Esempio n. 1
0
static int
hwloc_look_pci(struct hwloc_backend *backend)
{
  struct hwloc_topology *topology = backend->topology;
  struct hwloc_obj *first_obj = NULL, *last_obj = NULL;
#ifdef HWLOC_HAVE_LIBPCIACCESS
  int ret;
  struct pci_device_iterator *iter;
  struct pci_device *pcidev;
#else /* HWLOC_HAVE_PCIUTILS */
  struct pci_access *pciaccess;
  struct pci_dev *pcidev;
#endif

  if (!(hwloc_topology_get_flags(topology) & (HWLOC_TOPOLOGY_FLAG_IO_DEVICES|HWLOC_TOPOLOGY_FLAG_WHOLE_IO)))
    return 0;

  if (hwloc_get_next_pcidev(topology, NULL)) {
    hwloc_debug("%s", "PCI objects already added, ignoring pci backend.\n");
    return 0;
  }

  if (!hwloc_topology_is_thissystem(topology)) {
    hwloc_debug("%s", "\nno PCI detection (not thissystem)\n");
    return 0;
  }

  hwloc_debug("%s", "\nScanning PCI buses...\n");

  /* initialize PCI scanning */
#ifdef HWLOC_HAVE_LIBPCIACCESS
  ret = pci_system_init();
  if (ret) {
    hwloc_debug("%s", "Can not initialize libpciaccess\n");
    return -1;
  }

  iter = pci_slot_match_iterator_create(NULL);
#else /* HWLOC_HAVE_PCIUTILS */
  pciaccess = pci_alloc();
  pciaccess->error = hwloc_pci_error;
  pciaccess->warning = hwloc_pci_warning;

  if (setjmp(err_buf)) {
    pci_cleanup(pciaccess);
    return -1;
  }

  pci_init(pciaccess);
  pci_scan_bus(pciaccess);
#endif

  /* iterate over devices */
#ifdef HWLOC_HAVE_LIBPCIACCESS
  for (pcidev = pci_device_next(iter);
       pcidev;
       pcidev = pci_device_next(iter))
#else /* HWLOC_HAVE_PCIUTILS */
  for (pcidev = pciaccess->devices;
       pcidev;
       pcidev = pcidev->next)
#endif
  {
    const char *vendorname, *devicename, *fullname;
    unsigned char config_space_cache[CONFIG_SPACE_CACHESIZE];
    struct hwloc_obj *obj;
    unsigned os_index;
    unsigned domain;
    unsigned device_class;
    unsigned short tmp16;
    char name[128];
    unsigned offset;
#ifdef HWLOC_HAVE_PCI_FIND_CAP
    struct pci_cap *cap;
#endif

    /* initialize the config space in case we fail to read it (missing permissions, etc). */
    memset(config_space_cache, 0xff, CONFIG_SPACE_CACHESIZE);
#ifdef HWLOC_HAVE_LIBPCIACCESS
    pci_device_probe(pcidev);
    pci_device_cfg_read(pcidev, config_space_cache, 0, CONFIG_SPACE_CACHESIZE, NULL);
#else /* HWLOC_HAVE_PCIUTILS */
    pci_read_block(pcidev, 0, config_space_cache, CONFIG_SPACE_CACHESIZE); /* doesn't even tell how much it actually reads */
#endif

    /* try to read the domain */
#if (defined HWLOC_HAVE_LIBPCIACCESS) || (defined HWLOC_HAVE_PCIDEV_DOMAIN)
    domain = pcidev->domain;
#else
    domain = 0; /* default domain number */
#endif

    /* try to read the device_class */
#ifdef HWLOC_HAVE_LIBPCIACCESS
    device_class = pcidev->device_class >> 8;
#else /* HWLOC_HAVE_PCIUTILS */
#ifdef HWLOC_HAVE_PCIDEV_DEVICE_CLASS
    device_class = pcidev->device_class;
#else
    device_class = config_space_cache[PCI_CLASS_DEVICE] | (config_space_cache[PCI_CLASS_DEVICE+1] << 8);
#endif
#endif

