Getting Started with Windows Drivers

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Overview

Welcome to the world of Windows driver development! This guide will walk you through the essential steps to start building drivers for the Windows operating system. Driver development is a powerful way to interact directly with hardware and extend the functionality of Windows.

Developing drivers requires a solid understanding of C/C++, system internals, and the Windows Driver Model (WDM) or its successors like the Windows Driver Frameworks (WDF). This guide focuses on the modern WDF approach, which simplifies many aspects of driver development.

Prerequisites

Before you begin, ensure you have the following:

Note: Ensure your WDK and Visual Studio versions are compatible. Check the official Microsoft documentation for the latest compatibility information.

Setting Up Your Environment

Once you have installed the necessary tools, you need to configure your development environment correctly.

1

Install Visual Studio and WDK

Follow the installation wizards for both Visual Studio and the Windows Driver Kit. During Visual Studio installation, make sure to select the C++ desktop development workload. The WDK installation will add necessary templates and build tools for driver development.

2

Configure a Test Machine

It is highly recommended to test your drivers on a separate physical machine (a "test machine") rather than your primary development machine. This prevents potential system instability. You'll need to enable kernel debugging on the test machine.

To enable kernel debugging:

  1. Restart the test machine and enter the BIOS/UEFI settings.
  2. Enable debugging options if available.
  3. On the test machine, open an elevated Command Prompt or PowerShell and run:
bcdedit /debug on

You might also need to configure the boot settings further depending on your debugging method (e.g., serial, network, or USB debugging).

3

Configure Visual Studio for Remote Debugging

In Visual Studio, you will configure your project to connect to the test machine for debugging. This typically involves specifying the network or serial connection details for the test machine.

Your First Driver

Let's create a simple kernel-mode driver using the Windows Driver Frameworks (WDF) Kernel-Mode Driver (KMDF) template.

1

Create a New Project in Visual Studio

Launch Visual Studio. Select "Create a new project". Search for "KMDF driver" and select the template. Click "Next".

2

Configure Your Project

Give your project a name (e.g., "MyFirstDriver") and choose a location. Click "Create".

3

Examine the Generated Code

The template generates a basic driver structure. Key files include:

  • Driver.c: Contains the driver entry point (DriverEntry) and the driver's EvtDriverDeviceAdd callback.
  • MyFirstDriver.inx: An INF file that describes how to install the driver.
  • MyFirstDriver.vcxproj: The project file.

The DriverEntry function is the first code that runs when your driver is loaded. It typically calls WdfDriverCreate to initialize the WDF driver object.

The EvtDriverDeviceAdd callback is crucial. It's called by the framework when Plug and Play (PnP) manager indicates that a device for which this driver is responsible has appeared.

// Driver.c (simplified example) #include
#include

EVT_WDF_DRIVER_DEVICE_ADD MyDriverEvtDeviceAdd;

NTSTATUS DriverEntry(PDRIVER_OBJECT DriverObject, PUNICODE_STRING RegistryPath)
{
NTSTATUS status;
WDF_DRIVER_CONFIG config;
// Create a framework driver object.
WDF_DRIVER_CONFIG_INIT(&config, MyDriverEvtDeviceAdd);
status = WdfDriverCreate(DriverObject, RegistryPath, WDF_NO_OBJECT_ATTRIBUTES, &config, WDF_NO_HANDLE);
return status;
}

NTSTATUS MyDriverEvtDeviceAdd(WDFDRIVER Driver, PWDFDEVICE_INIT DeviceInit)
{
// Create a framework device object.
WDFDEVICE device;
NTSTATUS status;
UNREFERENCED_PARAMETER(Driver);
status = WdfDeviceCreate(&DeviceInit, WDF_NO_OBJECT_ATTRIBUTES, &device);
return status;
}

Testing and Debugging

Deploying and debugging your driver is a critical part of the development process.

1

Configure Driver Signing

For kernel-mode drivers, Microsoft requires code signing for security. For development and testing, you can use test certificates.

  • In Visual Studio, right-click your driver project.
  • Go to Properties -> Driver Signing.
  • Select "Test Sign" and choose a "Test Certificate for Driver Signing".
2

Deploy and Load the Driver

You can deploy your driver using Visual Studio's built-in deployment tools or by manually copying the driver package (including the INF file) to the test machine and installing it via Device Manager.

  • Open Device Manager on the test machine.
  • Find a suitable device or create a "Test Device".
  • Right-click and select "Update driver".
  • Choose "Browse my computer for drivers" and point to the directory containing your INF file.
3

Set Up Kernel Debugging

Ensure your debugging connection (e.g., WinDbg connected via network or serial) is established between your development machine and the test machine.

4

Debug Your Driver

Once the driver is loaded and debugging is active, you can set breakpoints in your driver code within Visual Studio and step through its execution.

Tip: Use KdPrintEx or DbgPrintEx to output diagnostic messages to the debugger console. These messages will help you trace the driver's execution flow.

Next Steps

Once you've successfully built and debugged your first driver, you can explore more advanced topics:

The official Windows driver documentation is your primary resource for in-depth information, examples, and API references.