# Sensors FAQ for lm_sensors version 2.12

Copyright (C) 1998 - 2004
Frodo Looijaard,
Philip Edelbrock,
and
Mark Studebaker

## Short Contents

- lm_sensors
- 1 PC and Sensor Overview
- 2 Sensor and Bus Basics
- 3 Installation and Management
- 4 Problems
- 5 How to Ask for Help
- 6 How to Contribute
- 7 Version 1 Specific Questions
- Appendix A Revision History of This Document

## Table of Contents

- lm_sensors
- 1 PC and Sensor Overview
  - 1.1 What sensors are available on my PC?
  - 1.2 What can a sensor chip like the "LM78" do?
  - 1.3 Where do I find out more about any of these chips?
- 2 Sensor and Bus Basics
  - 2.1 How are these sensors read?
  - 2.2 What is the SMBus? And the I2C bus?
  - 2.3 I don't have an ISA bus!
  - 2.4 What sensors do processors have?
  - 2.5 How often are the sensor values updated?
  - 2.6 How are alarms triggered?
- 3 Installation and Management
  - 3.1 Why so many modules, and how do I cope with them?
  - 3.2 How do I know which chips I own?
    - 3.2.1 What chips are on motherboard XYZ?
    - 3.2.2 Do you support motherboard XYZ?
    - 3.2.3 Do you support chip XYZ?
    - 3.2.4 Anybody working on a driver for chip XYZ?
  - 3.3 Which modules should I insert?
  - 3.4 Do I need the configuration file /etc/sensors.conf?
    - 3.4.1 The labels for the voltage and temperature readings in sensors are incorrect!
    - 3.4.2 The min and max for the readings in sensors are incorrect!
    - 3.4.3 The min and max settings in /etc/sensors.conf didn't take effect!
    - 3.4.4 One sensor isn't hooked up on my board!
    - 3.4.5 I need help with sensors.conf!
    - 3.4.6 Do you have a database of sensors.conf entries for specific boards?
  - 3.5 What about the No such file or directory warnings when I compile?
  - 3.6 I get all kinds of weird compilation errors?
    - 3.6.1 No rule to make target xxxx needed by xxxx - how to fix?
  - 3.7 It still does not compile or patch!
  - 3.8 make install fails on Mandrake kernels
  - 3.9 I get unresolved symbols when I modprobe modules (Red Hat especially)
  - 3.10 I2C_DRIVERID_ADM1024 undefined (Red Hat especially)
- 4 Problems
  - 4.1 My fans report exactly half/double their values compared to the BIOS?
    - 4.1.1 Fans sometimes/always read 0!!
    - 4.1.2 I doubled the fan divisor and the fan still reads 7000!
  - 4.2 Why do my two LM75's report "-48 degrees"?
  - 4.3 Why do I have two Vcore readings, I have only one processor!
  - 4.4 How do those ALARMS work? The current value is within range but there is still an ALARM warning!
  - 4.5 My voltage readings seem to drift a bit. Is something wrong?
  - 4.6 Some measurements are way out of range. What happened?
  - 4.7 What are VID lines? Why is the VID reading wrong?
  - 4.8 I read sensor values several times a second, but they are only updated only each second or so. Why?
  - 4.9 It sometimes seems to take almost a second before I see the sensor reading results. Why?
  - 4.10 Can I be alerted when an ALARM occurs?
  - 4.11 SMBus transactions on my PIIX4 simply don't work (timeouts happen). Why?
  - 4.12 My BIOS reports a much higher CPU temperature than your modules!
  - 4.13 I try to read the raw /proc files, but the values are strange?!?
  - 4.14 How do I set new limits?
    - 4.14.1 I set new limits and it didn't work?
  - 4.15 Some sensors are doubly detected?
  - 4.16 I ran sensors-detect, but now I get very strange readings?!?
  - 4.17 Bad readings from particular chips
    - 4.17.1 Bad readings from the AS99127F!
    - 4.17.2 Bad readings from the VIA 686A!
    - 4.17.3 Bad readings from the MTP008!
    - 4.17.4 Bad temperature readings from the SIS5595!
    - 4.17.5 Bad readings from a w8378[12]d!
    - 4.17.6 Bus hangs on Ali 1543 on Asus P5A boards!
    - 4.17.7 Bad readings from LM75!
    - 4.17.8 Bad readings from LM78!
    - 4.17.9 Bad readings from LM80!
    - 4.17.10 Bad readings from it87!
  - 4.18 How do I configure two chips (LM87) differently?
  - 4.19 Dmesg says Upgrade BIOS! I don't want to!
    - 4.19.1 Dmesg says use force_addr=0xaddr! What address do I use?
  - 4.20 Sensors says Can't access procfs/sysfs file
  - 4.21 Sensors says No sensors found!
  - 4.22 Sensors output is not correct!
  - 4.23 What is at I2C address XXX?
    - 4.23.1 What is at I2C address 0x69?
    - 4.23.2 What is at I2C addresses 0x50 - 0x57?
    - 4.23.3 What is at I2C addresses 0x30 - 0x37?
  - 4.24 Sensors-detect doesn't work at all
    - 4.24.1 Sensors-detect says "Couldn't open /proc/bus/i2c?!?"
    - 4.24.2 Sensors-detect says "Can't open /dev/i2c[-/]0"
    - 4.24.3 Sensors-detect doesn't find any sensors!
  - 4.25 Sensors says Error: Line xxx: zzzzzzz
  - 4.26 Sensors only gives the name, adapter, and algorithm for my chip
  - 4.27 Sensors says ERROR: Can't get xxxxx data!
  - 4.28 Sensors doesn't find any sensors, just eeproms.
  - 4.29 Inserting modules hangs my board
  - 4.30 Inserting modules slows down my board
  - 4.31 Problems on particular motherboards
    - 4.31.1 Asus P4B
    - 4.31.2 Tyan 2460, 2462
    - 4.31.3 Tyan 2466
    - 4.31.4 Tyan 2688
  - 4.32 Problems on particular systems
  - 4.33 Problems on 2.6 kernels
- 5 How to Ask for Help
  - 5.1 What to send us when asking for help
  - 5.2 What to do if a module won't insert?
  - 5.3 What to do if it inserts, but nothing happens?
  - 5.4 What to do if I read only bogus information?
  - 5.5 What to do if you have other problems?
  - 5.6 What if it just works like a charm?
  - 5.7 How do I update a ticket?
  - 5.8 How do I follow up on a ticket?
- 6 How to Contribute
  - 6.1 How to write a driver
  - 6.2 How to get CVS access
  - 6.3 How to donate hardware to the project
  - 6.4 How to join the project mailing list
  - 6.5 How to access mailing list archives
  - 6.6 How to submit a patch
  - 6.7 How to REALLY help
  - 6.8 How to get release announcements
  - 6.9 How to block spam on the project mailing list
- 7 Version 1 Specific Questions
  - 7.1 My manufacturer swears that my mainboard has an SMBus, but your code reports that it can't find it. What's wrong?
  - 7.2 The modules won't load, saying 'SMBus not detected'.
  - 7.3 I try to read /proc/sensors, and I get a "No sensor data yet (try again in a few moments)" message. Why?
  - 7.4 On my Dell, a LM80 is detected, but all readings are 0!
- Appendix A Revision History of This Document

Next: Overview, Up: (dir)

## lm_sensors

The lm_sensors package includes a collection of modules for general SMBus access and hardware monitoring. NOTE: this requires special support which is not in standard 2.2-vintage kernels.

