path: root/hwloc-1.2.1/src/topology-xml.c

/*
 * Copyright © 2009 CNRS
 * Copyright © 2009-2011 INRIA.  All rights reserved.
 * Copyright © 2009-2011 Université Bordeaux 1
 * Copyright © 2009-2011 Cisco Systems, Inc.  All rights reserved.
 * See COPYING in top-level directory.
 */

#include <private/autogen/config.h>
#include <hwloc.h>
#include <private/private.h>
#include <private/debug.h>

#ifdef HWLOC_HAVE_XML

#include <libxml/parser.h>
#include <libxml/tree.h>

#include <assert.h>
#include <strings.h>

int
hwloc_backend_xml_init(struct hwloc_topology *topology, const char *xmlpath, const char *xmlbuffer, int buflen)
{
  xmlDoc *doc = NULL;

  assert(topology->backend_type == HWLOC_BACKEND_NONE);

  LIBXML_TEST_VERSION;

  if (xmlpath)
    doc = xmlReadFile(xmlpath, NULL, 0);
  else if (xmlbuffer)
    doc = xmlReadMemory(xmlbuffer, buflen, "", NULL, 0);
  if (!doc)
    return -1;

  topology->backend_params.xml.doc = doc;
  topology->is_thissystem = 0;
  topology->backend_type = HWLOC_BACKEND_XML;
  return 0;
}

void
hwloc_backend_xml_exit(struct hwloc_topology *topology)
{
  assert(topology->backend_type == HWLOC_BACKEND_XML);
  xmlFreeDoc((xmlDoc*)topology->backend_params.xml.doc);
  topology->backend_type = HWLOC_BACKEND_NONE;
}

/******************************
 ********* XML import *********
 ******************************/

static void hwloc__xml_import_node(struct hwloc_topology *topology, struct hwloc_obj *parent, xmlNode *node, int depth);

static const xmlChar *
hwloc__xml_import_attr_value(xmlAttr *attr)
{
  xmlNode *subnode;
  /* use the first valid attribute content */
  for (subnode = attr->children; subnode; subnode = subnode->next) {
    if (subnode->type == XML_TEXT_NODE) {
      if (subnode->content && subnode->content[0] != '\0' && subnode->content[0] != '\n')
	return subnode->content;
    } else {
      fprintf(stderr, "ignoring unexpected xml attr node type %u\n", subnode->type);
    }
  }
  return NULL;
}

static void
hwloc__xml_import_object_attr(struct hwloc_topology *topology __hwloc_attribute_unused, struct hwloc_obj *obj,
			      const xmlChar *_name, const xmlChar *_value)
{
  const char *name = (const char *) _name;
  const char *value = (const char *) _value;

  if (!strcmp(name, "type")) {
    /* already handled */
    return;
  }

  else if (!strcmp(name, "os_level"))
    obj->os_level = strtoul(value, NULL, 10);
  else if (!strcmp(name, "os_index"))
    obj->os_index = strtoul(value, NULL, 10);
  else if (!strcmp(name, "cpuset")) {
    obj->cpuset = hwloc_bitmap_alloc();
    hwloc_bitmap_sscanf(obj->cpuset, value);
  } else if (!strcmp(name, "complete_cpuset")) {
    obj->complete_cpuset = hwloc_bitmap_alloc();
    hwloc_bitmap_sscanf(obj->complete_cpuset,value);
  } else if (!strcmp(name, "online_cpuset")) {
    obj->online_cpuset = hwloc_bitmap_alloc();
    hwloc_bitmap_sscanf(obj->online_cpuset, value);
  } else if (!strcmp(name, "allowed_cpuset")) {
    obj->allowed_cpuset = hwloc_bitmap_alloc();
    hwloc_bitmap_sscanf(obj->allowed_cpuset, value);
  } else if (!strcmp(name, "nodeset")) {
    obj->nodeset = hwloc_bitmap_alloc();
    hwloc_bitmap_sscanf(obj->nodeset, value);
  } else if (!strcmp(name, "complete_nodeset")) {
    obj->complete_nodeset = hwloc_bitmap_alloc();
    hwloc_bitmap_sscanf(obj->complete_nodeset, value);
  } else if (!strcmp(name, "allowed_nodeset")) {
    obj->allowed_nodeset = hwloc_bitmap_alloc();
    hwloc_bitmap_sscanf(obj->allowed_nodeset, value);
  } else if (!strcmp(name, "name"))
    obj->name = strdup(value);

