| Rafael J. Wysocki | 40b4ac3 | 2008-07-23 21:28:36 -0700 | [diff] [blame] | 1 | APM or ACPI? |
| 2 | ------------ |
| 3 | If you have a relatively recent x86 mobile, desktop, or server system, |
| 4 | odds are it supports either Advanced Power Management (APM) or |
| 5 | Advanced Configuration and Power Interface (ACPI). ACPI is the newer |
| 6 | of the two technologies and puts power management in the hands of the |
| 7 | operating system, allowing for more intelligent power management than |
| 8 | is possible with BIOS controlled APM. |
| 9 | |
| 10 | The best way to determine which, if either, your system supports is to |
| 11 | build a kernel with both ACPI and APM enabled (as of 2.3.x ACPI is |
| 12 | enabled by default). If a working ACPI implementation is found, the |
| 13 | ACPI driver will override and disable APM, otherwise the APM driver |
| 14 | will be used. |
| 15 | |
| 16 | No, sorry, you cannot have both ACPI and APM enabled and running at |
| 17 | once. Some people with broken ACPI or broken APM implementations |
| 18 | would like to use both to get a full set of working features, but you |
| 19 | simply cannot mix and match the two. Only one power management |
| 20 | interface can be in control of the machine at once. Think about it.. |
| 21 | |
| 22 | User-space Daemons |
| 23 | ------------------ |
| 24 | Both APM and ACPI rely on user-space daemons, apmd and acpid |
| 25 | respectively, to be completely functional. Obtain both of these |
| 26 | daemons from your Linux distribution or from the Internet (see below) |
| 27 | and be sure that they are started sometime in the system boot process. |
| 28 | Go ahead and start both. If ACPI or APM is not available on your |
| 29 | system the associated daemon will exit gracefully. |
| 30 | |
| 31 | apmd: http://worldvisions.ca/~apenwarr/apmd/ |
| 32 | acpid: http://acpid.sf.net/ |