Next: Basics, Previous: Top, Up: Top

## 1 PC and Sensor Overview

Next: Section 1.2, Up: Overview

### 1.1 What sensors are available on my PC?

Most PC's built since late 1997 now come with a hardware health monitoring chip. This chip may be accessed via the ISA bus or the SMBus, depending on the motherboard.

Some motherboard chipsets, notably the Via 686 and the SiS 5595, contain hardware monitor functions.

This FAQ frequently refers to the "LM78". This chip has been obsoleted by National Semiconductor. Most motherboards today contain a chip with similar functions.

Next: Section 1.3, Previous: Section 1.1, Up: Overview

### 1.2 What can a sensor chip like the "LM78" do?

The LM78 is a chip made by National Semiconductor which can monitor 7 voltages (5 positive, 2 negative) from 0 to 4.08V. The inputs are usually in series with voltage dividers which lower the +/- 12V and +/- 5V supplies to measurable range. Therefore, the readings for such inputs need to be re-scaled appropriately by software.

The LM78 also has 3 fan speed monitoring inputs, an internal temperature sensor, a chassis intrusion sensor, and a couple maskable interrupt inputs. The LM78 can also relay the processor's (P6 or Pent II) VID lines which are hardwired and used to indicate to the power regulator (usually on the mainboard close to the processor socket/slot) what voltage to supply to the processor.

The LM78 can be interfaced to a system via the ISA bus and/or the SMBus.

Most other sensor chips have comparable functionality. Each supported chip is documented in the doc/chips directory.

Previous: Section 1.2, Up: Overview

### 1.3 Where do I find out more about any of these chips?

Most semiconductor companies have comprehensive documentation, including complete datasheets, on their websites. Analog Devices, Dallas Semiconductor, Maxim, and National Semiconductor have the widest selection of sensor chips. Their websites are:

- http://www.analog.com
- http://www.dalsemi.com
- http://www.maxim-ic.com
- http://www.national.com

Please see the file http://www2.lm-sensors.nu/~lm78/useful_addresses.html for links to other companies' websites.

Next: Installation, Previous: Overview, Up: Top

## 2 Sensor and Bus Basics

Next: Section 2.2, Up: Basics

### 2.1 How are these sensors read?

Sensor chips reside on either the ISA bus, the SMBus, or both. See the file doc/chips/SUMMARY in our package for a list.

To communicate with chips on the ISA bus, the software uses simple I/O reads and writes.

To communicate with chips on the SMBus, the software must use an SMBus interface device, explained below.

Next: Section 2.3, Previous: Section 2.1, Up: Basics

### 2.2 What is the SMBus? And the I2C bus?

The SMBus is the "System Management Bus". More specifically, it is a 2-wire, low-speed serial communication bus used for basic health monitoring and hardware management. It is a specific implementation of the more general I2C (pronunciation: I-squared-C) bus. In fact, both I2C devices and SMBus devices may be connected to the same (I2C) bus.

The SMBus (or I2C bus) starts at the host controller, used for starting transactions on the SMBus. From the host interface, the devices communicated with are the slave devices. Each slave device has a unique 7-bit address which the host uses to refer to that device.

For each supported SMBus host, there is a separate kernel module which implements the communication protocol with the host. Some SMBus hosts really operate on the SMBus level; these hosts can not cope with pure I2C devices. Other hosts are in fact I2C hosts: in this case, we implement the SMBus protocol in terms of I2C operations. But these hosts can also talk to pure I2C devices.

Next: Section 2.4, Previous: Section 2.2, Up: Basics

### 2.3 I don't have an ISA bus!

We promise, you do, even if you don't have any old ISA slots. The "ISA Bus" exists in your computer even if you don't have ISA slots; it is simply a memory-mapped area, 64KB in size (0x0000 - 0xFFFF) where many "legacy" functions, such as keyboard and interrupt controllers, are found. It isn't necessarily a separate physical bus. See the file /proc/ioports for a list of devices living on the "ISA Bus" in your system. If you don't like the term "ISA Bus" think "I/O Space".

Next: Section 2.5, Previous: Section 2.3, Up: Basics

### 2.4 What sensors do processors have?

Most new processors contain a thermal diode on the die itself. The electical properties of all diodes and transistors vary slightly with temperature. The thermal diode is exceptionally accurate because it is directly on the die. Newer temperature sensor chips, like the Analog Devices ADM1021 and clones, and the Winbond chips, have circuitry for measuring the the electrical properties of an external diode and converting this data to a temperature. Any sensor chip listed in doc/chips/SUMMARY in our package which has support for more than one temperature supports external temperature sensing.

Older motherboards and processors without this feature generally use an LM75 placed close to the processor. This is much less accurate.

The Pentium 2 'boxed' processor usually has an LM75 very close to the base of the box. It can be read through the SMBus to report the approximate temperature of the processor. The processor also contains an internal temperature sensor (of low accuracy) used as a fail-safe to disable the processor in case it gets much too hot (usually around 130 degrees C). And, the Pentium 2 also has a hard-wired signal (VID lines) on it's SEC (single edge connector) which indicates what power supply is required to operate the processor.

The P6 (Pentium-Pro) may have an LM75 in or just under the socket. P6's also have VID lines.

Pentiums and Pentium w/ MMX do not have VID lines, and sometimes have LM75's under the sockets (depends on the mainboard, and how 'modern' the mainboard is).

The P2 Xeon was the first Intel processor to include the SMBus interface on the P2 Xeon SEC.

Next: Section 2.6, Previous: Section 2.4, Up: Basics

### 2.5 How often are the sensor values updated?

The LM78, and most other sensor chips like it, reads its sensors one by one. A complete scanning sweep will take about 1.5 seconds. The LM78 stops readings sensors if you try to access it, so if you access it very often (by reading sensor values; writing new limits is safe) it will not find the time to update its sensor values at all! Fortunately, the kernel module takes care not to do this, and only reads new values each 1.5 seconds. If you read the values again, you will get the 'old' values again.

Previous: Section 2.5, Up: Basics

### 2.6 How are alarms triggered?

It is possible to monitor each sensor and have an alarm go off if it crosses some pre-determined limits. There are two sorts of interrupts which can be generated by sensor chips if this happens (it depends a bit on the actual chip if both are supported; the LM80, for example, has only IRQ interrupts): IRQ interrupts and SMI interrupts. IRQ stands for Interrupt Request and are the interrupt lines you can find in /proc/interrupts. SMI stands for System Management Interrupt, and is a special interrupt which puts the processor in a secure environment independent of any other things running. SMI is currently not supported by the Linux kernel. IRQs are supported, of course.