  else if (!strcmp(name, "cache_size")) {
    unsigned long long lvalue = strtoull(value, NULL, 10);
    if (obj->type == HWLOC_OBJ_CACHE)
      obj->attr->cache.size = lvalue;
    else
      fprintf(stderr, "ignoring cache_size attribute for non-cache object type\n");
  }

  else if (!strcmp(name, "cache_linesize")) {
    unsigned long lvalue = strtoul(value, NULL, 10);
    if (obj->type == HWLOC_OBJ_CACHE)
      obj->attr->cache.linesize = lvalue;
    else
      fprintf(stderr, "ignoring cache_linesize attribute for non-cache object type\n");
  }

  else if (!strcmp(name, "local_memory"))
    obj->memory.local_memory = strtoull(value, NULL, 10);

  else if (!strcmp(name, "depth")) {
    unsigned long lvalue = strtoul(value, NULL, 10);
    switch (obj->type) {
      case HWLOC_OBJ_CACHE:
	obj->attr->cache.depth = lvalue;
	break;
      case HWLOC_OBJ_GROUP:
	obj->attr->group.depth = lvalue;
	break;
      default:
	fprintf(stderr, "ignoring depth attribute for object type without depth\n");
	break;
    }
  }



  /*************************
   * deprecated (from 1.0)
   */
  else if (!strcmp(name, "dmi_board_vendor")) {
    hwloc_add_object_info(obj, "DMIBoardVendor", strdup(value));
  }
  else if (!strcmp(name, "dmi_board_name")) {
    hwloc_add_object_info(obj, "DMIBoardName", strdup(value));
  }

  /*************************
   * deprecated (from 0.9)
   */
  else if (!strcmp(name, "memory_kB")) {
    unsigned long long lvalue = strtoull(value, NULL, 10);
    switch (obj->type) {
      case HWLOC_OBJ_CACHE:
	obj->attr->cache.size = lvalue << 10;
	break;
      case HWLOC_OBJ_NODE:
      case HWLOC_OBJ_MACHINE:
      case HWLOC_OBJ_SYSTEM:
	obj->memory.local_memory = lvalue << 10;
	break;
      default:
	fprintf(stderr, "ignoring memory_kB attribute for object type without memory\n");
	break;
    }
  }
  else if (!strcmp(name, "huge_page_size_kB")) {
    unsigned long lvalue = strtoul(value, NULL, 10);
    switch (obj->type) {
      case HWLOC_OBJ_NODE:
      case HWLOC_OBJ_MACHINE:
      case HWLOC_OBJ_SYSTEM:
	if (!obj->memory.page_types) {
	  obj->memory.page_types = malloc(sizeof(*obj->memory.page_types));
	  obj->memory.page_types_len = 1;
	}
	obj->memory.page_types[0].size = lvalue << 10;
	break;
      default:
	fprintf(stderr, "ignoring huge_page_size_kB attribute for object type without huge pages\n");
	break;
    }
  }
  else if (!strcmp(name, "huge_page_free")) {
    unsigned long lvalue = strtoul(value, NULL, 10);
    switch (obj->type) {
      case HWLOC_OBJ_NODE:
      case HWLOC_OBJ_MACHINE:
      case HWLOC_OBJ_SYSTEM:
	if (!obj->memory.page_types) {
	  obj->memory.page_types = malloc(sizeof(*obj->memory.page_types));
	  obj->memory.page_types_len = 1;
	}
	obj->memory.page_types[0].count = lvalue;
	break;
      default:
	fprintf(stderr, "ignoring huge_page_free attribute for object type without huge pages\n");
	break;
    }
  }
  /*
   * end of deprecated (from 0.9)
   *******************************/



  else
    fprintf(stderr, "ignoring unknown object attribute %s\n", name);
}

static void
hwloc__xml_import_object_node(struct hwloc_topology *topology, struct hwloc_obj *parent, struct hwloc_obj *obj, xmlNode *node, int depth)
{
  xmlAttr *attr = NULL;

