Power management and virtual devices

NTDEV
1

A couple of questions I can’t find the answers to:

  1. What is the impact of a non-PNP (NT style) device driver for a virtual
    device on power managment? I believe that a non-PNP driver for a physical
    device messes up power management.

  2. For a virtual device what besides forwarding the power IRP’s is needed?

Don Burn

2

> 1. What is the impact of a non-PNP (NT style) device driver for a virtual

device on power managment? I believe that a non-PNP driver for a physical
device messes up power management.

Yes. What disables power management is - calling NT4-style routines for
hardware resources like IoAssignResources or HalAssignSlotResources. The
hardware-less virtual driver will never need to call these.

  1. For a virtual device what besides forwarding the power IRP’s is needed?

Only if it is a PnP (root-enumerated) device.

Maxim Shatskih, Windows DDK MVP
StorageCraft Corporation
xxxxx@storagecraft.com
http://www.storagecraft.com