Even if no interrupt is generated, some bits in a status register will be set until the register is read the next time. If the alarm condition persists after that, the bits will be set on the next scanning sweep, etc.

Most drivers in our package do not support interrupts at this time.

Next: Problems, Previous: Basics, Up: Top

## 3 Installation and Management

Next: Section 3.2, Up: Installation

### 3.1 Why so many modules, and how do I cope with them?

We tried to make this package as modular as possible. This makes it easy to add new drivers, and unused drivers will take no precious kernel space. On the other hand, it can be a bit confusing at first.

Here are two simple guidelines:

- Run sensors-detect and do what it tells you.
- Always use modprobe, not insmod.

Further information is in doc/modules.

Next: Section 3.3, Previous: Section 3.1, Up: Installation

### 3.2 How do I know which chips I own?

We have an excellent program that scans all your hardware. It is called sensors-detect and is installed in /usr/local/sbin by make install. Just execute this script, and it will tell you.

Chip detection in the drivers is fairly good. That means that it is usually harmless to insert more chip drivers than you need. However, this can still lead to problems, so we do not recommend it.

If sensors-detect didn't find any sensors, either you don't have any, or the ones you have, we don't support. (Look at your motherboard for candidates, then see Help)

#### 3.2.1 What chips are on motherboard XYZ?

!!!!!!!!! YES THIS IS THE MOST FREQUENT QUESTION WE GET !!!!!!!!!

We have no idea. Here is what you should do:

1. Run sensors-detect.

If that doesn't work:

2. Look at your motherboard.
3. Check the manufacturer's website or ask their support
4. Check the Motherboard Monitor website and the "links" page on our website some good cross-references.

#### 3.2.2 Do you support motherboard XYZ?

We don't support boards, we support chips. See What chips are on motherboard XYZ.

#### 3.2.3 Do you support chip XYZ?

This we have good answers for.

- Sorted by Manufacturer: README
- Sorted by Manufacturer: http://www2.lm-sensors.nu/~lm78/supported.html
- Sorted by Sensor Driver: doc/chips/SUMMARY
- Newest Driver Status: http://www2.lm-sensors.nu/~lm78/newdrivers.html

#### 3.2.4 Anybody working on a driver for chip XYZ?

Newest Driver Status: http://www2.lm-sensors.nu/~lm78/newdrivers.html

Next: Section 3.4, Previous: Section 3.2, Up: Installation

### 3.3 Which modules should I insert?

sensors-detect will tell you. Take the modprobe lines it recommends and paste them into the appropriate /etc/rc.d/xxxx file to be executed at startup.

You need one module for each sensor chip and bus adapter you own; if there are sensor chips on the ISA bus, you also need i2c-isa.o. for each type of chip you own. That's all. On my computer, I could use the following lines:

- modprobe i2c-isa
- modprobe i2c-piix4
- modprobe lm78
- modprobe lm75
- modprobe i2c-dev
- sensors -s

Next: Section 3.5, Previous: Section 3.3, Up: Installation

### 3.4 Do I need the configuration file /etc/sensors.conf?

Yes, for any applications that use libsensors, including the sensors application included in our package. It tells libsensors how to translate the values the chip measures to real-world values. This is especially important for voltage inputs. The default configuration file should usually do the trick. It is automatically installed as /etc/sensors.conf, but it will not overwrite any existing file with that name.

#### 3.4.1 The labels for the voltage and temperature readings in sensors are incorrect!

Every motherboard is different. You can customize the labels in the file /etc/sensors.conf. That's why it exists! The default labelling (in lib/chips.c and /etc/sensors.conf) is just a template.

#### 3.4.2 The min and max for the readings in sensors are incorrect!

You can customize them in the file /etc/sensors.conf. See above.

#### 3.4.3 The min and max settings in /etc/sensors.conf didn't take effect!

You forgot to run sensors -s. See above.

#### 3.4.4 One sensor isn't hooked up on my board!

Use an ignore line in /etc/sensors.conf so it isn't displayed in sensors.

#### 3.4.5 I need help with sensors.conf!

There is detailed help at the top of that file.

#### 3.4.6 Do you have a database of sensors.conf entries for specific boards?

No. Good idea though. If you would like to set one up on your website send us mail and we will set up a link to it.

Next: Section 3.6, Previous: Section 3.4, Up: Installation

### 3.5 What about the No such file or directory warnings when I compile?

Don't worry about them. The dependency files (which tell which files should be recompiled when certain files change) are created dynamically. They are not distributed with the package. The make program notices they are not there, and warns about that - and the first thing it will do is generate them. So all is well.

Next: Section 3.7, Previous: Section 3.5, Up: Installation

### 3.6 I get all kinds of weird compilation errors?

Check that the correct i2c header files are used. Depending on how you installed, they should be under either /usr/local/include or /usr/src/linux*/include. Try to edit the Makefile for the other setting.

#### 3.6.1 No rule to make target xxxx needed by xxxx - how to fix?

- See I get all kinds of weird compilation errors, also try make clean in lm_sensors.
- If that doesn't work, try make clean in i2c.
- If that doesn't work, try make clean in the kernel.
- Also make sure /usr/include/linux points to /usr/src/linux/include/linux.

Next: Section 3.8, Previous: Section 3.6, Up: Installation

### 3.7 It still does not compile or patch!

Have you installed the matching version of the i2c package? Remember, compilation is not enough, you also need to install it for the header files to be found!

If you want to patch the kernel, you will have to apply the i2c patches first!

Next: Section 3.9, Previous: Section 3.7, Up: Installation

### 3.8 make install fails on Mandrake kernels

Mandrake uses a non-standard version.h file which confuses our Makefile. Edit our Makefile on the `MODDIR :=` line to hard-code the module directory.

Next: Section 3.10, Previous: Section 3.8, Up: Installation

### 3.9 I get unresolved symbols when I modprobe modules (Red Hat especially)

Example:

         *** Unresolved symbols in /lib/modules/2.4.5/kernel/drivers/i2c/i2c-i810.o
         i2c_bit_add_bus_R8c3bc60e
         i2c_bit_del_bus_R92b18f49

You can also run depmod -a -e to see all unresolved symbols.

These are module versioning problems. Generally you did not compile against the kernel you are running. Sometimes the Red Hat source you have is not for the kernel you are running. You must compile our package against the source for the kernel you are running with something like make LINUX=/usr/src/linux-2.4.14.

Try the following to be sure:

- nm --extern MODULE.o Filter out the kernel symbols, like `kmalloc`, `printk` etc. and note the number code behind them, like `printk_R1b7d4074`. If there is no numeric code after them, note this too.
- grep SYMBOL /proc/ksyms Substitute SYMBOL by the basename of the symbols above, like `kmalloc`, `printk` etc. Note the number code behind them, or the lack thereof.
- Compare both sets of symbols. Are they the same? If so, the problem lies somewhere else. Are they different? If so, you have a module versioning problem.

