Advanced Configuration and Power Interface Specification

ACPI Source Language (ASL)Reference
Region Type Permitted Access Type(s) Description
SystemIO
PCI_Config
ByteAcc, WordAcc, DWordAcc,
QWordAcc, or AnyAcc
ByteAcc, WordAcc, DWordAcc,
QWordAcc, or AnyAcc
All access allowed
All access allowed
EmbeddedControl ByteAcc Byte access only
SMBus BufferAcc Reads and writes to this operation region
involve the use of a region specific data buffer.
(See below.)
SystemCMOS ByteAcc Byte access only
PciBarTarget ByteAcc, WordAcc, DWordAcc, All access allowed
QWordAcc, or AnyAcc
IPMI BufferAcc Reads and writes to this operation region
involve the use of a region specific data buffer.
(See below.)
GeneralPurposeIO ByteAcc Byte access only
GenericSerialBus BufferAcc Reads and writes to this operation region
involve the use of a region-specific data buffer.
(See below.)
The named FieldUnit data objects are provided in the FieldList as a series of names and bit widths.
Bits assigned no name (or NULL) are skipped. The ASL compiler supports the Offset (ByteOffset)
macro within a FieldList to skip to the bit position of the supplied byte offset, and the AccessAs
macro to change access within the field list.
GenericSerialBus, SMBus and IPMI regions are inherently non-linear, where each offset within the
respective address space represents a variable sized (0 to 32 bytes) field. Given this uniqueness,
these operation regions include restrictions on their field definitions and require the use of a regionspecific
data buffer when initiating transactions. For more information on the SMBus data buffer
format, see Section 13, “ACPI System Management Bus Interface Specification,”. For more
information on the IPMI data buffer format, see Section 5.5.2.4.3, “Declaring IPMI Operation
Regions". For more information on the Generic Serial Bus data buffer format, see Section 5.5.2.4.5
"Declaring Generic Serial Bus Operation Regions."
For restrictions on the use of Fields with GeneralPurposeIO OpRegions, see Section 5.5.2.4.4,
"Declaring General PurposeIO Operation Regions".
Example
OperationRegion (MIOC, PCI_Config, Zero, 0xFF)
Field (MIOC, AnyAcc, NoLock, Preserve)
{
Offset (0x58),
HXGB, 32,
HXGT, 32,
GAPE, 8,
Version 6.0 839