Technologies›Low-level, Kernel & Legacy

IOKit

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IOKit is a low-level framework for device driver development and hardware access on macOS, spanning I/O families such as HID, graphics, storage, and USB. With it you describe and exchange data with hardware using structures like IOPhysicalRange and IOVirtualRange for memory ranges, the _IODataQueueEntry and _IODataQueueMemory types that back shared data queues, and IORPC message structures such as IORPCMessage and IORPCMessageMach for driver remote-procedure calls. You also handle service notifications and asynchronous completions through types like OSNotificationHeader, IOServiceInterestContent, and IOAsyncCompletionContent.

Memory Ranges 2

Structures that describe physical and virtual memory regions used in I/O transfers.

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    IOPhysicalRange
    A structure that describes a contiguous range of physical memory by address and length.
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    IOVirtualRange
    A structure that describes a contiguous range of virtual memory by address and length.

Shared Data Queues 3

Structures that back the lock-free shared memory queues used to pass entries between drivers and clients.

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    _IODataQueueEntry
    @typedef IODataQueueEntry
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    _IODataQueueMemory
    @typedef IODataQueueMemory
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    _IODataQueueAppendix
    @typedef IODataQueueAppendix

Remote Procedure Calls 5

Message structures that carry driver remote-procedure-call requests, replies, and error returns.

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    IORPC
    A structure that encapsulates a driver remote-procedure-call request and its response messages.
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    IORPCMessage
    A structure that describes a driver remote-procedure-call message and its arguments.
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    IORPCMessageMach
    A structure that wraps an IOKit remote-procedure-call message for transport over Mach IPC.
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    IORPCMessageErrorReturn
    A structure that represents an error reply returned from a driver remote-procedure call.
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    IORPCMessageErrorReturnContent
    A structure carrying the payload of an error returned from a remote-procedure call.

Service Notifications & Completions 5

Structures that deliver service-interest notifications and asynchronous I/O completion data.

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    OSNotificationHeader
    A structure that heads a service notification message delivered to a client.
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    OSNotificationHeader64
    A 64-bit structure that heads a service notification message delivered to a client.
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    IOServiceInterestContent
    A structure carrying the payload of a service-interest notification.
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    IOServiceInterestContent64
    A 64-bit structure carrying the payload of a service-interest notification.
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    IOAsyncCompletionContent
    A structure carrying the result data delivered when an asynchronous I/O operation completes.

Plug-ins & Class Metadata 3

Structures that describe device interface plug-ins and runtime class information.

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    IOCFPlugInInterfaceStruct
    A structure defining the function table for a Core Foundation device interface plug-in.
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    OSClassDescription
    A structure that describes runtime metadata for an OSObject-derived class.
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    IONamedValue
    A structure that pairs an integer value with a human-readable name for lookups and descriptions.

Errors 1

Structures that report I/O and URL-related error conditions.

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    IOURLError
    A structure that reports a URL-related error encountered during an I/O operation.

Type Aliases 43

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    IOReturn
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    IOOptionBits
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    IOFixed
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    IOVersion
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    IOItemCount
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    IOCacheMode
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    IOByteCount32
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    IOByteCount64
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    IOPhysicalAddress32
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    IOPhysicalAddress64
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    IOPhysicalLength32
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    IOPhysicalLength64
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    IOVirtualAddress
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    IOByteCount
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    IOLogicalAddress
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    IOPhysicalAddress
Show 27 more
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    IOPhysicalLength
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    IOAddressRange
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    IOAlignment
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    io_object_t
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    io_connect_t
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    io_enumerator_t
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    io_ident_t
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    io_iterator_t
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    io_registry_entry_t
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    io_service_t
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    uext_object_t
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    IODeviceNumber
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    OSAsyncReference64
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    OSAsyncReference
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    IONotificationPortRef
    @header IOKitLib
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    IOServiceMatchingCallback
    @typedef IOServiceMatchingCallback
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    IOServiceInterestCallback
    @typedef IOServiceInterestCallback
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    IOAsyncCallback0
    @typedef IOAsyncCallback0
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    IOAsyncCallback1
    @typedef IOAsyncCallback1
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    IOAsyncCallback2
    @typedef IOAsyncCallback2
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    IOAsyncCallback
    @typedef IOAsyncCallback
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    IODataQueueEntry
    @typedef IODataQueueEntry
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    IODataQueueMemory
    @typedef IODataQueueMemory
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    IODataQueueAppendix
    @typedef IODataQueueAppendix
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    IOCFPlugInInterface
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    IOMessage
    @header IOMessage.h
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    OSObjectRef
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