ERROR:root:Failed to apply core: set -0.9765625, read 0.0

[przemyslawmaluj]

I used undervolt without any issues for several months. Last week I noticed that something is not right. Then I ran sudo undervolt -v --core -1 --cache -1 and got

INFO:root:Setting core offset to -1mV
INFO:root:Writing 0x80000011ffe00000L to /dev/cpu/0/msr
INFO:root:Writing 0x80000011ffe00000L to /dev/cpu/1/msr
INFO:root:Writing 0x80000011ffe00000L to /dev/cpu/2/msr
INFO:root:Writing 0x80000011ffe00000L to /dev/cpu/3/msr
INFO:root:Writing 0x80000011ffe00000L to /dev/cpu/4/msr
INFO:root:Writing 0x80000011ffe00000L to /dev/cpu/5/msr
INFO:root:Writing 0x80000011ffe00000L to /dev/cpu/6/msr
INFO:root:Writing 0x80000011ffe00000L to /dev/cpu/7/msr
INFO:root:Writing 0x8000001000000000L to /dev/cpu/0/msr
INFO:root:Writing 0x8000001000000000L to /dev/cpu/1/msr
INFO:root:Writing 0x8000001000000000L to /dev/cpu/2/msr
INFO:root:Writing 0x8000001000000000L to /dev/cpu/3/msr
INFO:root:Writing 0x8000001000000000L to /dev/cpu/4/msr
INFO:root:Writing 0x8000001000000000L to /dev/cpu/5/msr
INFO:root:Writing 0x8000001000000000L to /dev/cpu/6/msr
INFO:root:Writing 0x8000001000000000L to /dev/cpu/7/msr
INFO:root:Read 0x0 from /dev/cpu/0/msr
ERROR:root:Failed to apply core: set -0.9765625, read 0.0

Secure Boot is disabled. I have i7-8650U, undervolt 0.2.10. My system was running fine with --core -150 --cache --150

[georgewhewell]

Hm, strange.. no ideas.. did anything else change since it was working? bios update?

[gierdo]

I've got the same issue on a core m7-6Y75, and I also suspect a bios or microcode (if that can affect it, independently from the bios?) update.

[przemyslawmaluj]

Right, it looks like BIOS was updated.

[gierdo]

Just for the fun of it I tested the behavior with https://github.com/kitsunyan/intel-undervolt
Same symptoms, of course.
I guess we have to wait for / hope for a new bios that may or may not allow us to undervolt again.
But with plundervolt, I'm afraid the exact opposite is going to happen for many of us!

[przemyslawmaluj]

That sucks... CPU without undervolting is heavily throttling almost all the time.

[przemyslawmaluj]

I rolled back BIOS to previous version and can use undervolt again.

[georgewhewell]

Thanks for confirm.

[owenjm]

I'm also suddenly experiencing this issue (been using undervolt for months, and is suddenly not working) ... and downgrading the bios does not fix it. (The downgrade worked fine except for updating the Intel ME firmware -- which I don't think should affect this, but I'm not entirely sure?) Any suggestions here would be greatly appreciated, as undervolting massively helps in preventing my laptop's fans from running constantly.

[owenjm]

(Sorry, scratch that -- needed to reset BIOS to defaults, and with the BIOS downgrade it's back.)

[mich2k]

I have got the same error
console_log
on dell xps 15 7590
any way to fix? I just installed undervolt
root@mich-XPS-15-7590:/home/mich# undervolt -v --core -75 --cache -75 INFO:root:Setting core offset to -75mV INFO:root:Writing 0x80000011f6600000L to /dev/cpu/0/msr INFO:root:Writing 0x80000011f6600000L to /dev/cpu/1/msr INFO:root:Writing 0x80000011f6600000L to /dev/cpu/2/msr INFO:root:Writing 0x80000011f6600000L to /dev/cpu/3/msr INFO:root:Writing 0x80000011f6600000L to /dev/cpu/4/msr INFO:root:Writing 0x80000011f6600000L to /dev/cpu/5/msr INFO:root:Writing 0x80000011f6600000L to /dev/cpu/6/msr INFO:root:Writing 0x80000011f6600000L to /dev/cpu/7/msr INFO:root:Writing 0x80000011f6600000L to /dev/cpu/8/msr INFO:root:Writing 0x80000011f6600000L to /dev/cpu/9/msr INFO:root:Writing 0x80000011f6600000L to /dev/cpu/10/msr INFO:root:Writing 0x80000011f6600000L to /dev/cpu/11/msr INFO:root:Writing 0x8000001000000000L to /dev/cpu/0/msr INFO:root:Writing 0x8000001000000000L to /dev/cpu/1/msr INFO:root:Writing 0x8000001000000000L to /dev/cpu/2/msr INFO:root:Writing 0x8000001000000000L to /dev/cpu/3/msr INFO:root:Writing 0x8000001000000000L to /dev/cpu/4/msr INFO:root:Writing 0x8000001000000000L to /dev/cpu/5/msr INFO:root:Writing 0x8000001000000000L to /dev/cpu/6/msr INFO:root:Writing 0x8000001000000000L to /dev/cpu/7/msr INFO:root:Writing 0x8000001000000000L to /dev/cpu/8/msr INFO:root:Writing 0x8000001000000000L to /dev/cpu/9/msr INFO:root:Writing 0x8000001000000000L to /dev/cpu/10/msr INFO:root:Writing 0x8000001000000000L to /dev/cpu/11/msr INFO:root:Read 0x0 from /dev/cpu/0/msr ERROR:root:Failed to apply core: set -75.1953125, read 0.0 root@mich-XPS-15-7590:/home/mich#

