Message-ID: <4D015ACF.1050105@zytor.com>
Date: Thu, 09 Dec 2010 14:40:15 -0800
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Matthew Garrett <mjg59@srcf.ucam.org>
CC: x86@kernel.org, linux-acpi@vger.kernel.org, lenb@kernel.org,
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Subject: Re: [PATCH 1/3] X86: Revamp reboot behaviour to match Windows more
 closely
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On 12/09/2010 02:38 PM, Matthew Garrett wrote:
> On Thu, Dec 09, 2010 at 02:32:52PM -0800, H. Peter Anvin wrote:
>> On 12/09/2010 02:32 PM, Matthew Garrett wrote:
>>> On Thu, Dec 09, 2010 at 02:25:05PM -0800, H. Peter Anvin wrote:
>>>> When this was discussed before we agreed to use ACPI reboot by default
>>>> with an ACPI cutoff date; this doesn't have any such cutoff.
>>>
>>> Windows doesn't either. Older machines simply won't have the appropriate
>>> flag set in their FADT.
>>>
>>
>> Windows doesn't get validated on old hardware.
>
> XP does this, and older hardware predates the version of the ACPI spec
> that introduced this flag.
>

ACPI is very buggy on early implementations, presumably because WHQL had 
not yet been extended to include it.  That is exactly why we combine 
these kinds of things with a date check.

	-hpa

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