MPC5777C CSE Boot MAC

[jeffcampbell]

Quick question on the CSE - in the manual in the section for Secure Boot, it say that the MAC calculated over the secure boot region is compared with the stored BOOT_MAC, and if the stored value is zero, the new MAC is stored there instead.  If the secure boot section were to be modified at some point, is it possible to overwrite the value stored in BOOT_MAC?

[petervlna · Accepted solution]

Hi,

Yes, it is possible to change the BOOT_MAC if secure boot section needs to be modified. But this assumes some conditions and there can be different scenarios. Please refer to the CSE App Note "AN4234-Using CSE" for detailed description. Particularly refer the "Section 2.10: Code flash update procedure" which discusses this question. There are also SW examples for this App Note. Please see example "D.1.2: Reprogramming of a programmed part".

Peter

[petervlna]

Hi,

I have spoken to application team and looks like we need to ask design directly.

I will inform you as soon as I will get reply from design.

Peter