Intel GMA

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The Intel Graphics Media Accelerator, or GMA, is Intel's current line of graphics processors (GPUs) built into various motherboard chipsets.

These integrated graphics products allow a computer to be built without a separate graphics card, which can lower overall costs and lower power consumption. They are commonly found on low-priced notebook and desktop computers. They rely on the computer's main memory for storage, which imposes a performance penalty as both the CPU and GPU have to access memory over the same bus.

Contents 1 History 2 Hardware: graphics cores 2.1 GMA 900 2.2 GMA 950 2.3 GMA 3000 2.4 GMA 3100 2.5 GMA X3000 2.6 GMA X3100 2.7 GMA X3500 2.8 GMA X4500 2.9 GMA 500 3 Table of GMA graphics cores and chipsets 4 Software support 4.1 Mac OS X 4.2 FreeBSD 4.3 Linux 4.3.1 intel_hal.so 4.4 Microsoft Windows 4.4.1 GMA 900 4.4.2 GMA 950 4.4.3 GMA X3000 5 Modern gaming 6 References 7 See also 8 External links

[edit] History

The GMA line of GPUs replaces the earlier “Extreme Graphics”, Intel’s first series of integrated graphics chips, and Intel740 line, which were discrete units in the form of AGP cards.

The original architecture of GMA systems supported only a few functions in hardware, and relied on the host CPU to handle at least some of the graphics pipeline, further decreasing performance. However, with the introduction of Intel’s 4th generation of GMA architecture (GMA X3000) in 2006, many of the functions are now built into the hardware, providing an increase in performance. The 4th generation of GMA combines fixed function capabilities with a threaded array of programmable executions units, providing advantages to both graphics and video performance. Many of the advantages of the new GMA architecture come from the ability to flexibly switch as needed between executing graphics-related tasks or video-related tasks. While GMA performance has been widely criticized in the past as being too slow for computer games, the latest GMA generation should ease many of those concerns for the casual gamer.

Despite similarities, GMA is not based on the PowerVR technology Intel licensed from Imagination Technologies. Intel uses the low-power PowerVR MBX designs in chipsets that support their XScale platform. With the sale of XScale in 2006, it is not clear if Intel will continue to use PowerVR systems with their x86-based XScale replacements, although they have licensed the PowerVR SGX from Imagination Technologies, which is the more powerful successor to the MBX.

Intel has begun working on a new series of discrete graphics hardware products, under the codename Larrabee.

[edit] Hardware: graphics cores

[edit] GMA 900

The GMA 900 was the first graphics core produced under Intel's Graphics Media Accelerator product name, and was incorporated in the Intel 910G, 915G, and 915Gx chipsets.

The 3D architecture of the GMA 900 was a significant upgrade from the previous Extreme 3D graphics processors. It is a 4 pixel per clock cycle design supporting DirectX 9 pixel shader model 2.0. It operates at a clock rate ranging from 160 to 333 MHz, depending on the particular chipset. At 333 MHz, it has a peak pixel fill-rate of 1,332 megapixels per second. However, the architecture still lacks support for hardware transform and lighting and the similar vertex shader technologies.

Like previous Intel integrated graphics parts, the GMA 900 has hardware support for MPEG-2 motion compensation, color-space conversion and DirectDraw overlay.

The processor uses different separate clock generators for display and render cores. The display unit includes a 400MHz RAMDAC, 2 25-200Mpixel/s serial DVO ports, and 2 display controllers. In mobile chipsets, up to 2 18-bit 25-112MHz LVDS transmitters are included.

[edit] GMA 950

The GMA 950 is Intel's second-generation Graphics Media Accelerator graphics core, which was also referred by Intel as 'Gen 3.5 Integrated Graphics Engine' in datasheets. It is used in the Intel 940GML, 945G, 945GU and 945GT system chipsets. The amount of video-decoding hardware has increased; VLD, iDCT, and dual video overlay windows are now handled in hardware. The maximum core clock is up to 400 MHz (on Intel 945G, 945GC, 945GZ), boosting pixel fill-rate to a theoretical 1600 megapixels/s.

The GMA 950 shares the same architectural weakness as the GMA 900: no hardware geometry processing. Neither basic (DX7) hardware transform and lighting,^[1] nor more advanced vertex shaders (DX8 and later) are handled in the GMA hardware.

