Quoting Corey Osgood corey.osgood@gmail.com:
Patch description, long version: This patch comments out the code to set up the vga framebuffer to allow the system to boot, without this fix the system hangs during elfboot. The only line that is absolutely necessary to change is the SMRAM setup, however I've commented out all vga setup to make it very obvious to both the kernel/payload and anyone looking at the code that vga isn't currently working. This setup might also be better handled in northbridge.c, if it doesn't need to be done before ram init, yet another reason to comment it all. In the future, LinuxBIOS needs to be told that the graphics memory area, 1mb or 512kb (at the user or developer's option), is reserved for the onchip vga, but I'm not sure if it's taken at the top or bottom of the memory, yet. LB may also need to set a base address for the AGP aperture and/or be told that range is reserved as well, whether this was originally the job of the system bios or vga bios is still a mystery. It also corrects the number of entries in irq_tables.c, without this fix the kernel would probably complain and hang due to unmapped IRQs.
Corey, As far as I understand you don't need to define any of the vga registers in the northbridge code. Intel's video bios will do all of this when initialized, that is if you are using onboard vga. I believe it may cause clocking issues if you use both. Some of the registers would probibly need to be set if you are using external graphics via PCI or AGP. Hope that helps.
Thanks - Joe