  /* first determine the object type */
  for (attr = node->properties; attr; attr = attr->next) {
    if (attr->type == XML_ATTRIBUTE_NODE && !strcmp((const char*) attr->name, "type")) {
      const xmlChar *value = hwloc__xml_import_attr_value(attr);
      if (!value) {
	fprintf(stderr, "ignoring xml object without type attr %s\n", (const char*) value);
	return;
      }
      obj->type = hwloc_obj_type_of_string((const char*) value);
      if (obj->type == (hwloc_obj_type_t)-1) {
	fprintf(stderr, "ignoring unknown object type %s\n", (const char*) value);
	return;
      }
      break;
    } else {
      fprintf(stderr, "ignoring unexpected xml attr type %u\n", attr->type);
    }
  }
  if (obj->type == HWLOC_OBJ_TYPE_MAX) {
    fprintf(stderr, "ignoring object without type\n");
    return;
  }

  /* process attributes now that the type is known */
  for (attr = node->properties; attr; attr = attr->next) {
    if (attr->type == XML_ATTRIBUTE_NODE) {
      const xmlChar *value = hwloc__xml_import_attr_value(attr);
      if (value)
	hwloc__xml_import_object_attr(topology, obj, attr->name, value);
    } else {
      fprintf(stderr, "ignoring unexpected xml object attr type %u\n", attr->type);
    }
  }

  if (depth > 0) { /* root object is already in place */
    /* add object */
    hwloc_insert_object_by_parent(topology, parent, obj);
  }

  /* process children */
  if (node->children)
    hwloc__xml_import_node(topology, obj, node->children, depth+1);
}

static void
hwloc__xml_import_pagetype_node(struct hwloc_topology *topology __hwloc_attribute_unused, struct hwloc_obj *obj, xmlNode *node)
{
  uint64_t size = 0, count = 0;
  xmlAttr *attr = NULL;

  for (attr = node->properties; attr; attr = attr->next) {
    if (attr->type == XML_ATTRIBUTE_NODE) {
      const xmlChar *value = hwloc__xml_import_attr_value(attr);
      if (value) {
	if (!strcmp((char *) attr->name, "size"))
	  size = strtoul((char *) value, NULL, 10);
	else if (!strcmp((char *) attr->name, "count"))
	  count = strtoul((char *) value, NULL, 10);
	else
	  fprintf(stderr, "ignoring unknown pagetype attribute %s\n", (char *) attr->name);
      }
    } else {
      fprintf(stderr, "ignoring unexpected xml pagetype attr type %u\n", attr->type);
    }
  }

  if (size) {
    int idx = obj->memory.page_types_len;
    obj->memory.page_types = realloc(obj->memory.page_types, (idx+1)*sizeof(*obj->memory.page_types));
    obj->memory.page_types_len = idx+1;
    obj->memory.page_types[idx].size = size;
    obj->memory.page_types[idx].count = count;
  } else
    fprintf(stderr, "ignoring pagetype attribute without size\n");
}

static void
hwloc__xml_import_distances_node(struct hwloc_topology *topology __hwloc_attribute_unused, struct hwloc_obj *obj, xmlNode *node)
{
  unsigned long reldepth = 0, nbobjs = 0;
  float latbase = 0;
  xmlAttr *attr = NULL;
  xmlNode *subnode;

  for (attr = node->properties; attr; attr = attr->next) {
    if (attr->type == XML_ATTRIBUTE_NODE) {
      const xmlChar *value = hwloc__xml_import_attr_value(attr);
      if (value) {
	if (!strcmp((char *) attr->name, "nbobjs"))
	  nbobjs = strtoul((char *) value, NULL, 10);
	else if (!strcmp((char *) attr->name, "relative_depth"))
	  reldepth = strtoul((char *) value, NULL, 10);
	else if (!strcmp((char *) attr->name, "latency_base"))
          latbase = (float) atof((char *) value);
	else
	  fprintf(stderr, "ignoring unknown distances attribute %s\n", (char *) attr->name);
      } else
	fprintf(stderr, "ignoring unexpected xml distances attr name `%s' with no value\n", (const char*) attr->name);
    } else {
      fprintf(stderr, "ignoring unexpected xml distances attr type %u\n", attr->type);
    }
  }

