Reset secure boot mode on Zynq-7002

[zapparello]

Hello!

We've got a relatively large number of Zynq 7002 based boards which were programmed to use secure boot mode.

We're using same type of board for a new project, and would like to reuse these boards.

Is it possible to reset secure boot mode somehow? We're not interested in the old firmware (which is stored in QSPI flash), we need just the hardware.

[timduffy]

If by "secure boot mode" you mean the eFUSE register was burned to only boot using the AES key, then you'll need the AES key to re-encrypt your BOOT.bin that will reside in the QSPI.

If you don't know the AES key, you're out of luck - that's the whole point of Secure Boot: only authorized and authenticated code can be executed.

If you didn't burn the eFUSE registers, and it is just using a key in battery backed RAM, then you can just pull the battery, and you should be good to go.

[zapparello]

Yes, the eFUSE is burned to boot only in secure mode using the eFUSE key. I just was wondering, since other microcontrollers usually can be recovered from similar situations by a total erase. This is sad, it's possible the keys were lost, too much time passed.

[allanherriman]

I understand that the Xilinx eFuse really is a fuse (in polysilicon?) - it can only be blown once.  A microcontroller with a "total erase" function will be using a different technology, probably EEPROM or Flash.