It there a way to limit how much memory is allocatable by the AGPGART code?

The reason I am asking is I am seeing some odd behaviour that I suspect is 
related to that code.

When I boot the machine, it says something like "200 megs maximum available 
for AGP memory.  X seems to grab 3/4 of that number and then never quite let 
go of it. (The memory map under /proc shows big blocks of memory allocated 
and marked "deleted" for the X PID.)

I used to have a memory leak in another library that would push the system 
into a rather bad state because of the big chunk o' memory that seems to be 
eaten by X.

I have looked at the code, but I did not see anything obvious for that 
function. I could just be going blind though...

Is AGP memory limatable or do I have to look at the X side of things?

Attached is a memory mapp for the X process...