  if (nbobjs && reldepth && latbase) {
    int idx = obj->distances_count;
    unsigned nbcells, i;
    float *matrix, latmax = 0;

    nbcells = 0;
    if (node->children)
      for(subnode = node->children; subnode; subnode = subnode->next)
 	if (subnode->type == XML_ELEMENT_NODE)
	  nbcells++;
    if (nbcells != nbobjs*nbobjs) {
      fprintf(stderr, "ignoring distances with %u cells instead of %lu\n", nbcells, nbobjs*nbobjs);
      return;
    }

    obj->distances = realloc(obj->distances, (idx+1)*sizeof(*obj->distances));
    obj->distances_count = idx+1;
    obj->distances[idx] = malloc(sizeof(**obj->distances));
    obj->distances[idx]->relative_depth = reldepth;
    obj->distances[idx]->nbobjs = nbobjs;
    obj->distances[idx]->latency = matrix = malloc(nbcells*sizeof(float));
    obj->distances[idx]->latency_base = latbase;

    i = 0;
    for(subnode = node->children; subnode; subnode = subnode->next)
      if (subnode->type == XML_ELEMENT_NODE) {
	/* read one cell */
	for (attr = subnode->properties; attr; attr = attr->next)
	  if (attr->type == XML_ATTRIBUTE_NODE) {
	    const xmlChar *value = hwloc__xml_import_attr_value(attr);
	    if (value) {
	      if (!strcmp((char *) attr->name, "value")) {
                float val = (float) atof((char *) value);
		matrix[i] = val;
		if (val > latmax)
		  latmax = val;
	      } else
		fprintf(stderr, "ignoring unknown distance attribute %s\n", (char *) attr->name);
	    } else
	      fprintf(stderr, "ignoring unexpected xml distance attr name `%s' with no value\n", (const char*) attr->name);
	  } else {
	    fprintf(stderr, "ignoring unexpected xml distance attr type %u\n", attr->type);
	  }
	/* next matrix cell */
	i++;
      }

    obj->distances[idx]->latency_max = latmax;
  }
}

static void
hwloc__xml_import_info_node(struct hwloc_topology *topology __hwloc_attribute_unused, struct hwloc_obj *obj, xmlNode *node)
{
  char *infoname = NULL;
  char *infovalue = NULL;
  xmlAttr *attr = NULL;

  for (attr = node->properties; attr; attr = attr->next) {
    if (attr->type == XML_ATTRIBUTE_NODE) {
      const xmlChar *value = hwloc__xml_import_attr_value(attr);
      if (value) {
	if (!strcmp((char *) attr->name, "name"))
	  infoname = (char *) value;
	else if (!strcmp((char *) attr->name, "value"))
	  infovalue = (char *) value;
	else
	  fprintf(stderr, "ignoring unknown info attribute %s\n", (char *) attr->name);
      }
    } else {
      fprintf(stderr, "ignoring unexpected xml info attr type %u\n", attr->type);
    }
  }

  if (infoname)
    /* empty strings are ignored by libxml */
    hwloc_add_object_info(obj, infoname, infovalue ? infovalue : "");
  else
    fprintf(stderr, "ignoring info attribute without name\n");
}

static void
hwloc__xml_import_node(struct hwloc_topology *topology, struct hwloc_obj *parent, xmlNode *node, int depth)
{
  for (; node; node = node->next) {
    if (node->type == XML_ELEMENT_NODE) {
      if (!strcmp((const char*) node->name, "object")) {
	/* object attributes */
	struct hwloc_obj *obj;
	if (depth)
	  obj = hwloc_alloc_setup_object(HWLOC_OBJ_TYPE_MAX, -1);
	else
	  obj = topology->levels[0][0];
	hwloc__xml_import_object_node(topology, parent, obj, node, depth);

