VPR XPDM XXDM

video request packet (VRP)

A mechanism used to communicate device I/O control requests from a display driver to its corresponding adapter-specific miniport driver. For example, when a display driver calls EngDeviceIoControl, this function calls a system service causing the NT-based operating system I/O manager to set up an IRP and call the Microsoft-supplied video port driver with that IRP. The video port driver uses the IRP to set up a VRP in a VIDEO_REQUEST_PACKETstructure. The video port driver then calls the corresponding video miniport driver's StartIo entry point with the VRP.

显示驱动--(EngDeviceIoContrl)-->GDI Engine--()-->I/O Manager--(IRP)-->System Video Port--(VRP)-->Miniport