Lm-sensor config in 25.05

riza · May 21, 2025, 8:50pm

Hi all,

when switching to 25.05 beta, my lm_sensor config stopped working:

_: {
  config = {
    environment.etc = {
      "sensors3.conf".text = ''
        chip "nct6795-isa-*"
          ignore fan1
          ignore fan4
          ignore fan5
          ignore in10
          ignore temp4
          ignore temp5
          ignore temp6
          ignore temp8
          ignore temp9
          ignore temp10
          ignore temp11
          ignore temp12
          label fan2 "CPU Fan"
          ignore fan3 #"Case Fan"
        chip "amdgpu-pci-*"
          label fan1 "GPU Fan"
      '';
    };
  };
}

Calling sensors via cli:

sensors
nct6795-isa-0a20
Adapter: ISA adapter
Vcore:                 816.00 mV (min =  +0.00 V, max =  +1.74 V)
in1:                     1.01 V  (min =  +0.00 V, max =  +0.00 V)  ALARM
AVCC:                    3.42 V  (min =  +0.00 V, max =  +0.00 V)  ALARM
+3.3V:                   3.39 V  (min =  +0.00 V, max =  +0.00 V)  ALARM
in4:                     1.02 V  (min =  +0.00 V, max =  +0.00 V)  ALARM
in5:                   160.00 mV (min =  +0.00 V, max =  +0.00 V)  ALARM
in6:                   672.00 mV (min =  +0.00 V, max =  +0.00 V)  ALARM
3VSB:                    3.41 V  (min =  +0.00 V, max =  +0.00 V)  ALARM
Vbat:                    3.33 V  (min =  +0.00 V, max =  +0.00 V)  ALARM
in9:                     1.84 V  (min =  +0.00 V, max =  +0.00 V)  ALARM
in10:                    0.00 V  (min =  +0.00 V, max =  +0.00 V)
in11:                  616.00 mV (min =  +0.00 V, max =  +0.00 V)  ALARM
in12:                    1.01 V  (min =  +0.00 V, max =  +0.00 V)  ALARM
in13:                  680.00 mV (min =  +0.00 V, max =  +0.00 V)  ALARM
in14:                    1.53 V  (min =  +0.00 V, max =  +0.00 V)  ALARM
fan1:                     0 RPM  (min =    0 RPM)
fan2:                   269 RPM  (min =    0 RPM)
fan3:                     0 RPM  (min =    0 RPM)
fan4:                     0 RPM  (min =    0 RPM)
fan5:                     0 RPM  (min =    0 RPM)
SYSTIN:                 +43.0°C  (high =  +0.0°C, hyst =  +0.0°C)  ALARM  sensor = CPU diode
CPUTIN:                 +38.0°C  (high = +115.0°C, hyst = +90.0°C)  sensor = thermistor
AUXTIN0:                +44.5°C  (high = +115.0°C, hyst = +90.0°C)  sensor = thermistor
AUXTIN1:               -128.0°C    sensor = thermistor
AUXTIN2:                +49.0°C    sensor = thermistor
AUXTIN3:                 -2.0°C    sensor = thermistor
SMBUSMASTER 0:          +40.5°C
PCH_CHIP_CPU_MAX_TEMP:   +0.0°C
PCH_CHIP_TEMP:           +0.0°C
PCH_CPU_TEMP:            +0.0°C
PCH_MCH_TEMP:            +0.0°C
Agent0 Dimm0:            +0.0°C
TSI0_TEMP:              +40.9°C
intrusion0:            ALARM
intrusion1:            ALARM
beep_enable:           disabled

nvme-pci-0100
Adapter: PCI adapter
Composite:    +52.9°C  (low  =  -5.2°C, high = +83.8°C)
                       (crit = +87.8°C)

k10temp-pci-00c3
Adapter: PCI adapter
Tctl:         +40.1°C
Tccd1:        +51.0°C

amdgpu-pci-2b00
Adapter: PCI adapter
vddgfx:      862.00 mV
fan1:           0 RPM  (min =    0 RPM, max = 3300 RPM)
edge:         +45.0°C  (crit = +110.0°C, hyst = -273.1°C)
                       (emerg = +115.0°C)
junction:     +51.0°C  (crit = +110.0°C, hyst = -273.1°C)
                       (emerg = +115.0°C)
mem:          +46.0°C  (crit = +105.0°C, hyst = -273.1°C)
                       (emerg = +110.0°C)
PPT:           9.00 W  (cap = 194.00 W)

It works if you provide a full path to the (default) config file:

