Arm TrustZone for Cortex-M technology is an optional core extension, which enables the system and the software to be partitioned into Secure and Non-Secure domains.
Secure software can access both Secure and Non-Secure memories and resources,
while Non-Secure software can only access Non-Secure memories and resources.
Figure 1. TrustZone for ARMv8-M
If the TrustZone is implemented (SAM L11 devices), the system starts up in Secure state by default.
The security state of the processor can be either Secure or Non-Secure.
Important: For additional
information, refer to “TrustZone Technology for ARMv8-M Architecture”, which
is available on the Arm web site (www.arm.com).