This is the gart device driver for the linux kernel, written by Jeff
Hartmann and others as part of the accelerated glx project.

To build, you should just be able to type make.  The makefile is extremely simple, so if it doesn't work, fix it... 

You should get a module you can start with:

insmod agpgart.o

To create the device file:

mknod /dev/gart c 174 0

Then recompile the glx module:

./configure --with-mesa=<mesasrc> --enable-agp && make
make install (as root)
restart X

For the i810 beta release I (Keith Whitwell) have removed support for the LX,BX and Via chipsets originally in this module.  The i810 changes haven't been tested on those boards yet, so this is probably prudent.