[OpenIndiana-discuss] bmc-watchdog SMF dependencies

[Rennie Allen]

I don't see what is wrong with option #1.  Just leave the watchdog running
until the kernel shuts down the computer. There is no reason the watchdog
should ever stop (that way it offers protection continuously until the
system is otherwise shut off).



On 6/26/12 1:26 PM, "Jim Klimov" <jimklimov at cos.ru> wrote:

>Hello all, I've got a new small matter for generic discussion:
>
>   Some of my systems have hardware watchdogs, either on motherboards
>features or in IPMI addons.
>
>   A small intro for newcomers: Watchdogs include a timer that can be
>started by BIOS or a watchdog driver in the OS, and the driver should
>regularly restart this timer (a trivial driver is just a loop with
>long sleeps and a write of a byte into a certain port's address).
>If the computer freezes and the driver no longer functions, the
>hardware watchdog issues a reset on the motherboard, or a similar
>administrative action (if configurable).
>
>   Now, in OpenSolaris (and portable to OI) there is a bmc-watchdog
>package for some proprietary hardware implementations, as well as
>a newly ported open-source driver is brewing. There is also an SMF
>service to wrap the watchdog. From what I see, upon service startup
>the HW timer is started, and for the duration of the service uptime
>the timer-resets are regularly issued. Upon service shutdown there
>are two possible approaches (as I tweaked the method script a lot,
>I am not sure what was there originally): either the daemon for
>regularly-restarting the timer is just killed (and the timer keeps
>ticking), or the timer is also stopped. On my system it happened
>to be the former, and during a shutdown which took longer than usual
>to proceed (for valid reasons), the box got reset by the timer.
>
>   Now I looked at the SMF manifest, and see that the service only
>depends on filesystem/usr. In my practice this meant that upon OS
>shutdown, the bmc-watchdog daemon was quickly killed (as nothing
>depends on this service) and the timer ticked down to zero - boom!
>
>   Question is: what is a valid way to avoid the watchdog killing
>the system upon lengthy shutdowns?
>
>   I came up with a few ideas:
>1) Redefine the stop method to not kill the daemon - not good, for
>    pedantic reasons at least ;)
>2) Redefine the stop method to kill the daemon and stop the timer -
>    not good because the box can potentially also freeze during
>    shutdown, and in that case we would want it automagically reset;
>3) Make milestone/single-user a dependency of bmc-watchdog (I also
>    tried to redefine bmc-watchdog instance to have a dependent -
>    but this did not get picked up properly) - in this case the
>    daemon works until all heavy services in miletone/multi-user
>    get shut down properly, and only gets killed then (and the HW
>    timer ticks for a few more seconds, until the system is rebooted).
>
>So far I like the idea#3 (alone) best. Are there any reasons not to
>do so, or to do something different? Ultimately, I hope, the best
>method should end up in the illumos-gate ;)
>
>Thanks,
>//Jim Klimov
>
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