AMDTEMP(4)

📦
version 15.1 · 2 versions
, in freebsd 14.5, freebsd 15.1, nixpkgs unstable

👑 AMDTEMP(4) — the AMD temp-sensor driver, explained by your favorite unix bestie

okay so real talk, we're in the Kernel Interfaces Manual rn and this page is all about amdtemp, the device driver for the AMD processor on-die digital thermal sensor. like yes, the thing that tells you how toasty your CPU is. 🌡️✨

💖 NAME

amdtemp — device driver for AMD processor on-die digital thermal sensor

it's giving "thermometer but make it kernel-level" fr fr 🫶

✨ SYNOPSIS

so to compile this driver into the kernel, you drop this line in your kernel config file:

device amdtemp

or, alternatively, if you'd rather load it as a module at boot time — which, honestly, slay — put this line in loader.conf(5):

amdtemp_load="YES"

pick your lane bestie, both work 💅

🦋 DESCRIPTION

The amdtemp driver provides support for the on-die digital thermal sensor present in AMD Family 0Fh, 10h, 11h, 12h, 14h, 15h, 16h, and 17h processors. that's a whole lineup, no cap 🔥

🌸 Family 0Fh processors

For Family 0Fh processors, the amdtemp driver reports each core's temperature through sysctl nodes, named:

dev.amdtemp.%d.core{0,1}.sensor{0,1}

The driver also creates dev.cpu.%d.temperature in the corresponding CPU device's sysctl tree, displaying the maximum temperature of the two sensors located in each CPU core. so like, it's not playing favorites, it's picking the hottest one 😭

🎀 Family 10h, 11h, 12h, 14h, 15h, 16h, and 17h processors

For Family 10h, 11h, 12h, 14h, 15h, 16h, and 17h processors, the driver reports each package's temperature through a sysctl node, named:

dev.amdtemp.%d.core0.sensor0

The driver also creates dev.cpu.%d.temperature in the corresponding CPU device's sysctl tree, displaying the temperature of the shared sensor located in each CPU package. one sensor per package, living its main character life 👑

🧚 SYSCTL VARIABLES

the following variable is available as both a sysctl(8) variable and a loader(8) tunable — dual citizenship, we love to see it:

  • dev.amdtemp.%d.sensor_offset — adds the given offset to the temperature of the sensor. default is 0.

so if your readings are feeling a little off, this is your little knob to nudge them. ✨

🌈 SEE ALSO

go read those too bestie, iykyk 📚

⭐ HISTORY

The amdtemp driver first appeared in FreeBSD 7.1. a legend was born, periodt 💫

💜 AUTHORS

  • Rui Paulo <rpaulo@FreeBSD.org>
  • Norikatsu Shigemura <nork@FreeBSD.org>
  • Jung-uk Kim <jkim@FreeBSD.org>

three icons, one driver. we stan 🫶

💀 CAVEATS

okay this part is important so like, pay attention bestie 🙈

For Family 10h and later processors, according to the BIOS and Kernel Developer's Guide (BKDG) for AMD Processors, “(the reported temperature) is a non-physical temperature measured on an arbitrary scale and it does not represent an actual physical temperature like die or case temperature. Instead, it specifies the processor temperature relative to the point at which the system must supply the maximum cooling for the processor's specified maximum case temperature and maximum thermal power dissipation”.

so like — do not read that number and think "ah yes, my CPU is exactly 47.3°C of physical reality." it is not that. it's a relative, arbitrary-scale number. the BKDG says so, and the BKDG does not lie. 💀

the BKDG lives here if you wanna go read the source material: http://developer.amd.com/resources/developer-guides-manuals/

and that's the whole page!! mwah 💋 this edition came to you from Debian, dated September 5, 2017 — so like, a little vintage, but the vibes are timeless 🎀✨

📦 where this page comes from