      } else if (!strcmp((const char*) node->name, "page_type")) {
	hwloc__xml_import_pagetype_node(topology, parent, node);

      } else if (!strcmp((const char*) node->name, "info")) {
	hwloc__xml_import_info_node(topology, parent, node);

      } else if (!strcmp((const char*) node->name, "distances")) {
	hwloc__xml_import_distances_node(topology, parent, node);

      } else {
	/* unknown class */
	fprintf(stderr, "ignoring unexpected node class `%s'\n", (const char*) node->name);
	continue;
      }

    } else if (node->type == XML_TEXT_NODE) {
      if (node->content && node->content[0] != '\0' && node->content[0] != '\n')
	fprintf(stderr, "ignoring object text content %s\n", (const char*) node->content);
    } else {
      fprintf(stderr, "ignoring unexpected xml node type %u\n", node->type);
    }
  }
}

static void
hwloc__xml_import_topology_node(struct hwloc_topology *topology, xmlNode *node)
{
  xmlAttr *attr = NULL;

  if (strcmp((const char *) node->name, "topology") && strcmp((const char *) node->name, "root")) {
    /* root node should be in "topology" class (or "root" if importing from < 1.0) */
    fprintf(stderr, "ignoring object of class `%s' not at the top the xml hierarchy\n", (const char *) node->name);
    return;
  }

  /* process attributes */
  for (attr = node->properties; attr; attr = attr->next) {
    if (attr->type == XML_ATTRIBUTE_NODE) {
      const xmlChar *value = hwloc__xml_import_attr_value(attr);
      if (value) {
	fprintf(stderr, "ignoring unknown root attribute %s\n", (char *) attr->name);
      }
    } else {
      fprintf(stderr, "ignoring unexpected xml root attr type %u\n", attr->type);
    }
  }

  /* process children */
  if (node->children)
    hwloc__xml_import_node(topology, NULL, node->children, 0);
}

void
hwloc_look_xml(struct hwloc_topology *topology)
{
  xmlNode* root_node;
  xmlDtd *dtd;

  topology->support.discovery->pu = 1;

  dtd = xmlGetIntSubset((xmlDoc*) topology->backend_params.xml.doc);
  if (!dtd)
    fprintf(stderr, "Loading XML topology without DTD\n");
  else if (strcmp((char *) dtd->SystemID, "hwloc.dtd"))
    fprintf(stderr, "Loading XML topology with wrong DTD SystemID (%s instead of %s)\n",
	    (char *) dtd->SystemID, "hwloc.dtd");

  root_node = xmlDocGetRootElement((xmlDoc*) topology->backend_params.xml.doc);

  hwloc__xml_import_topology_node(topology, root_node);
  if (root_node->next)
    fprintf(stderr, "ignoring non-first root nodes\n");

  /* keep the "Backend" information intact */
  /* we could add "BackendSource=XML" to notify that XML was used between the actual backend and here */
}

static void
hwloc_xml__check_distances(struct hwloc_topology *topology, hwloc_obj_t obj)
{
  hwloc_obj_t child;
  unsigned i=0;
  while (i<obj->distances_count) {
    unsigned depth = obj->depth + obj->distances[i]->relative_depth;
    unsigned nbobjs = hwloc_get_nbobjs_inside_cpuset_by_depth(topology, obj->cpuset, depth);
    if (nbobjs != obj->distances[i]->nbobjs) {
      fprintf(stderr, "ignoring invalid distance matrix with %u objs instead of %u\n",
	      obj->distances[i]->nbobjs, nbobjs);
      hwloc_free_logical_distances(obj->distances[i]);
      memmove(&obj->distances[i], &obj->distances[i+1], (obj->distances_count-i-1)*sizeof(*obj->distances));
      obj->distances_count--;
    } else
      i++;
  }

  child = obj->first_child;
  while (child != NULL) {
    hwloc_xml__check_distances(topology, child);
    child = child->next_sibling;
  }
}

void
hwloc_xml_check_distances(struct hwloc_topology *topology)
{
  /* now that the topology tree has been properly setup,
   * check that our distance matrice sizes make sense */
  hwloc_xml__check_distances(topology, topology->levels[0][0]);
}