[edit] GMA 3000

The 946GZ, Q965 and Q963 chipsets use GMA 3000.^[2][3] The GMA 3000 3D core is very different from the X3000, despite similar names. It is based more directly on the previous generation GMA 900 and GMA 950 graphics, and belonging to the same "i915" family with them. It has pixel and vertex shaders which only supports shader model 2.0 features, and the vertex shaders are still only software provided. In addition, hardware video acceleration such as hardware-based iDCT computation, ProcAmp (video stream independent color correction), VC-1 decoding are not implemented in hardware. Of the GMA 3000-equipped chipsets, only Q965 retains dual independent display support. The core speed is rated 400 MHz with 1.6 Gpixel/s fill rate in datasheets, but was listed as 667MHz core in white paper.^[4]

Memory controller can now address maximum 256MB memory.

The integrated serial DVO ports has increased top speed to 270Mpixel/s.

[edit] GMA 3100

The G31, G33, Q33 and Q35 chipsets use the GMA 3100, which is DX9 capable. The 3D core is very similar to the older GMA 3000, including the lack of hardware accelerated vertex shaders. However, the RAMDAC is reduced to 350MHz, and the DVO ports were reduced to 225Mpixel/s.

[edit] GMA X3000

The GMA X3000 represents a dramatic architectural change from previous GMA iterations. Most notably, X3000's underlying 3D rendering hardware is organized as a unified shader processor consisting of 8 scalar execution units. Each pipeline can process video, vertex, or texture operations. A central scheduler dynamically dispatches threads to pipeline resources, to maximize rendering throughput (and decrease the impact of individual pipeline stalls.) However, due to the scalar nature of the execution units, they can only process data on a single pixel component at a time.^[5] GMA X3000's shader supports vertex and pixel Shader Model 3.0 features. Specifically, shading precision was increased to 32-bit floating point per vector. Anisotropic filtering uses up to 16 samples instead of 4 in previous generation.

The processor consists of different clock domains, meaning that the entire chip does not operate the same clock speed. This causes some difficulty when measuring peak throughput of its various functions. Further adding to the confusion, it is listed as 667MHz in Intel G965 white paper, but listed as 400MHz in Intel G965 datasheet. There are various rules that define the IGP's processing capabilities. Most of the time, the core is capable of 1.6 pixels and 3.2 textures per clock cycle. It has a maximum potential pixel fill-rate of 2.0 pixels per clock, but only during a "clear" cycle. Similarly, while it can process depth operations at 4 pixels per clock, with texturing this falls to 3.2 pixels per clock. Resulting theoretical fill-rates are 1067 megapixels/s and 2133 megatexel/s at the X3000's overall 667 MHz.^[5]

Intel again updated the video processing capabilities of their graphics product. The X3000 features WMV9 (VC-1) video acceleration. VC-1 acceleration only accelerates deblocking and motion compensation.

Memory controller can now address maximum 384MB memory according to white paper, but only 256MB in datasheet.

GMA X3000 is used in the Intel G965 north bridge controller.

[edit] GMA X3100

The GMA X3100 is the mobile version of the GMA X3000 used in the Intel GL960 and GM965 chipsets. The X3100 supports hardware transform and lighting, up to 128 programmable shader units, and up to 384 MB memory. Its display cores can run up to 333 MHz on GM965 and 320 MHz on GL960. Its render cores can run up to 500 MHz on GM965 and 400 MHz on GL960. The X3100 display unit includes a 300 MHz RAMDAC, two 25-112 MHz LVDS transmitters, 2 DVO encoders, and a TV encoder. In addition, the product can support DirectX 10.

[edit] GMA X3500

GMA X3500 is an upgrade of the GMA X3100 and used in the desktop G35. The shaders support shader model 4.0 features. The display unit is derived from GMA X3000.

[edit] GMA X4500

This section contains information about a scheduled or expected future product. It may contain preliminary information that does not reflect the final version of the product.

