How to debug debugger?

Yes, title says it all.
If you've ever tried to create your own debugger extension to ease the task of debugging your own program/kernel module, you probably wanted to know how to debug your own debugger extension as that is running within debugger.

The answer is pretty simple. You can use a couple of windbg commands to accomplish your task.
First, traditional '.dbgdbg' command. This will spawn CDB session and create remote session so you can either just use cdb session to debug or use windbg and connect to the remote session.
But as you can see, cdb session is not so friendly so I often start new windbg session to debug my own debugger extension. This works but requires a couple of steps.

Then, today I learned new command. That is '!debugme -lw'. What this will do is that it simply creates windbg session attached to your own debugger so it cuts out the extra CDB and remote. Very simple and nicely done!

So next time you need to debug your own debugger extension, try '!debugme -lw'

In this post I assumed that you know how to develop windbg debugger extension. Please refer to Advanced Windows Debugging for more information on that topic. The book has a nice example where you can probably just replace some of the code to create your own debugger extension.