Even when a removable storage device is detected as supporting asynchronous notification (storage.removable.support_async_notification = true), hald-add-on-storage still polls the device every 2 seconds and wastes CPU time.

Note that without the kernel patch I just submitted to linux-kernel, "[PATCH] scsi: properly export media change notification capability in block device flags", this flag will never actually get set since the kernel wasn't exporting the capability in the block device capability sysfs file when it should have been.

Looking through the hal code, I can see where the support_async_notification flag is set, but not where it gets used for anything.

Output from lshal:

udi = '/org/freedesktop/Hal/devices/storage_model_iHAS324___A'
  access_control.file = '/dev/sr0'  (string)
  access_control.type = 'cdrom'  (string)
  block.device = '/dev/sr0'  (string)
  block.is_volume = false  (bool)
  block.major = 11  (0xb)  (int)
  block.minor = 0  (0x0)  (int)
  block.storage_device = '/org/freedesktop/Hal/devices/storage_model_iHAS324___A'  (string)
  info.addons = {'hald-addon-storage'} (string list)
  info.callouts.add = {'hal-acl-tool --add-device'} (string list)
  info.callouts.remove = {'hal-acl-tool --remove-device'} (string list)
  info.capabilities = {'storage', 'block', 'storage.cdrom', 'access_control'} (string list)
  info.category = 'storage'  (string)
  info.interfaces = {'org.freedesktop.Hal.Device.Storage', 'org.freedesktop.Hal.Device.Storage', 'org.freedesktop.Hal.Device.Storage.Removable'} (string list)
  info.parent = '/org/freedesktop/Hal/devices/pci_8086_3b22_scsi_host_1_scsi_device_lun0'  (string)
  info.product = 'iHAS324   A'  (string)
  info.udi = '/org/freedesktop/Hal/devices/storage_model_iHAS324___A'  (string)
  info.vendor = 'ATAPI'  (string)
  linux.hotplug_type = 3  (0x3)  (int)
  linux.sysfs_path = '/sys/devices/pci0000:00/0000:00:1f.2/host2/target2:0:0/2:0:0:0/block/sr0'  (string)
  org.freedesktop.Hal.Device.Storage.method_argnames = {'extra_options', 'extra_options'} (string list)
  org.freedesktop.Hal.Device.Storage.method_execpaths = {'hal-storage-eject', 'hal-storage-closetray'} (string list)
  org.freedesktop.Hal.Device.Storage.method_names = {'Eject', 'CloseTray'} (string list)
  org.freedesktop.Hal.Device.Storage.method_signatures = {'as', 'as'} (string list)
  storage.automount_enabled_hint = true  (bool)
  storage.bus = 'pci'  (string)
  storage.cdrom.bd = false  (bool)
  storage.cdrom.bdr = false  (bool)
  storage.cdrom.bdre = false  (bool)
  storage.cdrom.cdr = true  (bool)
  storage.cdrom.cdrw = true  (bool)
  storage.cdrom.dvd = true  (bool)
  storage.cdrom.dvdplusr = true  (bool)
  storage.cdrom.dvdplusrdl = true  (bool)
  storage.cdrom.dvdplusrw = true  (bool)
  storage.cdrom.dvdplusrwdl = false  (bool)
  storage.cdrom.dvdr = true  (bool)
  storage.cdrom.dvdram = true  (bool)
  storage.cdrom.dvdrdl = true  (bool)
  storage.cdrom.dvdrw = true  (bool)
  storage.cdrom.hddvd = false  (bool)
  storage.cdrom.hddvdr = false  (bool)
  storage.cdrom.hddvdrw = false  (bool)
  storage.cdrom.mo = false  (bool)
  storage.cdrom.mrw = true  (bool)
  storage.cdrom.mrw_w = true  (bool)
  storage.cdrom.read_speed = 8468  (0x2114)  (int)
  storage.cdrom.support_media_changed = true  (bool)
  storage.cdrom.support_multisession = true  (bool)
  storage.cdrom.write_speed = 8468  (0x2114)  (int)
  storage.drive_type = 'cdrom'  (string)
  storage.firmware_version = 'BL1N'  (string)
  storage.hotpluggable = false  (bool)
  storage.lun = 0  (0x0)  (int)
  storage.media_check_enabled = true  (bool)
  storage.model = 'iHAS324   A'  (string)
  storage.no_partitions_hint = true  (bool)
  storage.originating_device = '/org/freedesktop/Hal/devices/computer'  (string)
  storage.partitioning_scheme = ''  (string)
  storage.removable = true  (bool)
  storage.removable.media_available = false  (bool)
  storage.removable.support_async_notification = true  (bool)
  storage.requires_eject = true  (bool)
  storage.size = 0  (0x0)  (uint64)
  storage.vendor = 'ATAPI'  (string)