Date: Tue, 26 Aug 2008 14:24:20 +0100 (BST)
From: "Maciej W. Rozycki" <macro@linux-mips.org>
To: Avi Kivity <avi@qumranet.com>
cc: Alan Cox <alan@lxorguk.ukuu.org.uk>, Pavel Machek <pavel@suse.cz>,
       Ingo Molnar <mingo@elte.hu>,
       "Eric W. Biederman" <ebiederm@xmission.com>,
       linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Subject: Re: [PATCH] x86: default to reboot via ACPI
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On Tue, 26 Aug 2008, Avi Kivity wrote:

> Most machines are recent machines.

 This is a bold statement I would say.  Any numbers to back it up?

> If a machine doesn't have acpi, this change is safe.
> 
> If a machine has acpi, but doesn't have the reset register set in the 
> FADT, this change is safe.
> 
> If a machine has acpi, and the reset register is set incorrectly, this 
> change is safe.
> 
> If a machine has acpi, and the reset register is wired to the launch 
> controller, then perhaps this change is unsafe.  Don't issue sysrq-b on 
> such machines.

 If a machine has ACPI and it is broken randomly, then the results can be
arbitrary.  Hopefully not destructively.  If even such a simple thing as
wiring the reset line so that it functions correctly can be got wrong,
more so can be more complex matters.

 Failing a better alternative, I suppose the change has to go in though.

  Maciej
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