Description
- Related to Optional source: Provide temperature for disk if module drivetemp is loaded #821 and FIX#821 Allow code to keep temperature data for device without label. #823
- State: Mostly brain dumping of an informal conversion with Guillaume and I.
On Linux at least /sys/class/hwmon know as Hwmon or Hardware Monitoring sub system is able to gather data from various places in the kernel through loadable modules like amdgpu, drivetemp or thinkpad module.
Nowadays we limit the reading to CPU and GPU monitor. The schema description of what can be read in hwmon files is somewhat "loose", the numeric values are defined as long * kernel side, and can include fan Rotation Per Minute, Volts, Temperature in mili celcius; read value from hardware, critical value and Max-value and also minimal functionally working value.
Exemple from hwmon interface:
| HWMON_C_xxxx | Chip attributes, for use with hwmon_chip. |
|---|---|
| HWMON_T_xxxx | Temperature attributes, for use with hwmon_temp. |
| HWMON_I_xxxx | Voltage attributes, for use with hwmon_in. |
| HWMON_C_xxxx | Current attributes, for use with hwmon_curr. Notice the prefix overlap with chip attributes. |
| HWMON_P_xxxx | Power attributes, for use with hwmon_power. |
| HWMON_E_xxxx | Energy attributes, for use with hwmon_energy. |
| HWMON_H_xxxx | Humidity attributes, for use with hwmon_humidity. |
| HWMON_F_xxxx | Fan speed attributes, for use with hwmon_fan. |
| HWMON_PWM_xxxx | PWM control attributes, for use with hwmon_pwm. |
It may be interesting to design a way to expose this data in two form one low level with Components
The design may retain the "optional" availability of these data since, if the kernel module is not loaded files will not exists and must support a way to make a difference between "no data" and a default value. Aka failing to read shall return None, so the user may get this data for his own purpose (prometheus or something else).
And maybe (not now) a unified view to monitor physical info about for example a Disk or a Network Interface Card without relying on too much vendor specific API.
Kernel Documentation
- Kernel hwmon API: https://www.kernel.org/doc/html/latest/hwmon/hwmon-kernel-api.html
- DriveTemp kernel API: https://docs.kernel.org/gpu/amdgpu/thermal.html#hwmon-interfaces
- Amdgpu hwmon interface: https://www.kernel.org/doc/html/latest/hwmon/drivetemp.html
End of the day goal
Have something like sensors display, may need breaking Component API or doing an other.