---
title: IOKit Constants
framework: IOKit
role: collectionGroup
role_heading: API Collection
path: iokit/iokit_constants
---

# IOKit Constants

## Topics

### Constants

- [IOKIT](iokit/iokit.md)
- [IOPhysSize](iokit/iophyssize.md)
- [IO_OBJECT_NULL](iokit/io_object_null.md)
- [kIOAppPowerStateInterest](iokit/kioapppowerstateinterest.md)
- [kIOAudioPlane](iokit/kioaudioplane.md)
- [kIOBSDKey](iokit/kiobsdkey.md)
- [kIOBSDMajorKey](iokit/kiobsdmajorkey.md)
- [kIOBSDMinorKey](iokit/kiobsdminorkey.md)
- [kIOBSDNameKey](iokit/kiobsdnamekey.md)
- [kIOBSDNamesKey](iokit/kiobsdnameskey.md)
- [kIOBSDUnitKey](iokit/kiobsdunitkey.md)
- [kIOBootDeviceKey](iokit/kiobootdevicekey.md)
- [kIOBootDevicePathKey](iokit/kiobootdevicepathkey.md)
- [kIOBootDeviceSizeKey](iokit/kiobootdevicesizekey.md)
- [kIOBundleDevelopmentRegionKey](iokit/kiobundledevelopmentregionkey.md)
- [kIOBundleExecutableKey](iokit/kiobundleexecutablekey.md)
- [kIOBundleIdentifierKey](iokit/kiobundleidentifierkey.md)
- [kIOBundleInfoDictionaryVersionKey](iokit/kiobundleinfodictionaryversionkey.md)
- [kIOBundleNameKey](iokit/kiobundlenamekey.md)
- [kIOBundleResourceFileKey](iokit/kiobundleresourcefilekey.md)
- [kIOBundleVersionKey](iokit/kiobundleversionkey.md)
- [kIOBusBadgeKey](iokit/kiobusbadgekey.md)
- [kIOBusyInterest](iokit/kiobusyinterest.md)
- [kIOCFPlugInTypesKey](iokit/kiocfplugintypeskey.md)
- [kIOCatalogueKey](iokit/kiocataloguekey.md)
- [kIOClassKey](iokit/kioclasskey.md)
- [kIOCommandPoolSizeKey](iokit/kiocommandpoolsizekey.md)
- [kIODTNVRAMPanicInfoKey](iokit/kiodtnvrampanicinfokey.md)
- [kIODefaultMatchCategoryKey](iokit/kiodefaultmatchcategorykey.md)
- [kIODeviceIconKey](iokit/kiodeviceiconkey.md)
- [kIODeviceTreePlane](iokit/kiodevicetreeplane.md)
- [kIOFireWirePlane](iokit/kiofirewireplane.md)
- [kIOFirstMatchNotification](iokit/kiofirstmatchnotification.md)
- [kIOFirstPublishNotification](iokit/kiofirstpublishnotification.md)
- [kIOGeneralInterest](iokit/kiogeneralinterest.md)
- [kIOIconKey](iokit/kioiconkey.md)
- [kIOKitBuildVersionKey](iokit/kiokitbuildversionkey.md)
- [kIOKitDebugKey](iokit/kiokitdebugkey.md)
- [kIOKitDiagnosticsKey](iokit/kiokitdiagnosticskey.md)
- [kIOLocationMatchKey](iokit/kiolocationmatchkey.md)
- [kIOMapperIDKey](iokit/kiomapperidkey.md)
- [kIOMatchCategoryKey](iokit/kiomatchcategorykey.md)
- [kIOMatchedNotification](iokit/kiomatchednotification.md)
- [kIOMatchedServiceCountKey](iokit/kiomatchedservicecountkey.md)
- [kIOMaximumBlockCountReadKey](iokit/kiomaximumblockcountreadkey.md)
- [kIOMaximumBlockCountWriteKey](iokit/kiomaximumblockcountwritekey.md)
- [kIOMaximumByteCountReadKey](iokit/kiomaximumbytecountreadkey.md)
- [kIOMaximumByteCountWriteKey](iokit/kiomaximumbytecountwritekey.md)
- [kIOMaximumPriorityCountKey](iokit/kiomaximumprioritycountkey.md)
- [kIOMaximumSegmentAddressableBitCountKey](iokit/kiomaximumsegmentaddressablebitcountkey.md)
