VirtualKD is a tool that improves your kernel debugging performance with VMWare and VirtualBox. It seamlessly integrates with WinDbg and dramatically reduces debugging latency. Just run the Virtual Machine Monitor, select a VM and press "Run debugger". A ready-to-go WinDbg window will appear and a faster-than-ever debugging session will start.

New in version 3.0: Now compatible with Windows 10 and VirtualBox 5.x.

Want to debug Linux kernel from Visual Studio? Check out our VisualKernel product!


  • Significantly improves kernel debugging performance with VMWare and VirtualBox.
  • Supports Windows XP to Windows 10, 32-bit and 64-bit.
  • Fixes truncated Driver Verifier load messages.
  • Compatible with WinDbg and VisualDDK.
  • Easy installation.


screenshot vm monitor screenshot TraceAssist parameters


To download VirtualKD, see this page. The packages available to download include release build, debug build with PDB files for source-level debugging, and full source archive. Note that you need to download BazisLib library and VirtualBox sources to build VirtualKD.


Please report at the forum.


If something goes wrong, I strongly recommend you to download the sources and see everything in a debugger. Feel free to ask any questions on the SysProgs forum.


You can modify some parameters in registry under SOFTWARE\BazisSoft\KDVMWare\Patcher:

  • AllowPatchingAtTableStart. Set it to 0 if your VMWare crashes when being patched.

  • AllowReplacingFirstCommand. Set it to 1 if patching fails (and debug output indicates something like "0 free entries").

  • DefaultPatchingAtTableStart. You can try setting this to increase the performance (just a bit), but in can make VMWare crash on patching. Feel free to try ;) Additionally, you can set the WaitForOS to 0 in VirtualKD\Monitor to let the debugger be started immediately when a VM is detected (without waiting for OS to load).

Source structure

The information about source code structure and some hints for experimenting with it can be found at the following address: http://virtualkd.sysprogs.org/dox


I would like to thank the following people for making the creation of this tool possible: