When you try building by setting
different mainboards, are you running make distclean between those
attempts? If not, you can easily wind up with a .config where settings
and options aren't appropriate for your board.
For your Sapphire
system, the AMD Bettong board might be close enough to get you started.
If you want to give it a shot, you can try the following. Make sure
you have some method for reflashing your original BIOS, of course,
because this probably won't work initially.
1) Create a .config file using the following
2) Run make olddefconfig
I've assumed the board's two serial connectors are connected to the APU
and not on a SuperIO (CONFIG_HUDSON_UART=y). Unfortunately, the Merlin
Falcon binaryPI has a "feature" that prevents this from working.
Ricardo has an easy workaround to allow the UART to function.
Cherry-pick the patch here:https://review.coreboot.org/#/c/17924/