Advanced Configuration and Power Interface Specification

Advanced Configuration and Power Interface Specification
8.4.6.5 _PSD (P-State Dependency)
This optional object provides P-state control cross logical processor dependency information to
OSPM. The _PSD object evaluates to a packaged list of information that correlates with the P-state
information returned by the _PSS object. Each packaged list entry identifies a dependency domain
number for the logical processor’s P-states, the coordination type for that P-state, and the number of
logical processors belonging to the domain.
Arguments:
None
Return Value:
A variable-length Package containing a list of P-state dependency Packages as described below.
Return Value Information
Package {
PStateDependency[0]
….
PStateDependency[n]
}
// Package
// Package
Each PStateDependency sub-Package contains the elements described below:
Package {
NumEntries
Revision
Domain
CoordType
NumProcessors
}
// Integer
// Integer (BYTE)
// Integer (DWORD)
// Integer (DWORD)
// Integer (DWORD)
Table 8-249 PStateDependency Package Values
Element Object Type Description
NumEntries Integer The number of entries in the PStateDependency package including this field.
Current value is 5.
Revision Integer
(BYTE)
The revision number of the PStateDependency package format. Current
value is 0.
Domain
CoordType
Num
Processors
Integer
(DWORD)
Integer
(DWORD)
Integer
(DWORD)
The dependency domain number to which this P state entry belongs.
The type of coordination that exists (hardware) or is required (software) as a
result of the underlying hardware dependency. Could be either 0xFC
(SW_ALL), 0xFD (SW_ANY) or 0xFE (HW_ALL) indicating whether OSPM is
responsible for coordinating the P-state transitions among processors with
dependencies (and needs to initiate the transition on all or any processor in
the domain) or whether the hardware will perform this coordination.
The number of processors belonging to the domain for this logical
processor’s P-states. OSPM will not start performing power state transitions
to a particular P-state until this number of processors belonging to the same
domain have been detected and started.
474 April, 2015 Version 6.0