Re: Problems with SMP & ACPI powering off

[Mark Lord <lkml@rtr.ca>]

Rafael J. Wysocki wrote:
> On Thursday, 27 September 2007 23:29, Mark Lord wrote:
>> Question:  do we disable all CPUs except 0 when doing ACPI power off?
> 
> No, but we should.
> 
>> Background:
>> I have a machine here dedicated to running MythTV.
>> It powers up to record, and then sets the RTC alarm for next time
>> and powers down again in between recordings.
>>
>> It has an Intel Core2duo E6300 CPU, currently on an ICH8 motherboard.
>> Previously it was on a completely different (vendor,bios,...) ICH7 motherboard.
>>
>> In both cases, "halt -p" sometimes fails to actually turn off the power,
>> which means that it later then fails to "turn on" to record again.
>>
>> Annoying.
>>
>> This is a 32-bit kernel/runtime, with full ACPI (not APM) kernel support enabled.
>>
>> So I'm wondering if it may be due to the old SMP-poweroff bogeyman ?
> 
> May be.
> 
> Which kernel?

Latest 2.6.23-rc-git.  Same problem from time to time on 2.6.17, as well.
Dunno about in between those Revs., but it's much more common on the latest
than it was on the old kernel.

> 
>> For now, I've hardcoded a cpu_down(1) into the poweroff code,
>> and we'll see if that helps or is merely redundant.
>>
>> But I do wonder where else to look for a cause?
>>
>> Two different boards, vendors, BIOSs, same CPU chip.  Same problem.
> 
> Same chipset, perchance?

Mmmm I originally didn't think so.

But actually one board is ICH8, the other ICH8R,
so yes, they use the same chipset.

Cheers