    /* might be useful for debugging (note that domain might be truncated) */
    os_index = (domain << 20) + (pcidev->bus << 12) + (pcidev->dev << 4) + pcidev->func;

    obj = hwloc_alloc_setup_object(HWLOC_OBJ_PCI_DEVICE, os_index);
    obj->attr->pcidev.domain = domain;
    obj->attr->pcidev.bus = pcidev->bus;
    obj->attr->pcidev.dev = pcidev->dev;
    obj->attr->pcidev.func = pcidev->func;
    obj->attr->pcidev.vendor_id = pcidev->vendor_id;
    obj->attr->pcidev.device_id = pcidev->device_id;
    obj->attr->pcidev.class_id = device_class;
    obj->attr->pcidev.revision = config_space_cache[PCI_REVISION_ID];

    obj->attr->pcidev.linkspeed = 0; /* unknown */
#ifdef HWLOC_HAVE_PCI_FIND_CAP
    cap = pci_find_cap(pcidev, PCI_CAP_ID_EXP, PCI_CAP_NORMAL);
    offset = cap ? cap->addr : 0;
#else
    offset = hwloc_pci_find_cap(config_space_cache, PCI_CAP_ID_EXP);
#endif /* HWLOC_HAVE_PCI_FIND_CAP */

    if (0xffff == pcidev->vendor_id && 0xffff == pcidev->device_id) {
      /* SR-IOV puts ffff:ffff in Virtual Function config space.
       * The actual VF device ID is stored at a special (dynamic) location in the Physical Function config space.
       * VF and PF have the same vendor ID.
       *
       * libpciaccess just returns ffff:ffff, needs to be fixed.
       * linuxpci is OK because sysfs files are already fixed the kernel.
       * pciutils is OK when it uses those Linux sysfs files.
       *
       * Reading these files is an easy way to work around the libpciaccess issue on Linux,
       * but we have no way to know if this is caused by SR-IOV or not.
       *
       * TODO:
       *  If PF has CAP_ID_PCIX or CAP_ID_EXP (offset>0),
       *  look for extended capability PCI_EXT_CAP_ID_SRIOV (need extended config space (more than 256 bytes)),
       *  then read the VF device ID after it (PCI_IOV_DID bytes later).
       *  Needs access to extended config space (needs root on Linux).
       * TODO:
       *  Add string info attributes in VF and PF objects?
       */
#ifdef HWLOC_LINUX_SYS
      /* Workaround for Linux (the kernel returns the VF device/vendor IDs). */
      char path[64];
      char value[16];
      FILE *file;
      snprintf(path, sizeof(path), "/sys/bus/pci/devices/%04x:%02x:%02x.%01x/vendor",
	       domain, pcidev->bus, pcidev->dev, pcidev->func);
      file = fopen(path, "r");
      if (file) {
	fread(value, sizeof(value), 1, file);
	fclose(file);
	obj->attr->pcidev.vendor_id = strtoul(value, NULL, 16);
      }
      snprintf(path, sizeof(path), "/sys/bus/pci/devices/%04x:%02x:%02x.%01x/device",
	       domain, pcidev->bus, pcidev->dev, pcidev->func);
      file = fopen(path, "r");
      if (file) {
	fread(value, sizeof(value), 1, file);
	fclose(file);
	obj->attr->pcidev.device_id = strtoul(value, NULL, 16);
      }
#endif
    }

    if (offset > 0 && offset + 20 /* size of PCI express block up to link status */ <= CONFIG_SPACE_CACHESIZE)
      hwloc_pci_find_linkspeed(config_space_cache, offset, &obj->attr->pcidev.linkspeed);

    hwloc_pci_prepare_bridge(obj, config_space_cache);

    if (obj->type == HWLOC_OBJ_PCI_DEVICE) {
      memcpy(&tmp16, &config_space_cache[PCI_SUBSYSTEM_VENDOR_ID], sizeof(tmp16));
      obj->attr->pcidev.subvendor_id = tmp16;
      memcpy(&tmp16, &config_space_cache[PCI_SUBSYSTEM_ID], sizeof(tmp16));
      obj->attr->pcidev.subdevice_id = tmp16;
    } else {
      /* TODO:
       * bridge must lookup PCI_CAP_ID_SSVID and then look at offset+PCI_SSVID_VENDOR/DEVICE_ID
       * cardbus must look at PCI_CB_SUBSYSTEM_VENDOR_ID and PCI_CB_SUBSYSTEM_ID
       */
    }

    /* starting from pciutils 2.2, pci_lookup_name() takes a variable number
     * of arguments, and supports the PCI_LOOKUP_NO_NUMBERS flag.
     */

