CSEc Keys and User Data on the 4kB EERAM

[nevozade]

Hello, 

I am working on S32K148 and I am going to enable CSE module for secure booting. According to the application note ('Using S32K148 FlexNVM Memory', AN12003, Rev.0, July 2017), in section 3.3, 64 kB of the FlexNVM are used as E-flash (EEPROM backup and key storage together) and CSEc uses up to 512 Bytes for key storage, leaving EEPROM to use the remaining 3.5 kB EERAM for the EEPROM and CSEc enabled use case (attached). 

What I'm wondering about in this usage is whether the user data is somehow preserved overwriting or deleting the registered keys. Briefly, I want to know whether the 512 bytes where the keys are recorded are randomly recorded in this EERAM or are they recorded in specific locations such as the beginning/end of the 4 kB FlexRAM.

I urge you to assist in this matter.

Best Regards.

[danielmartynek · Accepted solution]

Hello @nevozade,

If the allocated CSEc space is 512B, the space 0x14000E00-0x14000FFF will not be accessible in the FlexRAM (EEPROM).

Any access to this region generates a bus fault exception.

Regads,

Daniel