19.4.1 ACPI Activated with Hardware
Support but Functions Do Not Work
If you experience problems with ACPI, search the output of dmesg for ACPI-specic
messages by using the command dmesg|grep -i acpi.
A BIOS update may be required to resolve the problem. Go to the home page of your
laptop manufacturer, look for an updated BIOS version, and install it. Ask the manufac-
turer to comply with the latest ACPI specication. If the errors persist after the BIOS
update, proceed as follows to replace the faulty DSDT table in your BIOS with an up-
dated DSDT:
Procedure 19.1
Updating the DSDT Table in the BIOS
For the procedure below, make sure the following packages are installed:
kernel-source, acpica, and mkinitrd.
1
Download the DSDT for your system from http://acpi.sourceforge.net/
dsdt/index.php. Check if the le is decompressed and compiled as shown by
the le extension .aml (ACPI machine language). If this is the case, continue with
step 3.
2
If the le extension of the downloaded table is .asl (ACPI source language) instead,
compile it by executing the following command:
iasl -sa file.asl
3
Copy the (resulting) le DSDT.aml to any location (/etc/DSDT.aml is recom-
mended).
4
Edit /etc/sysconfig/kernel and adapt the path to the DSDT le accordingly.
5
Start mkinitrd. Whenever you install the kernel and use mkinitrd to create an
initrd le, the modied DSDT is integrated and loaded when the system is
booted.
358 Reference
