Advanced Configuration and Power Interface Specification

Advanced Configuration and Power Interface Specification
Root
\_PR
P
CPU0
– Processor Tree
– Processor 0 object
R
\PID0
_STA
_ON
_OFF
\_SB
– Power resource for IDE0
– Method to return status of power resource
– Method to turn on power resource
– Method to turn off power resource
– System bus tree
d
PCI0
– PCI bus
_HID
– Device ID
_CRS
– Current resources (PCI bus number)
d
IDE0
– IDE0 device
Key
_ADR
– PCI device #, function #
Package
_PR0
\_GPE
_L01
– Power resource requirements for D0
– General purpose events (GP_STS)
– Method to handle level GP_STS.1
P
R
d
Processor Object
Power Resource
Object
Bus/Device Object
_E02
– Method to handle edge GP_STS.2
Data Object
_L03
– Method to handle level GP_STS.3
Control Method (AML code)
Figure 5-31 Example ACPI NameSpace
Care must be taken when accessing namespace objects using a relative single segment name because
of the namespace search rules. An attempt to access a relative object recurses toward the root until
the object is found or the root is encountered. This can cause unintentional results. For example,
using the namespace described in Figure 5.5, attempting to access a _CRS named object from within
the \_SB_.PCI0.IDE0 will have different results depending on if an absolute or relative path name is
used. If an absolute pathname is specified (\_SB_.PCI0.IDE0._CRS) an error will result since the
object does not exist. Access using a single segment name (_CRS) will actually access the
\_SB_.PCI0._CRS object. Notice that the access will occur successfully with no errors.
5.3.1 Predefined Root Namespaces
The following namespaces are defined under the namespace root.
Table 5-136 Namespaces Defined Under the Namespace Root
Name
\_GPE
Description
General events in GPE register block.
214 April, 2015 Version 6.0