    /* get the vendor name */
#ifdef HWLOC_HAVE_LIBPCIACCESS
    vendorname = pci_device_get_vendor_name(pcidev);
#else /* HWLOC_HAVE_PCIUTILS */
    vendorname = pci_lookup_name(pciaccess, name, sizeof(name),
#if HAVE_DECL_PCI_LOOKUP_NO_NUMBERS
			      PCI_LOOKUP_VENDOR|PCI_LOOKUP_NO_NUMBERS,
			      pcidev->vendor_id
#else
			      PCI_LOOKUP_VENDOR,
			      pcidev->vendor_id, 0, 0, 0
#endif
			      );
#endif /* HWLOC_HAVE_PCIUTILS */
    if (vendorname && *vendorname)
      hwloc_obj_add_info(obj, "PCIVendor", vendorname);

    /* get the device name */
#ifdef HWLOC_HAVE_LIBPCIACCESS
    devicename = pci_device_get_device_name(pcidev);
#else /* HWLOC_HAVE_PCIUTILS */
    devicename = pci_lookup_name(pciaccess, name, sizeof(name),
#if HAVE_DECL_PCI_LOOKUP_NO_NUMBERS
			      PCI_LOOKUP_DEVICE|PCI_LOOKUP_NO_NUMBERS,
			      pcidev->vendor_id, pcidev->device_id
#else
			      PCI_LOOKUP_DEVICE,
			      pcidev->vendor_id, pcidev->device_id, 0, 0
#endif
			      );
#endif /* HWLOC_HAVE_PCIUTILS */
    if (devicename && *devicename)
      hwloc_obj_add_info(obj, "PCIDevice", devicename);

    /* generate or get the fullname */
#ifdef HWLOC_HAVE_LIBPCIACCESS
    snprintf(name, sizeof(name), "%s%s%s",
	     vendorname ? vendorname : "",
	     vendorname && devicename ? " " : "",
	     devicename ? devicename : "");
    fullname = name;
    if (*name)
      obj->name = strdup(name);
#else /* HWLOC_HAVE_PCIUTILS */
    fullname = pci_lookup_name(pciaccess, name, sizeof(name),
#if HAVE_DECL_PCI_LOOKUP_NO_NUMBERS
			      PCI_LOOKUP_VENDOR|PCI_LOOKUP_DEVICE|PCI_LOOKUP_NO_NUMBERS,
			      pcidev->vendor_id, pcidev->device_id
#else
			      PCI_LOOKUP_VENDOR|PCI_LOOKUP_DEVICE,
			      pcidev->vendor_id, pcidev->device_id, 0, 0
#endif
			      );
    if (fullname && *fullname)
      obj->name = strdup(fullname);
#endif /* HWLOC_HAVE_PCIUTILS */
    hwloc_debug("  %04x:%02x:%02x.%01x %04x %04x:%04x %s\n",
		domain, pcidev->bus, pcidev->dev, pcidev->func,
		device_class, pcidev->vendor_id, pcidev->device_id,
		fullname && *fullname ? fullname : "??");

    /* queue the object for now */
    if (first_obj)
      last_obj->next_sibling = obj;
    else
      first_obj = obj;
    last_obj = obj;
  }

  /* finalize device scanning */
#ifdef HWLOC_HAVE_LIBPCIACCESS
  pci_iterator_destroy(iter);
  pci_system_cleanup();
#else /* HWLOC_HAVE_PCIUTILS */
  pci_cleanup(pciaccess);
#endif

  return hwloc_insert_pci_device_list(backend, first_obj);
}
static int
hwloc_look_pci(struct hwloc_backend *backend)
{
  struct hwloc_topology *topology = backend->topology;
  struct hwloc_obj *first_obj = NULL, *last_obj = NULL;
  int ret;
  struct pci_device_iterator *iter;
  struct pci_device *pcidev;
#ifdef HWLOC_LINUX_SYS
  DIR *dir;
#endif

  if (!(hwloc_topology_get_flags(topology) & (HWLOC_TOPOLOGY_FLAG_IO_DEVICES|HWLOC_TOPOLOGY_FLAG_WHOLE_IO)))
    return 0;

  if (hwloc_get_next_pcidev(topology, NULL)) {
    hwloc_debug("%s", "PCI objects already added, ignoring pci backend.\n");
    return 0;
  }

  if (!hwloc_topology_is_thissystem(topology)) {
    hwloc_debug("%s", "\nno PCI detection (not thissystem)\n");
    return 0;
  }

  hwloc_debug("%s", "\nScanning PCI buses...\n");

