You can configure when a serial port is connected to a virtual machine. You can also configure whether to send output to a physical port or to a file on the host system, set up a direct connection between two virtual machines, and specify whether the guest operating system uses the port in polled mode.

To configure serial port settings for a selected virtual machine, select the virtual machine, select VM > Settings, click the Hardware tab, and select the serial port.

Table 1. Serial Port Settings
Setting Description
Connected Connect the port while the virtual machine is running.
Connect at power on Connect the port when you power on the virtual machine.
Use a physical serial port Select a host serial port.
Use output file Send output from the virtual serial port to a file on the host system. Either locate an existing output file or navigate to the desired directory and type a filename for the file to create.
Use named pipe or Use socket (named pipe) Set up a direct connection between two virtual machines or a connection between a virtual machine and an application on the host system.
Yield CPU on poll

The guest operating system uses the port in polled mode rather than interrupt mode. It yields processor time if its only task is to poll the virtual serial port.

If the guest operating system uses the serial port in interrupt mode, do not select this setting.

Note: This setting is useful for developers who are using debugging tools that communicate over a serial connection. Selecting this setting can improve performance when the guest operating system uses the serial port in polled mode.