Hi Bohdan,

Right, this integration process can be improved. If I understand you correctly you propose to generate several implementations of the interface for typical use cases.

I see an alternative in creating a set of typical integration examples in tf-m-extras repo. Ahead of that we need to split and decouple S <> NS build process for simplicity and avoid redo examples later.

Cheers and looking for other opinions,

Anton

From: Bohdan.Hunko--- via TF-M <tf-m@lists.trustedfirmware.org>
Sent: Thursday, December 22, 2022 3:24 PM
To: tf-m@lists.trustedfirmware.org
Subject: [TF-M] Default implementation of tfm_ns_interface_dispatch()

Hi all,

While working on TFM TZ related stuff I have noticed that TFM docs/integration_guide/index.rst states that

• On Armv8-M TrustZone based platforms, NS OS shall implement interface API ``tfm_ns_interface_dispatch()`` to integrate with TF-M implementation of PSA APIs.

But currently  neither CMSIS RToS nor FreeRToS implements this function, also there is no default implementation for bare metal case. So currently it is user responsibility to implement this function. Also currently for TFM tests it is implemented in test repository (<tf-m-tests repo>/ app/tfm_ns_interface.c).

I think this is bad user experience because each user have to implement this function. I think TFM should provide implementation of this function for most common use cases (for example, CMSIS RToS, AWS FreeRToS, bare metal, …). Files with implementation should be installed during build process.

Default implementations will cover most of use cases and will fit for majority of the users.

This way TFM will be more user friendly.

What are your thoughts on this topic? Will TFM accept such a patch?

Regards,

Bohdan Hunko

Cypress Semiconductor Ukraine

Engineer

CSUKR CSS ICW SW FW

Mobile: +38099 50 19 714
Bohdan.Hunko@infineon.com