Ways to backup AMD Combo AM4 BIOS/UEFI flash?

Since recent AGESA (1.2.0.0) update apparently “protected” BIOS/UEFI flash memory. One cannot use trusty flashrom anymore to backup/update BIOS on AM4 motherboards that have recent firmware.

Is there any software solutions that work?

I tested AMI (Aptio) Firmware Update Utility v5.16.01.0109 on ASRock B550M-ITX/ac motherboard. While it seems to “successfully” save a backup of current firmware, it is only doing partial dump. Board has 32Mb flash chip (Winbond W25Q256JWEIQ), but AMI tool only saves 16Mb image (“TOP16M” it would seem).

I was testing with latest AfuEfix64.efi (downloaded directly from AMI).

Backup seems to work without any errors:

FS0:\> AfuEfix64.efi backup.rom /O
+---------------------------------------------------------------------------+
|                 AMI Firmware Update Utility v5.16.01.0109                 |
|      Copyright (c) 1985-2023, American Megatrends International LLC.      |
|         All rights reserved. Subject to AMI licensing agreement.          |
+---------------------------------------------------------------------------+
 - System ACAU Support .............. Enabled
 - ACAU Version = 101.
 Saving current BIOS into file: backup.rom
 Reading flash ............... done                

 Process completed.

But results only a 16Mb file, not full 32Mb dump of the flash. Saved file seems to only contain the “top” 16Mb portion (ATR : D) part of the flash…

Reading ROM ID from the ASRock bios update file shows two (16Mb) blocks:

FS0:\> AfuEfix64.efi B55MITA2.62 /U
+---------------------------------------------------------------------------+
|                 AMI Firmware Update Utility v5.16.01.0109                 |
|      Copyright (c) 1985-2023, American Megatrends International LLC.      |
|         All rights reserved. Subject to AMI licensing agreement.          |
+---------------------------------------------------------------------------+
 - System ACAU Support .............. Enabled
 - ACAU Version = 101.
 - ATR : U
 - ROM File ROM ID = 1AWQH262
 - ROM File ROM GUID = abfa34a6-267f-788d-d26accd71b33ec90

 - ATR : D
 - ROM File ROM ID = 1AWQG262
 - ROM File ROM GUID = eaa86116-35d6-1bb1-448d3b1085ee1f41

 Process completed.

While reading ROM ID from the backup created earlier only shows the “ATR : D” section:

FS0:\> AfuEfix64.efi backup.rom /U
+---------------------------------------------------------------------------+
|                 AMI Firmware Update Utility v5.16.01.0109                 |
|      Copyright (c) 1985-2023, American Megatrends International LLC.      |
|         All rights reserved. Subject to AMI licensing agreement.          |
+---------------------------------------------------------------------------+
 - System ACAU Support .............. Enabled
 - ACAU Version = 101.
 - ROM File ROM ID = 1AWQG262
 - ROM File ROM GUID = eaa86116-35d6-1bb1-448d3b1085ee1f41

 Process completed.

I did try following options, but looks like when using “/O” no other command line options have any effect (?)

AFU offers command /ATR: U, /ATR:D to be chosen by users for which ROM region should be flashed. BIOS offers command /CMD:{TOP16M}, /CMD:{BOTTOM16M} to be chosen by users for which ROM region should be flashed.