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Athlon Powersaving HOWTO Linux

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Athlon Powersaving HOWTO

Daniel Nofftz

<[email protected]>

Revision History                                                             
Revision 1.1.11             2005-03-05           Revised by: dn              
SiS741 was false ... now it should be right. some command-line hacks         
Revision 1.1.10             2005-02-17           Revised by: dn              
SiS741 added, minor corrections                                              
Revision 1.1.9              2004-12-19           Revised by: dn              
minor update for sound fix                                                   
Revision 1.1.8              2004-12-12           Revised by: dn              
new rtsensors link added                                                     
Revision 1.1.7              2004-12-10           Revised by: dn              
Kernel Patch for Kernel 2.6.9 added, translation index updated, minor other  
Revision 1.1.6              2004-11-28           Revised by: dn              
SIS746/748 and KT880 added. recommanded solutions are now the                
commandline-hack and athcool                                                 

  How to enable the power-saving functionality of the Athlon/Duron/AthlonXP
processor on some motherboards/chipsets. This is usefull for saving Power and
lowering the Temperature of the CPU and the System. (It also will reduce
noise if you use temperature controlled fans in your case/on your cpu

Table of Contents
1. Introduction
    1.1. Basics on the Athlon Power Saving Mode
    1.2. Copyright and License
    1.3. Disclaimer
    1.4. Feedback/Questions/Support
    1.5. New Versions of this Document
2. The Different Approaches
    2.1. The Command-line Hack (recommanded)
    2.2. The Athcool Program (recommanded)
    2.3. BIOS updates
    2.4. Kernel Patches
    2.5. The LVCool Solution
    2.6. The FVCool Program
    2.7. AMD 760MP Powersaving
3. What Else?
    3.1. How to test whether it works
    3.2. Known Bugs/Problems
    3.3. Fix for sound skips and other problems
    3.4. Another Fix for sound skips and other problems (on some
    3.5. ToDo
    3.6. Translations

1. Introduction

1.1. Basics on the Athlon Power Saving Mode

  The HLT signal which is used by the normal idle-loop of the Linux kernel
doesn't normaly bring any significant power-saving on processors of the
Athlon/Duron family (hereafter referred to as Athlon processors). To get real
power-saving on an Athlon processor, you have to put the processor in the
STPGNT-Mode (Stop Grant Mode). In this mode, the processor is disconnected
from the front-side bus (FSB), and can turn off parts of the CPU as well as
reduce the clock to save power.

  Some modern Motherboards/Chipsets also support a Function to make a STPGNT
when a HLT signal is detected.

1.2. Copyright and License

  This document, Athlon Powersaving HOWTO, is copyrighted (c) 2003,2004,2005
by Daniel Nofftz.

  Permission is granted to copy, distribute and/or modify this document under
the terms of the GNU Free Documentation License, Version 1.2 or any later
version published by the Free Software Foundation; with no Invariant
Sections, with no Front-Cover Texts, and with no Back-Cover Texts. A copy of
the license is available at []   http://

  Linux is a registered trademark of Linus Torvalds.

1.3. Disclaimer

  No liability for the contents of this document can be accepted. Use the
concepts, examples and information at your own risk. There may be errors and
inaccuracies, that could be damaging to your system. Proceed with caution,
and although this is highly unlikely, the author(s) do not take any

  All copyrights are held by their respective owners, unless specifically
noted otherwise. Use of a term in this document should not be regarded as
affecting the validity of any trademark or service mark. Naming of particular
products or brands should not be seen as endorsements.

1.4. Feedback/Questions/Support

  Feedback is most essential for this document. New solutions for new
chipsets are especially needed, as are comments, whether the provided
solutions work or don't work. Also please report spelling errors if you find
them, cause i am no native english speaker. Send your additions, comments,
criticisms and questions to the following email address: <
[email protected]>. You can email me in German or English!

  If you want to support me, you could donate through Paypal (to the same
email-adress) or send me some new Hardware to play with. ;)

1.5. New Versions of this Document

  The newest version of this HOWTO will always first be made available [http:
//] here.

2. The Different Approaches

  In the following section I present different approaches to achieve the same
goal: power-saving on your Athlon/Athlon-XP based system. My recommended
approach at the moment is to use the "command-line hack" or the athcool
programm (the kernel patch is outdated and will not be developed any further,
and the LVCool patch supports only one chipset family.)

  Nearly all of these approaches will set the " Disconnect enable when STPGNT
detected" bit in the north bridge of the chipset. All other work is done by
the ACPI subsystem of the kernel which sends a STPGNT signal to the
processor, when it enters the acpi-c2 idle mode.

