components: add envvar to annotate global components

If the envvar HWLOC_ANNOTATE_GLOBAL_COMPONENTS=1,
global components don't exclude the ANNOTATE phase anymore.

Hence, the pci component may add PCI vendor/device strings to
objects if the XML generation was performed without pciaccess.

Note that it doesn't check whether those names are already
available, so they may be duplicated if enabled blindly.

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

Author: bgoglin

doc/hwloc.doxy

@@ -1091,6 +1091,14 @@ following environment variables.
   Setting this environment variable to 1 will expose it as a proper Memory-side cache.
   </dd>
 
+<dt>HWLOC_ANNOTATE_GLOBAL_COMPONENTS=0</dt>
+  <dd>Allow components to annotate the topology even if they are
+  usually excluded by global components by default.
+  Setting this variable to 1 and also setting <tt>HWLOC_COMPONENTS=xml,pci,stop</tt>
+  enables the addition of PCI vendor and model info attributes to a XML topology
+  that was generated without those names (if pciaccess was missing).
+  </dd>
+
 <dt>HWLOC_FSROOT=/path/to/linux/filesystem-root/</dt>
   <dd>switches to reading the topology from the specified
   Linux filesystem root instead of the main file-system root.

hwloc/components.c

@@ -574,10 +574,19 @@ hwloc_disc_component_force_enable(struct hwloc_topology *topology,
   backend = comp->instantiate(topology, comp, 0U /* force-enabled don't get any phase blacklisting */,
 			      data1, data2, data3);
   if (backend) {
+    int err;
     backend->envvar_forced = envvar_forced;
     if (topology->backends)
       hwloc_backends_disable_all(topology);
-    return hwloc_backend_enable(backend);
+    err = hwloc_backend_enable(backend);
+
+    if (comp->phases == HWLOC_DISC_PHASE_GLOBAL) {
+      char *env = getenv("HWLOC_ANNOTATE_GLOBAL_COMPONENTS");
+      if (env && atoi(env))
+	topology->backend_excluded_phases &= ~HWLOC_DISC_PHASE_ANNOTATE;
+    }
+
+    return err;
   } else
     return -1;
 }

hwloc/topology.c

@@ -3215,10 +3215,12 @@ hwloc_discover(struct hwloc_topology *topology,
    * automatically propagated to the whole tree after detection.
    */
 
-  if (topology->backend_phases == HWLOC_DISC_PHASE_GLOBAL) {
+  if (topology->backend_phases & HWLOC_DISC_PHASE_GLOBAL) {
+    /* usually, GLOBAL is alone.
+     * but HWLOC_ANNOTATE_GLOBAL_COMPONENTS=1 allows optional ANNOTATE steps.
+     */
     struct hwloc_backend *global_backend = topology->backends;
     assert(global_backend);
-    assert(!global_backend->next);
     assert(global_backend->phases == HWLOC_DISC_PHASE_GLOBAL);
 
     /*
@@ -3237,7 +3239,6 @@ hwloc_discover(struct hwloc_topology *topology,
    */
 
   if (topology->backend_phases & HWLOC_DISC_PHASE_CPU) {
-    assert(!(topology->backend_phases & HWLOC_DISC_PHASE_GLOBAL));
     /*
      * Discover CPUs first
      */