Some of the power saving functions are performed by the APM BIOS itself. On many laptops, standby and suspend states can be activated with key combinations or by closing the lid without any special operating system function. However, to activate these modes with a command, certain actions must be triggered before the system is suspended. To view the battery charge level, you need special program packages and a suitable kernel.
SUSE Linux kernels have built-in APM support.
However, APM is only activated if ACPI is not implemented in the
BIOS and an APM BIOS is detected. To activate APM support, ACPI must be
acpi=off at the boot prompt. Enter
/proc/apm to check if APM is
active. An output consisting of various numbers indicates that everything is
OK. You should now be able to shut down the computer with the command
BIOS implementations that are not fully standard-compliant can cause
problems with APM. Some problems can be circumvented with special boot
parameters. All parameters are entered at the boot prompt in the form of
parameter is one of:
Enable or disable APM support.
Allow interrupts during the execution of BIOS functions.
The “GetPowerStatus” function of the BIOS does not work properly.
Reset processor to real mode prior to shutdown.
Log APM events in system log.
Power system off after shutdown.
Time in hundredths of a second after a suspend event during which additional suspend events are ignored.
System inactivity percentage from which the BIOS function idle is executed (0=always, 100=never).
Time in hundredths of a second after which the system activity is measured.
The APM daemon (apmd) is no longer used. Its functionality is now handled by the new powersaved, which also supports ACPI and provides many other features.