Writing Windows WDM Device Drivers
A nuts-and-bolts reference highlighting the Windows Driver Model (WDM).
TABLE OF CONTENTS Writing Windows WDM Device Drivers
Advanced Plug and Play
This section looks at some advanced Plug and Play topics.
Bus Drivers
This section looks briefly at the job a bus driver must do. Please consult the DDK documentation for full details. The W2000 DDK source code kernel\serenum example shows how a bus driver is coded.
Bus drivers must manage their device objects carefully. A bus driver has a Functional Device Object (FDO) for each instance of a bus. A bus driver detects any devices on its bus and creates child device objects for each device. These are actually the Physical Device Objects (PDOs) to which higher driver layers attach.
The IRP dispatch routines in a bus driver handle requests for both FDOs and child PDOs. Use a flag in a common portion of the FDO and PDO device extensions to indicate whether the device is an FDO or a child PDO.
If a bus driver detects a Plug and Play device arriving or removing, it must call IoInvalidateDeviceRelations. The PnP Manager then sends an IRP_MN_QUERY_DEVICE_RELATIONS PnP IRP to get the new details. Non-Plug and Play devices can be reported in W2000 using IoReportDetectedDevice.
Creating Child Devices
A bus driver must enumerate its own bus to find any attached devices. It must also keep checking to see if any devices are removed or added. A bus driver might use a system worker thread, described in chapter 14, to schedule its device checks.
A bus driver must call IoInvalidateDeviceRelations if it detects...
Copyright CMP Books 1999 under license agreement with Books24x7