The X4500 GPU is scheduled to appear in the forthcoming GM45 ("Cantiga") and G45 ("Eaglelake-G") chipsets and will be manufactured with 65nm technology. Like the X3500, X4500 will support DirectX 10 and Shader Model 4.0 features. Intel is aiming this solution to be 3x faster than the GMA 3100 (G33) in 3DMark06 performance, resulting in a score of around 1000 points.^[6] In addition to the increase in performance, a more advanced version of Intel Clear Video technology as well as HDCP support will be integrated, allowing for smooth HD-DVD and Blu-Ray playback. The X4500 was scheduled to be released in Q2 2008, but has been delayed until July 14, 2008.^{[7] [8]}

[edit] GMA 500

The Intel System Controller Hub U15W for the Atom embedded processor features a GMA 500 graphic system. Rather than being developed in-house, this core is a PowerVR SGX core licensed from Imagination Technologies. ^[9]

Intel describes this as "a flexible, programmable architecture that supports shader-based technology, 2D, 3D and advanced 3D graphics, high-definition video decode, and image processing. Features include screen tiling, internal true color processing, zero overhead anti-aliasing, programmable shader 3D accelerator, and 32-bit floating-point operations."^[10]

[edit] Table of GMA graphics cores and chipsets

Graphics core	GMA 900		GMA 950			GMA 3000			GMA 3100		GMA X3000	GMA X3100		GMA X3500	GMA X4500[11]
Chipset	910GL, 910GML, 915G, 915GL, 915GM, 915GME, 915GV		945GU	945GM	945G, 945GZ	946GZ	Q963	Q965	G31, Q33, Q35	G33	G965	GL960	GM965	G35	GL40	GS45	GM45	GM47
Clock speed (MHz)	160/166[12] 190/200[12] 333[12]		133[13]	250[14]	400[15]	667[2]/400[16]	667 [3]	667 [3]		400[17]	667 [3]	400 [18]	667 [18]	667 [19]	333	266	533	640
Vertex shader model	2.0		3.0									4.0
Pixel shader model	2.0										3.0	4.0
Pixel Pipelines	4					NA			4		NA
Unified shader processors	NA					?			NA		8				10
Hardware vertex shaders	No										Yes
Peak memory bandwidth (GB/s)	8.5		10.7				12.8			17.1	12.8[20]
Max video memory (MB)	128[21]		192[22]/ 224[23]			256			384
OpenGL support	1.4 [2]										1.5[24]			2.0
DirectX API support	9.0											10.0 [23]
MPEG-2 Hardware Acceleration	MC		VLD + iDCT + MC
VC-1 Hardware Acceleration	No										MC (for WMV9 only)			MC + LDF	No	VLD + iMDCT + MC + LDF
AVC Hardware Acceleration	No															VLD + iMDCT + MC + LDF

This table is derived from these sources: ^{[2] [3] [5] [19] [23] [22] [21] [14] [16] [15] [17] [25] [13] [20] [19] [18] [24] [12]}

Notes:

• VLD: Variable-length decoding, sometimes referred to as slice-level acceleration
• iDCT: inverse discrete cosine transform
• iMDCT: inverse modified discrete cosine transform
• MC: Motion compensation
• LDF: In-loop deblocking filter
• WMV9: Windows media video 9 codec
• NA: Not Applicable

[edit] Software support

[edit] Mac OS X

Mac OS X 10.4 supports the GMA 950, since it was used in previous revisions of the MacBook (but not MacBook Pros) and even some 17-inch iMacs.^[26] It has been used in all Intel-based Mac minis.^[27] The recently released Mac OS X 10.5 Leopard contains drivers for the GMA X3100, which are used in the latest revision of the MacBook range.^[28]

Late-release versions of Mac OS X 10.4 also support the GMA 900 (due to its use in the Apple Developer Transition Kit, which was used in the PowerPC-to-Intel transition). However, special modifications to the kext file must be made to enable Core Image and Quartz Extreme. OS X 10.5 however does not support the 900.

[edit] FreeBSD

FreeBSD 7.0 supports the following Intel graphic chipsets: G965/Q965/GM965/GME965/GME945. Support for G33/Q35/Q33 is also included, but disabled due to lack of testing.^[29]

[edit] Linux

Intel has had a long history of producing or commissioning open source drivers for its graphics chips, with all chipsets dating back to the i810 having open 2D and 3D drivers for Linux. It is the only major graphics hardware vendor to do so: for an analysis by company see Graphics hardware and FOSS.

