Advanced Configuration and Power Interface Specification

Device Configuration
whether the Global Lock must be acquired when accessing the device. OS-based device accesses
must be performed while in acquisition of the Global Lock when potentially contentious accesses to
device resources are performed by non-OS code, such as System Management Mode (SMM)-based
code in Intel architecture-based systems.
Note: Default behavior: if _GLK is not present within the scope of a given device, then the Global Lock is
not required for that device.
Arguments:
None
Return Value:
An Integer that contains the Global Lock requirement code
0 – The Global Lock is not required for this device
1 – The Global lock is required for this device
An example of device resource contention is a device driver for an SMBus-based device contending
with SMM-based code for access to the Embedded Controller, SMB-HC, and SMBus target device.
In this case, the device driver must acquire and release the Global Lock when accessing the device to
avoid resource contention with SMM-based code that accesses any of the listed resources.
6.5.8 _DEP (Operation Region Dependencies)
_DEP evaluates to a package and designates device objects that OSPM should assign a higher
priority in start ordering due to future operation region accesses.
To increase the likelihood that an SPB operation region handler is available when needed, OSPM
needs to know in advance which methods will access it -- _DEP provides OSPM with this
information. While the _DEP keyword may be used to determine start ordering, only the _REG
method (Section 6.5.4) callbacks can be relied upon to determine whether a region is accessible at a
given point in time.
Arguments:
None.
Return Value:
A variable-length Package containing object references.
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