Graphics Device Overview

graphics Device Overview

GMCH(Graphics Memory Controller Hub)

Intel gfx device集成在GMCH(Graphics Memory Controller Hub), 也就是北桥。

 

Graphics Processing Unit (GPU)

The Graphics Processing Unit is controlled by the CPU through a direct interface of memory-mapped IO registers, and indirectly by parsing commands that the CPU has placed in memory. The display interface and blitter (block image transferrer) are controlled primarily by direct CPU register addresses, while the 3D and Media pipelines and the parallel Video Codec Engine (VCE) are controlled primarily through instruction lists in memory.

The Gen4 subsystem contains an array of cores, or execution units, along with a number of “shared functions”, which receive and process messages at the behest of programs running on the cores. The shared functions perform critical tasks such as sampling textures and updating the render target (usually the frame buffer). The cores themselves are described by an instruction set architecture, or ISA.

Graphics Processing Engine (GPE)

GPE由4部分组成：1。3D fixed-function pipeline ；2。Media fixed-function pipeline ；3。Command Streamer (CS) unit ；4。GEN4 Subsystem 。

这四部分在以后会详细的介绍，3D/Media ff pipeline 很好理解。Command Streamer 简单的说就是用来解析CMDs，并把CMDs分发给3D或Media的pipeline. GEN4 Subsystem provides the bulk of the computations required by the pipelines, 也就是为GPE提供计算的core, 由很多EUs (excution unit)组成。

Graphics hw Command introduction

1。Memory Interface Commands

MI cmd是那些不需要2D/3D Rendering/Mapping engines处理的cmds, 完成以下功能：（主要是控制和同步）

• Control of the command stream (e.g., Batch Buffer commands, breakpoints, ARB On/Off, etc.)

• Hardware synchronization (e.g., flush, wait-for-event)

• Software synchronization (e.g., Store DWORD, report head)

• Graphics buffer definition (e.g., Display buffer, Overlay buffer)

• Miscellaneous functions

2。2D Commands

主要是进行Blt操作， 通过cmd来设置Blt engine的状态

3。3D/Media  Command

4. Video codec CMDs

 

CMDs类型的确定是通过CMD的head, 也就是CMD的第一个DWORD。它只包含一个client域。Gfx cmd 要求4字节对齐，存放在ring buffer 或者batch buffer.通过cmd head的client，可以确定命令类型。

一些Gen4 gfx device有2个独立的cmd处理引擎，RCP(Render command Parser) 和VCPP(Video Codec Command Paser)。例如：client = 0 表示这是一个Memory Interface Commands, 即MI_xxx