[Skiboot] [PATCH 3/3] ipmi/wdt: Add ipmi watchdog timer support

[Stewart Smith]

Alistair Popple <alistair at popple.id.au> writes:
> Add support for an ipmi watchdog timer. This patch will cause the
> system to be reset if opal_run_pollers() isn't called for more than
> about 60 seconds.
>
> The timer is reset just prior to running the payload. It is the
> responsibility of the payload to ensure either opal_run_pollers() is
> called frequently enough or to disable the watchdog timer by sending
> appropriate ipmi commands.

I'm a little uncomfortable in changing what is essentially an ABI here
without having the payload explicitly enable the WDT.

I worry about:
- existing payloads
  - will current payloads behave correctly? Do we have anything that
    will currently make sure opal_run_pollers() is called frequently?
- different ABI for payload kernel versus host kernel. If payload
  (i.e. petitboot environment) disables the watchdog timer, then we'll
  have different behavior if booted as payload versus as petitboot.
- some concern about really low power modes and having to muck with
  this.

I think I'd prefer us to have to enable the watchdog explicitly...

Ben, your thoughts?