Advanced Configuration and Power Interface Specification

Advanced Configuration and Power Interface Specification
Arg3 – A Package that contains function-specific arguments
Return Value:
If Function Index = 0, a Buffer containing a function index bitfield. Otherwise, the return value and
type depends on the UUID and revision ID (see below).
Argument Information:
Arg0: UUID – A Buffer containing the Universal Unique Identifier (16 Bytes)
Arg1: Revision ID – the function’s revision. This revision is specific to the UUID.
Arg2: Function Index – Represents a specific function whose meaning is specific to the UUID
and Revision ID. Function indices should start with 1. Function number zero is a query function (see
the special return code defined below).
Arg3: Arguments – a package containing the parameters for the function specified by the UUID,
Revision ID and Function Index. Successive revisions of Function Arguments must be backward
compatible with earlier revisions. See Section 9 “ACPI Devices and Device Specific Objects”, for
any _DSM definitions for ACPI devices. New UUIDs may also be created by OEMs and IHVs for
custom devices and other interface or device governing bodies (e.g. the PCI SIG), as long as the
UUID is different from other published UUIDs. Only the issuer of a UUID can authorize a new
Function Index, Revision ID or Function Argument for that UUID.
Return Value Information:
If Function Index is zero, the return is a buffer containing one bit for each function index, starting
with zero. Bit 0 indicates whether there is support for any functions other than function 0 for the
specified UUID and Revision ID. If set to zero, no functions are supported (other than function zero)
for the specified UUID and Revision ID. If set to one, at least one additional function is supported.
For all other bits in the buffer, a bit is set to zero to indicate if that function index is not supported for
the specific UUID and Revision ID. (For example, bit 1 set to 0 indicates that function index 1 is not
supported for the specific UUID and Revision ID.)
If the bit representing a particular function index would lie outside of the buffer, it should be
assumed to be 0 (that is, not supported).
If Function index is non-zero, the return is any data object. The type and meaning of the returned
data object depends on the UUID and Revision ID.
Note: For backward compatibility _DSM requires that each Revision ID support all of the functions
defined by all previous Revision IDs for the same UUID.
Implementation Note
Since the purpose of the _DSM method is to avoid the namespace collision, the implementation of
this method shall not use any other method or data object which is not defined in this specification
unless its driver and usage is completely under the control of the platform vendor.
532 April, 2015 Version 6.0