One small point is that I have a lot of different messages going through this same IPC buffer. Early ones are 4-20 bytes. Some are closer to the full buffer size of 992.
The information above on page 3 is for the 1st transfer which is only 4 bytes. That is the memcpy before the put() is size 4.
I should try to break on the big one if I can figure out how to. (It won't let me step to the big one.)
I mention this because perhaps only the 1st 64bytes are lit in blue because I am only updating the memory in that space. I need to force an example where I can break on where I write to the whole buffer.