/******************************
 ********* XML export *********
 ******************************/

static void
hwloc__xml_export_object (hwloc_topology_t topology, hwloc_obj_t obj, xmlNodePtr root_node)
{
  xmlNodePtr node = NULL, ptnode = NULL, dnode = NULL, dcnode = NULL;
  char *cpuset = NULL;
  char tmp[255];
  unsigned i;

  /* xmlNewChild() creates a new node, which is "attached" as child node
   * of root_node node. */
  node = xmlNewChild(root_node, NULL, BAD_CAST "object", NULL);
  xmlNewProp(node, BAD_CAST "type", BAD_CAST hwloc_obj_type_string(obj->type));
  sprintf(tmp, "%d", obj->os_level);
  xmlNewProp(node, BAD_CAST "os_level", BAD_CAST tmp);
  if (obj->os_index != (unsigned) -1) {
    sprintf(tmp, "%u", obj->os_index);
    xmlNewProp(node, BAD_CAST "os_index", BAD_CAST tmp);
  }
  if (obj->cpuset) {
    hwloc_bitmap_asprintf(&cpuset, obj->cpuset);
    xmlNewProp(node, BAD_CAST "cpuset", BAD_CAST cpuset);
    free(cpuset);
  }
  if (obj->complete_cpuset) {
    hwloc_bitmap_asprintf(&cpuset, obj->complete_cpuset);
    xmlNewProp(node, BAD_CAST "complete_cpuset", BAD_CAST cpuset);
    free(cpuset);
  }
  if (obj->online_cpuset) {
    hwloc_bitmap_asprintf(&cpuset, obj->online_cpuset);
    xmlNewProp(node, BAD_CAST "online_cpuset", BAD_CAST cpuset);
    free(cpuset);
  }
  if (obj->allowed_cpuset) {
    hwloc_bitmap_asprintf(&cpuset, obj->allowed_cpuset);
    xmlNewProp(node, BAD_CAST "allowed_cpuset", BAD_CAST cpuset);
    free(cpuset);
  }
  if (obj->nodeset && !hwloc_bitmap_isfull(obj->nodeset)) {
    hwloc_bitmap_asprintf(&cpuset, obj->nodeset);
    xmlNewProp(node, BAD_CAST "nodeset", BAD_CAST cpuset);
    free(cpuset);
  }
  if (obj->complete_nodeset && !hwloc_bitmap_isfull(obj->complete_nodeset)) {
    hwloc_bitmap_asprintf(&cpuset, obj->complete_nodeset);
    xmlNewProp(node, BAD_CAST "complete_nodeset", BAD_CAST cpuset);
    free(cpuset);
  }
  if (obj->allowed_nodeset && !hwloc_bitmap_isfull(obj->allowed_nodeset)) {
    hwloc_bitmap_asprintf(&cpuset, obj->allowed_nodeset);
    xmlNewProp(node, BAD_CAST "allowed_nodeset", BAD_CAST cpuset);
    free(cpuset);
  }

  if (obj->name)
    xmlNewProp(node, BAD_CAST "name", BAD_CAST obj->name);

  switch (obj->type) {
  case HWLOC_OBJ_CACHE:
    sprintf(tmp, "%llu", (unsigned long long) obj->attr->cache.size);
    xmlNewProp(node, BAD_CAST "cache_size", BAD_CAST tmp);
    sprintf(tmp, "%u", obj->attr->cache.depth);
    xmlNewProp(node, BAD_CAST "depth", BAD_CAST tmp);
    sprintf(tmp, "%u", (unsigned) obj->attr->cache.linesize);
    xmlNewProp(node, BAD_CAST "cache_linesize", BAD_CAST tmp);
    break;
  case HWLOC_OBJ_GROUP:
    sprintf(tmp, "%u", obj->attr->group.depth);
    xmlNewProp(node, BAD_CAST "depth", BAD_CAST tmp);
    break;
  default:
    break;
  }

