IoInitializeIrp function (wdm.h)
The IoInitializeIrp routine initializes a given IRP that was allocated by the caller.
Syntax
void IoInitializeIrp(
[in, out] PIRP Irp,
[in] USHORT PacketSize,
[in] CCHAR StackSize
);
Parameters
[in, out] Irp
Pointer to the IRP to be initialized.
[in] PacketSize
Specifies the size in bytes of the IRP.
[in] StackSize
Specifies the number of stack locations in the IRP.
Return value
None
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.
Requirements
| Requirement | Value |
|---|---|
| Minimum supported client | Available starting with Windows 2000. |
| Target Platform | Universal |
| Header | wdm.h (include Wdm.h, Ntddk.h, Ntifs.h) |
| Library | NtosKrnl.lib |
| DLL | NtosKrnl.exe |
| IRQL | <= DISPATCH_LEVEL |
| DDI compliance rules | HwStorPortProhibitedDDIs(storport), IoReuseIrp(wdm) |