What are Boot Steps of STM32H7 Secure Mode

[SPati.7]

As per my understanding Secure Mode of STM32H7 as follows:

RESET => Enter System Boot loader => Program OB register content => If (SECURITY) => RSS Boot => Configure Secure User Memory => Jump to Secure User memory on User Flash.

I have two open questions here

1. is the above understanding correct ?? OB registers programmed by System Bootrom or some different mechanism ??
2. Once Jump to application, Secure User Memory is disabled, as per concept. And if application trying to access Secure User memory from application context, the Flash access exception will come.

Who is checking this access ?? who will control this access ? how it is implemented ??

[Pavel A.]

1. Basically yes
2. The "jump to application" must be done via call to a RSS function (thru a pointer), otherwise it will stay in the secure mode!

> Who is checking this access ?? how it is implemented ??

The hardware.

[SPati.7]

Thanks for reply. But How it is implemented at HW level ??

[Pavel A.]

Hmm... They put a tiny gnome in every chip. These little guys do all the mаgi�?k.

[Tesla DeLorean]

I'm sure you have access to all the same public domain data ARM and ST have released on their respective cores and security methods.

Perhaps understand the basic expectations and processes there, and then ask specific questions about how bits of the blocked diagrammed pieces work.

There are perhaps white papers, app notes, and seminar slides out there too.

Unfamiliar with asymmetric encryption methods, hashes, elliptic curves, etc there's a lot of material on that stuff too.

Generally you don't want to expect senior engineers to read technical documentation to you or for you.

[SPati.7]

@Community member​ Thanks for details.

I thought people here in the community, may know already those details, that's why i asked.

I can do my research on whatever i am looking.

Anyway thanks for pointers 🙂