Re: [PATCH] watchdog: core: module param to activate watchdog

[Guenter Roeck <linux@roeck-us.net>]

>> To achieve what you want you should make sure that your "BIOS" starts
>> with the watchdog enabled and with a very long watchdog heartbeat (so
>> that it doesn't need to get pinged). Then the kernel can boot and
>> userspace can start and then you can do the necessary with the
>> /dev/watchdog functionality. Only thing you need to take care of is
>> that you don't stop the watchdog (via a module param or something
>> similar) during the probe/init of the driver.
>> I believe we allready have a winbond driver doing that. Just checked:
>> it's w83697hf_wdt.c with the early_disable module parameter.
>>
>> So, this is something that needs to be taken into account during
>> probe/init of the driver and for each watchdog that needs it.
>> And thus not for the first watchdog that get's registered.
>> Furthermore: not all watchdog devices have a heartbeat that is long
>> enough to achieve this functionality.
>
> Okay, thanks for the clarification. So I will change the driver and add
> an appropriate paramter to it instead as the winbond driver does.
>

Other drivers do the same, but don't even have a module parameter to
disable it if it is already running. They just ping the watchdog during
initialization to delay the timeout. w83627hf_wdt.c is an example.

Guenter