Overview

This chapter looks at how to find, allocate, and use hardware resources in non-WDM drivers that do not support Plug and Play. I call these "NT style" drivers because they run in NT 3.51, NT 4, and Windows 2000. These drivers sometimes also work in Windows 98, slightly to my surprise.

I have already shown how to use the translated hardware resource assignments in the last two chapters. The WdmIo and PHDIo drivers use MmMapIoSpace to map I/O ports into memory and IoConnectInterrupt to install an interrupt handler.

An NT style driver has three jobs to do to obtain its translated hardware resources.

1. Find its device's raw resource requirements.

2. Allocate these raw resources: check for conflicts with existing devices and reserve the resources so that other new devices cannot use them.

3. Translate the raw resource information.

The PHDIo driver receives its resource requirements from the Win32 application. The filename passed in the Create IRP specifies the I/O port details and optionally the Interrupt IRQ number. PHDIo can currently only accept ISA resource details.

This chapter shows how PHDIo allocates its raw resources and translates them. At the end of the chapter, I look at how NT and W2000 find various devices and make the resource information available to drivers.

First, I look at how to build and structure an NT style driver.

NT Style Driver Construction

An NT style driver is built in a slightly different way from a WDM driver. It...