How to make ACPI work
- 1 General
- 2 Screen blanking (Standby)
- 3 Suspend to RAM (Sleep)
- 4 Suspend to disk (Hibernate)
- 5 Troubleshooting
- 6 ThinkPads on which it is recommended to use ACPI
First, simply try using the power management features of Linux on your computer. Tell Linux to suspend (System > Preferences > Power Management in Gnome). Try closing the lid. ACPI may already work.
ACPI requires a relatively new BIOS version. In particular, if you get the message,
ACPI: Could not use ECDT
during startup, you probably need a BIOS Upgrade. For example, a BIOS upgrade from version 1.02 to 1.10 was all that was needed for ACPI to start working on an A31 2652 running Red Hat Enterprise Linux 5 (CentOS 5).
Many Kernel 2.6 distributions like Red Hat Enterprise Linux 5 (Centos 5) have ACPI built in and ready to go. If not, you must enable ACPI support in your 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 Support (CONFIG_ACPI)
You'd most likely want to enable the following ACPI options:
- Power management options → <*>Suspend to RAM and standby (CONFIG_SUSPEND)
- Power management options → ACPI → <*>AC Adapter (CONFIG_ACPI_AC)
- Power management options → ACPI → <*>Battery (CONFIG_ACPI_BATTERY)
- Power management options → ACPI → <*>Button (CONFIG_ACPI_BUTTON)
- 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=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_BLACKLIRG_YEAR=0 CONFIG_ACPI_EC=y CONFIG_ACPI_POWER=y CONFIG_ACPI_SYSTEM=y
Then recompile your kernel.
Kernel boot parameters
Many ThinkPads have been hit by a recent (kernel 2.6.16) change to ACPI4Linux that changed the default means of accessing the ACPI Embedded Controller as a way to shake out underlying bugs in the EC access code. If your ThinkPad fails to resume properly (a blinking Sleep light on resume that doesn't go away, or a hang when trying to suspend/standby a second time), adding
ec_intr=0 to your kernel command line may help.
ThinkPad specific ACPI driver
If you are using kernel version 2.6.22 and later, please use the thinkpad-acpi driver included with the kernel.
Backlight problems with post-2.6.26 kernels
According to [this thread], users with 2.6.26 kernel and higher may experience problems with ThinkPad backlight contols (Fn+Home, Fn+End on T61). The symptoms are:
- backlight brightness controls do not work;
- Using acpi_listen command, there is no reaction for brightness down button, but brightenss up gives:
ibm/hotkey HKEY 00000080 00001010
The solution is that one needs to enable `CONFIG_VIDEO_OUTPUT_CONTROL`:
Device Drivers ---> Graphics Support ---> <*> Lowlevel video output switch controls
Subsequently one should enable 'CONFIG_ACPI_VIDEO':
Power Management Options ---> [*] ACPI (Advanced Configuration and Power Interface) Support ---> <*> Video
ACPI S4 hardware signature mismatch
Around kernel 2.6.27, a feature was introduced to check the hardware signature on resume from S4 (hibernate). This feature might be broken on some models. Resume will halt and the following error message is shown:
- ACPI: Hardware changed while hibernated, cannot resume!
- Kernel panic - not syncing: ACPI S4 hardware signature mismatch
To fix it, add the following kernel parameter:
This problem appeared here on a T42p, but only if the power is unplugged while hibernated, even if the battery is still plugged. Another sympton is, that resume hangs with a dark screen if the acpi_cpufreq module is loaded, even if the power is not unplugged while hibernated. With the above mentioned kernel parameter, both problems go away.
Screen blanking (Standby)
Make sure you have
in the Monitor section of your /etc/X11/XF86Config or /etc/X11/xorg.conf.
$ 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.
For Troubleshooting, look at the Problems with ACPI suspend-to-ram page.
Suspend to disk (Hibernate)
There are two drivers for this available:
- swsusp, which is in the kernel and
- TuxOnIce 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.
See the according drivers page for instructions.
Machine reboots after shutting down
Try removing ehci_hcd before shutting down, eg, add the following line to rc.local.shutdown
ThinkPads on which it is recommended to use ACPI
- ThinkPad 770X, 770Z
- ThinkPad A20m, A20p, A20m, A20p, A21e, A21m, A21p, A22e, A22m, A22p, A30, A30p, A31, A31p
- ThinkPad G40, G41
- ThinkPad R30, R31, R32, R40, R40e, R50, R50e, R50p, R51, R52, R60
- ThinkPad T22, T23, T30, T40, T40p, T41, T41p, T42, T42p, T43, T43p, T61
- ThinkPad X20, X21, X22, X23, X24, X30, X31, X32, X40, X41, X41 Tablet
- ThinkPad Z60t, Z60m, Z61m
- ThinkPad X60s
- ThinkPad TransNote
- ThinkPad T20 and T21 have old ACPI implementations, but there have been some reports of using ACPI successfully on these models with Ubuntu and Mandriva in particular. Check the related pages about installing Linux on these models for details.