- [kIOMaximumSegmentByteCountReadKey](iokit/kiomaximumsegmentbytecountreadkey.md)
- [kIOMaximumSegmentByteCountWriteKey](iokit/kiomaximumsegmentbytecountwritekey.md)
- [kIOMaximumSegmentCountReadKey](iokit/kiomaximumsegmentcountreadkey.md)
- [kIOMaximumSegmentCountWriteKey](iokit/kiomaximumsegmentcountwritekey.md)
- [kIOMinimumSaturationByteCountKey](iokit/kiominimumsaturationbytecountkey.md)
- [kIOMinimumSegmentAlignmentByteCountKey](iokit/kiominimumsegmentalignmentbytecountkey.md)
- [kIONVRAMActivateCSRConfigPropertyKey](iokit/kionvramactivatecsrconfigpropertykey.md)
- [kIONVRAMDeletePropertyKey](iokit/kionvramdeletepropertykey.md)
- [kIONVRAMSyncNowPropertyKey](iokit/kionvramsyncnowpropertykey.md)
- [kIONameMatchKey](iokit/kionamematchkey.md)
- [kIONameMatchedKey](iokit/kionamematchedkey.md)
- [kIOParentMatchKey](iokit/kioparentmatchkey.md)
- [kIOPathMatchKey](iokit/kiopathmatchkey.md)
- [kIOPlatformDeviceMessageKey](iokit/kioplatformdevicemessagekey.md)
- [kIOPlatformSerialNumberKey](iokit/kioplatformserialnumberkey.md)
- [kIOPlatformUUIDKey](iokit/kioplatformuuidkey.md)
- [kIOPowerPlane](iokit/kiopowerplane.md)
- [kIOPriorityPowerStateInterest](iokit/kioprioritypowerstateinterest.md)
- [kIOProbeScoreKey](iokit/kioprobescorekey.md)
- [kIOPropertyExistsMatchKey](iokit/kiopropertyexistsmatchkey.md)
- [kIOPropertyMatchKey](iokit/kiopropertymatchkey.md)
- [kIOProviderClassKey](iokit/kioproviderclasskey.md)
- [kIOPublishNotification](iokit/kiopublishnotification.md)
- [kIORegistryEntryIDKey](iokit/kioregistryentryidkey.md)
- [kIORegistryEntryPropertyKeysKey](iokit/kioregistryentrypropertykeyskey.md)
- [kIORegistryPlanesKey](iokit/kioregistryplaneskey.md)
- [kIOResourceMatchKey](iokit/kioresourcematchkey.md)
- [kIOResourceMatchedKey](iokit/kioresourcematchedkey.md)
- [kIOResourcesClass](iokit/kioresourcesclass.md)
- [kIOReturnAborted](iokit/kioreturnaborted.md)
- [kIOReturnBadArgument](iokit/kioreturnbadargument.md)
- [kIOReturnBadMedia](iokit/kioreturnbadmedia.md)
- [kIOReturnBadMessageID](iokit/kioreturnbadmessageid.md)
- [kIOReturnBusy](iokit/kioreturnbusy.md)
- [kIOReturnCannotLock](iokit/kioreturncannotlock.md)
- [kIOReturnCannotWire](iokit/kioreturncannotwire.md)
- [kIOReturnDMAError](iokit/kioreturndmaerror.md)
- [kIOReturnDeviceError](iokit/kioreturndeviceerror.md)
- [kIOReturnError](iokit/kioreturnerror.md)
- [kIOReturnExclusiveAccess](iokit/kioreturnexclusiveaccess.md)
- [kIOReturnIOError](iokit/kioreturnioerror.md)
- [kIOReturnIPCError](iokit/kioreturnipcerror.md)
- [kIOReturnInternalError](iokit/kioreturninternalerror.md)
- [kIOReturnInvalid](iokit/kioreturninvalid.md)
- [kIOReturnIsoTooNew](iokit/kioreturnisotoonew.md)
- [kIOReturnIsoTooOld](iokit/kioreturnisotooold.md)
- [kIOReturnLockedRead](iokit/kioreturnlockedread.md)
- [kIOReturnLockedWrite](iokit/kioreturnlockedwrite.md)
- [kIOReturnMessageTooLarge](iokit/kioreturnmessagetoolarge.md)
