git: powerd: Wait hw.acpi.cpu.px_dom* sysctl to be created by kernel

[Thomas Nikolajsen]

>> A timeout would be nice, for now powerd(8) will wait indefinite
>> if hw.acpi.cpu.px_dom* isn't created on system.
>>
>> How long timeout is reasonable? Maybe 5 minutes; or 1 minute; or ..?
>
>Hmm, I think powerd will daemonize itself before endless waiting, so
>it should not choke the booting process at least.  Well, as about the
>timeout, I didn't measure; it mainly depends on how much time the
>tasks before pstate consumed (e.g. battery detection failure could
>take quite some time).

Yes, powerd is daemonized before waiting, so no stall of boot.

I just use existence of powerd process as indication of power managent
is done on system; and I see no reason for process to run if it can't do any benefit.
But if it is hard to give a reasonable timeout, just let it be; it will do no harm.

 -thomas