## The New WDMSTUB Sample

The New WDMSTUB Sample accompanies Appendix A and illustrates how to supply stubs for kernel-mode support functions that would otherwise be missing from Windows 98. This sample was added in Service Pack 4 for the 1st edition.

The sample includes one component:

- WDMSTUB.SYS is a lower filter driver for use with Windows 98.

### Building WDMSTUB

To build WDMSTUB.SYS, follow the general instructions for building a WDM sample. The project file is named WDMSTUB.DSP. The build settings depend on your having set the 98DDK environment variable to the directory where you installed the Windows 98 DDK. Depending on which version of the DDK you have, you may need to adjust the include or library paths in the project settings.

### Testing WDMSTUB

You use WDMSTUB.SYS as a lower filter driver for any WDM driver that calls the functions it exports. Simply modify your regular INF file to include additional statements, such as the ones shown in red here:

`

    [SourceDisksFiles]
    yourdvr.sys=1
    wdmstub.sys=1

    [DriverInstall]
    CopyFiles=DriverCopyFiles
    AddReg=DriverAddReg

    [DriverCopyFiles]
    yourdvr.sys,,,2
    wdmstub.sys,,,2

    [DriverAddReg]
    HKR,,DevLoader,,*ntkern
    HKR,,NTMPDriver,,"wdmstub.sys,,yourdvr.sys"

`

These changes cause WDMSTUB.SYS to be installed as a lower filter driver for YOURDVR.SYS. Windows 98 will load WDMSTUB.SYS before it attempts to load YOURDVR.SYS. The DriverEntry function in WDMSTUB defines a number of kernel-mode support functions that are missing from Windows 98 and Windows 98 Second Edition. Since WDMSTUB defines these functions before the system attempts to load your driver, you can install your driver without requiring a reboot.

### Redistributing WDMSTUB

WDMSTUB is an exception to the blanket license to use the sample programs for this book. The author will grant a royalty-free license to anyone to redistribute WDMSTUB as part of a WDM driver package. The license will, however, include conditions designed to insure the consistency and quality of WDMSTUB on end user machines. Send e-mail to waltoney@oneysoft.com for information about obtaining this conditional license.

Note: A special license is required even if you ship WDMSTUB under a different name. This driver includes special checking to make sure that it does not unload while some other vendor’s driver might be using it, and the special license will insure that you preserve that checking.

### What to look for

WDMSTUB is primarily a production driver rather than a sample. If you want to see how to define your own exports, look at the function named DefineStubs in wdmstub.cpp. Please don't write your own version of WDMSTUB to export some special function you need in your driver. Write me (waltoney@oneysoft.com) instead.