  If you haven't already got a kernel with ACPI support, you have to enable
it in the kernel setup and then recompile the new kernel. You'll find the
ACPI-options under General Setup+Power Management Setup->ACPI. You must have
at least the following options: ACPI Bus Manager, System and Processor.

  Or for the new 2.4.22 Kernel: General Setup+ACPI Support. You must have at
least the following option: Processor.

2.6.x Kernel: Powermanagment options+ACPI. You must have at least the option 
Processor enabled. You shouldn't enable Thermal Zone !!

  Some Chipsets also support a STPGNT if a HLT signal is detected. This
Motherboards/Chipsets don't need ACPI to be enabled! At the moment i look for
feedback which Chipsets work without ACPI and which need ACPI. Maybee you
could test it on your Motherboard and send me a mail. (see Section 3.1)

2.1. The Command-line Hack (recommanded)

  To use the command-line hack you normaly have to enable ACPI in the kernel,
otherwise it is mentioned. No reboot is needed to enable the Powersaving. You
could enable/disbale it from the command line with this commands:


on KT133/133A, KX133, KL/KLE133, KM/KN133, ...: (needs definitively acpi
      enable: setpci -v -H1 -s 0:0.0 52=$(printf %x $((0x$(setpci -H1 -s 0:
    0.0 52) | 0x80)))
      disable: setpci -v -H1 -s 0:0.0 52=$(printf %x $((0x$(setpci -H1 -s 0:
    0.0 52) & 0x7f)))
on KT266/266A/333,KM266/266A/333, ...:
    setpci -v -H1 -s 0:0.0 92=$(printf %x $((0x$(setpci -H1 -s 0:0.0 92) |
    setpci -v -H1 -s 0:0.0 95=$(printf %x $((0x$(setpci -H1 -s 0:0.0 95) |
    setpci -v -H1 -s 0:0.0 92=$(printf %x $((0x$(setpci -H1 -s 0:0.0 92) &
    setpci -v -H1 -s 0:0.0 95=$(printf %x $((0x$(setpci -H1 -s 0:0.0 95) &
on KT333CF/KT400/KT400A/KM400/KM400A/KT600:
    setpci -v -H1 -s 0:0.0 D2=$(printf %x $((0x$(setpci -H1 -s 0:0.0 D2) |
    setpci -v -H1 -s 0:0.0 D5=$(printf %x $((0x$(setpci -H1 -s 0:0.0 D5) |
    setpci -v -H1 -s 0:0.0 D2=$(printf %x $((0x$(setpci -H1 -s 0:0.0 D2) &
    setpci -v -H1 -s 0:0.0 D5=$(printf %x $((0x$(setpci -H1 -s 0:0.0 D5) &
on KT880:
    setpci -v -H1 -s 0:0.0 82=$(printf %x $((0x$(setpci -H1 -s 0:0.0 82) |
    setpci -v -H1 -s 0:0.0 85=$(printf %x $((0x$(setpci -H1 -s 0:0.0 85) |
    setpci -v -H1 -s 0:0.0 82=$(printf %x $((0x$(setpci -H1 -s 0:0.0 82) &
    setpci -v -H1 -s 0:0.0 85=$(printf %x $((0x$(setpci -H1 -s 0:0.0 85) &
on SIS730/733:
    enable: setpci -v -H1 -s 0:0.0 6B=$(printf %x $((0x$(setpci -H1 -s 0:0.0
    6B) | 0x01)))
    disable: setpci -v -H1 -s 0:0.0 6B=$(printf %x $((0x$(setpci -H1 -s 0:0.0
    6B) & 0xfe)))
on SIS735/740/745/755:
    enable: setpci -v -H1 -s 0:0.0 6A=$(printf %x $((0x$(setpci -H1 -s 0:0.0
    6A) | 0x0003)))
    disable: setpci -v -H1 -s 0:0.0 6A=$(printf %x $((0x$(setpci -H1 -s 0:0.0
    6A) & 0xfffc)))
on SIS741/741GX/746/748:
    setpci -v -H1 -s 0:0.0 6C=$(printf %x $((0x$(setpci -H1 -s 0:0.0 6C) |
    setpci -v -H1 -s 0:0.0 6C=$(printf %x $((0x$(setpci -H1 -s 0:0.0 6C) &
on Nforce:
    setpci -v -H1 -s 0:0.0 E7=$(printf %x $((0x$(setpci -H1 -s 0:0.0 E7) |
    setpci -v -H1 -s 0:0.0 E4=$(printf %x $((0x$(setpci -H1 -s 0:0.0 E7) &
on Nforce2: (works without acpi enabled)
    enable: setpci -v -H1 -s 0:0.0 6F=$(printf %x $((0x$(setpci -H1 -s 0:0.0
    6F) | 0x10)))
    disable: setpci -v -H1 -s 0:0.0 6F=$(printf %x $((0x$(setpci -H1 -s 0:0.0
    6F) & 0xef)))
on AMD751 and AMD760/761:(not for the 760MP!!!)(works without acpi enabled)
      enable: setpci -v -s 0:0.0 0x62=$(printf %x $((0x$(setpci -H1 -s 0:0.0
    62) | 0x06)))
      disable: setpci -v -s 0:0.0 0x62=$(printf %x $((0x$(setpci -H1 -s 0:0.0
    62) & 0xf9)))

