Reporting DDI Version
A DirectX 9.0 version driver must report the version of the DDI that it supports so that the DirectX 9.0 runtime can determine how to handle the driver. To report the DDI version, the driver responds to a GetDriverInfo2 request that uses the D3DGDI2_TYPE_GETDDIVERSION value. The dwDXVersion member of the DD_GETDDIVERSIONDATA structure is set to 9 to indicate that the DirectX 9.0 runtime makes the request.
The driver sets the dwDDIVersion member of DD_GETDDIVERSIONDATA to the DDI version that it supports for the DirectX 9.0 runtime. If the driver was built with a prereleased version of the DirectX 9.0 Driver Development Kit (DDK) in which the DDI version number was lower than the number in the final version of DirectX 9.0, the runtime treats the driver as DirectX 8.0 instead.