HOWTO Install Ubuntu Server 20.04 via Serial Console

Here is a short guide on how to boot an Ubuntu Server installation from USB using only the serial console.

This has been tested using Ubuntu Server 20.04 on a PCEngines APU1 device.

These instructions have not been tested with UEFI boot as this is not supported by the PCEngines APU1.

USB Boot Disk Setup

1. Download an Ubuntu Server amd64 ISO file.

2. Create a USB boot disk from the ISO (e.g., using Rufus).

3. Mount the USB boot disk and modify the following files:

   • isolinux/isolinux.cfg

   # D-I config version 2.0
   # search path for the c32 support libraries (libcom32, libutil etc.)
   CONSOLE 0
   SERIAL 0 115200 0
   path 
   include menu.cfg
   default vesamenu.c32
   prompt 0
   timeout 50
   

   • isolinux/txt.cfg

   default install
   label install
   menu label ^Install Ubuntu Server (ttyS0)
   kernel /casper/vmlinuz
   append vga=off initrd=/casper/initrd console=ttyS0,115200n8 
   

   • syslinux.cfg

   CONSOLE 0
   SERIAL 0 115200 0
   
   DEFAULT loadconfig
   
   LABEL loadconfig
   CONFIG /isolinux/isolinux.cfg
   APPEND /isolinux/
   

Hardware Configuration

Ensure that the hardware BIOS has been appropriately configured to use a serial port at 115200/8/N.

Installation

1. Attach serial console from client using PuTTY on Windows or screen on Linux:

% screen /dev/ttyS0 115200

2. Insert the USB boot drive and power on the device.
3. Proceed with normal Ubuntu installation.
4. After installation, edit /etc/default/grub as follows:

GRUB_CMDLINE_LINUX_DEFAULT=""
GRUB_TERMINAL='serial console'
GRUB_CMDLINE_LINUX="console=tty0 console=ttyS0,115200n8"
GRUB_SERIAL_COMMAND="serial --speed=115200 --unit=0 --word=8 --parity=no --stop=1"

5. Update the grub configuration:

# update-grub

Reference

• http://pcengines.info/forums/?page=post&id=E25612E9-84F0-4DCF-A876-1E92FD1D065C
• https://help.ubuntu.com/community/SerialConsoleHowto