Graphics address remapping table
Encyclopedia
The graphics address remapping table (GART), sometimes known as the graphics translation table (GTT), is an I/O memory management unit
(IOMMU) used by AGP
and PCI Express
graphics cards. The GART allows the graphics card direct memory access
to the host system memory, through which buffers of textures
, polygon mesh
es and other data are loaded. It's used as a means of data transfer between physical memory and video memory
, but can also be used to expand the amount of video memory available for graphics cards -- particularly for cards with no dedicated video memory, such as Intel integrated graphics.
's Utah-glx accelerated MesaGL driver project. The developers primarily targeted Linux 2.4.x kernels, but made patches available against older 2.2.x kernels. Dave Jones heavily reworked agpgart for the Linux 2.6x kernels, along with more contributions from Jeff Hartmann.
In FreeBSD, the agpgart driver appeared in FreeBSD 4.1.
AGPgart support was introduced into Solaris Express Developer Edition as of its 7/05 release.
IOMMU
In computing, an input/output memory management unit is a memory management unit that connects a DMA-capable I/O bus to the main memory...
(IOMMU) used by AGP
Accelerated Graphics Port
The Accelerated Graphics Port is a high-speed point-to-point channel for attaching a video card to a computer's motherboard, primarily to assist in the acceleration of 3D computer graphics. Since 2004 AGP has been progressively phased out in favor of PCI Express...
and PCI Express
PCI Express
PCI Express , officially abbreviated as PCIe, is a computer expansion card standard designed to replace the older PCI, PCI-X, and AGP bus standards...
graphics cards. The GART allows the graphics card direct memory access
Direct memory access
Direct memory access is a feature of modern computers that allows certain hardware subsystems within the computer to access system memory independently of the central processing unit ....
to the host system memory, through which buffers of textures
Texture mapping
Texture mapping is a method for adding detail, surface texture , or color to a computer-generated graphic or 3D model. Its application to 3D graphics was pioneered by Dr Edwin Catmull in his Ph.D. thesis of 1974.-Texture mapping:...
, polygon mesh
Polygon mesh
A polygon mesh or unstructured grid is a collection of vertices, edges and faces that defines the shape of a polyhedral object in 3D computer graphics and solid modeling...
es and other data are loaded. It's used as a means of data transfer between physical memory and video memory
Video memory
Video memory is a term generally used in computers to describe some form of writable memory, usually RAM, dedicated to the purpose of holding the information necessary for a graphics card to drive a display device...
, but can also be used to expand the amount of video memory available for graphics cards -- particularly for cards with no dedicated video memory, such as Intel integrated graphics.
Operating system support
Jeff Hartmann served as the primary maintainer of the Linux agpgart driver, which began as part of Brian PaulBrian Paul
Brian Paul is a computer programmer who wrote and continues to maintain the source code for the open source Mesa graphics library. Paul began programming initial source code in August 1993. Mesa is a free software/open source graphics library that provides a generic OpenGL implementation for...
's Utah-glx accelerated MesaGL driver project. The developers primarily targeted Linux 2.4.x kernels, but made patches available against older 2.2.x kernels. Dave Jones heavily reworked agpgart for the Linux 2.6x kernels, along with more contributions from Jeff Hartmann.
In FreeBSD, the agpgart driver appeared in FreeBSD 4.1.
AGPgart support was introduced into Solaris Express Developer Edition as of its 7/05 release.