sensors -c /etc/sensors3.conf
nct6795-isa-0a20
Adapter: ISA adapter
in0:           936.00 mV (min =  +0.00 V, max =  +1.74 V)
in1:             1.01 V  (min =  +0.00 V, max =  +0.00 V)  ALARM
in2:             3.42 V  (min =  +0.00 V, max =  +0.00 V)  ALARM
in3:             3.41 V  (min =  +0.00 V, max =  +0.00 V)  ALARM
in4:             1.02 V  (min =  +0.00 V, max =  +0.00 V)  ALARM
in5:           160.00 mV (min =  +0.00 V, max =  +0.00 V)  ALARM
in6:           672.00 mV (min =  +0.00 V, max =  +0.00 V)  ALARM
in7:             3.41 V  (min =  +0.00 V, max =  +0.00 V)  ALARM
in8:             3.33 V  (min =  +0.00 V, max =  +0.00 V)  ALARM
in9:             1.84 V  (min =  +0.00 V, max =  +0.00 V)  ALARM
in11:          616.00 mV (min =  +0.00 V, max =  +0.00 V)  ALARM
in12:            1.01 V  (min =  +0.00 V, max =  +0.00 V)  ALARM
in13:          680.00 mV (min =  +0.00 V, max =  +0.00 V)  ALARM
in14:            1.53 V  (min =  +0.00 V, max =  +0.00 V)  ALARM
CPU Fan:        268 RPM  (min =    0 RPM)
SYSTIN:         +43.0°C  (high =  +0.0°C, hyst =  +0.0°C)  ALARM  sensor = CPU diode
CPUTIN:         +39.0°C  (high = +115.0°C, hyst = +90.0°C)  sensor = thermistor
AUXTIN0:        +45.0°C  (high = +115.0°C, hyst = +90.0°C)  sensor = thermistor
SMBUSMASTER 0:  +41.0°C
TSI0_TEMP:      +41.4°C
intrusion0:    ALARM
intrusion1:    ALARM
beep_enable:   disabled

nvme-pci-0100
Adapter: PCI adapter
Composite:    +52.9°C  (low  =  -5.2°C, high = +83.8°C)
                       (crit = +87.8°C)

k10temp-pci-00c3
Adapter: PCI adapter
Tctl:         +41.2°C
Tccd1:        +50.5°C

amdgpu-pci-2b00
Adapter: PCI adapter
vddgfx:      862.00 mV
GPU Fan:        0 RPM  (min =    0 RPM, max = 3300 RPM)
edge:         +45.0°C  (crit = +110.0°C, hyst = -273.1°C)
                       (emerg = +115.0°C)
junction:     +52.0°C  (crit = +110.0°C, hyst = -273.1°C)
                       (emerg = +115.0°C)
mem:          +46.0°C  (crit = +105.0°C, hyst = -273.1°C)
                       (emerg = +110.0°C)
PPT:          10.00 W  (cap = 194.00 W)

I also tried different config files without any success:

/etc/sensors3.conf (default)
/etc/sensors.conf
/etc/sensors.d/misc.conf

Has anyone an idea what changed in 25.05 and how I can fix this?

Thanks in advance.

crazymevt · May 21, 2025, 11:35pm

I don’t know if this is the appropriate way to fix this issue or not, but it does work

        (final: prev: {
          sensors = final.lm_sensors.overrideAttrs (oldAttrs: 
          let 
            myconfigfile = ''
              chip "acpitz-acpi-0"
                label temp1 "NewTemp"
            '';
          in {

            postBuild = ''
              mkdir -p ${placeholder "out"}/etc/sensors.d/
              cp ${pkgs.writeText "myconfigfile" myconfigfile} ${placeholder "out"}/etc/sensors.d/;
            '';
          });
        })

TLATER · May 22, 2025, 6:41am

I suspect this change is what caused that: lm_sensors: fix build, split outputs, modernize and remove perl from library closure by oxalica · Pull Request #373242 · NixOS/nixpkgs · GitHub

I guess it also affects where it reads the file from at runtime, rather than just where it installs it to. This should be reported upstream, and someone needs to ask the PR author why that was necessary in the first place. If I knew I’d just patch it.

Your workaround obviously gets around this, but you can do it with much less build/eval overhead by skipping the overlay and using symlinkJoin:

{ pkgs, ... }: {
  environment.systemPackages = let
    sensors_config = pkgs.writeTextDir "etc/sensors.d/myconfigfile" ''
      chip "acpitz-acpi-0"
        label temp1 "NewTemp"
    '';
    sensors = pkgs.symlinkJoin {
      inherit (pkgs.sensors) name;
      paths = [
        pkgs.sensors
        sensors_config
      ];
    };
  in [
    sensors
  ];
}

Overriding it does make library dependents also read the correct config, though.

riza · May 24, 2025, 10:54am

I have tried your suggestion and adapted my config like this but problem still persists:

{pkgs, ...}: {
  environment.systemPackages = let
    sensors_config = pkgs.writeTextDir "etc/sensors.d/msib450mpro.conf" ''
      chip "nct6795-isa-*"
        ignore fan1
        ignore fan4
        ignore fan5
        ignore in10
        ignore temp4
        ignore temp5
        ignore temp6
        ignore temp8
        ignore temp9
        ignore temp10
        ignore temp11
        ignore temp12
        label fan2 "CPU Fan"
        ignore fan3 #"Case Fan"
      chip "amdgpu-pci-*"
        label fan1 "GPU Fan"
    '';
    sensors = pkgs.symlinkJoin {
      inherit (pkgs.lm_sensors) name;
      paths = [
        pkgs.lm_sensors
        sensors_config
      ];
    };
  in [
    sensors
  ];
}

TLATER · May 24, 2025, 11:04am

Interesting, make sure you don’t have sensors installed via some other file as well, or that you have not installed it with home-manager, nix-env or nix profile in the past.

crazymevt · May 24, 2025, 11:51am

interesting, I tried that method and it doesn’t work for me either, but the overlay does

crazymevt · May 24, 2025, 1:42pm

also as a note, if you use something like xsensors that depends on lm_sensors it will not read the config file either. You would have to override and build that package as well it seems.