We know that by opening
/dev/watchdog the watchdog activates and by sending a character in less that a minute it will reset. the instructions are here.
The processor used for BBB AM335x enables its internal watchdog by default. But when the U-Boot or Ubuntu starts, this watchdog is disabled. and after OS is booted up the
/dev/watchdog can be used.
I want to ensure that the watchdog works even when U-Boot or kernel can't boot. So how can it be done?
- The kernel and U-Boot should not disable the watchdog timer.
- The default timeout of watchdog should be more than a minute before U-Boot starts the kernel so that the OS can boot up completely
I need to mention that Changing some parts of U-Boot code or Linux kernel code is acceptable. but External watchdog is not an option.