Advanced Configuration and Power Interface - acpi

ACPI Event

acpi_listen

Backlight

$ ls /sys/class/backlight/

# echo 4000 > /sys/class/backlight/intel_backlight/brightness

Debugging Kernel Suspend

In order to simulate your suspend/resume process, enter the following commands:

sudo sh -c "sync && echo 1 > /sys/power/pm_trace && pm-suspend"

At this point your computer should enter the suspend state within a few seconds. Usually the power LED will slowly flash when in the suspended state. When that has happened, initiate the resume process by pressing the power button. Observe closely if the disk light comes on briefly. This indicates that resume has begun. If resume fails to complete, then press the power button until the computer turns off. Power on your computer making sure that it loads the same kernel that exhibited the resume problem. You have about 3 minutes to start this boot process before the information saved in the RTC gets corrupted.

Start a console and enter:

dmesg > dmesg.txt

64515.883724] ACPI: Waking up from system sleep state S3

Patching ACPI tables

• acpidump / acpixtract

First extract tables:

acpidump > acpidump.hex
acpixtract -a acpidump.hex

Alternative way to extract table through kernel:

cat /sys/firmware/acpi/tables/DSDT > dsdt.dat

Decompile tables with iasl / doc / Fork of Intel’s iasl

iasl -fe refs.txt -da dsdt.dat ssdt*.dat

DSDT

Differentiated System Description Table supplies information about supported power events in a given system.