Yes, I have the manual. I missed “GPP DRAM Region #2”, but in any case it wasn’t clear that the firmware would assign the addresses sequentially from the bottom.
Also, there seem to be regions that need to be avoided within the lower 2GB. I can boot a working system with 1GB (0x80000000-0xbfffffff) but not with 2GB. Still investigating that.
–Elad