- [kIOReturnNoBandwidth](iokit/kioreturnnobandwidth.md)
- [kIOReturnNoChannels](iokit/kioreturnnochannels.md)
- [kIOReturnNoCompletion](iokit/kioreturnnocompletion.md)
- [kIOReturnNoDevice](iokit/kioreturnnodevice.md)
- [kIOReturnNoFrames](iokit/kioreturnnoframes.md)
- [kIOReturnNoInterrupt](iokit/kioreturnnointerrupt.md)
- [kIOReturnNoMedia](iokit/kioreturnnomedia.md)
- [kIOReturnNoMemory](iokit/kioreturnnomemory.md)
- [kIOReturnNoPower](iokit/kioreturnnopower.md)
- [kIOReturnNoResources](iokit/kioreturnnoresources.md)
- [kIOReturnNoSpace](iokit/kioreturnnospace.md)
- [kIOReturnNotAligned](iokit/kioreturnnotaligned.md)
- [kIOReturnNotAttached](iokit/kioreturnnotattached.md)
- [kIOReturnNotFound](iokit/kioreturnnotfound.md)
- [kIOReturnNotOpen](iokit/kioreturnnotopen.md)
- [kIOReturnNotPermitted](iokit/kioreturnnotpermitted.md)
- [kIOReturnNotPrivileged](iokit/kioreturnnotprivileged.md)
- [kIOReturnNotReadable](iokit/kioreturnnotreadable.md)
- [kIOReturnNotReady](iokit/kioreturnnotready.md)
- [kIOReturnNotResponding](iokit/kioreturnnotresponding.md)
- [kIOReturnNotWritable](iokit/kioreturnnotwritable.md)
- [kIOReturnOffline](iokit/kioreturnoffline.md)
- [kIOReturnOverrun](iokit/kioreturnoverrun.md)
- [kIOReturnPortExists](iokit/kioreturnportexists.md)
- [kIOReturnRLDError](iokit/kioreturnrlderror.md)
- [kIOReturnStillOpen](iokit/kioreturnstillopen.md)
- [kIOReturnSuccess](iokit/kioreturnsuccess.md)
- [kIOReturnTimeout](iokit/kioreturntimeout.md)
- [kIOReturnUnderrun](iokit/kioreturnunderrun.md)
- [kIOReturnUnformattedMedia](iokit/kioreturnunformattedmedia.md)
- [kIOReturnUnsupported](iokit/kioreturnunsupported.md)
- [kIOReturnUnsupportedMode](iokit/kioreturnunsupportedmode.md)
- [kIOReturnVMError](iokit/kioreturnvmerror.md)
- [kIOServiceClass](iokit/kioserviceclass.md)
- [kIOServicePlane](iokit/kioserviceplane.md)
- [kIOTerminatedNotification](iokit/kioterminatednotification.md)
- [kIOURLFileDirectoryContents](iokit/kiourlfiledirectorycontents.md)
- [kIOURLFileExists](iokit/kiourlfileexists.md)
- [kIOURLFileLastModificationTime](iokit/kiourlfilelastmodificationtime.md)
- [kIOURLFileLength](iokit/kiourlfilelength.md)
- [kIOURLFileOwnerID](iokit/kiourlfileownerid.md)
- [kIOURLFilePOSIXMode](iokit/kiourlfileposixmode.md)
- [kIOURLImproperArgumentsError](iokit/kiourlimproperargumentserror.md)
- [kIOURLPropertyKeyUnavailableError](iokit/kiourlpropertykeyunavailableerror.md)
- [kIOURLRemoteHostUnavailableError](iokit/kiourlremotehostunavailableerror.md)
- [kIOURLResourceAccessViolationError](iokit/kiourlresourceaccessviolationerror.md)
- [kIOURLResourceNotFoundError](iokit/kiourlresourcenotfounderror.md)
- [kIOURLTimeoutError](iokit/kiourltimeouterror.md)
- [kIOURLUnknownError](iokit/kiourlunknownerror.md)
- [kIOURLUnknownPropertyKeyError](iokit/kiourlunknownpropertykeyerror.md)
- [kIOURLUnknownSchemeError](iokit/kiourlunknownschemeerror.md)
