Burn 2MB coreboot.rom on 8MB flash chip

[Zvi Vered]

Hello,

I have an Intel's ATOM Bay Trail board. The output of "inteltool" is:

CPU: ID 0x30679, Processor Type 0x0, Family 0x6, Model 0x37, Stepping 0x9
Northbridge: 8086:0f00 (Bay Trail)
Southbridge: 8086:0f1c (Bay Trail)
IGD: 8086:0f31 (unknown)

In coreboot configuration I selected:
Mainboard -> Mainboard model -> Bayley Bay FSP-based CRB
The default ROM chip size is 2MB.
This is also the size of coreboot.rom created after "make"

The board has 8MB BIOS flash.
It's delivered with a BIOS programming utility that runs under EFI shell.

The original BIOS has 2 versions: rom (5MB) and bin (8MB)
I tried to burn the 2MB coreboot.rom with the vendor's BIOS utlity.

I got:
3 - Error: ROM file size does not match existing BIOS size.
Should I convert coreboot.rom to coreboot.bin ? How ?
If not, how can I program coreboot.rom ?

Thank you,
Zvika