Previous: Section 3.9, Up: Installation

### 3.10 I2C_DRIVERID_ADM1024 undefined (Red Hat especially)

In some versions of Redhat, an RPM is included to provide i2c support. However, this RPM does not place the header files in the kernel directory structure. When you update kernels, they may persist. To get rid of these obsolete header files, at a command prompt:

1. rpm -qa | grep i2c
2. Look for kernel-i2c, or a similar rpm in the output
3. <as root> rpm -ev kernel-i2c (or the name of the similar package) If this complains about dependencies, you can try adding --nodeps, but this *MAY* break something else. Not likely, as you have upgraded kernels, and nothing should be using the old i2c stuff anymore anyway. Just don't use it with abandon.
4. Try (in the build directory of lm_sensors)

                 make clean
                 make

5. If you still have problems, you may have to replace the include paths in the .c/.h files with absolute paths to the header files. More of a workaround than a real fix, but at least you can get it to work.

Next: Help, Previous: Installation, Up: Top

## 4 Problems

Next: Section 4.2, Up: Problems

### 4.1 My fans report exactly half/double their values compared to the BIOS?

The problem with much of the sensor data is that it is impossible to properly interpret some of the readings without knowing what the hardware configuration is. Some fans report one 'tick' each rotation, some report two 'ticks' each rotation. It is easy to resolve this through the configuration file /etc/sensors.conf:

         chip lm78-*             # Or whatever chip this relates to
         compute fan1 2*@,@/2    # This will double the fan1 reading
                                 # -- or --
         compute fan1 @/2,2*@    # This will halve the fan1 reading

See doc/fan-divisors in our package for further information.

#### 4.1.1 Fans sometimes/always read 0!!

You may not have a three-wire fan, which is required.

You may need to increase the 'fan divisor'. See doc/fan-divisors in our package for further information.

#### 4.1.2 I doubled the fan divisor and the fan still reads 7000!

Believe it or not, doubling the 'fan divisor' will not halve the fan reading. You have to add a compute line in /etc/sensors.conf. See My fans report exactly half/double their values compared to the BIOS, and see doc/fan-divisors in our package for further information.

Next: Section 4.3, Previous: Section 4.1, Up: Problems

### 4.2 Why do my two LM75's report "-48 degrees"?

For starters, those aren't LM75's. Your mainboard actually has the Winbond W83781D which emulates two LM75's, but many systems which use the Winbond chip (such as the Asus P2B) don't have the thermo-resisters connected to the chip resulting in these strange -48 degree readings.

In upcoming versions, you will be able to disable non-interesting readings.

Next: Section 4.4, Previous: Section 4.2, Up: Problems

### 4.3 Why do I have two Vcore readings, I have only one processor!

The LM78 has seven voltage sensors. The default way of connecting them is used in the configuration file. This includes a VCore2, even if you do not have one. You can easily edit the configuration file to give it another name, or make this reading disappear using an ignore line.

Note that Vcore2 is often the same as Vcore on motherboards which only support one processor. Another possibility is that Vcore2 is not connected at all and will not have a valid reading at all. A third possibility, is that Vcore2 monitors something else, so you should not be too surprised if the values are completely different.

Next: Section 4.5, Previous: Section 4.3, Up: Problems

### 4.4 How do those ALARMS work? The current value is within range but there is still an ALARM warning!

The ALARM indications in sensors are those reported by the sensor chip itself. They are NOT calculated by sensors. sensors simply reads the ALARM bits and reports them.

An ALARM will go off when a minimum or maximum limit is crossed. The ALARM is then latched - that is, it will stay there until the chip's registers are next accessed - which will be the next time you read these values, but not within (usually) 1.5 seconds since the last update.

Reading the registers clears the ALARMS, unless the current value is still out of range.

The purpose of this scheme is to tell you if there has been a problem and report it to the user. Voltage or temperature spikes get detected without having to read the sensor chip hundreds of times a second. The implemetation details depend a bit on the kind of chip. See the specific chip documentation in doc/chips and the chip datasheet for more information.

Next: Section 4.6, Previous: Section 4.4, Up: Problems

### 4.5 My voltage readings seem to drift a bit. Is something wrong?

No, probably not. If your motherboard heats up a bit, the sensed voltages will drift a bit. If your power supply is loaded (because a disk gets going, for example), the voltages may get a bit lower. Heavy processor activity, in particular, dramatically increases core voltage supply load which will often cause variation in the other supplies. As long as they stay within a sensible range (say 5% of the nominal value for CPU core voltages, and 10% for other voltages), there is no reason to worry.

Next: Section 4.7, Previous: Section 4.5, Up: Problems

### 4.6 Some measurements are way out of range. What happened?

Each module tries to set limits to sensible values on initialization, but a module does not know how a chip is actually connected. This is described in the configuration file, which is not read by kernel modules. So limits can be strange, if the chip is connected in a non-standard way.

Readings can also be strange; there are several reasons for this. Temperature sensors, for example, can simply not be present, even though the chip supports them. Also, it can be that the input is used in a non-standard way. You can use the configuration file to describe how this measurement should be interpreted; see the comments the example file for more information.

Next: Section 4.8, Previous: Section 4.6, Up: Problems

### 4.7 What are VID lines? Why is the VID reading wrong?

These describe the core voltage for your processor. They are supported for most processors, however they are not always correctly connected to the sensor chip, so the readings may be invalid. A reading of 0V, +3.5V or +2.05V is especially suspect. If this is the case, add a line ignore vid to /etc/sensors.conf, and change the min and max settings for the Processor Core voltage (often in0_min and in0_max) in that file so that they don't depend on vid.

Next: Section 4.9, Previous: Section 4.7, Up: Problems

### 4.8 I read sensor values several times a second, but they are only updated only each second or so. Why?

If we would read the registers more often, it would not find the time to update them. So we only update our readings once each 1.5 seconds (the actual delay is chip-specific; for some chips, it may not be needed at all).

Next: Section 4.10, Previous: Section 4.8, Up: Problems

### 4.9 It sometimes seems to take almost a second before I see the sensor reading results. Why?

ISA bus access is fast, but SMBus access is really slow. If you have a lot of sensors, it just takes a lot of time to access them. Fortunately, this has almost no impact on the system as a whole, as another job can run while we are waiting for the transaction to finish.

Next: Section 4.11, Previous: Section 4.9, Up: Problems

### 4.10 Can I be alerted when an ALARM occurs?

No, you can't; and it may well be never supported.

Almost no mainboard we have encountered have actually connected the IRQ-out pin of sensor chips. That means that we could enable IRQ reporting, but nothing would happen. Also, even if a motherboard has it connected, it is unclear what interrupt number would be triggered. And IRQ lines are a scarce facility, which means that almost nobody would be able to use it anyway.

