Configure Windows Kernel Debug Port via Registry

This guide provides an overview of configuring the Windows kernel to initialize with a custom debug port using the Windows Registry Editor. Modifying these low-level settings enables developers and system administrators to direct kernel debugging traffic through specific hardware ports or custom network configurations during early boot stages. Below are the direct steps required to configure the custom debug port parameters in the registry.

Step 1: Open the Registry Editor with Administrative Privileges

1. Press Win + R to open the Run dialog box.
2. Type regedit and press Enter.
3. Select Yes when prompted by User Account Control (UAC) to grant administrative permissions.

Step 2: Navigate to the Kernel Configuration Key

In the Registry Editor address bar, navigate to the following path:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control

Step 3: Create or Open the KernelDebugger Key

1. Check if a key named KernelDebugger exists under Control.
2. If it does not exist, right-click the Control folder, select New > Key, and name it KernelDebugger.

Step 4: Configure the Custom Debug Port Values

Within the KernelDebugger key, configure the specific parameters required for your debugging interface:

• For Serial (COM) Debugging:
  • Right-click the right pane, select New > DWORD (32-bit) Value, and name it Port. Set its value to your desired COM port number (e.g., 1 for COM1, 2 for COM2) in decimal.
  • Right-click, select New > DWORD (32-bit) Value, and name it BaudRate. Set the value in decimal to your target baud rate (such as 115200).
• For Network (KDNET) Debugging:
  • Right-click, select New > DWORD (32-bit) Value, and name it DebugPort. Set the value to your preferred network port (default is typically 50000–50039 in decimal).
  • Right-click, select New > String Value, and name it Key if a specific encryption key is required for the connection.

Step 5: Apply Changes and Restart

1. Close the Registry Editor.
2. Restart the machine to force the Windows kernel to initialize with the new debug port configuration during the next boot cycle. Ensure the host debugger is listening on the matching port and transport medium.