Take the 2-minute tour ×
Server Fault is a question and answer site for system and network administrators. It's 100% free, no registration required.

Using VirtualBox, Is there a limit of two serial ports per VM? I'm currently engaging in a task that requires more than two, but less than or equal to four ports. I'm at a loss of what to do to get COM3 and COM4 up? How do I do it if the Virtual Box GUI doesn't currently support more than two serial host devices? Can I configure them external to the GUI? Is there a hard-cap on two devices? And, if so, for the love of god, please entertain me with the reasoning? I know Windows and Linux don't impose such a limit, it would seem awkward to impose it in virtualization layer.

This is for cheap dial-in project with proprietary Windows tools. I'm using a Quatech serial multiport adapter to provide the ports to multimodems.

share|improve this question

2 Answers 2

From the Serial Ports section of the Virtual Box Manual:

...you can configure up to two virtual serial ports simultaneously.

vboxmanage modifyvm --uart will let you configure these 2 virtual ports but not add an additional port.

share|improve this answer

I'm not 100% sure this will work, but it appears as if there is a utility VBoxManage which has the ability in modifyvm mode to add serial ports beyond the ability of the GUI.

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.