The SMI interrupt is only available on a few types of chips. It is really a very obscure way to handle interrupts, and supporting it under Linux might be quite hard to do.

Your best bet would be to poll the alarm file with a user-land daemon which alerts you if an alarm is raised. I am not aware of any program which does the job, though you might want to examine one of the graphical monitor programs under X, see http://www2.lm-sensors.nu/~lm78/useful_addresses.html for addresses.

Next: Section 4.12, Previous: Section 4.10, Up: Problems

### 4.11 SMBus transactions on my PIIX4 simply don't work (timeouts happen). Why?

Some chips which mainboard makers connect to the SMBus are not SMBus devices. An example is the 91xx clock generator chips. When read, these devices can lock up the SMBus until the next hard reboot. This is because they have a similar serial interface (like the I2C), but don't conform to Intel's SMBus standard.

Why did they connect these devices to the SMBus if they aren't compatible? Good question! :') Actually, these devices may support being written to, but lock things up when they are read.

Next: Section 4.13, Previous: Section 4.11, Up: Problems

### 4.12 My BIOS reports a much higher CPU temperature than your modules!

We display the actual temperature of the sensor. This may not be the temperature you are interested in, though. If a sensor should measure the CPU temperature, it must be in thermal contact with it. In practice, it is just somewhere near it. Your BIOS may correct for this (by adding, for example, thirty degrees to the measured temperature). The correction factor is regrettably different for each mainboard, so we can not do this in the module itself. You can do it through the configuration file, though:

         chip lm75-*-49                      # Or whatever chip this relates to
         label temp "Processor"
         compute temp @*1.2+13,(@-13)/1.2    # Or whatever formula

Next: Section 4.14, Previous: Section 4.12, Up: Problems

### 4.13 I try to read the raw /proc files, but the values are strange?!?

Remember, these values do not take the configuration file compute lines in account. This is especially obvious for voltage readings (usually called in? or vin?). Use a program linked to libsensors (like the provided sensors program) instead.

Next: Section 4.15, Previous: Section 4.13, Up: Problems

### 4.14 How do I set new limits?

Change the limit values in /etc/sensors.conf and then run sensors -s.

#### 4.14.1 I set new limits and it didn't work?

You forgot to run sensors -s. Put it in a /etc/rc.d/... file after the modprobe lines to run at startup.

Next: Section 4.16, Previous: Section 4.14, Up: Problems

### 4.15 Some sensors are doubly detected?

Yes, this is still a problem. It is partially solved by alias detection and confidence values in sensors-detect, but it is really tough.

Double detections can be caused by two things: sensors can be detected to both the ISA and the SMBus (and if you have loaded the approprate adapter drivers, it will be detected on both), and some chips simulate other chips (the Winbond W83781D simulates LM75 chips on the SMBus, for example). Remove the offending adapter or chip driver, or run sensors-detect and add the ignore= modprobe parameters it suggests.

Next: Section 4.17, Previous: Section 4.15, Up: Problems

### 4.16 I ran sensors-detect, but now I get very strange readings?!?

Your SMBus (PIIX4?) is probably crashed or hung. There are some mainboards which connect a clock chip to the SMBus. Unfortunately, this clock chip hangs the PIIX4 if it is read (it is an I2C device, but not SMBus compatible). We have found no way of solving this, except for rebooting your computer. Next time when you run sensors-detect, you may want to exclude addresses 0x69 and/or 0x6a, by entering `s` when you are asked whether you want to scan the PIIX4.

Next: Section 4.18, Previous: Section 4.16, Up: Problems

### 4.17 Bad readings from particular chips

See below for some particularly troublesome chips. Also be sure and check doc/chips/xxxxx for the particular driver.

#### 4.17.1 Bad readings from the AS99127F!

The Asus AS99127F is a modified version of the Winbond W83781D. Asus will not release a datasheet. The driver was developed by tedious experimentation. We've done the best we can. If you want to make adjustments to the readings please edit /etc/sensors.conf. Please don't ask us to fix the driver. Ask Asus to release a datasheet.

#### 4.17.2 Bad readings from the VIA 686A!

The Via 686A datasheet is incomplete. Via will not release details. The driver was developed by tedious experimentation. We've done the best we can. If you want to make adjustments to the readings please edit /etc/sensors.conf. Please don't ask us to fix the driver. Ask Via to release a better datasheet. Also, don't forget to modprobe i2c-isa.

#### 4.17.3 Bad readings from the MTP008!

The MTP008 has programmable temperature sensor types. If your sensor type does not match the default, you will have to change it. See doc/chips/mtp008 for details. Also, MTP008 chips seem to randomly refuse to respond, for unknown reasons. You can see this as 'XX' entries in i2cdump.

#### 4.17.4 Bad temperature readings from the SIS5595!

This chip can use multiple thermistor types and there are also two different versions of the chip. We are trying to get the driver working better and develop formulas for different thermistors but we aren't there yet. Sorry. Also, many times the chip isn't really a sis5595 but it was misidentified. We are working on improving that too.

#### 4.17.5 Bad readings from a w8378[12]d!

Do you own an ASUS motherboard? Perhaps your chip is being misidentified. Look on the motherboard (or at http://mbm.livewiredev.com) for a 'Winbond' or Asus chip. Often the real device is an Asus as99127f. If so, the driver can be forced to recognize the as99127f with force_as99127f=BUS,0x2d where `BUS` is your i2c bus number. Cat /proc/bus/i2c to see a list of bus numbers. Read the w83781d module documentation (doc/chips/w83781d) for more details.

#### 4.17.6 Bus hangs on Ali 1543 on Asus P5A boards!

The SMBus tends to hang on this board and it seems to get worse at higher temperatures. Use ISA accesses to reliably use the w83781d monitor chip on this board and use the ignore=1,0x2d or similar option to the w83781d module to prevent i2c accesses.

#### 4.17.7 Bad readings from LM75!

The LM75 detection is poor and other hardware is often misdetected as an LM75. Figure out what you really have See What chips are on motherboard XYZ.

#### 4.17.8 Bad readings from LM78!

The LM78 is no longer manufactured by National Semiconductor. You probably don't have a real LM78 but something similar that we do not recogize or support. Figure out what you really have See What chips are on motherboard XYZ.

#### 4.17.9 Bad readings from LM80!

The LM80 detection is poor and other hardware is often misdetected as an LM80. Figure out what you really have See What chips are on motherboard XYZ.

#### 4.17.10 Bad readings from it87!

The it87 temperature sesnsors are configured, unfortunately, in a way different from w83781d. They cannot be configured from /etc/sensors.conf; they must be set at modprobe insertion with modprobe it87 temp_type=0xXX. See doc/chips/it87 for details.

Next: Section 4.19, Previous: Section 4.17, Up: Problems

### 4.18 How do I configure two chips (LM87) differently?

There is a SuperMicro board with two LM87's on it that are not hooked up in the same way, so they need different defaults. For example, both CPU temperatures go to one LM87.

