Like the Raspberry π SoC is based on a television tuner box. The vast majority of the die is related to the TV tuner functions that are completely undocumented. What techniques exist to explore undocumented physical hardware? Are we limited to reverse engineering code to find when and how these undocumented areas are used, or are there other fuzzing type techniques to find relationships between memory, flags, and potential byte instructions?
This is an abstract thought and generalization that potentially patches a hole in my understanding. There is no broader purpose in asking.
I did not know JTAG was used like this, I thought it was passive in functionality
Even for debugging jtag is quite active. It can essentially (depending on the soc or micro you’re working with) override the device and force it into specific conditions or change register values.
Very useful.