When using the security extension supported by the ARMv8-M, It is cited that when switching from a secure to a non-secure world, a call to a non secure world is conducted. It is noted that the comeback to the secure world is done automatically as quoted:
"During the state transition, the return address and some processor state information are pushed onto the Secure stack, while the return address on the Link Register (LR) is set to a special value called FNC_RETURN. The Least Significant Bit (LSB) of thefunction address must be 0"
Using the "Hello_world" example provided in the MCUXpresso IDE (also shown in this blog ), I added a PRINTF("Comeback to the secure world again"); expecting that it will be printed in the console. However, no thing happened.
I added a break-point but it was not seen, this could mean that there where no switch back to the secure world.
Is there a missing step that I should have included? Does it has to do with the Secure stack?