Okay, this is mostly a shot in the dark, but it's the only thing I can find that might cause something like this. I'm looking at the AGP size register (APSIZE, 0xb4) in the datasheet, and the default value is 0x00, which is 256MB (!!). I also don't see anywhere that AGP has to be explicitly enabled, it looks like it's enabled by default (yes, I see AGPCMD, but it says cycles will be ignored, not that the device is actually disabled and freeing the aperture memory).
Long story short, try setting the AGP aperture to 32MB and moving the aperture base (APBASE, 0x10-13) to somewhere else, preferably wherever the stock bios moves it to. Even if it's not the root cause, it'll get it out of the way for later.
-Corey
Corey, After scatching my head for days (hair thinning even more) I think you may be onto something. I have tried changing the values in APBASE before with no luck and I think this is why:
1. APSIZE Bits[5:3] need to be set first to 111 too allow APBASE Bits[27:25] to become R/W.
2. Now we can set APBASE Bits[27:25] to 111 for 32MB Aperture.
3. I noticed this in my bootlogs:
PCI: 00:00.0 register 10(00000008), read-only ignoring it
Which is the APBASE register. I think LB is tring to configure an address range for it but not able to because the address range is set to read only.
4. Set register GCC0 Bit 9 to 1. This enables access to the Aperture allowing LB to configure an address range.
I wish there was a way to just disable the Aperture all togethor for now but the i82830 is not designed to run in headless mode (no graphics). I will try this out and report back.
Thanks - Joe