I'm using the current seabios (master or stable) as a payload for coreboot.
If I build the current seabios I've found that commit b98a4b1 "Convert PCIDevices list to use standard list manipultion code."
prevents the system from finding USB thumbdrives. The USB keyboard and mouse still work.

This problem occurs for multiple mainboards (persimmon/parmer/gizmo).

Let me know if there's something else I can try for anybody.

Thanks,
Dave