FreeBSD, with cleanup/KNF by me.
Note: These chipsets are not well supported by the i810 driver in
NetBSD's in-tree xsrc (based on XFree86 4.2.1 at this time). However,
the driver works perfectly using bleeding-edge XFree86-current on my
Omnibook's i830MG with these agp changes.
-Add a really bad hack: The X server (4.1.0 afaict) appearently overwrites
the PGTBL_CTL which contains the base address of the pseudo-GATT.
Restore the original value if we notice this happened.
The X server works now, but only with soft cursor.