You can go with MinnowMax which is based on Baytrail SoC and its compatible with core boot. In fact, I tested that yesterday only and I am actively using it with core boot from past few weeks. The latest version of the same board is Minnow3 that is I believe based on ApolloLake, though I am not sure if the HEAD of core boot works or not. I haven’t tested the core boot on Minnow3, but definitely the core boot supports Minnow3.
UP-Square is another board which recently came out and that should also be compatible with Coreboot as the support was added recently.
using flashrom if you type: -L | --list-supported print supported devices it says: Supported flash chips (total: 391):
This doesn’t list the boards. They are actually SPI flash chips present on the board. e.g. MinnowMax has 8MB Winbond flash chip and that is supported by flashrom.
Regards, Naveen