In the past week I have worked a lot to try to resolve some problems
regarding the use of the Power Management on my laptop. Thanks to google I
find a lot of useful information but I was unable to find a real definitive
solution for this kind of laptop.
The problem are:
1- This kind of laptops doesn't support APM (Advanced Power
Management) but only ACPI (Advanced Configuration and Power Interface)
2- Today many company build their BIOS only supporting
Microsoft OS, so they are incompatible with some standard used by every other
OS
3- I can't find anything in the directories /proc/acpi/ac_adapter and /proc/acpi/battery
so I was unable to see the status of my battery and I can't implement the
functionality of ACPI on my system
4- The DSDT (se below) resulted to be bugged, I had to
correct it
5- There is a missing ECDT (see below) on my system so I have
had to patch the kernel to resolve this problem
6- Acer Laptops uses a so called Smart Batteries that have a
different way to work
INTRO
What is DSDT?
Differentiated System Description Table (DSDT), from the ACPI Spec we can have
this definition: "An OEM must supply a DSDT to an ACPI-compatible OS. The
DSDT contains the Differentiated Definition Block, which supplies the
implementation and configuration information about the base system. The OS
always inserts the DSDT information into the ACPI Namespace at system boot
time and never removes it."
DSDT describes simply the hardware configuration of your system. It
describe all the functionality of ACPI and the devices that use it. Every OS
can extract it from the BIOS of your sytem.
What is ACPI?
Advanced Configuration and Power Interface (ACPI) is the
successor to APM, which places the responsibility of power management away
from the BIOS and into the hands of the operating system. ACPI Linux is newer
than APM Linux, more flexible in responding to power management events, has
seen much more development as of late, and as a result of all this is prone to
its own share of bugs from time to time.
ACPI site at sourceforge -
http://sourceforge.net/projects/acpi
acpi specification -
http://www.acpi.info/index.html
What is a ECDT?
The ECDT (Embedded Control Description Table) is used to provide some minimal information about the
Embedded Controller to the ACPI drivers before the Embedded Controller region
has actually been parsed from the DSDT.
Disclaimer
This document is not an official one, I have resolved my problem following
these steps but I don't guarantee anithing for you. Use this document as an
example and follow these instructions only if you know what you are doing. If
you want to try please conseder that you can broke your system. For official
assistance please contact your laptop constructors of the official ACPI
developers. I describe only the problem i found, I corrected them based on
what I have found on internet, I can't be sure everything is ok. Be careful!!
Tested System
I use Suse 9.3 Pro with its original kernel. But I think that with the
appropriate modifications you can apply this technique to other system
My laptop is Acer Aspire 1681WLCi, I'm not sure but I think for 1680 series is
the same
I have the version 20050513 of the Intel's iasl compiler
FIX BROKEN DSDT
1) Download the latest sbs-cm tgz-archive from http://sourceforge.net/projects/sbs-linux
2) Download the Intel's iasl compiler from http://developer.intel.com/technology/iapc/acpi/downloads.htm
3) Install iasl compiler
# tar xfz acpica-unix-20050513.tar.gz
# cd acpica-unix-20050513/compiler
# make
If everything is fine, you should have a binary file called "iasl" in this
directory. Copy it anywhere to your $PATH or remind where it's located.
4) Extract the current DSDT from your running kernel
#cat /proc/acpi/dsdt > dsdt.dat
This will give you a file, dsdt.dat that contains your current compiled dsdt. Now we have to disassemble it so we can recompile it.
5) Disassemble the DSDT
#PATH_TO_IASL/iasl -d dsdt.dat
This will create a file called dsdt.dsl, which contains the disassembled DSDT. You are able to see it with common text editor.
6) Recompile the disassembled DSDT
#PATH_TO_IASL/iasl -tc
dsdt.dsl
If it works it will create two files, dsdt.hex and DSDT.aml. But probably if
you are following these steps it doesn't work properly, and the compiler stops
with some errors.
You can find some fixed dsdt
at this address:
-
http://acpi.sourceforge.net/dsdt/view.php?id=140
I resolve my problems and I made a tar.gz file with
the fixed DSDT. There you can find it fixed for the other steps of this
document with two patches (see below). To have it please download:
- dsdtAspire1680.tar.gz
To solve other kind of problems have a look at:
-
www.google.it
-
http://forums.gentoo.org/viewtopic.php?t=122145
-
http://www.cpqlinux.com/acpi-howto.html#fix_broken_dsdt
7) Patch your fixed DSDT:
At this address
https://sourceforge.net/projects/sbs-linux/ you can find the
SourceForge project dedicate to Smart Battery System (SBS). It works to solve
the problems of that laptops that use this kind of battery. There you can find the
official patch, but
it doesn't work on 1680 series if you don't modify before the dsdt. In the file dsdtAspire1680.tar.gz you
can
find the work already done, you have only to untar the archive and follow next steps.
