Incorrect AMD Threadripper Temperatures on Linux 4.18 to be Fixed Soon

As we near the release of the Linux 4.18.6 stable kernel, more goodies just keep coming for Linux users – its now been reported that the Linux 4.18.6 stable kernel will be able to properly report CPU core temperatures of the new AMD Threadripper 2950X and AMD Threadripper 2990WX processors –

As these two CPUs just launched this month (and the AMD Threadripper has already been overclocked to world-record frequencies, beating the Intel Core i9-7980XE), Linux was unable to report correct temperature reports on the stock Linux kernel – until now. Basically, the current Linux kernels were reporting the CPU core temperatures on these brand new AMD Threadripper CPUs as being +27 degrees (Celsius) higher than what they really were. This was because of a missing Tctl offset.

For Linux users who saw these falsely reported temps, +27 degrees Celcius (or +80 degrees Fahrenheit) is a pretty extreme difference in temperature readout – we wouldn’t be surprised if some people thought their CPU was about to go up in smoke and flames. The 2950X has a 180 Watt TDP, and the 2990WX has a 250 Watt TDP, so we can imagine how easy it’d be to see those kinds of temps at first glance and think “Holy crap, my computer is literally about to explode”. And also, if you use air cooling, you really generally want accurate temperature readouts to see how stable of an overclock you can get, and how effective your cooling is.

In any case, with Linux 4.19-rc1 being recently pushed out the door as the very first development release of the new Linux 4.19 kernel, Greg Kroah-Hartman has pulled this stable-marked patch for back-porting to the older Linux kernels – and its already in his Linux kernel 4.18 stable queue. So these patches should be released as 4.18.6, and thus correct the temperature misreadings.

However, the k10temp patch will not be back-ported to earlier LTS kernels, because it was only around Linux 4.15 that the Zen temperature reporting code was in fact added – so if you want to the k10temp patch in Linux 4.16 to Linux 4.17 kernels, the patch should already be able to be cleanly applied to those versions.

Aside from this little issue, however, the new Threadripper series performs amazingly on Linux – even better than on Windows, as discovered on many Threadripper 2 benchmarks.

Kamil Anwar
Kamil is a certified MCITP, CCNA (W), CCNA (S) and a former British Computer Society Member with over 9 years of experience Configuring, Deploying and Managing Switches, Firewalls and Domain Controllers also an old-school still active on FreeNode.