API: add a misc support array for a "imported_support" feature

Passing HWLOC_TOPOLOGY_FLAG_IMPORT_SUPPORT won't import anything
if the XML comes from hwloc 2.2-. This new feature bit will be set
on success to import support.

The XML export doesn't contain that feature bit explicitly because
it's only meaningful locally. But it now contains a custom/fake
feature bit "custom.exported_support" that it always set on 2.3 export.
Then the importer knows whether support was unsupported in the exporter,
or just empty (likely rare, only on non-supported OS).

Signed-off-by: Brice Goglin <[email protected]>

Author: bgoglin

NEWS

@@ -23,6 +23,8 @@ Version 2.3.0
 * API
   + The new topology flag HWLOC_TOPOLOGY_FLAG_IMPORT_SUPPORT causes
     support arrays to be loaded from XML exported with hwloc 2.3+.
+    - hwloc_topology_get_support() now returns an additional "misc"
+      array with feature "imported_support" set when support was imported.
 * Backends
   + Add a ROCm SMI backend and a hwloc/rsmi.h helper file for getting
     the locality of AMD GPUs, now exposed as "rsmi" OS devices.

doc/Makefile.am

@@ -440,6 +440,7 @@ man3_configuration_DATA = \
         $(DOX_MAN_DIR)/man3/hwloc_topology_discovery_support.3 \
         $(DOX_MAN_DIR)/man3/hwloc_topology_cpubind_support.3 \
         $(DOX_MAN_DIR)/man3/hwloc_topology_membind_support.3 \
+        $(DOX_MAN_DIR)/man3/hwloc_topology_misc_support.3 \
         $(DOX_MAN_DIR)/man3/hwloc_topology_support.3 \
         $(DOX_MAN_DIR)/man3/hwloc_type_filter_e.3 \
         $(DOX_MAN_DIR)/man3/HWLOC_TYPE_FILTER_KEEP_ALL.3 \

hwloc/shmem.c

@@ -1,5 +1,5 @@
 /*
- * Copyright © 2017-2019 Inria.  All rights reserved.
+ * Copyright © 2017-2020 Inria.  All rights reserved.
  * See COPYING in top-level directory.
  */
 
@@ -214,11 +214,13 @@ hwloc_shmem_topology_adopt(hwloc_topology_t *topologyp,
   new->support.discovery = malloc(sizeof(*new->support.discovery));
   new->support.cpubind = malloc(sizeof(*new->support.cpubind));
   new->support.membind = malloc(sizeof(*new->support.membind));
-  if (!new->support.discovery || !new->support.cpubind || !new->support.membind)
+  new->support.misc = malloc(sizeof(*new->support.misc));
+  if (!new->support.discovery || !new->support.cpubind || !new->support.membind || !new->support.misc)
     goto out_with_support;
   memcpy(new->support.discovery, old->support.discovery, sizeof(*new->support.discovery));
   memcpy(new->support.cpubind, old->support.cpubind, sizeof(*new->support.cpubind));
   memcpy(new->support.membind, old->support.membind, sizeof(*new->support.membind));
+  memcpy(new->support.misc, old->support.misc, sizeof(*new->support.misc));
   hwloc_set_binding_hooks(new);
   /* clear userdata callbacks pointing to the writer process' functions */
   new->userdata_export_cb = NULL;
@@ -236,6 +238,7 @@ hwloc_shmem_topology_adopt(hwloc_topology_t *topologyp,
   free(new->support.discovery);
   free(new->support.cpubind);
   free(new->support.membind);
+  free(new->support.misc);
   free(new);
  out_with_components:
   hwloc_components_fini();
@@ -252,6 +255,7 @@ hwloc__topology_disadopt(hwloc_topology_t topology)
   free(topology->support.discovery);
   free(topology->support.cpubind);
   free(topology->support.membind);
+  free(topology->support.misc);
   free(topology);
 }
 

hwloc/topology-xml.c

@@ -1262,10 +1262,11 @@ hwloc__xml_v2import_support(hwloc_topology_t topology,
 
   if (name && topology->flags & HWLOC_TOPOLOGY_FLAG_IMPORT_SUPPORT) {
 #ifdef HWLOC_DEBUG
-    HWLOC_BUILD_ASSERT(sizeof(struct hwloc_topology_support) == 3*sizeof(void*));
+    HWLOC_BUILD_ASSERT(sizeof(struct hwloc_topology_support) == 4*sizeof(void*));
     HWLOC_BUILD_ASSERT(sizeof(struct hwloc_topology_discovery_support) == 5);
     HWLOC_BUILD_ASSERT(sizeof(struct hwloc_topology_cpubind_support) == 11);
     HWLOC_BUILD_ASSERT(sizeof(struct hwloc_topology_membind_support) == 15);
+    HWLOC_BUILD_ASSERT(sizeof(struct hwloc_topology_misc_support) == 1);
 #endif
 