[wlainer]

Its' no necessary downgrade bios, I have just reseted bios to factory's default and it worked.

[Kmiller0313]

Its' no necessary downgrade bios, I have just reseted bios to factory's default and it worked.

Just reset the bios to factory default and it still doesn't work.

[TerrorSquad]

Same here, cannot undervolt.

❯ sudo undervolt --core -100 --cache -100
ERROR:root:Failed to apply core: set -99.609375, read 0.0

Dell XPS 15 9570
Linux xps-9750 5.4.0-42-generic #46-Ubuntu SMP Fri Jul 10 00:24:02 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux
I was running the most recent BIOS update and reverted to 1.4.1 (cannot revert to an earlier version), and even after the revert undervolting is not possible.

What's weird is, undervolting is possible under Windows using Throttlestop. I set the the voltage offset to -125mV for core and cache and temps went down nearly 10C degrees. A substantial improvment.

I was reading online how kernel lockdown is actually responsible for this, denying access to /dev/mem paths required for undervolting. Also while reading, I found that ansible-on lots of places it said that disabling Secure Boot would resolve the issue. Secure Boot is disabled but undervolting under Linux is still not possible.

Can we get an update why is this happening and/or how to work around the issue and fix undervolt?

[afrish]

This solution worked for me: https://www.dell.com/community/XPS/Intel-Extreme-Tuning-Utility-Undervolt-Fails-after-Bios-update/td-p/7542653. Basically, go to BIOS -> Restore Settings -> Factory Settings, and after that undervolt works

[moritzschaefer]

@afrish thanks for the workaround. I'm honestly too afraid to crash my Linux-installation when restoring "factory setting". I needed to change quite some settings in the Bios before installation of NixOS was possible..

[afrish]

@moritzschaefer I'm using Kubuntu 20.04 on Dell XPS 9570 with Intel Core i5 and no discrete video card. After resetting to the default settings I just booted as usual and everything worked great. One small thing was changed: top-level F buttons changed their mode, but it's very easy to change them back. There are not so many settings in BIOS, maybe you can make couple photos of your BIOS screen before resetting?

[TerrorSquad]

@afrish thanks for the solution. It worked for me. No settings were lost after the reset. Also, after booting back into Windows, BIOS update started by itself, I presume triggered when Windows started to boot. BIOS is at the latest version now - 1.16.2 and undervolt works 🎉

[moritzschaefer]

Thank you for the encouragement (that's what I actually nedded). I'll try it later..

[moritzschaefer]

The issue persists for me! I actually have the BIOS version 1.19.2, maybe that's the issue. I'm therefore anyways surprised that @TerrorSquad reports version 1.16.2 to be the most recent one..

[sangemaru]

Same issue on XPS 15 9560 BIOS 1.21. Tried bios defaults, factory reset, etc. Probably not an issue with undervolt, as ThrottleStop won't work either.

[notstarboard]

This error has prevented me from undervolting my lab computer (details here). Any help would be much appreciated!

By the way, are there any other working undervolt tools on Linux for non-ancient firmware? Rolling back to an older BIOS version is only a possible workaround for folks who had an older BIOS version to begin with. People have been hitting this error with undervolt since 2019, so it stands to reason that there are a lot of people out there with newer machines that they're not able to undervolt. Are they just stuck, or is there some other working software out there?