Advanced Configuration and Power Interface Specification

Advanced Configuration and Power Interface Specification
2. ACPI 2 or greater is supported. Both 32-bit and 64-bit integers are supported.
Actual integer width depends on the revision of the DSDT (revision < 2 means 32-bit. >= 2
means 64-bit).
Other values - Reserved
5.7.5 _DLM (DeviceLock Mutex)
This object appears in a device scope when AML access to the device must be synchronized with the
OS environment. It is used in conjunction with a standard Mutex object. With _DLM, the standard
Mutex provides synchronization within the AML environment as usual, but also synchronizes with
the OS environment.
_DLM evaluates to a package of packages, each containing a reference to a Mutex and an optional
resource template protected by the Mutex, If only the Mutex name is specified, then the sharing rules
(i.e. which resources are protected by the lock) are defined by a predefined contract between the
AML and the OS device driver. If the resource template is specified, then only those resources
within the resource template are protected.
Arguments:
None
Return Value:
A variable-length Package containing sub-packages of Mutex References and resource templates.
The resource template in each subpackage is optional.
Return Value Information
Package {
DeviceLockInfo [0]
. . .
DeviceLockInfo [n]
}
// Package
// Package
Each variable-length DeviceLockInfo sub-Package contains either one element or 2 elements, as
described below:
Package {
DeviceLockMutex
Resources
}
// Reference to a Mutex object
// Buffer or Reference (Resource Template)
Table 5-166 DeviceLockInfo Package Values
Element Object Type Description
DeviceLockMutex Reference A reference to the mutex that is to be shared between the AML
code and the host operating system.
Resources
Buffer (or
reference to a
Buffer)
Optional. Contains a Resource Template that describes the
resources that are to be protected by the Device Lock Mutex.
274 April, 2015 Version 6.0