[coreboot] Burn 2MB coreboot.rom on 8MB flash chip

Nico Huber nico.h at gmx.de
Wed Sep 26 17:37:55 CEST 2018

Hi Zvika,

On 9/25/18 10:59 PM, Zvi Vered wrote:
> Thank you very much for the detail information.
> The output of ifdtool in layout.txt is:
> 00000000:00000fff fd
> 00300000:007fffff bios
> 00001000:002fffff me
> So the original bios size is 0x500000 = 5MB
> You wrote:
>  if the size of the original BIOS is bigger or equal than coreboot build
> you are good to go ahead.
> The original "ROM chip size" in menuconfig is 2MB. Should I change it to
> 8MB ?

yes, and CBFS_SIZE should be set to something <= 0x500000.

> I'm aware my board is not identical to the "Bayley Bay FSP-based CRB"
> Should I use another board as reference ?

You should use whatever reference is closest to your board. Major dif-
ferences to look out for are: GPIO/pin config, embedded controller (it's
unlikely that coreboot already has code for yours), how the RAM is con-
nected (e.g. DIMMs or soldered down?). Well, and everything else in the
mainboard's directory.

If your board is not obviously similar to a supported board, you have a
lot of work ahead of you.


> Best regards,
> Zvika
> On Tue, Sep 25, 2018 at 10:16 AM Jose Trujillo <ce.autom at protonmail.com>
> wrote:
>> Hello Zvika:
>> First get the correct original full 8MB FW from the manufacturer or dump
>> it from the board with the command in EFI:
>> "ftp -d BYT_orig.bin" and double save it.
>> 2.- in coreboot/util/ifdtool do make and sudo make install.
>> 3.- in terminal go to the FW directory and do:    "ifdtool BYT_orig.bin -f
>> fw_layout.txt"
>>       a).- in "fw_layout.txt" you will get the BIOS area size from the
>> original FW (just substract).
>>       b).- if the size of the original BIOS is bigger or equal than
>> coreboot build you are good to go ahead.
>> 4.- copy/move "BYT_orig.bin" in the directory which resides the coreboot
>> folder (not inside the coreboot folder) and do:
>>      ifdtool -i BIOS:./coreboot/build/coreboot.rom CB_baytrail.bin
>> 5.- flash it:   "fpt -f CB_baytrail.bin" booting from UEFI.
>> If the build was correctly done and followed accurately those steps the
>> system should boot.
>> Good luck,
>> Jose Trujillo.
>> ‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
>> On Monday, September 24, 2018 10:18 PM, Zvi Vered <veredz72 at gmail.com>
>> wrote:
>> 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

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