13.2.2 Memories Security Attribution
The IDAU is used to indicate the processor if a particular memory region is
Secure (S), Non-Secure Callable (NSC), or Non-Secure (NS). It can also mark a memory
region to be exempted from security checking.
| Attribute | Description |
|---|---|
| Non-Secure | Memory can be accessed in Secure or Non-Secure state. |
| Secure | Memory can only be accessed in Secure state. It cannot be called from Non-Secure state. |
| Non-Secure callable |
Memory can only be accessed in Secure state, but can be called from Non-Secure state. |
| Exempt | No attribution check will be done, and the operation will take place on the bus |
Note: Refer to " SAM
L11 Security Attribution" chapter for
the detailed SAM
L11 memories and
peripherals security attribution description.
The Cortex-M23 will search each access (fetch or data) in the IDAU, which returns the privilege information about that specific address. If the access is not permitted, the CPU enters a HardFault exception.
The IDAU memory region's attributes are partly hardwired and partly set by NVM configuration fuses, and are loaded into the IDAU by the Boot ROM before application execution. The IDAU memory region's attributes are blocked for further writes from the application, but their current state can still be read through dedicated IDAU registers.
Note: Refer to the "SAM L11 IDAU Memory Mapping Registers".