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How to identify the Windows version in ACPI by using _OSI

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This topic describes how to use the _OSI method in Advanced Configuration and Power Interface (ACPI) Source Language (ASL) to identify the host operating system. By using this method, ASL writers can create firmware that supports future operating systems versions and enables the operating system to change behavior based on the requested interface levels.

This information applies to the following operating systems:

  • Windows 11, version 22H2

  • Windows 11

  • Windows 10, version 2004

  • Windows 10, version 1903

  • Windows 10, version 1809

  • Windows 10, version 1803

  • Windows 10, version 1709

  • Windows 10, version 1703

  • Windows 10, version 1607

  • Windows Server Technical Preview

  • Windows 10

  • Windows Server 2012 R2

  • Windows 8.1

  • Windows Server 2012

  • Windows 8

  • Windows Server 2008 R2

  • Windows 7

  • Windows Server 2008

  • Windows Vista

  • Windows Server 2003

  • Windows XP

The _OSI Method

All recent versions of the Windows operating system support components of the Advanced Configuration and Power Interface (ACPI) Specification. The ACPI specification defines an interpreted language, ACPI Source Language (ASL), to enable the operating system to execute firmware-provided control methods for power management and configuration. To improve the ability for ASL writers to identify the host operating system version, ASL provides the Operating System Interface Level (_OSI).

By using the _OSI method, ASL writers can easily determine the version of the ACPI interfaces that the host operating system supports. This versioning method provides a solution for creating firmware that can support future operating systems and enable the operating system to change behavior based on the requested interface levels.

_OSI defined

The _OSI method has one argument and one return value. The argument is a string that is defined by and for each operating system. The return value is 0x00000000 if the interface is not supported or 0xFFFFFFFF if the interface is supported.

Recent versions of the ACPI specification have extended the use cases of the _OSI method beyond host operating system version identification.

However, Windows supports _OSI only for the use of identifying the host version of Windows that is running on the system.

The _OSI method is defined as follows:

  • _OSI - Operating System Interfaces

Argument

A string defined by and for each operating system. For example:

  • "Windows 2013" for Windows 8.1 and Windows Server 2012 R2

  • "Windows 2012" for Windows 8 and Windows Server 2012

  • "Windows 2009" for Windows 7 and Windows Server 2008 R2

  • "Windows 2001" for Windows XP

  • "Windows 2001.1" for Windows Server 2003

Return value

Return values are as follows:

  • 0x00000000 if the operating system does not support the version in the argument.

  • 0xFFFFFFFF if the operating system does support the version in the argument.

_OSI argument details for Windows

The table below lists the versions of Windows that ASL can identify by using the corresponding _OSI string.

Windows operating systems return 0xFFFFFFFF if the argument to the _OSI method specifies an earlier version of Windows. For example, Windows 7 returns 0xFFFFFFFF for both "Windows 2009" (Windows 7) and "Windows 2006" (Windows Vista).

_OSI strings for Windows operating systems

OSI string Target OS
Windows 2000 Windows 2000
Windows 2001 Windows XP
Windows 2001 SP1 Windows XP SP1
Windows 2001.1 Windows Server 2003
Windows 2001 SP2 Windows XP SP2
Windows 2001.1 SP1 Windows Server 2003 SP1
Windows 2006 Windows Vista
Windows 2006 SP1 Windows Vista SP1
Windows 2006.1 Windows Server 2008
Windows 2009 Windows 7, Win Server 2008 R2
Windows 2012 Windows 8, Win Server 2012
Windows 2013 Windows 8.1
Windows 2015 Windows 10
Windows 2016 Windows 10, version 1607
Windows 2017 Windows 10, version 1703
Windows 2017.2 Windows 10, version 1709
Windows 2018 Windows 10, version 1803
Windows 2018.2 Windows 10, version 1809
Windows 2019 Windows 10, version 1903
Windows 2020 Windows 10, version 2004
Windows 2021 Windows 11
Windows 2022 Windows 11, version 22H2

Implementation note

Place the routine that identifies the operating system in an _INI method under the _SB scope so that _OSI can run as early as possible.

This placement is important because the operating system makes features available based on the string argument to the _OSI method.

Additional resources

Advanced Configuration and Power Interface Specification