Hi,
Any chance you can update to the latest git and see if the elf file out/rom.bin.o works? I still need to setup a coreboot test environment.
I've tested it, the rom.bin.o has no program header thus cannot be loaded. I think you should generate at least one program header of type LOAD for elf loader to work with it(fix me if I'm wrong). you can reference function elfboot in src/boot/elfboot.c t see what the loader expects.
once you make the elf file for legacybios, I think the legacybios loader should be unnecessary.
-Aaron