Andrzej Kardaś Web Page

Foreword

My main computer has motherboard ASUS P5AD2 Deluxe, which has many useful sensors. As I'm using my computer in variety of ways including, video and audio editing, gaming and as every Gentoo Linux user I'm running lots of compilation tasks, I would like to know how this tasks are affecting my system. The lm_sensors are giving my detailed information of my current system state. What is extremely important for me is temperature monitors. I found out that my computer has a tendency to overheat, when the radiators cooling most important components of my computer are filled with dust. Watching system monitoring status gives direct information when I should open my computer case and clean it up. Do not underestimate this. Cleaning CPU radiator gives a temperature reading lower by about 10 degrees.

I will try to share here configuration that is coming from my ASUS P5AD2 Deluxe motherboard. Described below configuration is applicable to Gentoo Linux distribution but most important thing the lm_sensors configuration file should work on any Linux distribution. I will start with kernel configuration.

Kernel Configuration

My motherboead has Winbond W83627EHF/EF/EHG/EG Super IO family sensors. To configure my kernel I had to enter kernel catalog and start menuconfig by running following commands in terminal:

cd /usr/src/linux
make menuconfig

Next I had to mark all modules needed to make my sensors work. Below you will find list of needed kernel modules.

Device Drivers  --->
    <*> Hardware Monitoring Support --->
        <M> Winbond W83627EHF/EHG/DHG, W83667HG

As you can see support for sensor chip will be build as module. This is highly important because this module will be loaded by lm_sensors system service. Now we are ready to recompile, install and use new kernel. I usually do it by running this commands in terminal:

cd /usr/src/linux
make && make modules_install install

Now it's good time to reboot the machine with new kernel and install lm_sensors.

Lm Sensors Configuration

I use lm_sensors 3.x and I would not recommend using older version. To install lm_sensors in Gentoo system you need to run this commands in terminal:

emerge -av sys-apps/lm_sensors

Next thing we should do is to make sure that programs able to use system sensors will be compiled with this support. To do it we need to add lm_sensors use flag to our /etc/make.conf file. After doing this it is good idea to check which of installed programs should be recompiled. You can do it by using gentoolkit equery utility like this:

equery hasuse lm_sensors
 * Searching for USE flag lm_sensors ... 
[I--] [  ] app-admin/gkrellm-2.3.2-r1 (2)
[I--] [ ~] kde-base/ksysguard-4.4.4 (4.4)
[I--] [ ~] net-analyzer/net-snmp-5.4.2.1-r4 (0)

After rebuilding all packages we may go to lm_sensors configuration. First thing we need to provide is sensors module configuration. The sensors-detect utility which is part of lm_sensors package probed my sensor chip correctly. Below you can see /etc/conf.d/lm_sensors configuration file generated by sensors-detect.

# Generated by sensors-detect on Thu Jun 17 17:47:14 2010
# This file is sourced by /etc/init.d/lm_sensors and defines the modules to
# be loaded/unloaded.
#
# The format of this file is a shell script that simply defines variables:
# HWMON_MODULES for hardware monitoring driver modules, and optionally
# BUS_MODULES for any required bus driver module (for example for I2C or SPI).
 
# Load modules at startup
LOADMODULES=yes
 
# Initialize sensors at startup
INITSENSORS=yes
 
HWMON_MODULES="w83627ehf"
 
# For compatibility reasons, modules are also listed individually as variables
#    MODULE_0, MODULE_1, MODULE_2, etc.
# Please note that the numbers in MODULE_X must start at 0 and increase in
# steps of 1. Any number that is missing will make the init script skip the
# rest of the modules. Use MODULE_X_ARGS for arguments.
#
# You should use BUS_MODULES and HWMON_MODULES instead if possible.
 
MODULE_0=w83627ehf

As you can see the most important thing in this file is line on the bottom part which is responsible for loading sensor module. Fortunately this part of configuration did not required any additional work.

