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#Intel video drivers windows 7 xpdm driver#This driver does a few things one of which is to implement common code so that video driver writers do not need to rewrite the same code. In any case, VideoPrt.SYS exports APIs which your miniport driver will call. There is no API to "GetProcAddress" in the kernel so you would need to write one. In any case you can export APIs from one driver and link against and use those APIs from another driver. The DriverEntry itself is not called until the driver is directly loaded using ZwLoadDriver, loaded by the system or with the service API as we were shown previously. If a driver links against a driver that is not currently loaded into memory, that driver will become loaded into memory however the DriverEntry for that driver will not be called. I will note there is a slight difference between linking against kernel and user mode drivers. ![]() In fact all the APIs you use you are just linking against the kernel and other drivers. You can export APIs from your driver and allow other drivers to link against them just like a DLL. Drivers use the PE format and have export and import tables. Surprised a driver can export APIs? Don't be. This driver exports APIs which your driver will link against and use. This driver however uses another driver as its framework which is VIDEOPRT.SYS. The miniport driver is loaded into system space and is responsible for managing display device resources and enumerating devices. The following diagram shows the Windows display driver architecture: ![]() #Intel video drivers windows 7 xpdm full#The display driver has full control over how a line is drawn or how a transparency effect is implemented. ![]() The driver is responsible for implementing these calls however it wants which can be done in software or deferred to the graphics card itself. The display driver is loaded into session space and is responsible for implementing the actual GDI graphics calls. The miniport driver is loaded into system space and is responsible for enumerating devices and managing device resources. The display driver model consists of two pieces, the miniport driver and the display driver. This is essential in supporting the new Desktop Window Manager however Windows Vista still supports the old display driver model in conjunction with the old Window Manager. I will make a comment here that Windows Vista introduces a new display driver model known as LDDM. The first place to start is to show the display driver architecture as it is in Windows NT. This article will only be focusing on display drivers themselves and will not use VMWare but require just your local machine. This method was demonstrated in an article I wrote for the C/C++ User's Journal however that article was about extending VMWare to support multiple monitors. Instead this display driver will implement graphics to memory and an application will be used to display those graphics. ![]() #Intel video drivers windows 7 xpdm how to#The example driver for this article will show how to write a basic display driver which does not have any hardware associated with it. A display driver is a special type of driver which fits into a framework that is unlike what we have talked about so far in this series. In this article, we will take a look at how to write a simple display driver. It has been a while since I have updated this series and I have found some free time to write the next version. ![]()
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