Make two different sections in /etc/sensors.conf as follows:

         chip "lm87-i2c-*-2c"
             put configuration for the chip at 0x2c here
         chip "lm87-i2c-*-2d"
             put configuration for the chip at 0x2d here

There is a commented example in sensors.conf.eg which should be helpful.

Next: Section 4.20, Previous: Section 4.18, Up: Problems

### 4.19 Dmesg says Upgrade BIOS! I don't want to!

If the problem is a PCI device is not present in lspci, the solution is complex. For the ALI M7101 device, there is a solution which uses the 2.4 kernel's hotplug facility. See prog/hotplug in our package. For other PCI devices, you can try to modify the m7101 solution in prog/hotplug.

If dmesg says try force_addr, see below. Other drivers generally do not support the force_addr parameter. Sorry. Check the documentation for your driver in doc/[chips,busses] and if we don't support it you can send us your request.

#### 4.19.1 Dmesg says use force_addr=0xaddr! What address do I use?

If the problem is a PCI device whose base address is not set, you may be able to set the address with a force parameter. The via686a and sis5595 chip drivers, and some bus drivers, support the command line modprobe via686a force_addr=0xADDRESS where ADDRESS is the I/O address. You must select an address that is not in use. cat /proc/ioports to check (carefully) for conflicts. A high number like 0xf000 is generally safe.

Next: Section 4.21, Previous: Section 4.19, Up: Problems

### 4.20 Sensors says Can't access procfs/sysfs file

- (Linux 2.6) Did you modprobe i2c_sensor? Check lsmod.
- (Linux 2.4) Did you modprobe i2c-proc? Check lsmod.
- If you did sensors -s, did you run it as root?
- (Linux 2.6) Do you have sysfs support in your kernel (is /sys there and populated)?
- (Linux 2.4) Do you have procfs support in your kernel (is /proc there and populated)?

Next: Section 4.22, Previous: Section 4.20, Up: Problems

### 4.21 Sensors says No sensors found!

- Did sensors-detect find sensors? (If not see Sensors-detect doesnt find any sensors)
- Did you do what sensors-detect said?
- Did you modprobe your sensor modules?
- Did you modprobe your I2C adapter modules?
- Did you modprobe i2c-isa if you have ISA sensor chips?
- Check lsmod.

Next: Section 4.23, Previous: Section 4.21, Up: Problems

### 4.22 Sensors output is not correct!

What specifically is the trouble?

- Labels: See The labels for the voltage and temperature readings in sensors are incorrect.
- Min/max readings: See The min and max for the readings in sensors are incorrect, and See The min and max settings didnt take effect.
- AS99127F: See I ran sensors-detect but now I get very strange readings?.
- Via 686A: See I ran sensors-detect but now I get very strange readings?.
- Other specific chips: See I ran sensors-detect but now I get very strange readings?.
- No output for a particular sensors chip: See What to do if it inserts but nothing happens.
- No output at all: See Sensors says No sensors found, See What to do if it inserts but nothing happens.
- Completely bad output for a particular sensor chip: See What to do if I read only bogus information.
- One particular sensor readings:
  - Maybe it isn't hooked up? - tell 'sensors' to ignore it. See One sensor isnt hooked up on my board.
  - Maybe it is hooked up differently on your motherboard? - adjust sensors.conf calculation.

Next: Section 4.24, Previous: Section 4.22, Up: Problems

### 4.23 What is at I2C address XXX?

In general, we don't know. Start by running sensors-detect. If it doesn't recognize it, try running i2cdump. A partial list of manufacturers' IDs are at the bottom of doc/chips/SUMMARY.

#### 4.23.1 What is at I2C address 0x69?

A clock chip. Often, accessing these clock chips in the wrong way will instantly crash your computer. Sensors-detect carefully avoids these chips. If you really really want to play with your clock chip you can look at kernel/chips/icspll.c in our package. But we do not recommend it. You have been warned.

#### 4.23.2 What is at I2C addresses 0x50 - 0x57?

EEPROMs on your SDRAM DIMMs. Load the eeprom module to look at some basic data in sensors or use the program prog/eeprom/decode-dimms.pl to get more information than you ever wanted.

#### 4.23.3 What is at I2C addresses 0x30 - 0x37?

These are often 'shadows' of your EEPROMs on your SDRAM DIMMs at addresses 0x50 - 0x57. They are the 'software write-protect' registers of the SDRAM Serial Presence Detect EEPROMs. If you try and do a i2cdump on them to read the location, you won't get anything, because they contain a single write-only register. This register can be used to permanently write-protect the contents of the eeprom.

Next: Section 4.25, Previous: Section 4.23, Up: Problems

### 4.24 Sensors-detect doesn't work at all

It could be many things. What was the problem? See Problems on particular motherboards.

#### 4.24.1 Sensors-detect says "Couldn't open /proc/bus/i2c?!?"

You don't have i2c support in your kernel, or the i2c-core module was not loaded and you did not run sensors-detect as root.

#### 4.24.2 Sensors-detect says "Can't open /dev/i2c[-/]0"

Your /dev/i2c-0, /dev/i2c0, or /dev/i2c/0 files do not exist or you did not run sensors-detect as root. Run the script prog/mkdev/mkdev.sh to create the /dev/i2c-x files. Run devfs in the kernel to get the /dev/i2c/x files.

#### 4.24.3 Sensors-detect doesn't find any sensors!

Either

1. The board doesn't have any sensors.
2. We don't support the sensors on the board.
3. The sensors it has are on an I2C bus connected to an I2C bus adapter that we don't support.
4. You don't have the latest version of lm_sensors.

But in any case you should figure out what is on the board:

1. Look at your motherboard.
2. Check the manufacturer's website.
3. Check the Motherboard Monitor website.

When you know what chips you have, check the Newest Driver Status web page to see if support has been added for your chip in a later release or in CVS.

Next: Section 4.26, Previous: Section 4.24, Up: Problems

### 4.25 Sensors says Error: Line xxx: zzzzzzz

These are errors from the libsensors library in reading the /etc/sensors.conf configuration file. Go to that line number and fix it. If you have a parse error, perhaps you have to put the feature name in double quotes.

Next: Section 4.27, Previous: Section 4.25, Up: Problems

### 4.26 Sensors only gives the name, adapter, and algorithm for my chip

If sensors only says this, for example, and doesn't provide any actual data at all:

         it87-isa-0290
         Adapter: ISA adapter
         Algorithm: ISA algorithm

Your chip is not currently supported by sensors and so all it does is print out that information. Get the latest release and be sure you are running the sensors program it installed and not some older sensors.

Next: Section 4.28, Previous: Section 4.26, Up: Problems

### 4.27 Sensors says ERROR: Can't get xxxxx data!

- (Linux 2.6) Make sure you are using one of the recommended kernel/lm_sensors combination.
- You have a libsensors/sensors mismatch. sensors is unable to get a data entry from libsensors. You probably have an old libsensors in your /etc/ld.so.conf path. Make sure you did (as root) a make install (Linux 2.4) or make user_install (Linux 2.6) followed by a ldconfig. Then check the output of ldconfig -v | grep libsensors to verify that there is only ONE libsensors entry and that it matches the libsensors that was built in the lib/ directory in lm_sensors2.

