[PATCH] watchdog: Add support for the Avionic Design Xanthos watchdog timer.
Bill Gatliff
bgat at billgatliff.com
Thu Aug 27 21:32:57 EDT 2009
Wim Van Sebroeck wrote:
> Hi Bill,
>
>
>>> This is the only thing I'm still struggling with: the goal of a watchdog device driver is to make sure that the system reboots when the system isn't stable anymore. So why should you then trigger the interrupt?
>>>
>>>
>> ... because a hard reboot might not be the way he wants to resolve the
>> situation.
>>
>
> If your system is unstable then sending a keepalive to the watchdog during this interrupt is not going to change anything neither... Or am I missing something?
>
All I'm saying is that it isn't always a given that a watchdog timeout
should universally issue a hardware reset. I've worked with systems
where doing so would be a Really Bad Idea, and what we wanted instead
was the ability to know when the watchdog timer had expired so that we
could wrest control of the system away from the application.
Put another way, it isn't always the case that the _system_ has become
unstable. It's more likely that the _application_ has, and there are
other ways to fix that than by issuing a hardware reset.
In the bigger picture, getting all the benefits out of a watchdog timer
while at the same time avoiding their limitations can be a tricky
business. They're misused far more often than used properly,
unfortunately. I sense that you and I both recognize that.
b.g.
--
Bill Gatliff
bgat at billgatliff.com
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