  /* initialize PCI scanning */
  ret = pci_system_init();
  if (ret) {
    hwloc_debug("%s", "Can not initialize libpciaccess\n");
    return -1;
  }

  iter = pci_slot_match_iterator_create(NULL);

  /* iterate over devices */
  for (pcidev = pci_device_next(iter);
       pcidev;
       pcidev = pci_device_next(iter))
  {
    const char *vendorname, *devicename, *fullname;
    unsigned char config_space_cache[CONFIG_SPACE_CACHESIZE];
    struct hwloc_obj *obj;
    unsigned os_index;
    unsigned domain;
    unsigned device_class;
    unsigned short tmp16;
    char name[128];
    unsigned offset;

    /* initialize the config space in case we fail to read it (missing permissions, etc). */
    memset(config_space_cache, 0xff, CONFIG_SPACE_CACHESIZE);
    pci_device_probe(pcidev);
    pci_device_cfg_read(pcidev, config_space_cache, 0, CONFIG_SPACE_CACHESIZE, NULL);

    /* try to read the domain */
    domain = pcidev->domain;

    /* try to read the device_class */
    device_class = pcidev->device_class >> 8;

    /* fixup SR-IOV buggy VF device/vendor IDs */
    if (0xffff == pcidev->vendor_id && 0xffff == pcidev->device_id) {
      /* SR-IOV puts ffff:ffff in Virtual Function config space.
       * The actual VF device ID is stored at a special (dynamic) location in the Physical Function config space.
       * VF and PF have the same vendor ID.
       *
       * libpciaccess just returns ffff:ffff, needs to be fixed.
       * linuxpci is OK because sysfs files are already fixed the kernel.
       * (pciutils is OK when it uses those Linux sysfs files.)
       *
       * Reading these files is an easy way to work around the libpciaccess issue on Linux,
       * but we have no way to know if this is caused by SR-IOV or not.
       *
       * TODO:
       *  If PF has CAP_ID_PCIX or CAP_ID_EXP (offset>0),
       *  look for extended capability PCI_EXT_CAP_ID_SRIOV (need extended config space (more than 256 bytes)),
       *  then read the VF device ID after it (PCI_IOV_DID bytes later).
       *  Needs access to extended config space (needs root on Linux).
       * TODO:
       *  Add string info attributes in VF and PF objects?
       */
#ifdef HWLOC_LINUX_SYS
      /* Workaround for Linux (the kernel returns the VF device/vendor IDs). */
      char path[64];
      char value[16];
      FILE *file;
      size_t read;

      snprintf(path, sizeof(path), "/sys/bus/pci/devices/%04x:%02x:%02x.%01x/vendor",
	       domain, pcidev->bus, pcidev->dev, pcidev->func);
      file = fopen(path, "r");
      if (file) {
	read = fread(value, 1, sizeof(value), file);
	fclose(file);
	if (read)
	  /* fixup the pciaccess struct so that pci_device_get_vendor_name() is correct later. */
          pcidev->vendor_id = strtoul(value, NULL, 16);
      }

      snprintf(path, sizeof(path), "/sys/bus/pci/devices/%04x:%02x:%02x.%01x/device",
	       domain, pcidev->bus, pcidev->dev, pcidev->func);
      file = fopen(path, "r");
      if (file) {
	read = fread(value, 1, sizeof(value), file);
	fclose(file);
	if (read)
	  /* fixup the pciaccess struct so that pci_device_get_device_name() is correct later. */
          pcidev->device_id = strtoul(value, NULL, 16);
      }
#endif
    }

