cacheline size is: %d\n", opal_cache_line_size);
     /* Setup ORTE - note that we are an MPI process  */
     if (ORTE_SUCCESS != (ret = orte_init(NULL, NULL, ORTE_PROC_MPI))) {
         error = "ompi_mpi_init: orte_init failed";
@@ -1188,5 +1189,6 @@
     }
 #endif

+    opal_output(0, "Post orte_init -- cacheline size is: %d\n", opal_cache_line_size);
     return MPI_SUCCESS;
 }
Index: opal/runtime/opal.h
===================================================================
--- opal/runtime/opal.h	(revision 26313)
+++ opal/runtime/opal.h	(working copy)
@@ -30,11 +30,10 @@
 /** version string of opal */
 OPAL_DECLSPEC extern const char opal_version_string[];

-/* Size of a cache line.  To be replaced with real hwloc info (in
-   trunk/v1.5 and beyond, only), but for the moment, just move it here
-   so that we can remove opal/include/sys/cache.h whose only purpose
-   is life is to #define CACHE_LINE_SIZE (and has a conflict on
-   NetBSD). */
+/* Size of a cache line.  Initialized to -1 until hwloc data is
+   available, at which time it is filled with the smallest size of the
+   lowest cache line (e.g., the smallest line size from all L1 caches
+   found on the current system). */
 OPAL_DECLSPEC extern int opal_cache_line_size;

 /**
Index: opal/runtime/opal_init.c
===================================================================
--- opal/runtime/opal_init.c	(revision 26313)
+++ opal/runtime/opal_init.c	(working copy)
@@ -70,7 +70,10 @@

 int opal_initialized = 0;
 int opal_util_initialized = 0;
-int opal_cache_line_size;
+/* We have to put a guess in here in case hwloc is not available.  If
+   hwloc is available, this value will be overwritten when the
+   hwloc data is loaded. */
+int opal_cache_line_size = 128;

 static int
 opal_err2str(int errnum, const char **errmsg)
@@ -232,12 +235,6 @@
         return OPAL_SUCCESS;
     }

-    /* JMS See note in runtime/opal.h -- this is temporary; to be
-       replaced with real hwloc information soon (in trunk/v1.5 and
-       beyond, only).  This *used* to be a #define, so it's important
-       to define it very early.  */
-    opal_cache_line_size = 128;
-
     /* initialize the memory allocator */
     opal_malloc_init();

Index: opal/mca/hwloc/base/hwloc_base_util.c
===================================================================
--- opal/mca/hwloc/base/hwloc_base_util.c	(revision 26313)
+++ opal/mca/hwloc/base/hwloc_base_util.c	(working copy)
@@ -27,6 +27,7 @@
 #include <unistd.h>
 #endif

+#include "opal/runtime/opal.h"
 #include "opal/constants.h"
 #include "opal/util/argv.h"
 #include "opal/util/output.h"
@@ -169,6 +170,34 @@
     return OPAL_SUCCESS;
 }

+static void fill_cache_line_size(void)
+{
+    int i = 0;
+    unsigned size;
+    hwloc_obj_t obj;
+
+    size = 4096;
+    printf("Calculating cachlinesize:\n");
+    while (1) {
+        obj = opal_hwloc_base_get_obj_by_type(opal_hwloc_topology,
+                                              HWLOC_OBJ_CACHE, 1,
+                                              i, OPAL_HWLOC_LOGICAL);
+        if (NULL == obj) {
+            break;
+        } else { 
+            printf("Examining L1 cache %d\n", i);
+            if (NULL != obj->attr &&
+                size > obj->attr->cache.linesize) {
+                size = obj->attr->cache.linesize;
+            }
+        }
+        ++i;
+    }
+
+    opal_cache_line_size = (int) size;
+    printf("Calculated cachlinesize: %d\n", opal_cache_line_size);
+}
+
 int opal_hwloc_base_get_topology(void)
 {
     int rc;
@@ -186,6 +215,13 @@

     /* filter the cpus thru any default cpu set */
     rc = opal_hwloc_base_filter_cpus(opal_hwloc_topology);
+    if (OPAL_SUCCESS != rc) {
+        return rc;
+    }
+
+    /* fill opal_cache_line_size global with the smallest L1 cache
+       line size */
+    fill_cache_line_size();
     return rc;
 }