Re: ACPI on Tyan Motherboard

From: John Baldwin <jhb_at_FreeBSD.org>
Date: Wed, 20 Aug 2003 13:24:59 -0400 (EDT)
On 19-Aug-2003 David Xu wrote:
> On Wednesday 20 August 2003 02:49, John Baldwin wrote:
>>
>> Here's how it works:  The BIOS/hardware monitor the power button.  When an
>> OS tells the BIOS that it is ACPI, then the BIOS doesn't do an instant turn
>> off when the power button is pressed, but waits to do so until the power
>> button has been held down for 4 seconds.  If the power button after 4
>> seconds doesn't work, it's still a hardware problem.  FreeBSD can not fix
>> your hardware problem.  When you press the power button with an ACPI OS
>> running, the hardware sends an interrupt to the OS.  The OS then shuts down
>> and asks the BIOS (via ACPI) to power off the machine.  If the machine
>> doesn't physically turn off, it's because your BIOS is screwed up and
>> didn't handle the power down command properly.  The fact that the 4 second
>> trick (which as above bypasses FreeBSD completely and has the BIOS call
>> that power down method itself) produces the same broken results means that
>> this bug is in your hardware.
>>
>> FreeBSD sleeps for a bit when it does a halt -p as a workaround for broken
>> IDE disks which claim that writes have hit the media when they are still in
>> the disks cache, so that is a separate issue.
>>
>> If you want more info on ACPI and how it works, feel free to head on over
>> to www.acpi.info and read the spec for yourself.
> 
> Windows 2000 can shutdown my Tiger 230T in very short time, while FreeBSD
> is always timeouted with halt -p.
> I dont't think it is hardware or BIOS problem, FreeBSD must be wrong in 
> something, just like FreeBSD ATA bug for my Tiger 230T, all OS I have in
> hand work fine, only FreeBSD does not.

In this case, David, the machine still screws up even with the hardware
4 second override.  FreeBSD has no possible control over the override,
that is _only_ handled in hardware and the BIOS.

-- 

John Baldwin <jhb_at_FreeBSD.org>  <><  http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve!"  -  http://www.FreeBSD.org/
Received on Wed Aug 20 2003 - 08:24:40 UTC

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