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Device-Specific Method for Microsoft thermal extensions

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To support more flexible design of thermal zones and thermal sensors, Windows supports extensions to the ACPI thermal zone model. Specifically, Windows supports a thermal minimum throttle limit (MTL) for each thermal zone, and also supports sharing a temperature sensor between thermal zones.

For more information about MTL, see Thermal management in Windows

To use these features, OEMs can include the following Device-Specific Method (_DSM) in the namespace of any thermal zone.

Function 1: Minimum throttle limit

The _DSM control method parameters for the thermal minimum throttle limit are as follows:

Arguments (Minimum throttle limit)

  • Arg0: UUID = 14d399cd-7a27-4b18-8fb4-7cb7b9f4e500

  • Arg1: Revision ID = 0

  • Arg2: Function index = 1

  • Arg3: Empty package (not used)

Return (Minimum throttle limit)

An integer value with the current minimum throttle limit, expressed as a percentage. Windows will not set the throttle limit below this value.

Function 2: Temperature sensor device

The _DSM control method parameters for the temperature sensor device are as follows:

Arguments (Temperature sensor device)

  • Arg0: UUID = 14d399cd-7a27-4b18-8fb4-7cb7b9f4e500

  • Arg1: Revision ID = 0

  • Arg2: Function index = 2

  • Arg3: Empty package (not used)

Return (Temperature sensor device)

A reference to the device that will return the temperature of this thermal zone.

Temperature sensor device dependency requirement

If a temperature sensor device is reported via _DSM function index 2, the thermal zone is additionally required to include a _DEP object that identifies the thermal zone's dependence on the temperature sensor device.

Function index 0 of every _DSM is a query function that returns the set of supported function indexes, and is always required. For more information, see section 9.14.1, "_DSM (Device Specific Method)", of the ACPI 5.0 specification.