Getting Started with Windows Driver Development

Welcome to the world of Windows driver development! This guide will walk you through the essential steps to begin creating and debugging drivers for the Windows operating system.

What is a Driver?

A device driver is a software program that allows the operating system (Windows) and hardware devices to communicate with each other. Without drivers, the operating system wouldn't know how to use devices like graphics cards, printers, or network adapters.

Prerequisites

Before you begin, ensure you have the following:

A Windows development machine.
The Windows Driver Kit (WDK). Download the latest version from the Microsoft Driver Downloads page.
A supported version of Visual Studio. The WDK is integrated with Visual Studio, providing a seamless development experience.
A test machine or virtual machine for debugging. It's highly recommended to use a separate machine for testing drivers to avoid destabilizing your primary development environment.

Setting Up Your Development Environment

Install the WDK: Run the WDK installer and follow the on-screen instructions.
Install Visual Studio: If you haven't already, install Visual Studio with the "Desktop development with C++" workload.
Configure Visual Studio for Driver Development: The WDK installer typically handles this integration. You should see new project templates for driver development within Visual Studio.

Your First Driver: A Simple Example

Let's create a very basic kernel-mode driver that simply logs a message when it's loaded and unloaded. This example uses the KMDF (Kernel-Mode Driver Framework).

1. Create a New Project in Visual Studio

Open Visual Studio.
Select "Create a new project".
Search for "Kernel Mode Driver (KMDF)".
Select the template and click "Next".
Name your project (e.g., "MyFirstDriver") and choose a location. Click "Create".

2. Examine the Project Files

Visual Studio will generate several files. The most important ones for this basic example are:

Driver.c: Contains the main driver entry and exit points.
MyFirstDriver.vcxproj: The project file.
MyFirstDriver.vcxproj.filters: Filters for the project.

3. Add Code to Driver.c

Open Driver.c. You'll find code similar to this:

                
#include <ntddk.h>
#include <wdfdriver.h>

// Forward declarations
DRIVER_INITIALIZE DriverEntry;
EVT_WDF_DRIVER_DEVICE_ADD MyDriverEvtDeviceAdd;

//
// DriverEntry - This is the first function called after the driver is loaded.
//
NTSTATUS
DriverEntry(
    _In_ PDRIVER_OBJECT  DriverObject,
    _In_ PUNICODE_STRING RegistryPath
    )
{
    WDF_OBJECT_ATTRIBUTES attributes;
    WDF_DRIVER_CONFIG config;
    NTSTATUS status;

    // Initialize the WDF driver configuration object
    WDF_DRIVER_CONFIG_INIT(&config, MyDriverEvtDeviceAdd);

    // Create a framework driver object
    status = WdfDriverCreate(DriverObject,
                             RegistryPath,
                             WDF_NO_OBJECT_ATTRIBUTES,
                             &config,
                             WDF_NO_HANDLE);

    DbgPrintEx(DPFLTR_IHVDRIVER_ID, DPFLTR_INFO_LEVEL, "MyFirstDriver: DriverEntry called.\n");

    return status;
}

//
// MyDriverEvtDeviceAdd - Callback function called when a device is added.
//
NTSTATUS
MyDriverEvtDeviceAdd(
    _In_ WDFDRIVER Driver,
    _Inout_ PWDFDEVICE_INIT DeviceInit
    )
{
    UNREFERENCED_PARAMETER(Driver);

    NTSTATUS status;

    DbgPrintEx(DPFLTR_IHVDRIVER_ID, DPFLTR_INFO_LEVEL, "MyFirstDriver: MyDriverEvtDeviceAdd called.\n");

    // Create a framework device object. This call registers the driver with the framework
    // and creates a framework device object that represents the device in the driver stack.
    status = WdfDeviceCreate(&DeviceInit, WDF_NO_OBJECT_ATTRIBUTES, WDF_NO_HANDLE);

    return status;
}
                
            

The DbgPrintEx statements will output messages to the kernel debugger when the driver loads and attempts to create a device.

Note: For this simple example, we are not actually creating a device; we are just demonstrating the entry points.

4. Build and Install the Driver

To build and install your driver, you'll need to configure the project settings:

In Visual Studio, right-click on the project in the Solution Explorer and select "Properties".
Navigate to "Configuration Properties" > "Driver Settings".
Set "Target Platform" to the appropriate Windows version (e.g., x64 for 64-bit Windows).
Set "Configuration Type" to "Driver".
Ensure "INF file" is correctly set (usually the name of your project).
Navigate to "Configuration Properties" > "Driver Signing".
Select "Enable" for "Test Signing". You might need to choose a certificate or create a test certificate. For initial development, this is usually sufficient.
Build the solution (F7 or Build > Build Solution).

After building successfully, you'll find the driver files (.sys, .inf, etc.) in your project's output directory (e.g., x64\Debug).

5. Debugging

Debugging kernel-mode drivers requires a connection to a test machine, usually over a network (often wired Ethernet) or serial port.

Configure Debugging: In Visual Studio, go to "Debug" > "Attach to Running Custom Process...". Select "Kernel" as the connection type and enter the network name or IP address of your test machine.
Set Up the Test Machine: On your test machine, you'll need to enable kernel debugging. This is typically done via `bcdedit` commands in an elevated Command Prompt.
Install the Driver: Copy the driver files to your test machine and install the driver using Device Manager. Right-click on "Add legacy hardware" or find an appropriate device and update its driver, pointing to your driver's .inf file.
Break In: Once the driver is loaded and debugging is attached, you can set breakpoints in your code and use the standard Visual Studio debugging tools.

Tip: Familiarize yourself with kernel debugging commands and tools like WinDbg for more advanced scenarios.

Next Steps

This is just the beginning! As you progress, you'll want to explore:

DeviceIoControl: The primary mechanism for user-mode applications to communicate with drivers.
Kernel-Mode Driver Framework (KMDF) vs. User-Mode Driver Framework (UMDF): Understand the differences and choose the right framework for your needs.
Driver Signing: Learn about production-ready driver signing requirements.
Specific Driver Models: Explore models for storage, networking, display, and more.
DDI (Device Driver Interface): The vast set of functions and structures provided by the Windows Driver Kit.

Continue to explore the Windows Driver documentation for in-depth guides, API references, and sample code.