    /* might be useful for debugging (note that domain might be truncated) */
    os_index = (domain << 20) + (pcidev->bus << 12) + (pcidev->dev << 4) + pcidev->func;

    obj = hwloc_alloc_setup_object(HWLOC_OBJ_PCI_DEVICE, os_index);
    obj->attr->pcidev.domain = domain;
    obj->attr->pcidev.bus = pcidev->bus;
    obj->attr->pcidev.dev = pcidev->dev;
    obj->attr->pcidev.func = pcidev->func;
    obj->attr->pcidev.vendor_id = pcidev->vendor_id;
    obj->attr->pcidev.device_id = pcidev->device_id;
    obj->attr->pcidev.class_id = device_class;
    obj->attr->pcidev.revision = config_space_cache[PCI_REVISION_ID];

    obj->attr->pcidev.linkspeed = 0; /* unknown */
    offset = hwloc_pci_find_cap(config_space_cache, PCI_CAP_ID_EXP);

    if (offset > 0 && offset + 20 /* size of PCI express block up to link status */ <= CONFIG_SPACE_CACHESIZE)
      hwloc_pci_find_linkspeed(config_space_cache, offset, &obj->attr->pcidev.linkspeed);

    hwloc_pci_prepare_bridge(obj, config_space_cache);

    if (obj->type == HWLOC_OBJ_PCI_DEVICE) {
      memcpy(&tmp16, &config_space_cache[PCI_SUBSYSTEM_VENDOR_ID], sizeof(tmp16));
      obj->attr->pcidev.subvendor_id = tmp16;
      memcpy(&tmp16, &config_space_cache[PCI_SUBSYSTEM_ID], sizeof(tmp16));
      obj->attr->pcidev.subdevice_id = tmp16;
    } else {
      /* TODO:
       * bridge must lookup PCI_CAP_ID_SSVID and then look at offset+PCI_SSVID_VENDOR/DEVICE_ID
       * cardbus must look at PCI_CB_SUBSYSTEM_VENDOR_ID and PCI_CB_SUBSYSTEM_ID
       */
    }

    /* get the vendor name */
    vendorname = pci_device_get_vendor_name(pcidev);
    if (vendorname && *vendorname)
      hwloc_obj_add_info(obj, "PCIVendor", vendorname);

    /* get the device name */
    devicename = pci_device_get_device_name(pcidev);
    if (devicename && *devicename)
      hwloc_obj_add_info(obj, "PCIDevice", devicename);

    /* generate or get the fullname */
    snprintf(name, sizeof(name), "%s%s%s",
	     vendorname ? vendorname : "",
	     vendorname && devicename ? " " : "",
	     devicename ? devicename : "");
    fullname = name;
    if (*name)
      obj->name = strdup(name);
    hwloc_debug("  %04x:%02x:%02x.%01x %04x %04x:%04x %s\n",
		domain, pcidev->bus, pcidev->dev, pcidev->func,
		device_class, pcidev->vendor_id, pcidev->device_id,
		fullname && *fullname ? fullname : "??");

    /* queue the object for now */
    if (first_obj)
      last_obj->next_sibling = obj;
    else
      first_obj = obj;
    last_obj = obj;
  }

  /* finalize device scanning */
  pci_iterator_destroy(iter);
  pci_system_cleanup();

#ifdef HWLOC_LINUX_SYS
  dir = opendir("/sys/bus/pci/slots/");
  if (dir) {
    struct dirent *dirent;
    while ((dirent = readdir(dir)) != NULL) {
      char path[64];
      FILE *file;
      if (dirent->d_name[0] == '.')
	continue;
      snprintf(path, sizeof(path), "/sys/bus/pci/slots/%s/address", dirent->d_name);
      file = fopen(path, "r");
      if (file) {
	unsigned domain, bus, dev;
	if (fscanf(file, "%x:%x:%x", &domain, &bus, &dev) == 3) {
	  hwloc_obj_t obj = first_obj;
	  while (obj) {
	    if (obj->attr->pcidev.domain == domain
		&& obj->attr->pcidev.bus == bus
		&& obj->attr->pcidev.dev == dev
		&& obj->attr->pcidev.func == 0) {
	      hwloc_obj_add_info(obj, "PCISlot", dirent->d_name);
	      break;
	    }
	    obj = obj->next_sibling;
	  }
	}
	fclose(file);
      }
    }
    closedir(dir);
  }
#endif

  return hwloc_insert_pci_device_list(backend, first_obj);
}
Esempio n. 3
0
static int
hwloc_look_pci(struct hwloc_backend *backend)
{
  struct hwloc_topology *topology = backend->topology;
  enum hwloc_type_filter_e pfilter, bfilter;
  struct hwloc_obj *tree = NULL, *tmp;
  int ret;
  struct pci_device_iterator *iter;
  struct pci_device *pcidev;

  hwloc_topology_get_type_filter(topology, HWLOC_OBJ_PCI_DEVICE, &pfilter);
  hwloc_topology_get_type_filter(topology, HWLOC_OBJ_BRIDGE, &bfilter);
  if (bfilter == HWLOC_TYPE_FILTER_KEEP_NONE
      && pfilter == HWLOC_TYPE_FILTER_KEEP_NONE)
    return 0;

