Apm - Novell LINUX ENTERPRISE SERVER 10 SP2 - INSTALLATION AND ADMINISTRATION Installation Manual

with the duration of the sleep periods. Other components, like PCI devices that can
be put into a special power saving mode, can be deactivated with ACPI (at least
theoretically) or permanently disabled in the BIOS setup.
Processor Speed Control
In connection with the CPU, energy can be saved in three different ways: frequency
and voltage scaling (also known as PowerNow! or Speedstep), throttling, and
putting the processor to sleep (C states). Depending on the operating mode of the
computer, these methods can also be combined.

28.2 APM

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 Enterprise® 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 disabled with acpi=off at the boot prompt.
Enter cat /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 shutdown -h.
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 apm=parameter with parameter
being one of:
Power Management 509