If you want to patch your dsdt follow these simple steps:
7a) Patch dsdt.dsl with the patches from sbs-cm (verify, that all .asl
files and the diff file of your choice is in the same directory as dsdt.dsl)
# cd PATH_TO_PATCH_AND_DSDT.DSL
# patch <acer-tm4xxx-sbs-cm.diff
patching file dsdt.dsl
#
7b) Compile the modified dsdt.dsl with iasl - Follow the step 6
8) Add the fixed DSDT into the kernel, there are several ways to follow to do this work:
If you are using SuSe 9.3 there are non problems
8a) copy the compiled DSDT.aml
file e.g. to /etc
8b) add the path pointing to
e.g. /etc/DSDT.aml to /etc/sysconfig/kernel
ACPI_DSDT="/etc/DSDT.aml"
If you are not using Suse visit
http://forums.gentoo.org/viewtopic.php?t=122145 on this forum you can
find at chapter 9 some useful ways to follow.
9) Patch your kernel source code:
This kind of Laptops has another problem over the bugged DSDT, there is a
missing ECDT. The ECDT is used to provide some minimal information about the
Embedded Controller to the ACPI drivers before the Embedded Controller region
has actually been parsed from the DSDT. This is frequently necessary before
initializing the battery and ac adapter, so if you have errors in dmesg from
the battery, adapter or EmbeddedControl, the ECDT is the likely culprit. The
problem was that after booting, my /proc/acpi/ac_adapter and /proc/acpi/battery
directories were empty.
To resolve this problem there is a patch at this address
http://bugzilla.kernel.org/attachment.cgi?id=1690&action=view. This
patch restore the missing ECDT-related functionality. It may be applied to
both the 2.4 and 2.6 kernel source.
If you are using Suse 9.3 it doesn't work,
because the sources file name change, but the code is the same. In the file
acpi_patch.tar.gz you can find all the corrected files you need, you have only
to copy them into the appropriate directory of your system (after a back-up of
existing files!! - Naturally! ;P ).
I don't have the knowledge of how to make a patch, so I include in the tar
archive a file called "differences.txt". It is an approximation of a patch, I
hope someone is able to build one and send it to me.
Download: acpi_patch.tar.gz
Files to modify:
#################################
1) PATH_TO_KERNEL/drivers/acpi/ec.c
2) PATH_TO_KERNEL/drivers/acpi/events/evregion.c
3) PATH_TO_KERNEL/drivers/acpi/executer/exregion.c
4) PATH_TO_KERNEL/drivers/acpi/utilities/utglobal.c
5) PATH_TO_KERNEL/include/acpi/acglobal.h
6) PATH_TO_KERNEL/include/acpi/acinterp.h
Probably you have to change the "PATH_TO_KERNEL" with "/usr/src/linux", but is
better that you follow your system documentation.
10) Make sure you followed the steps 1, 2, 3, 4, 5, 6, 7, 8, 9
11) Recompile your kernel. If you don't know how
to do please refer to an official guide for your system. Basic steps are:
11a) cd /usr/src/linux
<- directory of your sources
11b) make menuconfig
<- to configure the parameters of your kernel
11c) make
<- built
11d) make modules_install
<- install modules
11e) make install
<- install kernel
12) Reboot
13) To verify:
- look at the directories /proc/acpi/ac_adapter and /proc/acpi/battery
and see if they contain something
- dmesg |grep -i acpi
<- to see if there are errors
Links:
http://www.whoopy.it/linux/ - This
document
http://forums.gentoo.org/viewtopic.php?t=122145 - HOWTO: Fix Common ACPI
Problems (DSDT, ECDT, etc.)
http://lists.suse.com/archive/suse-laptop/2005-Mar/0108.html - [suse-laptop
mailing list] Re: [ACPI] acpi related problem on ACER TM 4002WLMi running SuSE
9.2
https://sourceforge.net/projects/sbs-linux/ - SBS SouceForge project home
page
http://acpi.sourceforge.net/ - ACPI SourgeForge Project home page
http://www.acpi.info/ -
ACPI official site
http://www.renninger.de/powersave/
- Powersave Documentation / HOWTO
