Writing Windows WDM Device Drivers
A nuts-and-bolts reference highlighting the Windows Driver Model (WDM).
TABLE OF CONTENTS Writing Windows WDM Device Drivers
Chapter 14: DebugPrint
This chapter looks at a fully-fledged driver, DebugPrint. The DebugPrint software lets you use formatted print trace statements in your code and view the output in the DebugPrint Monitor Win32 program.
Along the way, I cover the following important device driver topics.
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System threads
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Dispatcher objects: events, Mutexes, and semaphores
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Linked lists
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File I/O in drivers
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Queuing IRPs
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Basic cancel routines
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Win32 overlapped I/O requests
Design Specification
The main design requirement for the DebugPrint software is that test drivers can do formatted prints that appear in a user mode application running on the same PC as the driver. The software must work under Windows 98 and Windows 2000. It should be easy for developers to include trace statements in their code. They should be able to use trace statements in most types of driver code.
This specification does not include source level debugging or breakpoints.
Design Implementation
Figure 14.1 shows the design used in the DebugPrint software. The figure shows that more than one test driver can run at the same time. In each test driver, the trace output is first stored internally in an EventList doubly-linked list. A DebugPrint system thread in the driver code reads the EventList and writes the events to the DebugPrint driver.
Figure 14.1: DebugPrint design
The DebugPrint driver write routine stores the trace events in its own EventList. The DebugPrint Monitor application issues read requests to the DebugPrint driver to...
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