After downloading a new firmware blob via YMODEM transmssion, why does SBSFU report that installation is not validated instead of installing the new firmware?
We implemented an OTA update procedure where we provide an STM32L476 with a new firmware via serial using the Ymodem protocol in a two-image SBSFU configuration.
We are executing long-running tests in which we use the same firmware image to test the update procedure over and over again.
The majority of update attempts succeed, but once in a while, we see that SBSFU manages to download the new firmware and reboots, but instead of installing the new firmware (swapping the images) , SBSFU reports that our installation was not validated and a rollback is attempted. A rollback should never be performed at this stage, because the backup firmware was overwritten with the new firmware and the image swap has not yet been executed.
This problem is difficult to reproduce but we have seen it on multiple of our hardware prototypes.
See SBSFU log below.
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= [SBOOT] System Security Check successfully passed. Starting...
======================================================================
= (C) COPYRIGHT 2017 STMicroelectronics =
= =
= Secure Boot and Secure Firmware Update =
======================================================================
= [SBOOT] SECURE ENGINE INITIALIZATION SUCCESSFUL
= [SBOOT] STATE: CHECK STATUS ON RESET
INFO: A Reboot has been triggered by a Hardware reset!
INFO: Last execution detected error was: No error. Success.
= [SBOOT] STATE: CHECK NEW FIRMWARE TO DOWNLOAD
= [SBOOT] STATE: DOWNLOAD NEW USER FIRMWARE
File> Transfer> YMODEM> Send
= [SBOOT] STATE: REBOOT STATE MACHINE
========= End of Execution ==========
= [SBOOT] System Security Check successfully passed. Starting...
======================================================================
= (C) COPYRIGHT 2017 STMicroelectronics =
= =
= Secure Boot and Secure Firmware Update =
======================================================================
= [SBOOT] SECURE ENGINE INITIALIZATION SUCCESSFUL
= [SBOOT] STATE: CHECK STATUS ON RESET
INFO: A Reboot has been triggered by a Software reset!
INFO: Last execution detected error was: No error. Success.
= [SBOOT] STATE: CHECK NEW FIRMWARE TO DOWNLOAD
= [SBOOT] STATE: CHECK USER FW STATUS
Installation not validated: rollback procedure initiated (SLOT_ACTIVE_1 / SLOT_DWL_1)
========= End of Execution ==========N TO PREVIOUS USER FIRMWARE
= [SBOOT] System Security Check successfully passed. Starting...
======================================================================
= (C) COPYRIGHT 2017 STMicroelectronics =
= =
= Secure Boot and Secure Firmware Update =
======================================================================
= [SBOOT] SECURE ENGINE INITIALIZATION SUCCESSFUL
= [SBOOT] STATE: CHECK STATUS ON RESET
INFO: A Reboot has been triggered by a Software reset!
INFO: Last execution detected error was: Backed-up firmware not identified.
= [SBOOT] STATE: CHECK NEW FIRMWARE TO DOWNLOAD
= [SBOOT New Fw to be installed from slot SLOT_DWL_1
= [SBOOT] STATE: HANDLE CRITICAL FAILURERE
= [EXCPT] INSTALLATION CANCELLED: FORBIDDEN VERSION!
= [SBOOT] STATE: REBOOT STATE MACHINE
========= End of Execution ==========
= [SBOOT] System Security Check successfully passed. Starting...
======================================================================
= (C) COPYRIGHT 2017 STMicroelectronics =
= =
= Secure Boot and Secure Firmware Update =
======================================================================
= [SBOOT] SECURE ENGINE INITIALIZATION SUCCESSFUL
= [SBOOT] STATE: CHECK STATUS ON RESET
INFO: A Reboot has been triggered by a Software reset!
INFO: Last execution detected error was: Firmware version rejected by anti-rollback.
= [SBOOT] STATE: CHECK NEW FIRMWARE TO DOWNLOAD
= [SBOOT] STATE: CHECK USER FW STATUS
No valid FW found in the active slots nor new FW to be installed
Waiting for the local download to start...
= [SBOOT] STATE: DOWNLOAD NEW USER FIRMWARE
File> Transfer> YMODEM> Send
[Ready to receive]..............................................................= [SBOOT] STATE: HANDLE CRITICAL FAILURE.........[Abort: hal busy]
= [EXCPT] COM ERROR DURING DOWNLOAD !
= [SBOOT] STATE: REBOOT STATE MACHINE
========= End of Execution ==========
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Any help would be appreciated.
Regards,
Tom