Wednesday, March 7, 2012

How to Setup a KD (Kernel Deugger) in Windows With 1394 or Over the Network

Lets say you are starting to write drivers and need some kernel mode (km) debugging, or lets say you've decided that user mode (UM) debugging using windbg on the host is for sissies.  In this post I will show you how to setup a KD.

You will need two machines: the TARGET machine that you want to debug, and the HOST machine that you will be doing the actual debugging.

First thing you need to do is install windbg on both the target and host.  You can find the installer here.

Pick a You KD Method:
Next decide what kind of debugging you want to do.  The options are:
NET (i.e. debugging over a TCP/IP network just using NICs) (supported on Win8+),
1394 (supported on WinXP+),
COM (serial) (supported since the dawn of KD), or
USB (2.0 supported on Vista+, 3.0 in Win8+)

Generally the port you use is decided for you based on what OS you need to debug, and what hardware your machines have.  I will make it simple, use 1394 (aka firewire) if you can, or if the machines aren't close, net.

If you two machines are next to each other favor 1394.  If you are going to be kernel debugging often and don't have 1394 in your machines, buy some cards.  1394 is simple and fast.

If your target isn't close to your debugger machine, use net, short for network, debugging, but note it is a Win8+ feature at the moment.  Net debugging is also great for getting someone else to remote debug something.  Also in Win8, over 90+% of the mainstream NICs are supported for net debugging; most Intel, Broadcom, and Realtek NICs are supported.

COM is slow, but works assuming your machines have serial ports.

USB might be a choice if your USB controllers support kernel debugging.  In my experience, they rarely do.  This is especially true when the machine doesn't have 1394 and you can't net debug.  You are kind of screwed at this point.  The joke is even funnier when you do find a port that does support KD, but it is internally wired to the built in webcam, or doesn't have an external port.

Setting Up a 1394 KD


  1. open a command prompt
  2. bcdedit -debug on
  3. bcdedit -dbgsettings 1394 channel:1
    - you will have to pass bus params if you have more than one 1394 controler)
    - channel can be 1-62
  4. reboot


  1. plug in 1394 cable into target and host
  2. open a command prompt
  3. kd -k 1394:channel=1

    windbg work instead of kd as well
Setting Up a NET KD

  1. open a command prompt
  2. bcdedit -dbgsettings net hostip: port:50000
    - for hostip, put your machine's IP instead of
    - you can pick whatever TCP port you want as long it is between 49151 and 65536.
  3. It will output something like:
    Save that string in a text file to a thumb drive or network share, you will need it again on the host
  4. bcdedit -debug on
  5. reboot
  1. open a command prompt
  2. windbg -k net:port= 50000,key=aaaaaaaaaaaaa.vvvvvvvvvvvvv.yyyyyyyyyyyyy.xxxxxxxxxxxxx

    you can use kd instead of windbg if you want

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