Disabling JTAG access on TB0818

[Bugtech]

I am using Trenz TB0818 with petalinux 2022.2. I want to disable JTAG access for testing purpose. Is there any way of achieving this?

I know it possible by burning the eFuse! I do not want to mess with the eFuses!!!

Any leads?

[Antti Lukats]

I am assuming you are using TEBF0818? There is no product named TB0818!

FIRST: please do not play around with efuses, it is easy to brick the device, then it is also not reparaible and not returnable, you end up having dead board eventually

option 1: you simple remove the TE0790 connected to the MPSoC, well you will loose on serial port then

option 2: you contact us per email and ask for TE0790 source code, there you comment out the JTAG bypass and reflash the TE0790 with new code. This will also disable JTAG access, well while preserving UART on the TE0790

option 3: you type: "jtag access disable on MPSoC" into google search bar and take the first hit, here direct link:
https://adaptivesupport.amd.com/s/article/69963?language=en_US

now this method says it disables the DAP (processor JTAG) it is not clear if FPGA JTAG remains active or not, also this method only works AFTER fsbl execution, meaning that if you power up without FSBL you still have jtag access

option 4: you boot in secure mode, this disable JTAG by default, again it is not exlicitly stated that FPGA JTAG is disabled as well, but I assume it must be disabled. Again this only works when the device is booting...

summary: there is no one single good solution

[Bugtech]

Thank you for you response!

You are correct, i am using TEBF0818.

I am aware of the eFuses and that is why would not want to play around with them. For sure i wont be using them.

option 1: Actually i have been working on TEBF0818. But my project demands a similar custom board as TEBF0818. So at the end i will not have the TE0790 on it.

option 2: That actually can help in testing purpose. Again it is a good option but my custom board will not have the TE0790.

option 3: Already read that article and tested it, JTAG works! Not suitable for my situation.


My Situation: While Petalinux boots, if it detects the JTAG, It should not boot further or require a password to boot. If JTAG is not detected, It should boot normally! Not sure if it makes sense (Just an idea).

Thanks a lot again!

[Antti Lukats]

I answered in email. TE0790 flashing will not help in your case, you need the actual disable to happen on MPSoC device itself not in the external adapter.