linux-kernel - Re: [patch 0/2] suspend/resume regression fixes

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Message-Id: <200709282340.23730.rjw@sisk.pl>
Date:	Fri, 28 Sep 2007 23:40:22 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Mark Lord <lkml@....ca>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>, Ingo Molnar <mingo@...e.hu>,
	Len Brown <lenb@...nel.org>,
	Venkatesh Pallipadi <venkatesh.pallipadi@...el.com>
Subject: Re: [patch 0/2] suspend/resume regression fixes

On Friday, 28 September 2007 23:17, Mark Lord wrote:
> Thomas Gleixner wrote:
> > On Fri, 2007-09-28 at 16:27 -0400, Mark Lord wrote:
> ..
> >> On a closely related note:  I just now submitted a patch to fix SMP-poweroff,
> >> by having it do disable_nonboot_cpus before doing poweroff.
> >>
> >> Which has led me to thinking..
> >> ..are similar precautions perhaps necessary for *all* ACPI BIOS calls?
> >>
> >> Because one never knows what the other CPUs are doing at the same time,
> >> and what the side effects may be on the ACPI BIOS functions.
> >>
> >> And also, I wonder if at a minimum we should be guaranteeing ACPI BIOS calls
> >> only ever happen from CPU#0 (or the "boot" CPU)?   Or do we do that already?
> > 
> > The ACPI calls are serialized in the kernel, AFAICT. But the fragile
> > situations (suspend, resume, shutdown, reboot) are probably those, where
> > some BIOS implementation expect that certain things are not called or
> > not active.
> 
> Mmm.. *do* we actually do this for reboot?  I don't see it there.
> And how about for kexec?
> 
> I'm probably just missing seeing it.  Right?

Nope.

Till now, only hibernation and suspend disabled the nonboot CPUs before
invoking the platform firmware.

Greetings,
Rafael
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