 #define DO(_cat,_name) if (!strcmp(#_cat "." #_name, name)) topology->support._cat->_name = value
@@ -1300,6 +1301,11 @@ hwloc__xml_v2import_support(hwloc_topology_t topology,
     else DO(membind,nexttouch_membind);
     else DO(membind,migrate_membind);
     else DO(membind,get_area_memlocation);
+
+    else if (!strcmp("custom.exported_support", name))
+      /* support was exported in a custom/fake field, mark it as imported here */
+      topology->support.misc->imported_support = 1;
+
 #undef DO
   }
 
@@ -2702,10 +2708,11 @@ hwloc__xml_v2export_support(hwloc__xml_export_state_t parentstate, hwloc_topolog
   char tmp[11];
 
 #ifdef HWLOC_DEBUG
-  HWLOC_BUILD_ASSERT(sizeof(struct hwloc_topology_support) == 3*sizeof(void*));
+  HWLOC_BUILD_ASSERT(sizeof(struct hwloc_topology_support) == 4*sizeof(void*));
   HWLOC_BUILD_ASSERT(sizeof(struct hwloc_topology_discovery_support) == 5);
   HWLOC_BUILD_ASSERT(sizeof(struct hwloc_topology_cpubind_support) == 11);
   HWLOC_BUILD_ASSERT(sizeof(struct hwloc_topology_membind_support) == 15);
+  HWLOC_BUILD_ASSERT(sizeof(struct hwloc_topology_misc_support) == 1);
 #endif
 
 #define DO(_cat,_name) do {                                     \
@@ -2752,6 +2759,15 @@ hwloc__xml_v2export_support(hwloc__xml_export_state_t parentstate, hwloc_topolog
   DO(membind,migrate_membind);
   DO(membind,get_area_memlocation);
 
+  /* misc.imported_support would be meaningless in the remote importer,
+   * but the importer needs to know whether we exported support or not
+   * (in case there are no support bit set at all),
+   * use a custom/fake field to do so.
+   */
+  parentstate->new_child(parentstate, &state, "support");
+  state.new_prop(&state, "name", "custom.exported_support");
+  state.end_object(&state, "support");
+
 #undef DO
 }
 

hwloc/topology.c

@@ -970,6 +970,7 @@ hwloc__topology_dup(hwloc_topology_t *newp,
   memcpy(new->support.discovery, old->support.discovery, sizeof(*old->support.discovery));
   memcpy(new->support.cpubind, old->support.cpubind, sizeof(*old->support.cpubind));
   memcpy(new->support.membind, old->support.membind, sizeof(*old->support.membind));
+  memcpy(new->support.misc, old->support.misc, sizeof(*old->support.misc));
 
   new->allowed_cpuset = hwloc_bitmap_tma_dup(tma, old->allowed_cpuset);
   new->allowed_nodeset = hwloc_bitmap_tma_dup(tma, old->allowed_nodeset);
@@ -3519,6 +3520,7 @@ hwloc_topology_setup_defaults(struct hwloc_topology *topology)
   memset(topology->support.discovery, 0, sizeof(*topology->support.discovery));
   memset(topology->support.cpubind, 0, sizeof(*topology->support.cpubind));
   memset(topology->support.membind, 0, sizeof(*topology->support.membind));
+  memset(topology->support.misc, 0, sizeof(*topology->support.misc));
 
   /* Only the System object on top by default */
   topology->next_gp_index = 1; /* keep 0 as an invalid value */
@@ -3595,6 +3597,7 @@ hwloc__topology_init (struct hwloc_topology **topologyp,
   topology->support.discovery = hwloc_tma_malloc(tma, sizeof(*topology->support.discovery));
   topology->support.cpubind = hwloc_tma_malloc(tma, sizeof(*topology->support.cpubind));
   topology->support.membind = hwloc_tma_malloc(tma, sizeof(*topology->support.membind));
+  topology->support.misc = hwloc_tma_malloc(tma, sizeof(*topology->support.misc));
 
   topology->nb_levels_allocated = nblevels; /* enough for default 10 levels = Mach+Pack+Die+NUMA+L3+L2+L1d+L1i+Co+PU */
   topology->levels = hwloc_tma_calloc(tma, topology->nb_levels_allocated * sizeof(*topology->levels));
@@ -3863,6 +3866,7 @@ hwloc_topology_destroy (struct hwloc_topology *topology)
   free(topology->support.discovery);
   free(topology->support.cpubind);
   free(topology->support.membind);
+  free(topology->support.misc);
   free(topology);
 }
 

include/hwloc.h

@@ -1950,7 +1950,10 @@ enum hwloc_topology_flags_e {
    * supported feature bits reported by hwloc_topology_get_support().
    *
    * The flag ::HWLOC_TOPOLOGY_FLAG_IMPORT_SUPPORT actually imports
-   * support bits from the remote machine.
+   * support bits from the remote machine. It also sets the flag
+   * \p imported_support in the struct hwloc_topology_misc_support array.
+   * If the imported XML did not contain any support information
+   * (exporter hwloc is too old), this flag is not set.
    *
    * Note that these supported features are only relevant for the hwloc
    * installation that actually exported the XML topology
@@ -2074,6 +2077,13 @@ struct hwloc_topology_membind_support {
   unsigned char get_area_memlocation;
 };
 
