Specifications

CHAPTER 8 Configuring Devices
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<n> is the number of the serial port, starting from 0. So the first serial port is
serial0.
<x> is any positive integer. It specifies the time taken to transmit a character,
expressed as a percentage of the default speed set for the serial port in the guest
operating system. For example, a setting of 200 forces the port to take twice as long
per character, or send data at half the default speed. A setting of 50 forces the port to
take only half as long per character, or send data at twice the default speed.
You should first use the guest operating system to configure the serial port for the
highest setting supported by the application you are running in the virtual machine.
Once the serial port speed is set appropriately in the guest operating system,
experiment with this setting. Start with a value of 100 and gradually decrease it until
you find the highest speed at which your connection works reliably.
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.
To prepare the target virtual machine, follow the steps in Connecting an Application
on the Host to a Virtual Machine on page 300. Make sure you configure the virtual
machine’s virtual serial port as follows:
• 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