Advanced Configuration and Power Interface Specification

Device Configuration
If a device indicates it does not have hardware cache coherency support, then OSPM must use a
software cache flushing algorithm to ensure stale or invalid data is not accessed from the caches.
__CCA objects are only relevant for devices that can access CPU-visible memory, such as devices
that are DMA capable. On ARM based systems, the _CCA object must be supplied all such devices.
On Intel platforms, if the _CCA object is not supplied, the OSPM will assume the devices are
hardware cache coherent.
Arguments:
None
Return Value:
An Integer indicating the device's support for hardware cache coherency
0 - The device does not have hardware managed cache coherency
1 - The device has hardware managed cache coherency
Other Values - Reserved
Note: There are restrictions related to when this object is evaluated which have implications for
implementing this object as a control method. The _CCA method must only access Operation
Regions that have been indicated to be available as defined by the _REG method. The _REG method
is described in Section 6.5.4, "_REG (Region)."
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