2.2. The Athcool Program (recommanded)

  Athcool is a small program which performs the same task as the setpci
commands above. It supports the same chipsets and detects what chipset you
have, issuing the right settings in the chipset to get the power-saving to

  You can read more about it (and download it) [http://]   here. I am not the
Author of this program!

2.3. BIOS updates

  On some newer boards the manufacturer provides a BIOS update which sets the
needed bit/bits in the chipset of the board (or let you choose in the
BIOS-setup whether it should be enabled). Refer to the homepage of your
motherboard manufacturer to see if such a BIOS-update is available.

2.4. Kernel Patches

  The patch is based on another patch (from Jan Niehusmann) I found on the
Newsnet. I modified the patch to also support the KT266/266A chipset. By the
way, my patch does the same as the command-line hack, except that the Patch
does it from within the kernel. This is why I recommend using the
command-line hack, which is really simple to use and you don't have to modify
your kernel.

Ok... now step by step, here's how to apply the patch:

 1.   First you have to download the patch:
    []   Kernel Patch for
    []   Kernel
    Patch for 2.4.21 (thx to Thomas Reinhardt for porting it to 2.4.21)
    []   Kernel
    Patch for 2.6.5 which supports all Via Chipsets up to the KT600 (thx to
    Sebastian Droege for porting it to 2.6.5 and adding the other Chipsets)
    []   Kernel
    Patch for 2.6.9 which supports all Via Chipsets up to the KT600 (thx to
    Alexander Hug for porting it from 2.6.5 to 2.6.9)
 2.   Login as root
 3.   cd /usr/src
 4.   Apply the patch: cat $path-to-patch/amd_cool.diff | patch -p0 (The new
    2.6.5 Patch: cd to linux and patch -p1)
 5.   cd linux
 6.   Make the new kernel
 7.   Reboot, and at the kernel boot-prompt, enter the statement 
    amd_disconnect=yes . This is because there are known bugs within the
    Athlon processor, which could cause problems on several boards. You
    should test the patch, and if it works, you can append the statement 
    amd_disconnect=yes to the file /etc/lilo.conf.

2.5. The LVCool Solution

  LVCool is a small port of the Windows programm []
VCool. It only supports the KT133/133A and KX133 chipset and I can't provide
support for it. You can download it []
here. This solutions needs no ACPI compiled in the kernel.

2.6. The FVCool Program

[]   Here is
another Powersaving program which supports several chipsets. I didn't test it
by myself but i heared it works. Check it out ... There is also a program
provided with which you could use the onboard monitoring chips on some
motherboards (like the lm-sensors package).

2.7. AMD 760MP Powersaving

  There is a kernel module which enables powersaving on the 760MP
multiprocessor chipset. You could find it [
amd-smp-idle/]   here. I don't know how good it works, but i got at least one
mail from someone who said it works for him. So check it out.

3. What Else?

3.1. How to test whether it works

  Ok ... you use one of the described powersaving possibilitys and you want
to verify, whether it works. Here are two ways to check it:

  If you have temperature controlled Fan on your CPU-Heatsink, you could
check for the noise level of the Fan to see whether it works or not. After a
few idle minutes you give the CPU somthing to do.

I normaly do it like this:

 1. get superuser (root)
 2. cd /usr/src/linux
 3. and give the computer something to do: while true; do make clean; make
    bzImage; done

After about 20 or 30 seconds you should notice that the noise of the fan is
getting louder while the fan is getting faster. Don't forget to end the
while-loop after some time ( a few minutes) with STRG-C.

  The same procedure as above works also with a monitoring program for the
cpu-temperature (like [] lm-sensors, [http:
//] xmbmon and
[] rtsensors).