  /* don't do anything if another backend attached PCI already
   * (they are attached to root until later in the core discovery)
   */
  tmp = hwloc_get_root_obj(topology)->io_first_child;
  while (tmp) {
    if (tmp->type == HWLOC_OBJ_PCI_DEVICE
	|| (tmp->type == HWLOC_OBJ_BRIDGE && tmp->attr->bridge.downstream_type == HWLOC_OBJ_BRIDGE_PCI)) {
      hwloc_debug("%s", "PCI objects already added, ignoring linuxpci backend.\n");
      return 0;
    }
    tmp = tmp->next_sibling;
  }

  hwloc_debug("%s", "\nScanning PCI buses...\n");

  /* initialize PCI scanning */
  ret = pci_system_init();
  if (ret) {
    hwloc_debug("%s", "Can not initialize libpciaccess\n");
    return -1;
  }

  iter = pci_slot_match_iterator_create(NULL);

  /* iterate over devices */
  for (pcidev = pci_device_next(iter);
       pcidev;
       pcidev = pci_device_next(iter))
  {
    const char *vendorname, *devicename;
    unsigned char config_space_cache[CONFIG_SPACE_CACHESIZE];
    hwloc_obj_type_t type;
    struct hwloc_obj *obj;
    unsigned domain;
    unsigned device_class;
    unsigned short tmp16;
    unsigned offset;

    /* initialize the config space in case we fail to read it (missing permissions, etc). */
    memset(config_space_cache, 0xff, CONFIG_SPACE_CACHESIZE);
    pci_device_probe(pcidev);
    pci_device_cfg_read(pcidev, config_space_cache, 0, CONFIG_SPACE_CACHESIZE, NULL);

    /* try to read the domain */
    domain = pcidev->domain;

    /* try to read the device_class */
    device_class = pcidev->device_class >> 8;

    /* bridge or pci dev? */
    type = hwloc_pci_check_bridge_type(device_class, config_space_cache);

    /* filtered? */
    if (type == HWLOC_OBJ_PCI_DEVICE) {
      enum hwloc_type_filter_e filter;
      hwloc_topology_get_type_filter(topology, HWLOC_OBJ_PCI_DEVICE, &filter);
      if (filter == HWLOC_TYPE_FILTER_KEEP_NONE)
	continue;
      if (filter == HWLOC_TYPE_FILTER_KEEP_IMPORTANT
	  && !hwloc_filter_check_pcidev_subtype_important(device_class))
	continue;
    } else if (type == HWLOC_OBJ_BRIDGE) {
      enum hwloc_type_filter_e filter;
      hwloc_topology_get_type_filter(topology, HWLOC_OBJ_BRIDGE, &filter);
      if (filter == HWLOC_TYPE_FILTER_KEEP_NONE)
	continue;
      /* HWLOC_TYPE_FILTER_KEEP_IMPORTANT filtered later in the core */
    }

    /* fixup SR-IOV buggy VF device/vendor IDs */
    if (0xffff == pcidev->vendor_id && 0xffff == pcidev->device_id) {
      /* SR-IOV puts ffff:ffff in Virtual Function config space.
       * The actual VF device ID is stored at a special (dynamic) location in the Physical Function config space.
       * VF and PF have the same vendor ID.
       *
       * libpciaccess just returns ffff:ffff, needs to be fixed.
       * linuxpci is OK because sysfs files are already fixed the kernel.
       * (pciutils is OK when it uses those Linux sysfs files.)
       *
       * Reading these files is an easy way to work around the libpciaccess issue on Linux,
       * but we have no way to know if this is caused by SR-IOV or not.
       *
       * TODO:
       *  If PF has CAP_ID_PCIX or CAP_ID_EXP (offset>0),
       *  look for extended capability PCI_EXT_CAP_ID_SRIOV (need extended config space (more than 256 bytes)),
       *  then read the VF device ID after it (PCI_IOV_DID bytes later).
       *  Needs access to extended config space (needs root on Linux).
       * TODO:
       *  Add string info attributes in VF and PF objects?
       */
#ifdef HWLOC_LINUX_SYS
      /* Workaround for Linux (the kernel returns the VF device/vendor IDs). */
      char path[64];
      char value[16];
      FILE *file;
      size_t read;

