Advanced Configuration and Power Interface Specification

Advanced Configuration and Power Interface Specification
Arguments:
None
Return Value:
An Integer containing a device status bitmap:
Bit [0] –
Bit [1] –
Bit [2] –
Bit [3] –
Bit [4] –
Set if the device is present.
Set if the device is enabled and decoding its resources.
Set if the device should be shown in the UI.
Set if the device is functioning properly (cleared if device failed its diagnostics).
Set if the battery is present.
Bits [31:5] – Reserved (must be cleared).
Return Value Information
If bit [0] is cleared, then bit 1 must also be cleared (in other words, a device that is not present cannot
be enabled).
A device can only decode its hardware resources if both bits 0 and 1 are set. If the device is not
present (bit [0] cleared) or not enabled (bit [1] cleared), then the device must not decode its
resources.
If a device is present in the machine, but should not be displayed in OSPM user interface, bit 2 is
cleared. For example, a notebook could have joystick hardware (thus it is present and decoding its
resources), but the connector for plugging in the joystick requires a port replicator. If the port
replicator is not plugged in, the joystick should not appear in the UI, so bit [2] is cleared.
_STA may return bit 0 clear (not present) with bit [3] set (device is functional). This case is used to
indicate a valid device for which no device driver should be loaded (for example, a bridge device.)
Children of this device may be present and valid. OSPM should continue enumeration below a
device whose _STA returns this bit combination.
Bit [4] of _STA applies only to the Control Method Battery Device (PNP0C0A). For all other
devices, OSPM must ignore this bit.
If a device object (including the processor object) does not have an _STA object, then OSPM
assumes that all of the above bits are set (i.e., the device is present, enabled, shown in the UI, and
functioning).
6.4 Resource Data Types for ACPI
The _CRS, _PRS, and _SRS control methods use packages of resource descriptors to describe the
resource requirements of devices.
6.4.1 ASL Macros for Resource Descriptors
ASL includes some macros for creating resource descriptors. The ASL syntax for these macros is
defined in Section 19.6, “ASL Operator Reference”, along with the other ASL operators.
342 April, 2015 Version 6.0