RELENG_6 power button ignored after halt if ACPI enabled

[Dana H. Myers]

Bruno Ducrot wrote:
> On Thu, Sep 21, 2006 at 03:28:55PM -0700, Nate Lawson wrote:
>> Wilkinson, Alex wrote:
>>>    0n Sun, Sep 17, 2006 at 10:29:26PM -0700, Nate Lawson wrote: 
>>>
>>>    >Try setting this sysctl:
>>>    >sysctl hw.acpi.disable_on_reboot=1
>>>    >
>>>    >It may be that you need acpi to stop managing your power button after 
>>>    halt.
>>>
>>> I dont get it ? I thought you needed ACPI to do the actual shutdown ?
>> He isn't doing halt -p, he's doing "halt", then hitting the power 
>> button.  If acpi is still enabled, it intercepts the button event but 
>> can't do anything because the OS is halted (i.e. no shutdown() 
>> available).  If ACPI is disabled by that point, the BIOS handles it and 
>> powers off the system.
>>
>> This only applies to his system, it's not necessarily true in general. 
>> Some systems won't work if ACPI is disabled during this process, hence 
>> the sysctl.

> 
> When ACPI mode is enabled, the system should power off after 4 seconds IIRC.

Not exactly; regardless of ACPI mode, the system should always power-off
if the power button is held down for 4 seconds (though some systems have been
known to require longer than 4 seconds).  This is a hardware over-ride in
the chipset to deal with the case that software fails (whether it's BIOS/SMI
code in legacy mode, or the OS/BIOS/SMI code in ACPI mode).

Dana