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

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Message-ID: <46FC20DE.9020205@rtr.ca>
Date:	Thu, 27 Sep 2007 17:30:06 -0400
From:	Mark Lord <lkml@....ca>
To:	Linux Kernel <linux-kernel@...r.kernel.org>, simon.derr@...l.net,
	len.brown@...el.com
Subject: Re: Problems with SMP & ACPI powering off

Mark Lord wrote:
> Question:  do we disable all CPUs except 0 when doing ACPI power off?
> 
> 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 ?
> 
> 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.

Oh, and two different power-supplies, too.

-ml
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