Why does the watchdog need to be turned off when the arm is powered on?

2.

Watchdog is generally a hardware module. Its function is to automatically restart the system for you in many embedded operating systems where the system runs for a long time without anyone watching over it. Therefore, it is inevitable or feared that the system will freeze.

So how does it achieve this function? Then we need to briefly explain its implementation principle.

The logic of the watchdog hardware is that it has a record timeout function, and then requires the user to perform certain operations on it at regular intervals (this time can be configured according to your needs), such as writing some fixed values ​​into it, commonly known as "feeding the dog", then I find that the timeout has occurred, that is, you have not fed me after such a long time, then I will think that your system is frozen and there is a problem, and I will help you restart the system. To put it simply, it is like getting a watchdog dog, you have to feed it regularly, if you do not feed it within the timeout, then the dog will think that you, its owner, your system, is frozen, and it will help you reset the system.

3.

After understanding the principle of watchdog, this problem is easy to understand.

If you do not disable the watchdog, you will have to write a separate program to "feed the dog" regularly, which is so troublesome and boring.

After all, we are only using uboot to initialize the necessary hardware and system resources here, and we don't need the watchdog mechanism at all. If you need to use it, it's because your Linux kernel is running, which is your system's concern, and has nothing to do with my uboot, so you must turn off the watchdog (reset function) here.