PVIDEO_HW_RESET_HW callback function

HwVidResetHw resets the adapter to character mode.



BOOLEAN PvideoHwResetHw(
  PVOID HwDeviceExtension,
  ULONG Columns,
  ULONG Rows



Pointer to the miniport driver's per-adapter storage area. For more information, see Device Extensions.


Specifies the number of columns of the mode to be set up.


Specifies the number of rows of the mode to be set up.

Return value

HwVidResetHw should return TRUE if it completely resets the adapter to the given character mode. Otherwise, it should return FALSE to indicate that the HAL should perform the equivalent of an INT10, MODE3-type BIOS call after HwVidResetHw returns control.


A video miniport driver must have a HwVidResetHw function if its adapter cannot be reset to a fully initialized state without a hard boot of the machine. For example, if the adapter's ROM initialization code cannot reset the adapter state to a boot-up mode, the miniport driver must have a HwVidResetHw function. Another reason the miniport driver must implement this function is to clean up the adapter's interrupt lines when the adapter is powered down, thereby avoiding a deluge of interrupts the next time the system boots.

The HAL calls HwVidResetHw if the system is about to crash, so that the HAL can display information on the screen while the system is being shut down. This call can occur at any IRQL, and the driver must be ready to handle it at any time. The HAL also calls HwVidResetHw just before the machine is rebooted when a soft boot occurs.

Most miniport drivers must provide this function, except for drivers of adapters that are reset to a VGA standard character mode on receipt of an INT10, MODE3-type command.

HwVidResetHw resets the adapter to character mode, according to the given Columns and Rows values. However, because the system is shutting down, HwVidResetHw cannot call the BIOS or any pageable code. HwVidResetHw should call only the VideoPortRead/WritePortXxx and/or VideoPortRead/WriteRegisterXxx functions. (See Functions Exported by the Video Port Driver.)

If HwVidResetHw cannot change the mode of the adapter by simply programming the adapter registers, it can set up the appropriate values in adapter registers and return FALSE. This causes the HAL to perform an extended INT10-type operation to reset the video adapter to character mode.

HwVidResetHw must not call VideoPortInt10. A miniport driver's HwVidStartIO function is called with the IOCTL_VIDEO_RESET_DEVICEVRP to reset the adapter whenever the Display program is used to test or change the graphics display mode, not the miniport driver's HwVidResetHw function.

HwVidResetHw must not be made pageable.


Target Platform Desktop
Header video.h (include Video.h)

See also

Functions Exported by the Video Port Driver