Announcing Driver Dispatch Routines
Before a driver can process I/O requests, it must announce what kinds of operations it supports. This section describes the I/O Manager's dispatching mechanism and explains how to enable receipt of appropriate I/O function codes. It also presents guidelines for deciding which function codes should be supported for different device types.
I/O Request Dispatching Mechanism
Windows 2000 I/O operations are packet-driven. When an I/O request is initiated, the I/O Manager first builds an IRP work-order to keep track of the request. Among other things, it stores a function code in the MajorField field of the IRP's I/O stack location to uniquely identify the type of request.
The MajorField code is used by the I/O Manager ...
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