      snprintf(path, sizeof(path), "/sys/bus/pci/devices/%04x:%02x:%02x.%01x/vendor",
	       domain, pcidev->bus, pcidev->dev, pcidev->func);
      file = fopen(path, "r");
      if (file) {
	read = fread(value, 1, sizeof(value), file);
	fclose(file);
	if (read)
	  /* fixup the pciaccess struct so that pci_device_get_vendor_name() is correct later. */
          pcidev->vendor_id = strtoul(value, NULL, 16);
      }

      snprintf(path, sizeof(path), "/sys/bus/pci/devices/%04x:%02x:%02x.%01x/device",
	       domain, pcidev->bus, pcidev->dev, pcidev->func);
      file = fopen(path, "r");
      if (file) {
	read = fread(value, 1, sizeof(value), file);
	fclose(file);
	if (read)
	  /* fixup the pciaccess struct so that pci_device_get_device_name() is correct later. */
          pcidev->device_id = strtoul(value, NULL, 16);
      }
#endif
    }

    obj = hwloc_alloc_setup_object(type, -1);
    obj->attr->pcidev.domain = domain;
    obj->attr->pcidev.bus = pcidev->bus;
    obj->attr->pcidev.dev = pcidev->dev;
    obj->attr->pcidev.func = pcidev->func;
    obj->attr->pcidev.vendor_id = pcidev->vendor_id;
    obj->attr->pcidev.device_id = pcidev->device_id;
    obj->attr->pcidev.class_id = device_class;
    obj->attr->pcidev.revision = config_space_cache[PCI_REVISION_ID];

    obj->attr->pcidev.linkspeed = 0; /* unknown */
    offset = hwloc_pci_find_cap(config_space_cache, PCI_CAP_ID_EXP);

    if (offset > 0 && offset + 20 /* size of PCI express block up to link status */ <= CONFIG_SPACE_CACHESIZE)
      hwloc_pci_find_linkspeed(config_space_cache, offset, &obj->attr->pcidev.linkspeed);

    if (type == HWLOC_OBJ_BRIDGE) {
      if (hwloc_pci_setup_bridge_attr(obj, config_space_cache) < 0)
	continue;
    }

    if (obj->type == HWLOC_OBJ_PCI_DEVICE) {
      memcpy(&tmp16, &config_space_cache[PCI_SUBSYSTEM_VENDOR_ID], sizeof(tmp16));
      obj->attr->pcidev.subvendor_id = tmp16;
      memcpy(&tmp16, &config_space_cache[PCI_SUBSYSTEM_ID], sizeof(tmp16));
      obj->attr->pcidev.subdevice_id = tmp16;
    } else {
      /* TODO:
       * bridge must lookup PCI_CAP_ID_SSVID and then look at offset+PCI_SSVID_VENDOR/DEVICE_ID
       * cardbus must look at PCI_CB_SUBSYSTEM_VENDOR_ID and PCI_CB_SUBSYSTEM_ID
       */
    }

    /* get the vendor name */
    vendorname = pci_device_get_vendor_name(pcidev);
    if (vendorname && *vendorname)
      hwloc_obj_add_info(obj, "PCIVendor", vendorname);

    /* get the device name */
    devicename = pci_device_get_device_name(pcidev);
    if (devicename && *devicename)
      hwloc_obj_add_info(obj, "PCIDevice", devicename);

    hwloc_debug("  %04x:%02x:%02x.%01x %04x %04x:%04x %s %s\n",
		domain, pcidev->bus, pcidev->dev, pcidev->func,
		device_class, pcidev->vendor_id, pcidev->device_id,
		vendorname && *vendorname ? vendorname : "??",
		devicename && *devicename ? devicename : "??");

    hwloc_pci_tree_insert_by_busid(&tree, obj);
  }

  /* finalize device scanning */
  pci_iterator_destroy(iter);
  pci_system_cleanup();

  hwloc_pci_tree_attach_belowroot(topology, tree);
  return 0;
}