I followed the instructions on *http://www.coreboot.org/AMD_SimNow*http://www.coreboot.org/AMD_SimNowbut the step ./buildtarget amd/serengeti_cheetah fails---lots of warnings, but the error is /home/kas/src/coreboot/coreboot-v2-4671/src/cpu/x86/mtrr/earlymtrr.c:22:3: error: #error "CONFIG_XIP_ROM_BASE is not a multiple of CONFIG_XIP_ROM_SIZE"
You could try applying the patch I just sent to the list if you decide you want to build this one again. It boots for me now.
Thanks, Myles