Ryzen CPUs On Linux Finally See CCD Temperatures, Current + Voltage Reporting
Written by Michael Larabel in AMD on 16 January 2020 at 01:39 PM EST. 42 Comments
AMD --
One of the few frustrations with the AMD Ryzen CPU support on Linux to date has been besides the often delayed support for CPU temperature reporting has been the mainline kernel not supporting voltage readings and other extra sensors. But that is finally changing with the "k10temp" driver being extended to include current and voltage reporting plus CCD temperature reporting on Zen 2 processors.

There has been the out-of-tree Zenpower driver and other efforts to provide this information on Linux but hasn't been officially backed by AMD and not mainlined in the kernel, thus greatly reducing the exposure to potential users. But now the k10temp driver is finally being extended to include these extra information outputs.

Linux HWMON maintainer Guenter Roeck has been working on these driver improvements to k10temp. Besides some code improvements, the new patches support reporting Core Complex Die (CCD) temperatures on Zen 2 processors. Additionally, for Ryzen CPUs (Zen 1 included) are core/SoC current and voltage information.

With this for current Ryzen 3000 series processors the patched k10temp Linux driver should expose Vcore, VSoc, Tdie, Tctl, Tccd1, Tccd2, Icore, and Isoc outputs.

Guenter posted these patches to the kernel mailing list. He's looking for more testing on these k10temp improvements before he will queue them up for mainline kernel inclusion... Thus if you are hoping to see this work for the upcoming Linux 5.6 cycle, you better start doing some testing on AMD CPUs ASAP and pass along your findings (and, yes, I'll be joining in on this testing party). Regardless of whether it happens for Linux 5.6 or takes another cycle, at least these driver improvements are now happening and hopefully moving forward AMD engineers will be able to make more proactive contributions.
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Michael Larabel is the principal author of Phoronix.com and founded the site in 2004 with a focus on enriching the Linux hardware experience. Michael has written more than 20,000 articles covering the state of Linux hardware support, Linux performance, graphics drivers, and other topics. Michael is also the lead developer of the Phoronix Test Suite, Phoromatic, and OpenBenchmarking.org automated benchmarking software. He can be followed via Twitter or contacted via MichaelLarabel.com.

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