Note
Access to this page requires authorization. You can try signing in or changing directories.
Access to this page requires authorization. You can try changing directories.
The following figure shows the video miniport driver within the NT-based operating system graphics subsystem.
Each video miniport driver provides hardware-level support for a display driver. The display driver calls the graphics engine EngDeviceIoControl function to request support from the underlying video miniport driver. EngDeviceIoControl, in turn, calls an I/O system service to send the request through the video port driver to the miniport driver.
In most circumstances, the display driver carries out time-critical operations that are visible to the user, while the underlying miniport driver provides support for infrequently requested operations or for truly time-critical operations that cannot be preempted by an interrupt or a context switch to another process.
A display driver cannot handle device interrupts, and only the miniport driver can set up device memory and map it into a display driver's virtual address space.
The video port driver is a system-supplied module provided to support video miniport drivers. It acts as the intermediary between the display driver and video miniport drivers
For more information about NT-based operating system display drivers, see Introduction to Display (Windows 2000 Model) and Display Drivers (Windows 2000 Model).