Are there any that are supported by coreboot but not by flashrom?
Yes, for example:
ASUS MEW-AM ASUS MEW-VM ASUS P3B-F Biostar M6TBA
Good to know.
coreboot support and flashrom support are not necessarily related. I have various boards (e.g. some of the above) which I can support in coreboot, but haven't yet found the time or energy to figure out a write-enable for flashrom (as I have other boards which work where I can program the flash chips).
I figured that Coreboot support required more information (in general) than flashrom support and thus coreboot support would be a subset. Thanks for the explanation.
Myles