linux-kernel - Re: ARPM shutdown oops (Re: [stable] [patch 09/12] Fix SMP poweroff hangs)

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Date:	Thu, 11 Oct 2007 14:42:01 -0400
From:	Jeff Garzik <jgarzik@...ox.com>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
CC:	Kevin <spaceman__spiff@....net>, Greg KH <greg@...ah.com>,
	Olof Johansson <olof@...om.net>, Greg KH <gregkh@...e.de>,
	"Rafael J. Wysocki" <rjw@...k.pl>, Theodore Ts'o <tytso@....edu>,
	Zwane Mwaikambo <zwane@....linux.org.uk>,
	Justin Forbes <jmforbes@...uxtx.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Chris Wedgwood <reviews@...cw.f00f.org>,
	Domenico Andreoli <cavokz@...il.com>,
	Mark Lord <mlord@...ox.com>,
	Randy Dunlap <rdunlap@...otime.net>,
	Michael Krufky <mkrufky@...uxtv.org>,
	Chuck Ebbert <cebbert@...hat.com>,
	Dave Jones <davej@...hat.com>, akpm@...ux-foundation.org,
	Chuck Wolber <chuckw@...ntumlinux.com>, stable@...nel.org,
	alan@...rguk.ukuu.org.uk, BDFL <volkerdi@...ckware.com>,
	Stephen Rothwell <sfr@...b.auug.org.au>
Subject: Re: ARPM shutdown oops (Re: [stable] [patch 09/12] Fix SMP poweroff
 hangs)

Linus Torvalds wrote:
> 
> On Wed, 10 Oct 2007, Kevin wrote:
>> The last kernel I used was 6.2.22 the "dmesg" the file is attached:
>>
>> dmesg 2.6.22 line 158 >  apm: overridden by ACPI.
>>
>> dmesg, APM on, has no line > apm: overridden by ACPI.
> 
> Ok, this is the real reason. 
> 
> The APM code does:
> 
>         if (PM_IS_ACTIVE()) {
>                 printk(KERN_NOTICE "apm: overridden by ACPI.\n");
>                 apm_info.disabled = 1;
>                 return -ENODEV;
>         }
> 
> and in previous kernels that would notice that you have ACPI enabled, and 
> APM gets shut out, and you never see your buggy APM BIOS.
> 
> In 2.6.23, this apparently doesn't happen for some reason.
> 
> And I think I see the problem: it's a config change. You don't have 
> PM_LEGACY enabled. Your config file diff shows:
> 
> 	-CONFIG_PM_LEGACY=y
> 	+# CONFIG_PM_LEGACY is not set
> 
> I suspect we should make CONFIG_APM either depend on, or select, 
> PM_LEGACY. But as far as I can see, nothing has actually changed in this 
> area in the kernel, and this bug has been there before - just your config 
> change made it appear. 
> 
> Rafael? Stephen? Opinions? I'd think that making APM depend on 
> CONFIG_PM_LEGACY is the right thing to do these days..

Speaking as the author of

	[PATCH] move pm_register/etc. to CONFIG_PM_LEGACY, pm_legacy.h

I agree.  arch/i386/kernel/apm.c clearly requires 
include/linux/pm_legacy.h and the legacy PM API.

I would vote for a dependency rather than select, but don't have any 
strong feelings on the matter...

	Jeff


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