linux-kernel - Re: Problems with SMP & ACPI powering off

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Message-Id: <200709280000.53001.rjw@sisk.pl>
Date:	Fri, 28 Sep 2007 00:00:52 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Mark Lord <lkml@....ca>
Cc:	Linux Kernel <linux-kernel@...r.kernel.org>, simon.derr@...l.net,
	Len Brown <lenb@...nel.org>
Subject: Re: Problems with SMP & ACPI powering off

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?

Greetings,
Rafael
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