In August 2006, Intel added support to the open-source X.Org/XFree86 drivers for the latest 965 series that include the GMA (X)3000 core.^[30] These drivers were developed for Intel by Tungsten Graphics.^[31]

In May 2007, version 2.0 of the driver (xorg-video-intel) was released, which added support for the 965GM chipset. In addition, the 2.0 driver added native video mode programming support for all chipsets from i830 forward. This version added support for automatic video mode detection and selection, monitor hot plug, dynamic extended and merged desktops and per-monitor screen rotation. These features are built in to the X.Org 7.3 X server release and will eventually be supported across most of the open source X.Org video drivers.^[32] Version 2.1, released in July 2007, added support for the G33, Q33 and Q35 chipsets.^[33] G35 is also supported by the Linux driver.^[34]

As is common for X.Org drivers on Linux, the license is a combination of GPL (for the Linux kernel parts) and MIT (for all other parts).^[35]

The drivers were mainly developed by Intel and Tungsten Graphics (under contract) since the chipsets documentations were not publicly available for a long time. On January 2008, Intel released the complete developer documentation for their latests chipsets (965 and G35), allowing for further external developers’ involvement. ^[36]

[edit] intel_hal.so

The driver source contains references to a currently-unavailable binary named "intel_hal.so". It is entirely optional, and the advantages are not clear; ostensibly they are increased performance and/or additional features. References in the open source code indicate that it contains or contained (at least) Macrovision support and some minor, optional 3D optimization routines. Calls to the Macrovision code inside the binary were later removed from the 2D driver.^[37][38]

[edit] Microsoft Windows

[edit] GMA 900

This IGP is capable of running Windows Vista’s Aero interface and certified as DirectX 9 compliant. However no WDDM driver has been made publicly available for this chipset. This is claimed to be due to the lack of a "hardware scheduler" in the GMA chipsets.^[39]

Many owners of GMA900 hardware believed they would be able to run Aero on their systems, as early release candidates of Vista permitted XPDM drivers to run Aero. However, Intel contends that Microsoft's final specs for Aero/WDDM certification did not permit releasing a WDDM driver for GMA900 (due to issues with the hardware scheduler, as mentioned above), so when the final version of Vista was released, no WDDM driver was released.^[40] The last minute pulling of OpenGL capabilities from the GMA drivers for Windows Vista leaves the large number of GMA based workstations unable to perform basic 3D hardware acceleration with OpenGL and unable to run many Vista Premium applications such as Windows DVD Maker.

[edit] GMA 950

This IGP is capable of displaying the Aero interface for Windows Vista. Drivers have shipped with Windows Vista since beta versions were made available in mid-2006.

[edit] GMA X3000

T&L and Vertex Shaders 3.0 are supported by Intel's newest 15.6 drivers for Windows Vista as of September 2, 2007. XP support for VS3 and T&L was introduced on August 10, 2007. Intel announced in March 2007 that beta drivers would be available in June of 2007.^{[41] [42]} On June 1, 2007 "pre-beta" (or Early Beta) drivers were released for Windows XP (but not for Vista).^[43] Beta drivers for Vista and XP were released on June 19.^[44]

Intel has released production version drivers for 32-bit and 64-bit Windows Vista that enable the Aero graphics. Intel has released Direct X 10 drivers for the X3100 and X3500 GPUs, though any release of DX10 drivers for the X3000 is uncertain.

Note that Windows drivers currently have no GLSL support.

[edit] Modern gaming

The Intel GMA products are designed to allow Intel to offer a full system platform that includes graphics hardware. However, due to the GMA's nature as a highly cost-sensitive product, performance and functionality is limited relative to more expensive discrete graphics components. Some games and 3D applications will not recognize support for some hardware functionality because of the simplification of parts of these graphics accelerators. The GMA X3x00's unified shader design allows for more complete hardware functionality, but the line still has issues with some games and has significantly limited performance.^[45]

Intel, not oblivious to these problems, has put up a page with 'Known Issues & Solutions' for each version.^[46] For Intel Graphics Media Accelerator Software Development concerns, there is the Integrated Graphics Software Development Forum.^[47]

With recent driver updates, many more games have become playable on this hardware.

[edit] References

[edit] See also

• Graphics hardware and FOSS
• Larrabee

[edit] External links

• [1]
• [2]
• [3]
• Linux Graphics Drivers from Intel
• [4]
• The Register: Intel vs AMD - integrated graphics shoot-out