How to make ACPI work

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Revision as of 14:54, 23 March 2006 by Ozi23 (Talk | contribs) (Kernel configuration)

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general

Kernel configuration

First of all you'll have to enable ACPI support in your kernel (if your distro doesn't already have an ACPI enabled kernel). To do this open your kernel config and enable ACPI Power Management:

Power management options → <*>Power Management support (CONFIG_PM)
Power management options → <*>ACPI (CONFIG_ACPI_SLEEP)

You'd most likely want to enable the following ACPI options:

Power management options → ACPI → <*>Sleep States (CONFIG_ACPI_SLEEP)
Power management options → ACPI → <*>AC Adapter (CONFIG_ACPI_AC)
Power management options → ACPI → <*>Battery (CONFIG_ACPI_BATTERY)
Power management options → ACPI → <*>Fan (CONFIG_ACPI_FAN)
Power management options → ACPI → <*>Processor (CONFIG_ACPI_PROCESSOR)
Power management options → ACPI → <*>Thermal Zone (CONFIG_ACPI_THERMAL)

If you prefer editing your .config file directly, you should set at least the following variables:

CONFIG_PM=y
CONFIG_ACPI_BOOT=y
CONFIG_ACPI_INTERPRETER=y
CONFIG_ACPI_SLEEP=y
CONFIG_ACPI_SLEEP_PROC_FS=y
CONFIG_ACPI_AC=y
CONFIG_ACPI_BATTERY=y
CONFIG_ACPI_BUTTON=y
CONFIG_ACPI_FAN=y
CONFIG_ACPI_PROCESSOR=y
CONFIG_ACPI_THERMAL=y
CONFIG_ACPI_BUS=y
CONFIG_ACPI_EC=y
CONFIG_ACPI_POWER=y
CONFIG_ACPI_PCI=y
CONFIG_ACPI_SYSTEM=y

Then recompile your kernel.

Hint:
ACPI SLEEP option did only show up for me after patching Software Suspend 2 into the kernel .

IBM specific ACPI driver

Unfortunately, special drivers for ACPI on ThinkPads were not included with kernels prior 2.6.10. So you'll have to compile one yourself or get it as precompiled module for your kernel.

You have the choice between thinkpad-acpi and ibm-acpi, with the latter being the recommended one.

If you use a post-2.6.10 kernel and you want to use ibm-acpi, it is recommended to look on its projects page for a possibly newer version.

Hint:
Generally it is a good idea to read the README included with the driver.

ACPI daemon

Also you'll need to install acpid, if it isn't present on your system. acpid is a daemon that handles the ACPI events generated by the system. Read How to configure acpid.

Screen blanking (Standby)

Make sure you have

Option "DPMS"

in the Monitor section of your /etc/X11/XF86Config or /etc/X11/xorg.conf.

Running $ xset +dpms and then $ xset dpms force off will turn off the backlight on a laptop screen.

Note that this may not work in combination with $ echo -n "mem" > /sys/power/state because switching to console causes the backlight to come back on before sleeping.

Suspend to RAM (Sleep)

ACPI Sleep/suspend-to-ram with recent 2.6.x kernels usually works fine. Have a look at the acpid configuration HOWTO. It includes a specific example for going to sleep on lid close.

The following glitches may or may not occur in relation to suspending to RAM:

  • If your suspend is failing, and a # tail /var/log/acpid shows "Permission denied" errors, be sure that your new ACPI event and action scripts have the appropriate permissions.
  • When resuming from a suspend-to-ram the display might remain black or might only show the pre-suspend output (the system is still rebootable via ctrlaltdel). Look here for solutions.
  • When your system is equiped with a Radeon Mobility graphic controller your LCD backlight may not turn off automatically. Use radeontool to switch off your backlight prior suspend in your sleep action script.
  • Also, you might want to take note of the Problem with high power drain in ACPI sleep.
  • You may experience problems when using # echo standby > /sys/power/state or # echo mem > /sys/power/state (machine goes to sleep and wakes up immediately). This can be avoided by using # echo -n 3 >/proc/acpi/sleep to get it to sleep. This can be also happen if hotplug daemon is still running.
  • If you're running MySQL, sleep may also not work, so stop MySQL first, then sleep. Remember to restart MySQL when you wakeup.
  • Problems with the serial port of the port replicator after the wake up from ram have also been experienced.
  • Problems with the parallel port after wake up from ram have been experienced. (Possible Fix: rmmod lp parport_pc parport / modprobe lp)
  • Problems with the CD-RW/DVD after wake up from ram have been experienced.
  • Crash on resume
    • ...when using ATI proprietary drivers can be solved by using vbetool. Note that this is no longer necessary with recent revisions of the ATI proprietary driver.
    • ...might be solved by disabling APIC (@Processor type and features) in the kernel configuration
    • ...when using Savage chipset, might be solved by disabling savagefb (or compiling as a module) in favor of vesafb
  • Due to the fact that Sonoma chipset based laptops (R52, T43, T43p, X41, X41 Tablet) utilize the SATA layer for disk access and SATA does not have power-management support yet Suspend to RAM does not work on these machines. See the according section on the Problems with SATA and Linux page.

Suspend to disk (Hibernate)

There are two drivers for this available:

  • swsusp, which is in the kernel and
  • Software Suspend 2 which is more feature rich, but not yet in the kernel, so you have to patch it in yourself

Both are reported to work fine as long as you use open-source graphic drivers. A comparison of the features can be found on this page.

Just in case you are in doubt...yes, it is safe in both cases to use the same swap partition as active swap and as suspend partition.

using swsusp

See swsusp.

using Software Suspend 2

See Software Suspend 2.

ThinkPads on which it is recommended to use ACPI