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Chapter 11, Hardware
#96 Control Your Power with ACPI
HACK
HACK
#96
Control Your Power with ACPI Hack #96
Extend the life of your laptop battery by limiting your computer’s appetite for
power.
The Advanced Configuration and Power Interface (ACPI) is an open indus-
try specification that allows for power management on laptops, desktops,
and servers. Compaq/Hewlett-Packard, Intel, Microsoft, Phoenix, and
Toshiba first released it in 1996. These developers aimed to replace
Advanced Power Management (APM), the previous industry standard for
power management.
You can configure ACPI and control it from within the operating system.
This is a step forward from APM, which was affected only by system idle
time and could be configured only from within the BIOS screens during star-
tup. ACPI can be used by most new laptops, although some brands have
specific configuration issues. Be sure to do a web search for your specific
machine to see what limitations your system has.
ACPI has several different software components:
• A subsystem, which monitors and affects hardware, including thermal
control, motherboard configuration, and power states
• A policy manager, which allows the user to modify system states
• Drivers to control and monitor devices, such as laptop batteries, SMBus
(communications/transmission path), and EC (embedded controller)
Installing ACPI
A number of things must be in place to use ACPI successfully. ...