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Graphics address remapping table

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The graphics aperture remapping table (GART)[1] or AGP-GART when used with Accelerated Graphics Port, sometimes known as the graphics translation table (GTT)[2], and often misintepreted as graphics address remapping table is an I/O memory management unit (IOMMU) allowing the graphics card to perform a direct memory access (DMA) to the host system memory. Introduced by AMD for mapping of 32-bit AGP graphics cards accesses to the 64-bit memory space of the AMD64 processors[3], it was later reused for PCI Express (PCIe) as well.

GART is used as a means of data transfer between the main memory and video memory through which buffers of textures, polygon meshes and other data are loaded, 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 HD Graphics processors.

Operating system support

Linux

Jeff Hartmann served as the primary maintainer of the Linux kernel's agpgart driver, which began as part of Brian Paul's Utah GLX accelerated Mesa 3D 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 2.6.x kernels, along with more contributions from Jeff Hartmann.[4]

FreeBSD

In FreeBSD, the agpgart driver appeared in its 4.1 release.[5]

Solaris

AGPgart support was introduced into Solaris Express Developer Edition as of its 7/05 release.[6]

See also

References

  1. ^ Software Optimization Guide for AMD64 Processors
  2. ^ freedesktop.org. "GART". Retrieved 2010-03-05.
  3. ^ Utilizing IOMMUs for Virtualization in Linux and Xen
  4. ^ Jones, Dave (2003-07-24). "Ugly Ducklings: Resurrecting unmaintained code – agpgart adapted for Linux 2.6 kernel" (PDF). Archived from the original (PDF) on 2014-02-03. Retrieved 2014-06-05.
  5. ^ "agp(4)". FreeBSD Man Pages: FreeBSD Kernel Interfaces Manual. freebsd.org. 2007-11-28. Retrieved 2014-06-10.
  6. ^ "agpgart_io manpage". docs.sun.com. Sun Microsystems. Retrieved 2007-12-04.
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