Is it possible to re-flash the bootloader if Secure Boot V2 with UART ROM dowload is enabled?

morozov-5f
Posts: 4
Joined: Fri Apr 23, 2021 12:27 pm

Is it possible to re-flash the bootloader if Secure Boot V2 with UART ROM dowload is enabled?

Postby morozov-5f » Tue May 25, 2021 9:15 am

Basically a subject title. I am considering the following secure boot v2 environment:
  • Production config, where all the default secure boot options are enabled and it has its own private key that is kept in a secret. Images are signed remotely.
  • Development config, where we have a separate dev key, UART ROM Download, JTAG and eFuse modifications are enabled.
I wonder if it will be possible to update the bootloader for development environment if we, for example, want to modify it at some point? I know that the production boards won't be updated, we are OK with that.

Documentation is somewhat unclear. It says that bootloader cannot be updated in one place (item 5 of How To Enable Secure Boot V2) and implies that the bootloader can be updated in another (item 1 of Restrictions after Secure Boot is enabled).

My assumption is that if the UART ROM download is enabled, we can update the bootloader as log as it is signed with the same private key that was used to enable the secure boot the first time?

morozov-5f
Posts: 4
Joined: Fri Apr 23, 2021 12:27 pm

Re: Is it possible to re-flash the bootloader if Secure Boot V2 with UART ROM dowload is enabled?

Postby morozov-5f » Fri May 28, 2021 10:05 am

Hey guys, any thoughts on that topic? Any input would really help.

morozov-5f
Posts: 4
Joined: Fri Apr 23, 2021 12:27 pm

Re: Is it possible to re-flash the bootloader if Secure Boot V2 with UART ROM dowload is enabled?

Postby morozov-5f » Fri Jun 18, 2021 5:06 pm

My assumption is that if the UART ROM download is enabled, we can update the bootloader
For those who are wondering the answer is yes, it is indeed possible to update the bootloader when the UART ROM download is enabled.

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