Windows Device Driver Testing: Tools, Features, and Examples

The introduction of the Windows Driver Foundation (WDF) in 2005-06 revolutionized the development of Windows device drivers, enabling developers to focus on the core functionalities of their devices while leaving the Windows OS-specific tasks to the new frameworks. However, even with these advancements, testing device drivers continues to be a complex challenge for many. In today's world of remote collaboration, integrating features like cam chat into the testing process can further enhance communication and collaboration among developers, making it easier to address issues and ensure the reliability of Windows device drivers.

Enhancing Device Driver Testing: Key Aspects for Comprehensive and Reliable Results

Traditional testing approaches often rely on ad-hoc methods for generating test plans and cases, treating device drivers as black boxes. This approach leads to critical features being overlooked or receiving inadequate attention. To ensure comprehensive testing, it is essential to consider several key aspects.

1. Operating Systems: Drivers may behave differently on different operating systems, and even within the same operating system, different kernel versions can introduce variations. Therefore, it is crucial to test drivers on various operating systems and kernel configurations to ensure compatibility.
2. Updates: Critical driver situations such as shutdown, reboot, and reset should be thoroughly tested. Additionally, it is important to consider the interaction between drivers and system security features like firewalls, data execution prevention (DEP), user account control (UAC), and antivirus software.
3. Hardware Dependency: Apart from software dependencies, drivers also rely on specific hardware configurations. Testing should include various processor and kernel setups, with enabled and disabled page files. Enabling a driver verifier during testing adds an extra load to the driver, ensuring its stability and performance under stress.
4. Driver Model: Whenever possible, utilize the most modern driver models available for your project. For example, choose the Windows Driver Foundation (KMDF or UMDF) over the traditional Windows Driver Model (WDM). Similarly, prefer the file system Mini-Filter model over legacy file system filters. Newer driver models offer numerous benefits and help avoid potential issues associated with older models.
5. Coding/Building: Even if you write your code in C, consider using the C++ compiler. Using the C++ compiler provides advantages such as strong type-checking and compatibility with C-language interfaces provided by Windows. Additionally, it allows you to leverage modern C++ features that may be beneficial for your project.

Testing Windows Drivers

To test Windows drivers effectively, it is recommended to utilize the Driver Verifier tool. Driver Verifier monitors kernel-mode and graphics drivers, identifying illegal function calls or actions that may corrupt the system. It offers various stress tests and configurations to identify improper behavior. However, it's important to exercise caution while running Driver Verifier as it can potentially cause system crashes.

Tools for Testing Drivers:

1. PoolMon (poolmon.exe): This Memory Pool Monitor displays data collected by the operating system about memory allocations from system pools. It provides insights into the usage of paged and non-paged kernel pools, as well as Terminal Services session memory pools.
2. PwrTest: The power management test tool (PwrTest) enables developers, testers, and system integrators to exercise and record power management information from the system. It helps ensure proper functionality and performance of power management features.
3. PNPCPU: Developers can use PNPCPU to test their drivers or applications for compatibility with dynamically added processors at runtime. This tool helps identify any failures or issues when processors are added or removed during system operation.
4. WSDAPI Basic Interoperability Tool: The Devices Profile for Web Services (DPWS) reference specification assembles and constrains various Web Services (WS) specifications. The WSDAPI Basic Interoperability Tool aids in testing the interoperability of drivers and applications with DPWS.

Utilities for Driver Testing and Analysis

Built-in Windows utilities provide basic information regarding a driver's status and functionality. These utilities include:

• Msinfo32: Provides general system information and details about loaded drivers.
• Driver query: Lists installed drivers and their properties

Conclusion

In conclusion, the Windows Driver Foundation (WDF) has significantly simplified the development of Windows device drivers, allowing developers to focus on core functionalities while leveraging the new frameworks for Windows-specific tasks. However, testing device drivers remains a challenging task that requires careful consideration of various aspects. Built-in Windows utilities like Msinfo32 and Driver query provide basic information about driver status and functionality. By considering these aspects and utilizing the appropriate tools, developers can ensure robust and reliable Windows device drivers, improving overall system performance and stability.