Re: Problems with SMP & ACPI powering off

From: Rafael J. Wysocki
Date: Thu Sep 27 2007 - 17:46:45 EST

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?

> 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?

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at