Unique board identifier

Is there anything on the board itself which can provide unique id?

so can flash serval boards with the same firmware and all will have different ethernet mac addresses based on that id?

cause I’d rather not pre-program each board with just different uboot env

I need the answer this question too. How to uniquely identify boards? As I understood NIC MAC addresses are random. So what could be source of unique id?

Why not generate one on first bootup and write to a file? Or using the random mac and write to file if the file does not exist

Yes it’s true. You can generate number and write it down to the flush. But it will be RANDOM number! That is the problem! I need to generate a PREDICTABLE number based on something static and fixed inside the board. Is it possible? Are there something permanent on the board that can be a static source and I could read it via shell?