Permission denied is quite different from a missing file or subdirectory. I was simply showing sudo for the command you had entered. On my system I do not have the “/sys/kernel/debug/bpmp/debug/cons”, so I don’t know anything about that feature.
The content in “/sys” is entirely “synthetic” in the sense that none of this is on the disk. All such content lives in RAM and is the result of a kernel driver or kernel feature creating this content. Either a kernel version is installed without this feature, or the feature is not available on that kernel version. Since this was your question:
Q3: I want to use WDT_RESET_OUT_N pin and I followed this topic, but it's not worked.
…I have to assume this watchdog timer feature is what would provide that file or subdirectory.
My question is this: You mentioned a crash or kernel panic. Flashing would reset everything, and if a software issue came about during development, then probably when flashed things would work well again. On the other hand, if you’ve added or modified a kernel feature, then adding or modifying that feature again would probably result in the same state.
I have no ability to tell you about the difference between the two watchdog timers, but if you are interested in flashing then this is not difficult. Are you looking to flash? Are you looking to add some watchdog timer features? Which software release is the Jetson currently running?