IoIsWdmVersionAvailable function

The IoIsWdmVersionAvailable routine checks whether a given WDM version is supported by the operating system.


BOOLEAN IoIsWdmVersionAvailable(
  UCHAR MajorVersion,
  UCHAR MinorVersion



Specifies the major version number of WDM that is requested.


Specifies the minor version number of WDM that is requested.

Return Value

IoIsWdmVersionAvailable returns TRUE if the version of WDM that the operating system provides is greater than or equal to the version number of WDM being requested. Otherwise, it returns FALSE.


Drivers should use the RtlIsNtDdiVersionAvailable routine instead of the IoIsWdmVersionAvailable routine.

Cross-platform drivers should use this routine to check the WDM version before performing any operations that vary by platform or are not supported in all versions of WDM.

The WDM_MAJORVERSION and WDM_MINORVERSION constants, which are defined in the Wdm.h header file, specify the WDM major and minor version numbers for the current version of Windows. The following lists the WDM version provided with each operating system.

Operating system WDM major version WDM minor version
Windows 7 6 0x00
Windows Server 2008 R2 6 0x00
Windows Server 2008 6 0x00
Windows Vista 6 0x00
Windows Server 2003 1 0x30
Windows XP 1 0x20
Windows 2000 1 0x10
Windows Me 1 0x05
Windows 98 1 0x00

Note that the minor version number is defined as a hexadecimal value.

Later versions of WDM support all the features available in earlier versions of WDM; that is, each version of WDM is a superset of the previous WDM version.

The following call returns TRUE on any of the listed operating systems, because all these systems support all the features of WDM 1.0:

bVersion = IoIsWdmVersionAvailable(1,0);
The following example shows how a driver can dynamically detect the current operating system:
if (IoIsWdmVersionAvailable(1, 0x10)) {
    //If WDM 1.10 is supported, this is Windows 2000
    //or better.
} else if (IoIsWdmVersionAvailable(1, 5)) {
    //If WDM 1.05 is supported, this is Windows ME
    //or better.
} else {
    //WDM 1.0 is always supported, so this is Windows 98, 
    //Windows 98 SE, or better.
As the example shows, calling IoIsWdmVersionAvailable(1, 5) returns TRUE on Windows Me, Windows 2000, and any succeeding operating systems, but FALSE on Windows 98 and Windows 98 SE.


Minimum supported client Available starting with Windows 2000.
Target Platform Universal
Header wdm.h (include Wdm.h, Ntddk.h, Ntifs.h)
Library NtosKrnl.lib
DLL NtosKrnl.exe
DDI compliance rules IrqlIoPassive5, PowerIrpDDis, HwStorPortProhibitedDDIs

See Also