3.2. Known Bugs/Problems

There are two known bugs in the Athlon/Duron processor. This is number 11 and
number 14 in the AMD Athlon Processor Revision Guide. It looks like the
Athlon XP is significantly less often affected by these bugs. So if you have
an Athlon XP you are on the lucky side (like me).

There could be following problems (caused by the bugs):

  * skips during sound playback
  * skips and slowdown during video playback
  * slowdown of the ultra-DMA harddisk transfers
  * system hangs
  * USB problems
  * someone reported a high cheeping noise

Sometimes a BIOS-update will help (it exists as a workaround for bug 11,
which could be done by the BIOS). But as far as I know there are only a few
boards out there which have this workaround in the BIOS.

For the Asus A7V133-C, it is known that the BIOS-option PCI master read
caching will solve most problems when it is enabled. So look at your BIOS to
see whether it has such functionality.

It is also known that on some boards, the BIOS option Delayed Transaction
solves some of the problems. You may want to give this option a try too.

WARNING: On boards with KT133A, this could enable the famous VIA-Southbridge

From a Newsnet post, regarding Asus A7V:

  * without delayed transaction: sound-skips and TV-skips
  * with delayed transaction: no sound skips and only slight TV problems
  * with delayed transcation and master read caching: nearly no TV problems
    and no sound skips at all

There are other causes for problems:

  * the PSU is not strong enough to handle the fluctuations in the power
    consumption of the processor/motherboard
  * some motherboard voltage-regulators could have the same problems like the
    PSU ;)
  * you have a K7S5A (as far as I know, this board could be really wierd when
    power-saving is enabled)

  If you have minor problems with power-saving enabled, and nevertheless want
to use power-saving, you can enable the power-saving by default, and turn it
off if you want to playback music, watch TV, ...

3.3. Fix for sound skips and other problems

Thank you to Michael Hamilton for submitting me the idea how it works.

The working of this Fix was confirmed by two People, so it looks like it
works, but it may not work for everyone. Please feel free to submit further

Lets go: It looks like at least the sound skips are cureable by maximizing
the pci latency timer of the device.

First you have to find the "pci-address" of your Soundcard. This could be
done with lspci. You have to look for something like "Multimedia audio
controller" or "AudioPCI". Take the "pci-address" of the device (looks like
shomething like that: 01:06.0 -> it stands for: bus:slot.function) and
maximize the latency timer for it. This is done by setpci:

setpci -v -s "pci-address" latency_timer=ff

For additional Information on the Latency Timer you could look [http://] here.

Maybe this works also for other Problems like USB-Problems and
Harddisk-Transfer-Slowdowns, but this hasn't been tested for now. Feel free
to test it (but don't blame me, if it doesn't work or makes everything worse)
and report whether it works. The Problem is, that i have none of this
Problems and so can't test this by myself.

If it works, you have to perform this setpci command at every startup/reboot
of the Computer. So it would be wise to put it in one of the init-scripts
(after the driver module is loaded!).

3.4. Another Fix for sound skips and other problems (on some Via-Chipsets)

Thank you to Wijatmoko Prayitno for submitting this!

The working of this Fix was confirmed for KT266, KT/KM333 and KT/KM400
Chipsets. It may also work for other Via-Chipsets. Please report if it works
on other Via-Chipsets !

This is quite easy and works like the Commandline-Hack for enabling the

Soundfix on KT/KM333 and KT/KM400 Chipsets:
      enable: setpci -v -H1 -s 0:0.0 70=$(printf %x $((0x$(setpci -H1 -s 0:
    0.0 70) | 0x08)))
      disable: setpci -v -H1 -s 0:0.0 70=$(printf %x $((0x$(setpci -H1 -s 0:
    0.0 70) & 0xf7)))

If it works, you have to perform this setpci command at every startup/reboot
of the Computer. So it would be wise to put it in one of the init-scripts
(after the driver module is loaded!).

3.5. ToDo

Adding more chipsets and more informations to this document.

Adding some Informations on the Powersaving System of the Athlon64 and
Opteron CPUs.

Adding some Informations on Notebooks and Power-Saving.

3.6. Translations

  Translations into different languages also exist. At the moment, some of
them are not up to date.

Hungarianby Zsolt Mocza

Spanish by Carlos Mayo (very out-dated)

[]   brasilian Portuguese by
Bruno Buys

French by Mathieu Pillard (very out-dated)

Italian by Maurizio Fantino (very out-dated)

[]   German (only parts) by Fabian

Japanese by Seiji Kaneko