Re: What to set in struct watchdog_device::bootstatus?

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

On 5/9/19 12:25 PM, Uwe Kleine-König wrote:
> Hello Guenter,
> 
> On Wed, Feb 20, 2019 at 09:14:08PM +0100, Uwe Kleine-König wrote:
>> In a custom kernel patch stack I found a patch that uses (apart from
>> WDIOF_CARDRESET also) WDIOF_POWERUNDER and WDIOF_EXTERN1 to
>> differentiate the different reset causes. Now that you told using this
>> is wrong, I wonder how these are supposed to be used instead; and there
>> are a few more that according to
>> Documentation/watchdog/watchdog-kernel-api.txt might be used to set
>> bootstatus. Are these a relic? What do these signal?
> 
> I'm still interested in an answer here. While it is currently not
> possible to "fix" the custom kernel as some other software that is
> already shipping depends on this. Still I'd like to know the details
> here to maybe suggest an alternative for the longterm future.
> 
>> IMHO there is a patch opportunity waiting to improve the documenation
>> :-) Or maybe even change watchdog_get_status() to ensure that only
>> WDIOF_CARDRESET, WDIOF_MAGICCLOSE and WDIOF_KEEPALIVEPING can be set?
> 

The basic problem, as I see it, is that the bits were defined a long time
ago as standard API, even tough they really only apply to a small subset
of watchdog cards. Personally I tend to believe that any set of bits
would be insufficient. Maybe it should have been a string. Either case,
I don't believe in forcing more or less random reboot reasons into a
given set of bits. On the other side I also don't see the point in
arbitrarily limiting the bit values returned by WDIOC_GETSTATUS.
With that, my general approach would be some kind of report-what-makes-sense
approach. But using WDIOF_POWERUNDER for "power cycle" just goes a bit too
far.

Thanks,
Guenter