- [kIOUSBPlane](iokit/kiousbplane.md)
- [kIOUserClientClassKey](iokit/kiouserclientclasskey.md)
- [kIOUserClientCreatorKey](iokit/kiouserclientcreatorkey.md)
- [kIOUserClientCrossEndianCompatibleKey](iokit/kiouserclientcrossendiancompatiblekey.md)
- [kIOUserClientCrossEndianKey](iokit/kiouserclientcrossendiankey.md)
- [kIOUserClientSharedInstanceKey](iokit/kiouserclientsharedinstancekey.md)
- [kOSBuildVersionKey](iokit/kosbuildversionkey.md)
- [PRIIOByteCount](iokit/priiobytecount.md)
- [kIOAllCPUInitializedKey](iokit/kioallcpuinitializedkey.md)
- [kIOCompatibilityMatchKey](iokit/kiocompatibilitymatchkey.md)
- [kIOCompatibilityPropertiesKey](iokit/kiocompatibilitypropertieskey.md)
- [kIODEXTMatchCountKey](iokit/kiodextmatchcountkey.md)
- [kIODriverKitEntitlementKey](iokit/kiodriverkitentitlementkey.md)
- [kIODriverKitHIDFamilyDeviceEntitlementKey](iokit/kiodriverkithidfamilydeviceentitlementkey.md)
- [kIODriverKitHIDFamilyEventServiceEntitlementKey](iokit/kiodriverkithidfamilyeventserviceentitlementkey.md)
- [kIODriverKitHIDTransportEntitlementKey](iokit/kiodriverkithidtransportentitlementkey.md)
- [kIODriverKitRequiredEntitlementsKey](iokit/kiodriverkitrequiredentitlementskey.md)
- [kIODriverKitTestDriverEntitlementKey](iokit/kiodriverkittestdriverentitlementkey.md)
- [kIODriverKitTransportBuiltinEntitlementKey](iokit/kiodriverkittransportbuiltinentitlementkey.md)
- [kIODriverKitUSBTransportEntitlementKey](iokit/kiodriverkitusbtransportentitlementkey.md)
- [kIODriverKitUserClientEntitlementAdministratorKey](iokit/kiodriverkitusercliententitlementadministratorkey.md)
- [kIODriverKitUserClientEntitlementAllowAnyKey](iokit/kiodriverkitusercliententitlementallowanykey.md)
- [kIODriverKitUserClientEntitlementAllowThirdPartyUserClientsKey](iokit/kiodriverkitusercliententitlementallowthirdpartyuserclientskey.md)
- [kIODriverKitUserClientEntitlementCommunicatesWithDriversKey](iokit/kiodriverkitusercliententitlementcommunicateswithdriverskey.md)
- [kIODriverKitUserClientEntitlementsKey](iokit/kiodriverkitusercliententitlementskey.md)
- [kIOMainPortDefault](iokit/kiomainportdefault.md)
- [kIOMatchDeferKey](iokit/kiomatchdeferkey.md)
- [kIOMatchedPersonalityKey](iokit/kiomatchedpersonalitykey.md)
- [kIOMaximumSwapWriteKey](iokit/kiomaximumswapwritekey.md)
- [kIONVRAMBootArgsKey](iokit/kionvrambootargskey.md)
- [kIONVRAMDeletePropertyKeyWRet](iokit/kionvramdeletepropertykeywret.md)
- [kIONVRAMReadAccessKey](iokit/kionvramreadaccesskey.md)
- [kIONVRAMSystemAllowKey](iokit/kionvramsystemallowkey.md)
- [kIONVRAMWriteAccessKey](iokit/kionvramwriteaccesskey.md)
- [kIOPathKey](iokit/kiopathkey.md)
- [kIORegistryEntryAllowableSetPropertiesKey](iokit/kioregistryentryallowablesetpropertieskey.md)
- [kIORegistryEntryDefaultLockingSetPropertiesKey](iokit/kioregistryentrydefaultlockingsetpropertieskey.md)
