What is acpi?
"In computing, the Advanced Configuration and Power Interface (ACPI) specification provides an open standard for device configuration and power management by the operating system." (Wikipedia)
What is acpid?
"ACPID is a completely flexible, totally extensible daemon for delivering ACPI events. It listens on a file (
/proc/acpi/event) and when an event occurs, executes programs to handle the event. The programs it executes are configured through a set of configuration files, which can be dropped into place by packages or by the admin." (acpid Sourceforge)
Preparing to install
Before we are ready to emerge acpid, it is a good idea to modify a few things in the kernel. If you have not modified your kernel before, you may want to check out the following page on configuring a kernel manually (page to be added..).
Optional: Other ACPI features
Below are the locations and short descriptions of the function of different ACPI options in the kernel. In the majority of cases, you do not have to alter any of these to have a functional ACPI system.
- AC Adapter
If you have a system that can switch between being plugged into AC and using a battery (i.e. a laptop), you should compile this option into your kernel.
As its name would suggest, this option adds or removes support for the battery. More specifically, through /proc/acpi/battery. If you have a laptop or other mobile system, you should probably compile this into your kernel.
This driver handles power, sleep, and other buttons. This driver is recommended because it is necessary for software controlled power-off.
Implements ACPI extensions for integrated graphics devices. Also adds support for setting up a video output.
Allows user-controlled applications to control fan speeds and access status of fans.
Builds support in the kernel for docking stations like the Dell Module Bay and the IBM Ultrabay.
Helps save power while processor is idling and is required by several cpufreq drivers.
- Processor Aggregator
Allows the host system to practice logical processor idling (a way to reduce power consumption)
- Thermal Zone
Enables support for ACPI thermal zones. It is encouraged to enable this option, as your system may be damaged without it.
After configuring the kernel power management options, we are ready to install ACPI Daemon. To install acpid, run the following command:
# emerge acpid
Adding to rc
After you have finished emerging acpid, you may want to add it to the list of rc services to be started with your system at boot.
# rc-update add acpid default * service acpid added to runlevel default
Then, run the following to start acpid:
# rc * starting acpid ...