You need ACPI or APM for soft power-down.

[James Wilkinson]

I wrote:
> As for the poweroff, you need APM or ACPI for this to work. APM doesn't
> work in SMP mode (there's a line in the kernel messages you posted
> saying as much), and you've just turned off ACPI for nearly everything.
> 
> You will probably have turned off hibernation support and *possibly*
> some power-saving support when you disabled ACPI.

Antonio Montagnani wrote:
> no idea how I could have disabled any flag to disable poweroff, any 
> suggestion?

Um. Let me try again.

Soft power-down isn't a standard part of a PC. Linux doesn't know how to
do it without APM or ACPI.

APM is out the question on SMP, due to the way it's designed.

So you need ACPI properly working for soft power-down.

You've added acpi=ht to the kernel boot flags.

This is defined as "ht -- run only enough ACPI to enable Hyper
Threading" (in /usr/src/linux/Documentation/kernel-parameters.txt). In
other words -- not enough to do soft power-down.

James.

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