Resetting the Adapter in Video Miniport Drivers
Every miniport driver must have a HwVidResetHw function if its adapter cannot be reset to an initialized state without a hard reboot of the machine.
HwVidResetHw is called by the HAL if the machine is about to crash or if the user initiates a soft reboot of the machine. HwVidResetHw resets the adapter to a specified character mode, so the HAL can display crash-dump information as it shuts down the system or initialization information during a soft reboot.
HwVidResetHw cannot call the BIOS, cannot call any pageable code, nor may it be made pageable. If possible, it should call only the VideoPortReadXxx and VideoPortWriteXxx functions, but it also can call any of the following: