IoInitializeIrp - NtDoc

Native API online documentation, based on the System Informer (formerly Process Hacker) phnt headers
// wdm.h

VOID IoInitializeIrp(
  [in, out] PIRP   Irp,
  [in]      USHORT PacketSize,
  [in]      CCHAR  StackSize
);

View the official Windows Driver Kit DDI reference

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Windows Driver Kit DDI reference (nf-wdm-ioinitializeirp)

IoInitializeIrp function

Description

The IoInitializeIrp routine initializes a given IRP that was allocated by the caller.

Parameters

Irp [in, out]

Pointer to the IRP to be initialized.

PacketSize [in]

Specifies the size in bytes of the IRP.

StackSize [in]

Specifies the number of stack locations in the IRP.

Remarks

Drivers use IoInitializeIrp to initialize IRPs the driver allocated as raw memory. Do not use IoInitializeIrp to initialize an IRP allocated by IoAllocateIrp. IoAllocateIrp automatically initializes the members of the IRP.

Drivers can use IoInitializeIrp to reinitialize an IRP for reuse only under certain circumstances. See Reusing IRPs for details.

If the driver associates an MDL with the IRP it allocated, the driver is responsible for releasing the MDL when the IRP is completed.

An intermediate or highest-level driver also can call IoBuildDeviceIoControlRequest, IoBuildAsynchronousFsdRequest, or IoBuildSynchronousFsdRequest to set up requests it sends to lower-level drivers. Only a highest-level driver can call IoMakeAssociatedIrp.

See also

IRP

IoAllocateIrp

IoAllocateMdl

IoBuildPartialMdl

IoFreeIrp

IoFreeMdl

IoReuseIrp

IoSetNextIrpStackLocation

IoSizeOfIrp