From the Changelog for xorg-x11-drv-intel:
* Tue Sep 04 2012 Adam Jackson <firstname.lastname@example.org> 2.20.6-2
- Only bother to build UMS (read: i810) support on 32-bit. If you've
managed to build a machine with an i810 GPU but a 64-bit CPU, please
don't have done that.
This is hilarious on so many levels.