Advanced Configuration and Power Interface Specification

Advanced Configuration and Power Interface Specification
Device(GPE5) {
Name(_HID, “ACPI0006”)
}
Method(_L02) { … }
Method(_E07) { … }
Method(_W04) { … }
9.11 Module Device
This optional device is a container object that acts as a bus node in a namespace. It may contain child
objects that are devices or buses. The module device is declared using the ACPI0004 hardware
identifier (HID).
If the module device contains a _CRS object, the “bus” described by this object is assumed to have
these resources available for consumption by its child devices. If a _CRS object is present, any
resources not produced in the module device’s _CRS object may not be allocated to child devices.
Providing a _CRS object is undesirable in some module devices. For example, consider a module
device used to describe an add-in board containing multiple host bridges without any shared
resource decoding logic. In this case the resource ranges available to the host bridges are not
controlled by any entity residing on the add-in board, implying that a _CRS object in the associated
module device would not describe any real feature of the underlying hardware. A module device
must contain a _CRS object if the device contains any PCI host bridge devices.
To account for cases like this, the system designer may optionally omit the module device’s _CRS
object. If no _CRS object is present, OSPM will assume that the module device is a simple container
object that does not produce the resources consumed by its child devices. In this case, OSPM will
assign resources to the child devices as if they were direct children of the module device's parent
object.
For an example with a module device _CRS object present, consider a Module Device containing
three child memory devices. If the _CRS object for the Module Device contains memory from 2 GB
through 6 GB, then the child memory devices may only be assigned addresses within this range.
518 April, 2015 Version 6.0