Hi,

We have a prototype audit logging service and one of the purposes is to provide the event logging.

The reason we keep printf first is that it is so direct and some projects reference it, for example, booting or services. Eventually, we need can investigate the possibility of forwarding all printf into event logging.

One question is that there needs to be a buffer for collecting the events so it has limited capacity?

/Ken

From: TF-M <tf-m-bounces@lists.trustedfirmware.org> On Behalf Of Reinhard Keil via TF-M
Sent: Thursday, January 9, 2020 3:42 PM
To: tf-m@lists.trustedfirmware.org
Subject: [TF-M] The logging mechanism change in TF-M

I recommend instead of using printf with plain text strings, to change the concept to event annotations.

This is already implemented in several RTOS systems (i.e. FreeRTOS or RTX).

Event annotations give you more flexibility:

• can be mapped to memory buffer, printf output, or analysers like Event Recorder in MDK or Percepio
• annotations are described in XML file using event groups. Can be mapped to test automation systems and reduce overhead
• no direct mapping to a peripheral.  UART may be not available on all systems.
• overall less overhead in the system (as printf is expensive).  Can remain in production code when it just goes to memory buffer

Let me know if you want to have further pointers or information.

Reinhard

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