Re: [PATCH] x86: Add reboot quirk for Dell Precision M4600
From: Bruno Friedmann
Date: Mon Aug 08 2011 - 18:50:13 EST
On 08/08/2011 06:40 PM, H. Peter Anvin wrote:
> On 08/06/2011 10:30 AM, Matthew Garrett wrote:
>> On Sat, Aug 06, 2011 at 08:56:35AM +0200, Ingo Molnar wrote:
>>> Weird - ACPI is the default Windows method of reboot - how come it
>>> does not work on that box? Does Windows work around this specific
>>> machine (unlikely), or is our ACPI boot sequence not 100% compatible
>>> with the Windows method (more likely IMO)?
>> The ACPI reboot method on these machines hits the keyboard controller
>> rather than PCI, which is unusual. What I suspect is that the write
>> triggers some SMM or EC code that's making assumptions about system
>> state, and we're not quite identical. Bouncing on the keyboard
>> controller from userspace with init=/bin/bash wedges in the same way.
> I have a vague suspicion that Windows might have a meta-quirk for this
> class of machines, i.e. if the ACPI reboot method, say, points at the
> keyboard controller or points at the "PCI" reboot port then it actually
> uses its own special-purpose routines rather than general routines. It
> would be extremely interesting to know if "reboot=kbd" works on these boxen.
Ok I will try to activate reboot=kbd tomorrow morning and report the result about it.
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