TF-M SBSFU STM32B-U585-IOT2A External Flash Usage

[PJose.4]

Hi @Channel

Im using  the TF-M Application package for the STM32U585 development board from ST. My query is as per the memory map of the Internal Flash has a combined storage of 826kb for secure and non secure image.(Please refer to the figure below). But my project requirement needs more space and hence need to store the primary slot and bootloader associated partition in the internal flash and needs the secondary slot storage to be implemented in the external flash(for backup purpose). How can this requirement be achieved without altering the PSA Certified TF-M Bootloader Implementation.(Please suggest if there is an alternate approach).My application size (secure +non secure) would consume nearly the 826 kb or less. Please suggest any detailed approach on how this requirement can be achieved.

2. One more query is like which all crypto schemes have been implemented with the help of the PSA API in the released ST Package. and is there any particular guidance on the usage for the same.
The following user manuals have been referred, UM 2851 and UM2852

Thanks for the continued support
Regards
Philip

[Jocelyn RICARD]

Hello @PJose.4,

For first question this is far from being simple.

This was done on STM32L5 but with an older version of TFM.

The access to external flash is also implemented in the TF-M github for STM32U5 but in a later version of TFM (1.6 or 1.7).

In any case, there is no way to keep the certification. If you need a certification you will have to provide all changes you made to the certification authority.

I'm sorry I don't understand your second question.

Best regards

Jocelyn

[PJose.4]

Hi @Jocelyn RICARD 
Thanks for your continued support
1. Ok we will wait for the update from your side. Could you please let us know if there is any expected timeline when the firmware 1.6 or 1.7 could be available?
2. Is there any option with the existing firmware of the bootloader(TF-M SBSFU) where we can store the secondary image(2 image configuration where primary slot will be in internal flash and secondary slot in external memory) in an external memory. If so, how could the implementation be done?

Thanks again
Regards
Philip