Advanced Configuration and Power Interface Specification

Advanced Configuration and Power Interface Specification
8.4.2.2 _CSD (C-State Dependency)
This optional object provides C-state control cross logical processor dependency information to
OSPM. The _CSD object evaluates to a packaged list of information that correlates with the C-state
information returned by the _CST object. Each packaged list entry identifies the C-state for which
the dependency is being specified (as an index into the _CST object list), a dependency domain
number for that C-state, the coordination type for that C-state and the number of logical processors
belonging to the domain for the particular C-state. It is possible that a particular C-state may belong
to multiple domains. That is, it is possible to have multiple entries in the _CSD list with the same
CStateIndex value.
Arguments:
None
Return Value:
A variable-length Package containing a list of C-state dependency Packages as described below.
Return Value Information
Package {
CStateDependency[0]
….
CStateDependency[n]
}
// Package
// Package
Each CstateDependency sub-Package contains the elements described below:
Package {
NumEntries
Revision
Domain
CoordType
NumProcessors
Index
}
// Integer
// Integer (BYTE)
// Integer (DWORD)
// Integer (DWORD)
// Integer (DWORD)
// Integer (DWORD)
Table 8-237 CStateDependency Package Values
Element Object Type Description
NumEntries Integer The number of entries in the CStateDependency package including this field.
Current value is 6.
Revision Integer
(BYTE)
The revision number of the CStateDependency package format. Current
value is 0.
Domain
CoordType
Integer
(DWORD)
Integer
(DWORD)
The dependency domain number to which this C 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 C-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.
432 April, 2015 Version 6.0