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Date: Sat, 6 Dec 2008 21:01:26 -0500
From: Bruce Cran <bruce@cran.org.uk>
To: Unga <unga888@yahoo.com>
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Cc: freebsd-questions@freebsd.org
Subject: Re: FreeBSD cannot power down
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On Thu, Dec 04, 2008 at 03:42:51AM -0800, Unga wrote:
> --- On Tue, 12/2/08, Unga <unga888@yahoo.com> wrote:
> 
> > From: Unga <unga888@yahoo.com>
> > Subject: FreeBSD cannot power down
> > To: freebsd-questions@freebsd.org
> > Date: Tuesday, December 2, 2008, 11:22 PM
> > Hi all
> > 
> > After a kernel recompilation on i386 RELENG_7 (not the
> > latest), I cannot power down the machine.
> > 
> > kldstat shows acpi.ko is loaded.
> > 
> > It used to switch off but now the "shutdown -p
> > now" halts the system with following messages:
> > The operating system has halted.
> > Please press any key to reboot.
> > 
> > What else could I check to identify the cause? 
> > 
> > Appreciate your ideas on this.
> > 
> 
> I had a look at source code. The program flow seems to be is as follows:
> 
> shutdown => (signals) init => reboot() => boot() => shutdown_final => shutdown_halt() => cpu_halt()
> 
> I did not see which function is called to request a power down.
> 
> The __asm__ ("hlt") doesn't power down, isn't it?
> 
> Could you guys help me to identify how shutdown request a power down.
> 

HLT is just an old power-saving instruction that was traditionally run 
in the idle loop.  From reading the code it looks like the system 
should be powered off during poweroff_wait but I can't see where ACPI is 
told to remove power.   You might get more help by asking on the 
freebsd-acpi list.

-- 
Bruce Cran