From: Matthew Garrett <mjg59@srcf.ucam.org>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org, linux-acpi@vger.kernel.org, lenb@kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/3] X86: Revamp reboot behaviour to match Windows more closely
Date: Thu, 9 Dec 2010 22:58:33 +0000 [thread overview]
Message-ID: <20101209225833.GA25750@srcf.ucam.org> (raw)
In-Reply-To: <4D015DEF.9000302@zytor.com>
On Thu, Dec 09, 2010 at 02:53:35PM -0800, H. Peter Anvin wrote:
> On 12/09/2010 02:51 PM, Matthew Garrett wrote:
>> I'm afraid I don't understand your argument. The date cutoff would be on
>> the order of 2001 (anything after this will have been tested with XP).
>> The spec that defines this behaviour only came into existence in August
>> 2000, and any older hardware will be missing the flag that indicates
>> that this feature is supported. It doesn't seem realistic to believe
>> that there's any real body of hardware that sets the flag but otherwise
>> has a broken implementation.
>>
>
> 2001 is probably a good date, then.
>
> It's pretty safe you'll see the bit being set on systems which are older
> than that, even if it was not defined at the time it was created -- just
> being garbage. That's par for the course in BIOS land.
There's a revision field in the FADT. They'd need to simultaneously
provide an incorrect revision *and* by pure luck set the 10th bit of a
32-bit register. Is it possible? Yes. Is it likely? No, and I don't see
a benefit in adding extra code to force hardware into a less-tested
configuration.
--
Matthew Garrett | mjg59@srcf.ucam.org
prev parent reply other threads:[~2010-12-09 22:58 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-12-09 21:46 [PATCH 1/3] X86: Revamp reboot behaviour to match Windows more closely Matthew Garrett
2010-12-09 21:46 ` [PATCH 2/3] ACPICA: Fix access width for reset vector Matthew Garrett
2010-12-09 22:41 ` Rafael J. Wysocki
2010-12-09 23:12 ` H. Peter Anvin
2010-12-09 23:26 ` Matthew Garrett
2010-12-09 21:46 ` [PATCH 3/3] ACPI: Bug compatibility for Windows on the ACPI reboot vector Matthew Garrett
2010-12-09 22:36 ` H. Peter Anvin
2010-12-09 22:41 ` Rafael J. Wysocki
2010-12-09 22:25 ` [PATCH 1/3] X86: Revamp reboot behaviour to match Windows more closely H. Peter Anvin
2010-12-09 22:32 ` Matthew Garrett
2010-12-09 22:32 ` H. Peter Anvin
2010-12-09 22:38 ` Matthew Garrett
2010-12-09 22:40 ` H. Peter Anvin
2010-12-09 22:51 ` Matthew Garrett
2010-12-09 22:53 ` H. Peter Anvin
2010-12-09 22:58 ` Matthew Garrett [this message]
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