+/** \brief Flags describing miscellaneous features.
+ */
+struct hwloc_topology_misc_support {
+  /** Support was imported when importing another topology, see ::HWLOC_TOPOLOGY_FLAG_IMPORT_SUPPORT. */
+  unsigned char imported_support;
+};
+
 /** \brief Set of flags describing actual support for this topology.
  *
  * This is retrieved with hwloc_topology_get_support() and will be valid until
@@ -2084,6 +2094,7 @@ struct hwloc_topology_support {
   struct hwloc_topology_discovery_support *discovery;
   struct hwloc_topology_cpubind_support *cpubind;
   struct hwloc_topology_membind_support *membind;
+  struct hwloc_topology_misc_support *misc;
 };
 
 /** \brief Retrieve the topology support.
@@ -2104,7 +2115,8 @@ struct hwloc_topology_support {
  *
  * Topology flag ::HWLOC_TOPOLOGY_FLAG_IMPORT_SUPPORT may be used
  * to report the supported features of the original remote machine
- * instead.
+ * instead. If it was successfully imported, \p imported_support
+ * will be set in the struct hwloc_topology_misc_support array.
  */
 HWLOC_DECLSPEC const struct hwloc_topology_support *hwloc_topology_get_support(hwloc_topology_t __hwloc_restrict topology);
 

include/hwloc/rename.h

@@ -135,6 +135,7 @@ extern "C" {
 #define hwloc_topology_discovery_support HWLOC_NAME(topology_discovery_support)
 #define hwloc_topology_cpubind_support HWLOC_NAME(topology_cpubind_support)
 #define hwloc_topology_membind_support HWLOC_NAME(topology_membind_support)
+#define hwloc_topology_misc_support HWLOC_NAME(topology_misc_support)
 #define hwloc_topology_support HWLOC_NAME(topology_support)
 #define hwloc_topology_get_support HWLOC_NAME(topology_get_support)
 

include/private/private.h

@@ -1,6 +1,6 @@
 /*
  * Copyright © 2009      CNRS
- * Copyright © 2009-2019 Inria.  All rights reserved.
+ * Copyright © 2009-2020 Inria.  All rights reserved.
  * Copyright © 2009-2012, 2020 Université Bordeaux
  * Copyright © 2009-2011 Cisco Systems, Inc.  All rights reserved.
  *
@@ -40,7 +40,7 @@
 #endif
 #include <string.h>
 
-#define HWLOC_TOPOLOGY_ABI 0x20100 /* version of the layout of struct topology */
+#define HWLOC_TOPOLOGY_ABI 0x20300 /* version of the layout of struct topology */
 
 /*****************************************************
  * WARNING:

tests/hwloc/hwloc_topology_abi.c

@@ -61,12 +61,12 @@ int main(void)
     assert(offset == 648);
 
     offset = offsetof(struct hwloc_topology, first_dist);
-    assert(offset == 696);
+    assert(offset == 704);
     size = sizeof(struct hwloc_internal_distances_s);
     assert(size == 88);
 
     offset = offsetof(struct hwloc_topology, grouping_next_subkind);
-    assert(offset == 748);
+    assert(offset == 756);
 
     /* fields after this one aren't needed after discovery */
 
@@ -126,13 +126,15 @@ int main(void)
     assert(size == 16);
 
     size = sizeof(struct hwloc_topology_support);
-    assert(size == 24);
+    assert(size == 32);
     size = sizeof(struct hwloc_topology_discovery_support);
     assert(size == 5);
     size = sizeof(struct hwloc_topology_cpubind_support);
     assert(size == 11);
     size = sizeof(struct hwloc_topology_membind_support);
     assert(size == 15);
+    size = sizeof(struct hwloc_topology_misc_support);
+    assert(size == 1);
 
     size = sizeof(struct hwloc_distances_s);
     assert(size == 32);

tests/hwloc/xml/16-2gr2gr2n2c+misc.xml

@@ -139,4 +139,5 @@
   <support name="membind.interleave_membind"/>
   <support name="membind.migrate_membind"/>
   <support name="membind.get_area_memlocation"/>
+  <support name="custom.exported_support"/>
 </topology>