RRAMC can make a part of the RRAM code memory immutable.
The immutable boot region has configurable permissions settings. Read, write, and execute permissions are configured individually. By making the region read-execute only, that memory range of the RRAM becomes immutable.
The region starts at address 0x00000000 and the size of the region is configurable. Note that the region does not add additional storage, but enforces permission settings on the memory range.
The size and permission settings of the immutable boot region is configured in UICR. If UICR.BOOTCONF is not configured, RRAMC will not enforce the protection.
Once the boot region protection is enabled, it can only be removed by ERASEALL. Erase protection can be enabled to prevent ERASEALL operation. For more information about erase protection, see CTRL-AP — Control access port.