Advanced Configuration and Power Interface Specification

Advanced Configuration and Power Interface Specification
PackageList: Data Objects (Integers, Strings, Buffers, and Packages) and references to control
methods.
Evaluating an undefined element will yield an error, but elements can be assigned values at runtime
to make them defined (via the Index operator). It is an error for NumElements to be less than the
number of elements in the PackageList..
The ASL compiler can emit two different AML opcodes for a Package declaration, either
PackageOp or VarPackageOp. For small, fixed-length packages, the PackageOp is used and this
opcode is compatible with ACPI 1.0. A VarPackageOp will be emitted if any of the following
conditions are true:
• The NumElements argument is a TermArg that can only be resolved at runtime.
• At compile time, NumElements resolves to a constant that is larger than 255.
• The PackageList contains more than 255 initializer elements.
Note: The ability to create variable-sized packages was first introduced in ACPI 2.0. ACPI 1.0 only
allowed fixed-size packages with up to 255 elements.
Examples
Example 1:
Package () {
3,
9,
“ACPI 1.0 COMPLIANT”,
Package () {
“CheckSum=>”,
Package () {7, 9}
},
0
}
Example 2: This example defines and initializes a two-dimensional array.
Package () {
Package () {11, 12, 13},
Package () {21, 22, 23}
}
Example 3: This code allocates space for ten objects to be defined at runtime (see the Name and
Index term definitions).
Package (10) {}
Example 4: These package declarations will cause the compiler to emit a VarPackageOp AML
opcode.
872 April, 2015 Version 6.0