1.\" 2.\" This file and its contents are supplied under the terms of the 3.\" Common Development and Distribution License ("CDDL"), version 1.0. 4.\" You may only use this file in accordance with the terms of version 5.\" 1.0 of the CDDL. 6.\" 7.\" A full copy of the text of the CDDL should have accompanied this 8.\" source. A copy of the CDDL is also available via the Internet at 9.\" http://www.illumos.org/license/CDDL. 10.\" 11.\" 12.\" Copyright 2019, Joyent, Inc. 13.\" Copyright 2024 Oxide Computer Company 14.\" 15.Dd May 22, 2024 16.Dt SMNTEMP 4D 17.Os 18.Sh NAME 19.Nm smntemp 20.Nd AMD SMN Temperature Sensor Driver 21.Sh SYNOPSIS 22.Pa /dev/sensors/temperature/cpu/* 23.Sh DESCRIPTION 24The 25.Nm 26driver provides the system access to the temperature and control sensors found 27in the AMD System Management Network 28.Pq SMN 29on Zen 1-5 processors 30.Pq AMD Family 17h, 19h, and 1ah . 31.Pp 32Each CCD, core complex die, present in the SoC exposes its own temperature in 33degrees Celsius. 34This covers the temperature of the CCD as a whole and could be thought of as a 35temperature sensor for all the cores and caches in the die. 36There is no per-core temperature sensor available. 37.Pp 38In addition, a control temperature is exposed for each I/O die, Zen 2 and newer, 39or each Zeppelin die, Zen 1. 40The control temperature is a unitless measure derived from the temperature that 41indicates to cooling infrastructure what action to take and can take any value 42on the range 0 to 100. 43A value of 95 indicates that thermal throttling should be occurring and a value 44of 100 indicates that the chip will hit its thermal limit and shut down if no 45action is taken. 46Critically, the control temperature is not truly a measure of degrees! 47.Pp 48Temperature information is available to the system via the fault 49management architecture 50.Pq FMA . 51The file system location and programming interface to the 52.Nm 53driver are considered 54.Sy Volatile , 55subject to change without notice, and should not be used directly. 56Raw temperature information can be dumped through the FMA developer 57utility fmtopo. 58.Sh SEE ALSO 59.Xr amdnbtemp 4D , 60.Xr amdzen 4D , 61.Xr fmadm 8 62.Rs 63.%A AMD 64.%B Open-Source Register Reference For AMD Family 17h Processors Models 00h-2Fh 65.%D July, 2018 66.Re 67