- [kIORematchCountKey](iokit/kiorematchcountkey.md)
- [kIORematchPersonalityKey](iokit/kiorematchpersonalitykey.md)
- [kIOResourcesSetPropertyKey](iokit/kioresourcessetpropertykey.md)
- [kIOServiceDEXTEntitlementsKey](iokit/kioservicedextentitlementskey.md)
- [kIOStateNotificationEntitlementGetKey](iokit/kiostatenotificationentitlementgetkey.md)
- [kIOStateNotificationEntitlementSetKey](iokit/kiostatenotificationentitlementsetkey.md)
- [kIOStateNotificationItemCopyKey](iokit/kiostatenotificationitemcopykey.md)
- [kIOStateNotificationItemCreateKey](iokit/kiostatenotificationitemcreatekey.md)
- [kIOStateNotificationItemSetKey](iokit/kiostatenotificationitemsetkey.md)
- [kIOStateNotificationNameKey](iokit/kiostatenotificationnamekey.md)
- [kIOSupportedPropertiesKey](iokit/kiosupportedpropertieskey.md)
- [kIOSystemStateClamshellKey](iokit/kiosystemstateclamshellkey.md)
- [kIOSystemStateHaltDescriptionHaltStateKey](iokit/kiosystemstatehaltdescriptionhaltstatekey.md)
- [kIOSystemStateHaltDescriptionKey](iokit/kiosystemstatehaltdescriptionkey.md)
- [kIOSystemStatePowerSourceDescriptionACAttachedKey](iokit/kiosystemstatepowersourcedescriptionacattachedkey.md)
- [kIOSystemStatePowerSourceDescriptionKey](iokit/kiosystemstatepowersourcedescriptionkey.md)
- [kIOSystemStateSleepDescriptionHibernateStateKey](iokit/kiosystemstatesleepdescriptionhibernatestatekey.md)
- [kIOSystemStateSleepDescriptionKey](iokit/kiosystemstatesleepdescriptionkey.md)
- [kIOSystemStateSleepDescriptionReasonKey](iokit/kiosystemstatesleepdescriptionreasonkey.md)
- [kIOSystemStateWakeDescriptionContinuousTimeOffsetKey](iokit/kiosystemstatewakedescriptioncontinuoustimeoffsetkey.md)
- [kIOSystemStateWakeDescriptionKey](iokit/kiosystemstatewakedescriptionkey.md)
- [kIOSystemStateWakeDescriptionWakeReasonKey](iokit/kiosystemstatewakedescriptionwakereasonkey.md)
- [kIOUserClassKey](iokit/kiouserclasskey.md)
- [kIOUserClassesKey](iokit/kiouserclasseskey.md)
- [kIOUserClientDefaultLockingKey](iokit/kiouserclientdefaultlockingkey.md)
- [kIOUserClientDefaultLockingSetPropertiesKey](iokit/kiouserclientdefaultlockingsetpropertieskey.md)
- [kIOUserClientDefaultLockingSingleThreadExternalMethodKey](iokit/kiouserclientdefaultlockingsinglethreadexternalmethodkey.md)
- [kIOUserClientEntitlementsKey](iokit/kiousercliententitlementskey.md)
- [kIOUserServerCDHashKey](iokit/kiouserservercdhashkey.md)
- [kIOUserServerClassKey](iokit/kiouserserverclasskey.md)
- [kIOUserServerNameKey](iokit/kiouserservernamekey.md)
- [kIOUserServerOneProcessKey](iokit/kiouserserveroneprocesskey.md)
- [kIOUserServerPreserveUserspaceRebootKey](iokit/kiouserserverpreserveuserspacerebootkey.md)
- [kIOUserServerTagKey](iokit/kiouserservertagkey.md)
- [kIOUserServicePropertiesKey](iokit/kiouserservicepropertieskey.md)
- [kIOUserUserClientKey](iokit/kiouseruserclientkey.md)
- [kIOWillTerminateNotification](iokit/kiowillterminatenotification.md)