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Writing Dispatch Routines

Processing any I/O request packet (IRP) begins in a dispatch routine that the driver registers to handle an IRP major function code (IRP_MJ_XXX). The driver's DriverEntry routine exports entry points for dispatch routines in a dispatch table within the driver's DRIVER_OBJECT structure.

A driver can provide a separate dispatch routine for each major I/O function code that it handles. Alternatively, dispatch routines can be written to handle multiple I/O function codes.

This section contains the following topics:

Dispatch Routine Functionality

Required Dispatch Routines

Optional Dispatch Routines

Dispatch Routines and IRQLs

When to Check the Driver's I/O Stack Location

DispatchCreate, DispatchClose, and DispatchCreateClose Routines

DispatchCleanup Routines

DispatchRead, DispatchWrite, and DispatchReadWrite Routines

DispatchDeviceControl and DispatchInternalDeviceControl Routines

DispatchPnP Routines

DispatchPower Routines