Well, I made a mistake. Coreboot does not (yet) support DDR2 on GM45. So I will have to implement DDR2 before I can continue the motherboard specific code for the E6400. This will be much more work, but I embrace the challenge and will go ahead in my attempt to port this machine. Hopefully I will learn a lot doing this, making it easier to port future boards. DDR2 is not completely absent from coreboot, so I should be able to turn to other chipsets to get a grasp of how to add support on this chipset.