Extreme Graphics is a set of three boards that Indigo2 technical report called the most powerful graphics hardware currently offered by Silicon Graphics for a desktop workstation at the time when Indigo2 was introduced. Extreme Graphics includes eight Geometry Engine processors, two raster engines, high resolution 24-bit color, and a 24-bit Z-buffer. Note that in some SGI docs the board can be referred to as an "Ultra".
This page describes random bits and pieces of information that might be useful or interesting.
Address range Description Size 1F000000-1F03FFFF Shared data RAM 256K 1F040000-1F05FFFF FIFO 128K 1F060000-1F067FFF HQ2 microcode 32K 1F068000-1F069FFF GE7(0-7) 8K 1F06A000-1F06BFFF HQ internal regs 8K 1F06C000-1F06C01F Board version 32 bytes
More details can be found in include/video/extreme.h.
This is what the RD0-3 registers contain on my board:
rd0 = 0xffffffff rd1 = 0xbcbcbcbc rd2 = 0xffffffff rd3 = 0xbcbcbcbc
Drawing a Character
Linux kernel support
Still under development.