P12b ETC Slave CPU disassembly

[antus]

As part of PCM Hammer development, I wanted to understand more about how the main and slave CPUs communicate on this platform. Further, I wanted to try this new world of AI reverse engineering.

So, I grabbed the binary salve OS file, and loaded it in to ida, and set up a loop where I could export to lst, have an AI analyse part of it, and produce an idc to load annotations and name functions back in ida. Even though it did not take long to learn what I needed about how to flash the slave, I kept going and blew through my usage quota a few times to see if it could

a) document an annotate functions in the slave os
b) document the SPI protocol between the main cpu and the salve
c) document how the slave os works

I am posting this here because it was an AI, so there is no guarantee that anything is right. But so far, I think it has done a very good job.

[pman92]

Can you connect AI over MCP into IDA?

I've been using Ghidra with ghidraMCP and claude desktop setup.
Having the AI be able to see the entire project and disassembly as it needs, label addresses and functions, decompile itself etc. has been game changing.

[antus]

Yes you can. I only hooked that up for a look first time in the last day but first impression so far i've found it to be a lot less efficient than having it work with .lst files and providing me idc to run and perform tasks such as involve search and replace and logic across the code base. In particular for the P12b I wanted it to look for nop instruction bytes as there were a lot of them used as padding, to mark them as code and then the byte after as program. It wrote me an idc to do this, as well as look for other opcodes as bytes that typically start a function. It worked really well to seek the code and disassemble the whole thing. But when I asked it to do the same with with MCP it stated pulling bytes little by little and doing it opcode at a time blowing my token quota in a big way way achieving little. I guess even with an MCP you can get it to write a python script or idc script to perform a task more efficiently, but it'll take time to see where the benifits are, and there are definately traps like above that risk wasting time and causing an ai billing headache.

[hjtrbo]

How you ask the ai to script the work has a huge difference on speed & cost. Asking it to perform large operations server side avoids the round trip cost. I don't use IDA, however I found big gains in switching to predominantly server side code execution in ghidra.