Advanced Configuration and Power Interface Specification

Processor Configuration and Control
the corresponding state entry in the _TSS as indicated by the value returned by the _TPC method or
any lower power (higher numbered) state entry in the _TSS.
Arguments:
None
Return Value:
An Integer containing the number of states supported:
0 – states 0 ... n th state available (all states available)
1 – state 1 ... n th state available
2 – state 2 ... n th state available
…
n – state n available only
In order to support dynamic changes of _TPC object, Notify events on the processor object of type
0x82 will cause OSPM to reevaluate any _TPC object in the processor’s object list. This allows
AML code to notify OSPM when the number of supported throttling states may have changed as a
result of an asynchronous event. OSPM ignores _TPC Notify events on platforms that support P-
states unless the platform has limited OSPM’s use of P-states to the lowest power P-state. OSPM
may choose to disregard any platform conveyed T-state limits when the platform enables OSPM
usage of other than the lowest power P-state.
8.4.5.4 _TSD (T-State Dependency)
This optional object provides T-state control cross logical processor dependency information to
OSPM. The _TSD object evaluates to a packaged list of information that correlates with the T-state
information returned by the _TSS object. Each packaged list entry identifies a dependency domain
number for the logical processor’s T-states, the coordination type for that T-state, and the number of
logical processors belonging to the domain.
Arguments:
None
Return Value:
A variable-length Package containing a list of T-state dependency Packages as described below.
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