This optional object is a method that is used by OSPM to communicate to the platform the level ofprocessor power management support provided by OSPM. This object is a child object of theprocessor. OSPM evaluates _PDC prior to evaluating any other processor power managementobjects returning configuration information.
The _PDC object provides OSPM a mechanism to convey to the platform the capabilities supportedby OSPM for processor power management. This allows the platform to modify the ACPInamespace objects returning configuration information for processor power management based onthe level of support provided by OSPM. Using this method provides a mechanism for OEMs toprovide support for new technologies on legacy OSes, while also allowing OSPM to leverage newtechnologies on platforms capable of supporting them. This method is evaluated once duringprocessor device initialization, and will not be re-evaluated during resume from a sleep statetransition. The platform must preserve state information across S1-S3 sleep state transitions.
Arguments: (1)
Arg0 – A variable-length Buffer containing a list of capabilities as described below
The buffer argument contains a list of DWORDs in the following format:
RevisionId –
Count –Capabilities[Count] –
Revision of the buffer format
The number of capability values in the capabilities arrayCapabilities array
Each DWORD entry in the capabilities array is a bitfield that defines capabilities and featuressupported by OSPM for processor configuration and power management as specified by the CPUmanufacturer.
The use of _PDC is deprecated in ACPI 3.0 in favor of _OSC. For backwards compatibility, _PDCmay be implemented using _OSC as follows: