Manual browser: lm(4)

LM(4) Kernel Interfaces Manual LM(4)


lmNational Semiconductor LM78, LM79 and compatible hardware monitors


lm0 at isa? port 0x280 flags 0x00
lm1 at isa? port 0x290 flags 0x00
lm2 at isa? port 0x310 flags 0x00
lm3 at isa? port 0xa00 flags 0x00
lm0 at pnpbios0 index ? flags 0x00
lm0 at iic? addr 0x2e flags 0x00
lm* at wbsio?


The lm driver provides support for the National Semiconductor LM series hardware monitors and register compatible chips to be used with the envsys(4) API.

Most supported devices possess 11 sensors:

Sensor Units Typical Use
IN0 uV DC Core voltage
IN1 uV DC unknown
IN2 uV DC +3.3V
IN3 uV DC +5V
IN4 uV DC +12V
IN5 uV DC -12V
IN6 uV DC -5V
Temp uK Motherboard Temperature
Fan0 RPM Fan
Fan1 RPM Chassis Fan
Fan2 RPM Fan
for some devices (most Winbond devices) sensor names and numbers will be different.

Due to hardware limitations, fresh sensor data is only available every 2 seconds.


Chips supported by the lm driver include:
  • National Semiconductor LM78, LM78-J, LM79 and LM81.
  • Winbond W83627HF*, W83627THF*, W83627EHF*, W83627DHG*, W83637HF*, W83697HF*, W83781D, W83782D*, W83783S*, W83791D*, W83791SD and W83792D.
  • ASUS AS99127F.

For most of the Winbond chips (identified with a * above), the flags configuration option can be specified to select the type of temperature sensor:

flags Sensor Type
0 Thermistor diode (Power-On default)
1 Pentium-II diode
2 2N3904 Bipolar
4 Thermistor diode


The lm device appeared in NetBSD 1.5.


Interrupt support is unimplemented.

There are currently no known pnpbios IDs assigned to LM chips.

February 16, 2010 NetBSD 7.0