Runlevels and poweroff

Kevin P. Fleming kpfleming at
Sat Sep 25 12:18:37 PDT 2004

Jeremy Utley wrote:

> To enable the system to power off, there's a kernel setting in the APM 
> section that allows this to work.  It's something to the effect of 
> "Allow real mode BIOS calls to power off" or something to that effect.  
> Make sure that's enabled.

Actually, there are a number of settings that can be used to support 
this, depending on the system.

At a minimum, "Power Management support" must be turned on.

Then, if your system support APM, you can turn on "APM BIOS support". 
For many machines, that will be enough. Some APM BIOSes are buggy, 
though, and require the "real mode APM BIOS call to power off" setting 
that Jeremy referred to.

Alternatively, if your system supports ACPI (as most recent 
systems/motherboards do), you can turn on "ACPI support" instead of APM 
support. Again, this will usually be enough to get the system to be able 
to power itself off.

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