"UXA was introduced in early August to allow 2D pixmaps
to become GEM objects. The EXA API was used as the basis of forming
UXA but the code was then stripped away and replaced with code to
support the Graphics Execution Manager for managing its memory. A
month later it was clarified by Keith Packard at the X Developers'
Summit with his UXA intentions. At that time he stated the UMA
Acceleration Architecture will be discontinued and the GEM changes
merged back into EXA once they decide how to split the pixmap
management and acceleration architecture components. Keith hoped to
have this revised EXA work done for X Server 1.6, but that hasn't
been completed in time.
"The UXA support is currently living within the xf86-video-intel
2.5 and xf86-video-video-intel 2.6 drivers and does require the
Linux 2.6.28 kernel or later for the Graphics Execution Manager
support. By default the Intel driver continues to use EXA so the
AccelMethod option within the xorg.conf must be set to UXA."