一、DRM 简介
In computing, the Direct Rendering Manager (DRM), a subsystem of the Linux kernel, interfaces with the GPUs of modern video cards. DRM exposes an API that user-space programs can use to send commands and data to the GPU, and to perform operations such as configuring the mode setting of the display. DRM was first developed as the kernel space component of the X Server‘s Direct Rendering Infrastructure,[1] but since then it has been used by other graphic stack alternatives such as Wayland.
User-space programs can use the DRM API to command the GPU to do hardware-accelerated 3D rendering and video decoding as well as GPGPU computing.
二、DRM 架构
原文：http://www.cnblogs.com/EaIE099/p/EaIE099_DRM.html