Next: Section 4.29, Previous: Section 4.27, Up: Problems

### 4.28 Sensors doesn't find any sensors, just eeproms.

See Sensors-detect doesnt work at all, if sensors-detect failed to find any sensors.

If sensors-detect did find sensors, did you insert your modules? For chips on the ISA bus, did you insert i2c-isa?

See What to do if a module wont insert, if the modules didn't insert, also Sensors says No sensors found.

Next: Section 4.30, Previous: Section 4.28, Up: Problems

### 4.29 Inserting modules hangs my board

There are several possible causes:

1. Bus driver problems. Insert the bus driver first, before you have inserted any chip drivers, to verify.
2. Wrong chip driver. Verify that you have a chip supported by the chip driver, see What chips are on motherboard XYZ.
3. The chip driver is reinitializing the chip, which undoes critical initialization done by the BIOS. Try the parameter init=0 for the w83781d driver; this is the only driver supporting this parameter.
4. Some chips on the bus don't like to be probed at all. After inserting the bus driver (but not the chip drivers), run i2cdetect on the bus, then i2cdump on each address responding to i2cdetect. This may find the culprit. Do not i2cdump address 0x69, the clock chip.
5. The chip driver is incorrectly finding a second chip on the bus and is accessing it. For example, with the Tyan 2688 with a w83781d at 0x29, use modprobe ignore_range=0,0x00,0x28,0,0x2a,0x7f to prevent access to other addresses. (init=0 also req'd for the Tyan 2688).

Next: Section 4.31, Previous: Section 4.29, Up: Problems

### 4.30 Inserting modules slows down my board

Generally this is caused by an overtemperature alarm output from the sensor chip. This triggers hardware on the board which automatically slows down the CPU clock. Be sure that your temperature limits are above the temperature reading. Put the new limits in /etc/sensors.conf and run sensors -s.

Next: Section 4.32, Previous: Section 4.30, Up: Problems

### 4.31 Problems on particular motherboards

The following boards have unique problems and solutions.

#### 4.31.1 Asus P4B

See prog/hotplug/README.p4b if your SMBus master is not found.

#### 4.31.2 Tyan 2460, 2462

See support tickets 805, 765, 781, 812, 813, and 867 for information.

#### 4.31.3 Tyan 2466

See support tickets 941, 840, and 841 for information.

#### 4.31.4 Tyan 2688

For board hangs, see support ticket 721 for information. Also Inserting modules hangs my board.

Next: Section 4.33, Previous: Section 4.31, Up: Problems

### 4.32 Problems on particular systems

For IBM systems, see README.thinkpad.

Previous: Section 4.32, Up: Problems

### 4.33 Problems on 2.6 kernels

Not all drivers have been ported to 2.6. If your favorite driver is not in 2.6, the reason is that nobody has ported it. Please don't bother asking us why it is not in 2.6. If you would like to port the driver, see the file Documentation/i2c/porting-clients in the 2.6 kernel tree for help, then send us the ported driver when you are done.

Next: Contribute, Previous: Problems, Up: Top

## 5 How to Ask for Help

Next: Section 5.2, Up: Help

### 5.1 What to send us when asking for help

We are always willing to answer questions if things don't work out. Please email sensors@stimpy.netroedge.com, and not the individual authors, unless you have something private to say.

Instead of using email, you can also use the web-based support area, at http://secure.netroedge.com/~lm78/support.html. You will be helped just as fast, and others may profit from the answer too. You will be emailed automatically when your question has been answered.

Here's what you should send us:

- The dmesg or syslog output if applicable
- The output of (as root) prog/detect/sensors-detect
- The output of lsmod
- If a PCI chip problem:
  - The output of lspci -n
- If an I2C sensor chip problem:
  - The output of (as root) prog/detect/i2cdetect X where X = the bus number (run i2cdetect with no arguments to list the busses) (please send this only if it's not all XX)
  - The output of (as root) prog/dump/i2cdump X 0xXX where XX = the address of each chip you see in the output of i2cdetect. (run once for each chip) (please send this only if it's not all ff)
- If an ISA sensor chip problem:
  - The output of (as root) prog/dump/isadump 0x295 0x296 (only if it's not all XX)
- Part numbers of chips on your motherboard you think are the sensor chips (look at your motherboard)
- Motherboard type
- Sensors version
- Kernel version

Next: Section 5.3, Previous: Section 5.1, Up: Help

### 5.2 What to do if a module won't insert?

Did you use modprobe instead of insmod??? Don't use insmod.

Were there unresolved symbols? Did you run depmod -a? Run depmod -a -e to see where the symbol problem is.

ALWAYS inspect the output of dmesg. That's where the error messages come out!!! Don't rely on the generic message from modprobe. If you still can't figure it out, send us the information listed above.

Next: Section 5.4, Previous: Section 5.2, Up: Help

### 5.3 What to do if it inserts, but nothing happens?

For an ISA sensor chip, did you also modprobe i2c-isa? It must be inserted.

For an I2C sensor chip, did you also modprobe i2c-xxx where xxx is your I2C bus adapter? It must be inserted.

Always inspect the output of dmesg. That's where the error messages come out. If you still can't figure it out, send us the information listed above.

Next: Section 5.5, Previous: Section 5.3, Up: Help

### 5.4 What to do if I read only bogus information?

It may be that this was a mis-detection: the chip may not be present. If you are convinced there is something wrong, verify that you indeed have the devices on your motherboard that you think you do. Look at the motherboard and make sure. If you are still stuck, please send us the usual information (see Help)

Next: Section 5.6, Previous: Section 5.4, Up: Help

### 5.5 What to do if you have other problems?

Again, send the output listed above.

Next: Section 5.7, Previous: Section 5.5, Up: Help

### 5.6 What if it just works like a charm?

Drop us a mail if you feel like it, mentioning the mainboard and detected chip type. That way, we have some positive feedback, too!

Next: Section 5.8, Previous: Section 5.6, Up: Help

### 5.7 How do I update a ticket?

You can't. Only developers can. Follow up by emailing us at sensors@stimpy.netroedge.com and reference your ticket number in the subject. Please don't enter a new ticket with follow-up information, email us instead. Thanks.

Previous: Section 5.7, Up: Help

### 5.8 How do I follow up on a ticket?

Follow up by emailing us at sensors@stimpy.netroedge.com and reference your ticket number in the subject.

Next: Version 1 Specifics, Previous: Help, Up: Top

## 6 How to Contribute

Next: Section 6.2, Up: Contribute

### 6.1 How to write a driver

See doc/developers/new_drivers in our package for instructions.

