Question:

My application has a requirement for the flash contents to be irrevocably locked.

The documentation states that setting the CSM password to all zeroes permanently locks the device.  Does this mean that the CSM is permanently locked, but that the device can still boot and execute from flash?

If that is true, it would still be possible for code running from secure RAM to erase the flash and the password.  Is there any way that code could erase the password without erasing the flash?

Answer:

A password of all 0's will lock the device permanently but does not effect its operation otherwise - it is just a locked device. 

Secure code can still access secure areas and thus erase/program the flash.

Erase is a by sector process.  So the minimum amount that you must erase in order to erase the password is all of sector A.  The other sectors do not need to be erased.

Please also refer to this wiki page:

http://processors.wiki.ti.com/index.php/Code_Security_Module_FAQ_for_C2000