Use WinDbg (windbg.exe) from the Microsoft® Win32® SDK to debug Windows NT® drivers. Install your driver on one machine (the target) and run WinDbg on another (the host).
For a kernel-mode driver, you run WinDbg (with kernel debugging options) on the host machine. The host and target, that has had debugging enabled, communicate with each other across a serial cable. For information on kernel-mode driver debugging, see Section 4.1.
For a user-mode driver, you run a remote debugging session with WinDbg on the host and WinDbgRm, the WinDbg remote debugging component, on the target. In remote debugging, the host and target machines communicate with each other across the network or across a serial cable. For information on user-mode driver debugging, see Section 4.2.
To assist in debugging device drivers for Windows NT, WinDbg is extensible through the use of debugger extensions. There are system supplied debugger extensions for common operations as well as the ability to define custom extensions. For information on debugger extensions, see Section 4.4.