Next: Section 6.3, Previous: Section 6.1, Up: Contribute

### 6.2 How to get CVS access

For anonymous CVS read access, see the instructions on our download page. Sorry, we don't have automatically generated CVS tarballs.

For write access, run the script doc/developers/genpasswd.pl in our package and follow the instructions. Let us know what part of the package you would like to work on.

Next: Section 6.4, Previous: Section 6.2, Up: Contribute

### 6.3 How to donate hardware to the project

Send us email sensors@stimpy.netroedge.com.

Next: Section 6.5, Previous: Section 6.3, Up: Contribute

### 6.4 How to join the project mailing list

Send us email sensors@stimpy.netroedge.com. Sorry, there is no automated subscribe/unsubscribe service yet (but we're seriously thinking of switching to majordomo). Please note that you do NOT need to be subscribed to the list in order to post. If you simply need help as a user, post your detailed problem and questions directly. Don't worry, you'll be CC'd on all replies.

Next: Section 6.6, Previous: Section 6.4, Up: Contribute

### 6.5 How to access mailing list archives

The mailing list archive is at: http://archives.andrew.net.au/lm-sensors Sorry, it only contains messages since October 28, 2001.

Next: Section 6.7, Previous: Section 6.5, Up: Contribute

### 6.6 How to submit a patch

Check out the latest from CVS, then copy the directory to another directory, and make your changes. Generate the diff with diff -u2 -r DIR1 DIR2. Or you can generate the diff in CVS with cvs diff -u2. Send us the patch in an email and tell us what it does.

Next: Section 6.8, Previous: Section 6.6, Up: Contribute

### 6.7 How to REALLY help

Believe it or not, what we really need help with are:

- Answering email
- Answering support tickets
- Submitting patches to Linus, etc.
- Creating a sensors.conf database
- Creating RPM's

Send us email sensors@stimpy.netroedge.com if you can help. No experience necessary :)

Next: Section 6.9, Previous: Section 6.7, Up: Contribute

### 6.8 How to get release announcements

We don't have a separate release announcement mailing list; however, we put all our releases on freshmeat: http://freshmeat.net and you can register on our freshmeat project page http://freshmeat.net/projects/lm_sensors to 'subscribe to new releases' and then freshmeat will email you announcement.

Previous: Section 6.8, Up: Contribute

### 6.9 How to block spam on the project mailing list

Sorry, we know the spam is a hassle. It would be nice to have a moderator who can screen everything, but that takes too much time and delays emails. Right now there is a procmail script which tags likely spam and puts in a X-SBClass: header. If it is followed by 'Spam', then it is almost certainly spam, if it is followed by 'Blocked', then it scores high as being potential spam. You should be able to set some rules in your mail client to throw those emails into a seperate folder. It's not bullet proof (some legit mails get tagged wrong, and vice versa), but it seems to be about 95% accurate in our experience.

Next: Document Revisions, Previous: Contribute, Up: Top

## 7 Version 1 Specific Questions

Note: Version 1 is very very old and is not recommended.

Next: Section 7.2, Up: Version 1 Specifics

### 7.1 My manufacturer swears that my mainboard has an SMBus, but your code reports that it can't find it. What's wrong?

Currently, our code only assumes that an SMBus exists if it originates from the Intel PIIX4 (82371AB). If your computer doesn't have one, or if your SMBus originates from a different SMBus 'host', then you are out of luck. :'( Our experience is, though, that most machines have a PIIX4, and that it is where the SMBus is hosted.

Regarding the VIA chip set(s):

Right now, the SMBus code depends on the Intel PIIX4 chip to handle SMBus transactions. The VIA chip set is NOT supported at this time because it forces much of the SMBus protocol to be implemented by software.

To implement the SMBus correctly with the VIA chip, it needs to be written at a low level to be quick. A more attractive alternative is to use the Bios SMBus interface (not always available nor standard).

Version 2 supports the VIA chipset, and will support other chipsets. Version 1 never will.

Next: Section 7.3, Previous: Section 7.1, Up: Version 1 Specifics

### 7.2 The modules won't load, saying 'SMBus not detected'.

This should no longer be an issue in 1.4.10 and later; it will continue loading, but it won't support SMBus-connected devices, of course.

Next: Section 7.4, Previous: Section 7.2, Up: Version 1 Specifics

### 7.3 I try to read /proc/sensors, and I get a "No sensor data yet (try again in a few moments)" message. Why?

It takes about 1.5 seconds for the LM78 to update all its sensor values. If we would try to read it before it finished that, you would get old garbage instead. So you have to wait 1.5 seconds after the module is inserted before you can access /proc/sensors.

Module versions 1.3.7 and later let the process sleep if it tries to access sensor data right after insertion time, and do not display this message anymore.

Previous: Section 7.3, Up: Version 1 Specifics

### 7.4 On my Dell, a LM80 is detected, but all readings are 0!

This is a bug we have only observed on Dell computers. There is probably a problem with the way the SMBus is accessed; but it is not yet clear whether the problem is in our code or with the Dells.

There are very probably no sensor chips at all on your computer; but until somebody contacts Dell about this and tells us the results, we can not be sure.

Previous: Version 1 Specifics, Up: Top

## Appendix A Revision History of This Document

- Rev 2.10 (MDS) Various updates, 20040103
- Rev 2.9 (CP) Converted to Gnu texinfo format, 20020910
- Rev 2.8 (MDS) Minor updates 20020710, released with lm_sensors 2.6.4
- Rev 2.7 (MDS) Minor updates 20020425
- Rev 2.6 (MDS) Minor updates 20020115, released with lm_sensors 2.6.3
- Rev 2.5 (MDS) Minor updates 20011111, released with lm_sensors 2.6.2
- Rev 2.4 (MDS) Minor updates 20010722
- Rev 2.3 (MDS) General update, 20010224, released with lm_sensors 2.6.0.
- Rev 2.2 (Frodo) Corrections for lm_sensors 2.4, 19990920
- Rev 2.1 (Frodo) Corrections for lm_sensors 2.2, 19990112
- Rev 2.0 (Frodo) Major revision for lm_sensors 2.1, 19981229
- Rev 1.10 (Frodo) Modified 3.8, updated some other things, 19980924
- Rev 1.9 (Frodo) Added 3.15, 19980906
- Rev 1.8 (Frodo) Added 3.14, 19980905
- Rev 1.7 (Phil) Added 3.13 and some other minor changes, 19980901
- Rev 1.6 (Frodo) Added 4, 4.1, 4.2, 4.3, 4.4, 4.5, 19980901
- Rev 1.5 (Frodo) Added 2.3, 2.4, 3.9, 3.10, 3.11, 19980826
- Rev 1.4 (Frodo) Added some more Winbond information, and 3.5-3.8, 19980817
- Rev 1.3 Added info on the Winbond chip, 19980816
- Rev 1.2 Adapation by Frodo Looijaard, 19980810
- Rev 1.1 Modifications by Philip Edelbrock, 19980809
- Rev 1.0 Written by Philip Edelbrock, 19980803