R500 XAA/EXA RadeonHD Performance

The public release of AMD's "tcore" sample code is imminent,
thereby steering the open-source development efforts toward R600 2D
acceleration and the basis of the 3D support for the RadeonHD driver.
However, in somewhat of a surprise, this afternoon XAA and EXA support
was added to the RadeonHD driver for the R500 series. For those that
aren't X enthusiasts or Linux veterans, XAA and EXA are architectures
for providing 2D graphics acceleration. With this accelerated 2D
support, we have benchmarked both XAA and EXA on the xf86-video-radeonhd
driver as well as with the xf86-video-ati driver and the binary fglrx
driver.