Documentation/hwmon/k8temp

   1 Kernel driver k8temp
   2 ====================
   3
   4 Supported chips:
   5   * AMD Athlon64/FX or Opteron CPUs
   6     Prefix: 'k8temp'
   7     Addresses scanned: PCI space
   8     Datasheet: http://support.amd.com/us/Processor_TechDocs/32559.pdf
   9
  10 Author: Rudolf Marek
  11 Contact: Rudolf Marek <r.marek@assembler.cz>
  12
  13 Description
  14 -----------
  15
  16 This driver permits reading temperature sensor(s) embedded inside AMD K8
  17 family CPUs (Athlon64/FX, Opteron). Official documentation says that it works
  18 from revision F of K8 core, but in fact it seems to be implemented for all
  19 revisions of K8 except the first two revisions (SH-B0 and SH-B3).
  20
  21 Please note that you will need at least lm-sensors 2.10.1 for proper userspace
  22 support.
  23
  24 There can be up to four temperature sensors inside single CPU. The driver
  25 will auto-detect the sensors and will display only temperatures from
  26 implemented sensors.
  27
  28 Mapping of /sys files is as follows:
  29
  30 temp1_input - temperature of Core 0 and "place" 0
  31 temp2_input - temperature of Core 0 and "place" 1
  32 temp3_input - temperature of Core 1 and "place" 0
  33 temp4_input - temperature of Core 1 and "place" 1
  34
  35 Temperatures are measured in degrees Celsius and measurement resolution is
  36 1 degree C. It is expected that future CPU will have better resolution. The
  37 temperature is updated once a second. Valid temperatures are from -49 to
  38 206 degrees C.
  39
  40 Temperature known as TCaseMax was specified for processors up to revision E.
  41 This temperature is defined as temperature between heat-spreader and CPU
  42 case, so the internal CPU temperature supplied by this driver can be higher.
  43 There is no easy way how to measure the temperature which will correlate
  44 with TCaseMax temperature.
  45
  46 For newer revisions of CPU (rev F, socket AM2) there is a mathematically
  47 computed temperature called TControl, which must be lower than TControlMax.
  48
  49 The relationship is following:
  50
  51 temp1_input - TjOffset*2 < TControlMax,
  52
  53 TjOffset is not yet exported by the driver, TControlMax is usually
  54 70 degrees C. The rule of the thumb -> CPU temperature should not cross
  55 60 degrees C too much.