On a headless Ubuntu 22.04 machine, I'd like to start a headless installation of NetBSD 9.2 in VirtualBox.

I have a prepared virtual machine with a set of blank disk images attached, as well as with the bootable NetBSD installation CD attached to the CDROM drive.

My idea was to perform the installation over the serial port, using minicom, but I'm unable to get the installation to switch over to use the serial console.

I'm starting the machine with

VBoxManage startvm netbsd --type=headless

Then I try to get it to switch over the console to the serial port:

VBoxManage controlvm netbsd keyboardputfile boot.conf

... where boot.conf is a file containing a line of text saying consdev com0, which is what you would type on the NetBSD boot prompt to switch to the serial console.

I know NetBSD's serial console is set up to use 9600 8N1, which is what I have minicom configured to use, and I have set up the serial port on the virtual machine like so:

UART 1:                      I/O base: 0x03f8, IRQ: 4, attached to pipe (server) '/tmp/netbsd.pipe', 16550A

I start minicom using

minicom -D 'unix#/tmp/netbsd.pipe'

I successfully use the serial console on another virtual machine in an identical way, and I can see the status in minicom switch from "Offline" to "Online" as soon as the NetBSD machine turns on, but there is no output in minicom.

Can anyone see what the issue is and how I would go about fixing it? I know the alternative would be to PXE boot the machine, but I was hoping to be able to avoid doing that (as I don't netboot anything else at the moment).

1 Answer 1


I was obviously thinking too much and reading too little. The main issue was that I got the installation ISO image off the main NetBSD website's front page, which does not contain a link to the installation instructions.

Had I read the instructions, I would have seen that there is a separate ISO image, boot-com.iso, specifically made for installations over serial console:

Quick install notes for the impatient

This section contains some brief notes describing what you need to install NetBSD 9.2 on a machine of the amd64 architecture.

Fetch files needed to install NetBSD.

  • Option 1: bootable CD-ROM images or USB images containing the full distribution.

    These can be found on an FTP site near you, usually located in the /pub/NetBSD/images/ directory. Check the list of NetBSD mirrors for details.

  • Option 2: bootable CD-ROM images from amd64/installation/cdrom/.

    These images are bootable, but do not contain binary sets. They are intended for network installs or system repair. boot.iso is for VGA console installation, and boot-com.iso is for installation over serial console (com0, 9600 baud).

Switching out the ISO image files, I now am able to start the installation the way I was intending.

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