SMNTEMP(4D) Devices SMNTEMP(4D)

NAME

smntemp - AMD SMN Temperature Sensor Driver

SYNOPSIS

/dev/sensors/temperature/cpu/*

DESCRIPTION

The smntemp driver provides the system access to the temperature and
control sensors found in the AMD System Management Network (SMN) on Zen
1-5 processors (AMD Family 17h, 19h, and 1ah).

Each CCD, core complex die, present in the SoC exposes its own
temperature in degrees Celsius. This covers the temperature of the CCD
as a whole and could be thought of as a temperature sensor for all the
cores and caches in the die. There is no per-core temperature sensor
available.

In addition, a control temperature is exposed for each I/O die, Zen 2
and newer, or each Zeppelin die, Zen 1. The control temperature is a
unitless measure derived from the temperature that indicates to cooling
infrastructure what action to take and can take any value on the range
0 to 100. A value of 95 indicates that thermal throttling should be
occurring and a value of 100 indicates that the chip will hit its
thermal limit and shut down if no action is taken. Critically, the
control temperature is not truly a measure of degrees!

Temperature information is available to the system via the fault
management architecture (FMA). The file system location and
programming interface to the smntemp driver are considered Volatile,
subject to change without notice, and should not be used directly. Raw
temperature information can be dumped through the FMA developer utility
fmtopo.

SEE ALSO

amdnbtemp(4D), amdzen(4D), fmadm(8)

AMD, Open-Source Register Reference For AMD Family 17h Processors
Models 00h-2Fh, July, 2018.

illumos May 22, 2024 illumos