  if (obj->memory.local_memory) {
    sprintf(tmp, "%llu", (unsigned long long) obj->memory.local_memory);
    xmlNewProp(node, BAD_CAST "local_memory", BAD_CAST tmp);
  }
  for(i=0; i<obj->memory.page_types_len; i++) {
    ptnode = xmlNewChild(node, NULL, BAD_CAST "page_type", NULL);
    sprintf(tmp, "%llu", (unsigned long long) obj->memory.page_types[i].size);
    xmlNewProp(ptnode, BAD_CAST "size", BAD_CAST tmp);
    sprintf(tmp, "%llu", (unsigned long long) obj->memory.page_types[i].count);
    xmlNewProp(ptnode, BAD_CAST "count", BAD_CAST tmp);
  }

  for(i=0; i<obj->infos_count; i++) {
    ptnode = xmlNewChild(node, NULL, BAD_CAST "info", NULL);
    xmlNewProp(ptnode, BAD_CAST "name", BAD_CAST obj->infos[i].name);
    xmlNewProp(ptnode, BAD_CAST "value", BAD_CAST obj->infos[i].value);
  }

  for(i=0; i<obj->distances_count; i++) {
    unsigned nbobjs = obj->distances[i]->nbobjs;
    unsigned j;
    dnode = xmlNewChild(node, NULL, BAD_CAST "distances", NULL);
    sprintf(tmp, "%u", nbobjs);
    xmlNewProp(dnode, BAD_CAST "nbobjs", BAD_CAST tmp);
    sprintf(tmp, "%u", obj->distances[i]->relative_depth);
    xmlNewProp(dnode, BAD_CAST "relative_depth", BAD_CAST tmp);
    sprintf(tmp, "%f", obj->distances[i]->latency_base);
    xmlNewProp(dnode, BAD_CAST "latency_base", BAD_CAST tmp);
    for(j=0; j<nbobjs*nbobjs; j++) {
      dcnode = xmlNewChild(dnode, NULL, BAD_CAST "latency", NULL);
      sprintf(tmp, "%f", obj->distances[i]->latency[j]);
      xmlNewProp(dcnode, BAD_CAST "value", BAD_CAST tmp);
    }
  }

  if (obj->arity) {
    unsigned x;
    for (x=0; x<obj->arity; x++)
      hwloc__xml_export_object (topology, obj->children[x], node);
  }
}

static void
hwloc__xml_export_topology_info (hwloc_topology_t topology __hwloc_attribute_unused, xmlNodePtr root_node __hwloc_attribute_unused)
{
}

static xmlDocPtr
hwloc__topology_prepare_export(hwloc_topology_t topology)
{
  xmlDocPtr doc = NULL;       /* document pointer */
  xmlNodePtr root_node = NULL; /* root pointer */
  xmlDtdPtr dtd = NULL;       /* DTD pointer */

  LIBXML_TEST_VERSION;

  /* Creates a new document, a node and set it as a root node. */
  doc = xmlNewDoc(BAD_CAST "1.0");
  root_node = xmlNewNode(NULL, BAD_CAST "topology");
  xmlDocSetRootElement(doc, root_node);

  /* Creates a DTD declaration. Isn't mandatory. */
  dtd = xmlCreateIntSubset(doc, BAD_CAST "topology", NULL, BAD_CAST "hwloc.dtd");

  hwloc__xml_export_object (topology, hwloc_get_root_obj(topology), root_node);

  hwloc__xml_export_topology_info (topology, root_node);

  return doc;
}

void hwloc_topology_export_xml(hwloc_topology_t topology, const char *filename)
{
  xmlDocPtr doc = hwloc__topology_prepare_export(topology);
  xmlSaveFormatFileEnc(filename, doc, "UTF-8", 1);
  xmlFreeDoc(doc);
}

void hwloc_topology_export_xmlbuffer(hwloc_topology_t topology, char **xmlbuffer, int *buflen)
{
  xmlDocPtr doc = hwloc__topology_prepare_export(topology);
  xmlDocDumpFormatMemoryEnc(doc, (xmlChar **)xmlbuffer, buflen, "UTF-8", 1);
  xmlFreeDoc(doc);
}


#endif /* HWLOC_HAVE_XML */