Contents
Previous Next
Examples: Debugging over a Virtual Serial Port
You can use Debugging Tools for Windows (
WinDbg) or Kernel Debugger (
KD) to debug kernel code in a virtual machine over a virtual serial port. You can download Debugging Tools for Windows from the Windows DDK Web site at
www.microsoft.com/whdc/devtools/debugging/default.mspx.
The following two examples illustrate how to use a virtual serial port to debug kernel code in a virtual machine:
With the debugging application on the GSX Server host (Windows hosts only)
With the debugging application in another virtual machine on the same GSX Server host (useful on a Linux host and can also be done on a Windows host)
Either of these methods lets you debug kernel code on one system, without requiring two physical computers, a modem or serial cable.
Debugging an Application in a Virtual Machine from the Windows Host
In this example, you have kernel code to debug in a virtual machine (called the target virtual machine) and are running WinDbg or KD on your Windows host.
Select This end is the server
Click Advanced, then under I/O Mode, select the Yield CPU on poll check box, as the kernel in the target virtual machine uses the virtual serial port in polled mode, not interrupt mode
To prepare the host, make sure you have a recent version of Debugging Tools for Windows — one that supports debugging over a pipe. You need version 4.0.18.0 or higher.
When you are ready to begin, complete the following steps:
1. Power on the virtual machine.
2. Check to make sure the serial port is connected. Choose VM > Removable Devices. On that menu, serial<n> should be reported as \\.\pipe\<namedpipe> (on Windows hosts) or /tmp/<socket> (on Linux hosts). If the serial port is not connected, choose the virtual serial port, then Connect.
3. On the host, open a Command Prompt window and do one of the following:
If you are using WinDbg, type the following:
windbg -k com:port=\\.\pipe\<namedpipe>,pipe
If you are using KD, type the following:
kd -k com:port=\\.\pipe\<namedpipe>,pipe
Then press Enter to start debugging.
Debugging an Application in a Virtual Machine from another Virtual Machine
In this situation, you have kernel code to debug in a virtual machine (called the target virtual machine) and are running Debugging Tools for Windows (WinDbg) or Kernel Debugger (KD) in another virtual machine (called the debugger virtual machine) on the same host.
This setup is useful if you are running GSX Server on a Linux host. The debugger virtual machine must be running Debugging Tools for Windows (WinDbg) or Kernel Debugger (KD) in a Windows guest operating system.
To prepare the target virtual machine, follow the steps for the
server virtual machine in
Connecting Two Virtual Machines. Make sure when you configure the target virtual machine's virtual serial port that you select the
Yield CPU on poll check box, as the kernel in the target virtual machine uses the virtual serial port in polled mode, not interrupt mode.
To prepare the debugger virtual machine, make sure you have downloaded Debugging Tools for Windows. Then follow the steps for the
client virtual machine in
Connecting Two Virtual Machines.
When you are ready to continue, complete the following steps:
1. Power on both virtual machines.
2. Check to make sure the serial port is connected. Choose VM > Removable Devices. If the serial port is not connected, choose the virtual serial port, then Connect.
3. In the debugger virtual machine, start debugging with WinDbg or KD normally.