Due to the early HPS software development stage during which the Agilex™ 3 FPGA is used during releases 25.1.1 and 25.3, there are some Linux peripheral drivers that increase the boot latency, resulting in watchdog timeout expiration when this is enabled from the bootloader (i.e., U-Boot). The watchdog timer expiration causes Linux to fail to boot, observing a reboot whose occurrence may vary depending on the timeout value assigned to the watchdog timer through the CONFIG_WATCHDOG_TIMEOUT_MSECS config. Because of this problem, the watchdog timer is getting disabled by default from U-Boot.
Currently, there is no workaround for this problem, as it is necessary to perform a fine-tuning in the Linux peripheral drivers to eliminate any undesired latency observed during the system bring-up. This problem will be fixed in a future release.
If, for any reason, you still need to get the watchdog timer enabled, you can make use of the following U-Boot commands to enable this:
wdt list : List the available watchdog timers.
wdt dev <device> : Select a watchdog timer.
wdt start <timeout> : Start the selected watchdog timer with a specific timeout in ms.
wdt reset : Kick the watchdog timer to prevent the timer expiration.
Note: It is important to mention that once the watchdog timer gets enabled, it cannot be disabled.