I think my i810 graphics chip is pretty nice, for the 0 extra it cost me -- it's on my motherboard. But there are a couple of frustrating things about it. First, with some games it runs out of texture memory. I'd like to give it some more system memory, but I don't know how. I have VideoRam set to 24600 in my XF86Config file, and that's as high as I can get it. Higher, and XFree86 aborts and complains it couldn't allocate agp memory. I think my agp aperture is 64M, so why can't I get more than 24.6? (Kernel bootup messages used to say the aperture was 64M, but after I installed extra memory, I no longer get messages about the aperture.) Maybe the i180 is already using some agp memory?

And second, whenever an SDL-based program asks for some bits of stencil buffer, it aborts, complaining that it can't find a matching glx visual. Yet glxinfo reports that I do have visuals available with 8 bits of stencil buffer. So why can't I use stencil buffer?

I'll be grateful for any suggestions.

Stencil buffers could be a problem with the driver, or it can't allocate enough continuious memory for the buffers.

AGP apperture isn't the memory used bu the GFX chip (Its a shared memory thing, used by GFX cards with there own memory, through the AGP slot ), The memory actually taken for the GFX is a seprate setting. Look under chipset stuff in the bios to assign more memory to the GFX chip. ( You din't mention your motherboard so poke around. )

I suppose the way I put it did confuse the i810 chip and the X Windows i810 driver. But it's the driver that needs to allocate agp memory for various purposes (and it also runs out of room for textures). And I want to give it more. (The i810 is just a chip, not a card -- it doesn't have any memory of its own.)

You can't do this dynamically. as I said

Its allocated a boot by the BIOS. It will be under something like Graphics memory, usually under the chipset part.

I'm just not understanding what you're saying. Can't do what dynamically? I asked about increasing the amount of AGP memory allocated by the driver. That's done dynamically. The driver reports on what it has allocated. Now, it says
My question was: why can it only allocate 24600K?

I understand that memory is also allocated for the i810 framebuffer at boot up. I don't see what good it would do me to change that.

BIOS assigns to that chip it can have so much memory. I've never got it working dynamically with the i810. ( Ignore AGP for this its nothing to do with it ).

You can only do it dynamically with the 830M chips or later with the agp/agpart drivers. ( kernel settings ).

Increasing the Value in BIOS works for all chips.

The manual page is slightly confusing on the point. But this is how I got it working for my friend with this chipset. Setting values dynamically doesn't always work, it needs to be supported by the chip/BIOS/Kernel and driver to work.