Re: [PATCH 1/3] X86: Revamp reboot behaviour to match Windows more closely

H. Peter Anvin
2010-12-09T22:40:20Z

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