If your device will be installed on both 32-bit platforms and 64-bit platforms, you must follow these steps when you create a driver package:
Provide both 32-bit and 64-bit compilations of all kernel-mode drivers, device installation application, class installers, and co-installers. For more information, see Porting Your Driver to 64-Bit Windows.
Provide one or more cross-platform INF files that use decorated INF sections to control platform-specific installation behavior.
If you are writing a device installation application, the 32-bit version must be the default version. That is, the 32-bit version should be invoked by Autorun (described in the Microsoft Windows SDK documentation), so that it starts automatically when a user inserts your distribution disk.
The 32-bit version of the application must check the value returned by UpdateDriverForPlugAndPlayDevices. If the return value is ERROR_IN_WOW64, the 32-bit application is executing on a 64-bit platform and cannot update inbox drivers. Instead, it must call CreateProcess (described in the Windows SDK documentation) to start the 64-bit version of the application. The 64-bit version can then call UpdateDriverForPlugAndPlayDevices, specifying a FullInfPath parameter that identifies the location of the 64-bit versions of all files.