One of my personal gripes with AMD’s Zen CPU support on Linux has been the lack of fast CPU temperature monitoring support with their “k10temp” driver. Although typically only new IDs are often needed and sometimes require adjusting lags or other minor changes, this has traditionally been done post-launch and sometimes left to patches from the open source community. Fortunately, that has changed and with Zen 4 it looks like support will be ready for launch day with the mainline Linux kernel.
AMD together with Rembrandt (Yellow Carp) they managed to land the pre-launch of k10temp support and for Zen 4 they have also been working for some time now to make sure CPU temperature monitoring in Linux works… Certainly not critical for most users but a personal frustration because for launch day CPU reviews it’s great to include thermal data that wasn’t possible when it required more only new ids whereas in the past there were sometimes questions about lags etc. From AMD’s side, it’s not a huge engineering effort, but something that appeals to tech-minded Linux enthusiasts.
Going back to last year, AMD was gearing up for next generation CPUs with k10temp changes to support up to 12 CCDs and making other driver fixes for new PCI IDs. Today, the latest set of patches for k10temp prepares for Zen 4 support.
Patches dating back to last year cited new Family 19h models when it now turns out that some model IDs were missing. AMD Linux engineer Mario Limonciello’s patch series explains: “This series started out as what looked like a fix to the previous commits, but I missed the fact that the previous commits were to a different family with the same chip designs. So while patching the series, I also noticed that a few upcoming chips have new PCIe IDs and CCD offsets not yet supported, so add those to amd_nb/k10temp.“
Lisa Su showing off Zen 4 during her Computex 2022 keynote.
This fifth iteration of the k10temp activation patches corresponds to support for the 17h family A0h-AFh, the 19h family 70h-7Fh, and the 19h family 60h-6Fh. The 17h family is for Zen/Zen 2 while the 19h family is for Zen 3 so far. 19h will include Zen 4 processors, so all indications so far have been the 60h and 70h parts are likely for different Zen 4 (and Zen 4C) chips. The new 17h family IDs are likely for upcoming Mendocino SoCs for budget laptops… Otherwise, I can’t see what other Zen 2 CPUs aren’t currently covered by Linux k10temp driver support.
Either way, v5 patches are now available with the AMD Linux “k10temp” temperature driver ready to support these upcoming processors. Hopefully these fixes will manage to land for the upcoming Linux 5.20 cycle so that there will be mainstream kernel support ahead of the Zen 4 desktop and server processor launches later this year.