What is the CSEc key, BOOT_MAC's debug protect attribute use for?

[yaojianhang]

HI,@lukaszadrapa

As the question head saying, I don't know what is the CSEc key, BOOT_MAC's debug protect attribute use for. I have tried to set this attribute, and found secure boot will also be succeed with debug attatched, would you give me some explains? thank you very much!

BR,

yaojianhang.

[lukaszadrapa]

Hi @yaojianhang 

not sure how you tested this but it works as expected on my side...

This is a state when I turn on the board and connect a debugger without reset (hot attach):

If debugger is connected and if I reset the board via debugger:

So, I can see no problem here.

How did you set the attribute? I used AN5401 for my test and I used:

calculate_M1_to_M5(M1, M2, M3, M4, M5, MASTER_ECU_KEY_VALUE, BOOT_MAC_KEY_VALUE, MASTER_ECU_KEY, BOOT_MAC_KEY, 1, 0b001000);

Regards,

Lukas

[yaojianhang]

HI, @lukaszadrapa

I teset BOOT_MAC's debug protect attribute not BOOT_MAC_KEY.'s, thanks for your reply!

[lukaszadrapa · Accepted solution]

OK, in case of BOOT_MAC, I can see that it really doesn't work as expected. Thanks for pointing this out, I will report it. The workaround is simple here - set this attribute for BOOT_MAC_KEY instead of BOOT_MAC. It is sufficient if at least one of them is set. The effect will be the same.

Regards,

Lukas