The latest release of the Windows Driver Foundation (WDF) comprises the Kernel-Mode Driver Framework (KMDF) 1.9 and the User-Mode Driver Framework (UMDF) 1.9. As usual, this release includes redistributable packages for earlier versions of the Windows operating system (OS). These packages are shipped in the Windows Driver Kit (WDK) Release Candidate (RC). For KMDF, earlier versions of Windows are supported back to Windows 2000; for UMDF, back to Windows XP SP2.

You can now begin testing your drivers with the latest WDF frameworks on Windows 7 RC and on previous versions of Windows by using the redistributable packages from the WDK RC. Please let us know if you find any compatibility issues in the new version 1.9. As always, you can reach us at (
Remember that the WDF frameworks are updated when a new driver is installed on the OS, and your driver will link to the new version of the frameworks. Even though Microsoft does a lot of testing on the new frameworks to ensure compatibility from version to version, we cannot test your code in your scenarios, so it is important that you test your own drivers on the new frameworks.

Following are some hints for testing:
  • Install your existing driver package on Windows 7 RC and test the common scenarios. Windows 7 has both KMDF 1.9 and UMDF 1.9 as the native framework versions.
  • Update your INF file to use the new version 1.9 redistributables from the WDK and install those redistributables on the earlier versions of Windows that your driver supports. Make sure the installation of your driver works and the new framework is present and active.
  • For testing purposes, rebuild your driver with the Windows 7 WDK and test it with the driver verifier turned on. The driver verifier now makes additional checks for framework drivers, which will help ensure compatibility and stability.
  • Install your drivers with the previous version of the WDF frameworks and then test an upgrade to Windows 7.

Note to UMDF developers: When testing, remember to use the Windows 7 RC version of the WinUSB 1.9 co-installer, named WinUsbCoinstaller2.dll. This new version is included in the RC release of the WDK and contains fixes to both the co-installer and the underlying WinUSB code. You will need it to fully test UMDF drivers against UMDF 1.9 on previous releases of Windows.
For information about how to get the RC release of the WDK and to read the WDK RC release notes, visit the WDK area of the Windows Hardware Developer Central (WHDC) Web site ( and


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