This section provides details about features and enhancements that were added in WDDM version 1.2, which is available starting with Windows 8. It also describes hardware requirements, implementation guidelines, and usage scenarios.

In this section

Introduction

The WDDM was introduced with Windows Vista as a replacement of the Windows XP orWindows 2000 Display Driver Model (XDDM). With its introduction in Windows Vista, the WDDM architecture offered functionality to enable new features such as Desktop Composition, enhanced fault tolerance, video memory manager, GPU scheduler, cross process sharing of Direct3D surfaces, and so on. WDDM was specifically designed for modern graphics devices that were Microsoft Direct3D 9 with pixel shader 2.0 or better, and had all the necessary hardware features to support the WDDM features. WDDM for Windows Vista was referred to as "WDDM 1.0."

Windows 7 made incremental changes to the driver model for supporting Windows 7 features and capabilities and was referred to as "WDDM 1.1." WDDM 1.1 is a strict superset of WDDM 1.0. WDDM 1.1 introduced support for Microsoft Direct3D 11, Windows Graphics Device Interface (GDI) hardware acceleration, Connecting and Configuring Displays, DirectX Video Acceleration (VA) High-Definition (DXVA-HD), and many other features. For more details on these features, see theGraphics Guide for Windows 7.

Windows 8 introduced an array of features and capabilities that required graphics driver changes. These incremental changes benefit end users and developers, and improve system reliability. The WDDM driver model that enables these Windows 8 features is referred to as "WDDM 1.2." WDDM 1.2 is a superset of WDDM 1.1 and WDDM 1.0. These changes can be represented in a simplified form, as shown in the following table.

Independent hardware vendors (IHVs) and system builders should adopt the alternative WDDM solution that works best for their customers. This means that a Windows 8 system will always have a WDDM-based driver.

WDDM 1.2 introduced new types of graphics drivers, targeting specific scenarios as described below:

• WDDM Full Graphics Driver: This is the full version of the WDDM graphics driver that supports hardware accelerated 2-D and 3-D operations. This driver is fully capable of handling all the render, display, and video functions. WDDM 1.0 and WDDM 1.1 are full graphics drivers. All Windows 8 client systems must have a full graphics WDDM 1.2 device as the primary boot device.
• WDDM Display Only Driver: This driver is supported only as a WDDM 1.2 driver and enables IHVs to write a WDDM based kernel-mode driver that is capable of driving display-only devices. Windows handles the 2-D or 3-D rendering by using software-simulated GPU. Display-only devices are not allowed as the primary graphics device on client systems.
• WDDM Render Only Driver: This driver is supported only as a WDDM 1.2 driver and enables IHVs to write a WDDM driver that supports rendering functionality only. Render-only devices are not allowed as the primary graphics device on client systems.

The following table summarizes driver model versus the supported driver categories.

The following table explains scenario usage for the new driver types:

WDDM 1.2 is required for all systems that are shipped with Windows 8. WDDM 1.0 and WDDM 1.1 will continue to work on Windows 8. However, the best experience and Windows 8-specific features are enabled only by a WDDM 1.2 driver.