Last thing we need to do is to provide our sensor configuration. The generic configuration for lm_sensors is kept in /etc/sensors3.conf file. I found out that kept there configuration need to be tuned up to match sensor configuration from my motherboard. Thats why I created my own configuration. The important thing is to remember not to change default file, because you will loose your configuration with every lm_sensors update. You should create your personal configuration in /etc/sensors.d/ catalog. Below you can see configuration file created for my motherboard sensors.

chip "w83627ehf-*"
 
# VOLTAGES
# Vcore
    label in0 "Vcore"
    set in0_min 0.85
    set in0_max 1.6
 
# +12V
    label in1   "+12V"
    compute in1 @*(66/10),  @/(66/10)
    set in1_min 10.2
    set in1_max 13.8
 
# unused
    ignore in2
 
# +5V
    label   in6   "5V"
    compute in6 @*(32/10),  @/(32/10)
    set in6_min   5.0*0.85
    set in6_max   5.0*1.05
 
# +3.3V
    label in3     "+3.3V"
    set in3_min   3.3*0.95
    set in3_max   3.3*1.05
 
# unused
    ignore in4
    ignore in5
    ignore in7
    ignore in8
    ignore in9
 
# Fans
   #Case Fan 1
   label fan1      "Case Fan1"
   set fan1_min    1300
 
   #Case Fan2
   label fan3      "Case Fan2"
   set fan3_min    1600
 
   #Case Fan3
   label fan5      "Case Fan3"
   #This dont seem to affect the settings
   #set fan5_min    1600
 
   #CPU Fan
   label fan2      "CPU Fan"
   set fan2_min    1600
 
#unused
   ignore fan4
 
# Temparatures
   #System temparature
   label temp1         "System Temp"
   set temp1_max       60
   set temp1_max_hyst  50
 
   #CPU Temp
   label temp2         "CPU Temp"
   set temp2_max       85
   set temp2_max_hyst  79
 
   #Motherboard Temp
   label temp3         "Mth Temp"
   set temp3_max       65
   set temp3_max_hyst  55

As you can see my motherboard has wide range of useful sensors. On the top of the file I'm providing sensor chip name. First part is defining voltage sensors. I'm providing minimum and maximum possible voltage values. You may noticed that some of my sensors are ignored. I found out that those sensors did not gave any output values, seems they are not available or not being used by my motherboard. Second part is fan speed meters. I have 3 chase and a CPU fan. For fan values I'm providing only minimal values. Last part and the most important one is temperature monitor. I have 3 temperature sensors: CPU, motherboard and system. You may see here a hyst and max settings. This settings make use of hysteresis mechanism. When my system will enter maximum defined temperature, it will trigger an Alarm, then another tool can react to alarm by for example lowering CPU performance. This should end up in lowering it's temperature. The hysteresis will trigger off the alarm when the hyst value is met. This mechanism prevents switching on and off alarm trigger to often.

Now I'm ready to use my sensors. I can start them by running following command in terminal:

/etc/init.d/lm_sensors start

For newer kernel there may be a problem with running sensors for P5AD2 Deluxe motherboard, to prevent this I had to pass additional kernel parameter. Here you can see my kernel configuration from boot up grub application:

kernel /boot/vmlinuz-2.6.33-r2-gentoo-sources root=/dev/sda5  noapic CONSOLE=/dev/tty1 acpi=on acpi_enforce_resources=lax

The last parameter acpi_enforce_resources=lax will make sensors running even with latest kernel.

To make my lm_sensors start as system service I have to run following command in terminal:

rc-update add lm_sensors default

To check my machine temperature state I have to run this simple command in terminal:

sensors
w83627ehf-isa-0290
Adapter: ISA adapter
Vcore:       +1.32 V  (min =  +0.85 V, max =  +1.60 V)
+12V:       +12.36 V  (min = +10.19 V, max = +13.46 V)
+3.3V:       +3.38 V  (min =  +2.98 V, max =  +3.63 V)
5V:          +4.99 V  (min =  +4.25 V, max =  +5.25 V)
Case Fan1:  1506 RPM  (min = 1308 RPM, div = 8)
CPU Fan:    2109 RPM  (min = 1607 RPM, div = 8)
Case Fan2:  1985 RPM  (min = 1607 RPM, div = 8)
Case Fan3:  1917 RPM  (min =    0 RPM, div = 4)
System Temp: +40.0°C  (high = +60.0°C, hyst = +50.0°C)  sensor = thermistor
CPU Temp:    +63.5°C  (high = +85.0°C, hyst = +79.0°C)  sensor = diode
Mth Temp:    +43.0°C  (high = +65.0°C, hyst = +55.0°C)  sensor = thermistor

Prove that it's working

Sources

• LM Sensors Project Page
• man sensors3.conf
• man sensors