ACPI support for 64-bit Windows

Updated: July 8, 2008

This topic describes ACPI support for 64-bit Windows systems.

Advanced Configuration and Power Interface (ACPI) Specification defines the system board, firmware, and operating system requirements for operating system control of configuration.

ACPI Revision 2.0 defines expanded interfaces to support 64-bit systems through extended Table definitions, new ACPI Source Language (ASL), and ACPI Machine Language(AML) 64-bit functions.

Required ACPI 2.0 tables

Itanium-based systems must support the ACPI 2.0 64-bit fixed tables, which allow for 64-bit addressing without namespace changes, so that ACPI 1.0 namespaces will still be valid. Windows will not support the Version 0.71 interim tables.

Root System Description Pointer (RSDP)StructureThe Length, XsdtAddress, Extended Checksum, and Reserved fields were added in ACPI 2.0.
Fixed ACPI Description Table (FADT) Extended with new fields for reset support as well as extended addressing support using the Generic Addressing Structure (GAS) format.
Firmware ACPI Control Structure (FACS) This table now includes the X_Firmware_Waking_Vector field, which is the 64-bit physical address of the Firmware Waking Vector that is reported using the GAS.
Multiple APIC Description Table (MADT) With new APIC structure entries: Local APIC Address Override Structure, I/O Streamlined (SAPIC), Local SAPIC, and Platform Interrupt Sources.
Extended System Description Table (XSDT) A new table that provides functionality identical to RSDT but accommodates physical addresses of DESCRIPTION HEADERs larger than 32 bits.


The initial release of the 64-bit edition of Windows will not include support for power management sleep states.

Related topics

Designing for 64-bit Windows
IA-64 Systems and ACPI 2.0 64-bit Tables



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