Running Ubuntu Core

Info Box Applies to Linux Applies to Naon Applies to Lizard

Introduction

Canonical, the company behind the well-known [www.ubuntu.com Ubuntu] GNU/Linux distribution, is now sharing a minimal filesystem for ARM architecture called Ubuntu Core. This basic root file system works perfectly with platforms based on the Sitara processors, as Naon and Lizard. It contains the APT software so the file system can be easily customized installing additional packages.

References

• Ubuntu Core project page: https://wiki.ubuntu.com/Core

• Ubuntu Core installation instructions: Ubuntu Core page on Omappedia

• Root file system image: Ubuntu Core 12.04 "Precise Pangolin" tar.gz archive

• Ubuntu OMAP Desktop: Ubuntu Omap Desktop Installation Instructions

Ubuntu Core - Quick Guide

Please follow these steps to run Ubuntu Core:

• Download the compressed archive containing the RFS
• Uncompress the archive to a folder on your disk
• Share the folder via NFS
• Configure the bootloader to boot from network, with RFS pointing to the Ubuntu Core NFS share
• Boot the system

Enabling the serial console

The following instructions show how to enable the serial console (eg: ttyO0)

• Create the /etc/init/serial-auto-detect-console.conf file with the following contents:

# serial-auto-detect-console - starts getty on serial console
#
# This service starts a getty on the serial port given in the 'console' kernel argument.
#

start on runlevel [23]
stop on runlevel [!23]

respawn

exec /bin/sh /bin/serial-console

• Create the /bin/serial-console file with the following contents:

for arg in $(cat /proc/cmdline)
do
    case $arg in
        console=*)
            tty=${arg#console=}
            tty=${tty#/dev/}
 
            case $tty in
                tty[a-zA-Z]* )
                    PORT=${tty%%,*}
 
                    # check for service which do something on this port
                    if [ -f /etc/init/$PORT.conf ];then continue;fi 
 
                    tmp=${tty##$PORT,}
                    SPEED=${tmp%%n*}
                    BITS=${tmp##${SPEED}n}
 
                    # 8bit serial is default
                    [ -z $BITS ] && BITS=8
                    [ 8 -eq $BITS ] && GETTY_ARGS="$GETTY_ARGS -8 "
 
                    [ -z $SPEED ] && SPEED='115200,57600,38400,19200,9600'
 
                    GETTY_ARGS="$GETTY_ARGS $SPEED $PORT"
                    exec /sbin/getty $GETTY_ARGS
            esac
    esac
done

• Create the /etc/init/ttyO0.conf file with the following contents:

# ttyO0 - getty
#
# This service maintains a getty on ttyO0 from the point the system is
# started until it is shut down again.

start on runlevel [23] and (
            not-container or
            container CONTAINER=lxc or
            container CONTAINER=lxc-libvirt)

stop on runlevel [!23]

respawn
exec /sbin/getty -8 115200 ttyO0

Networking

Setting the DNS

Assuming that network interface is properly configured, to set the DNS enter the following command:

echo "nameserver [dns ip address]" > /etc/resolv.conf

Cross-compile custom components

If you need to add custom components (applications, frameworks, ..) which are not provided by the Ubuntu repositories, you must build from the sources using the proper toolchain. In particular, the toolchain used to build the Ubuntu Core 12.04 LST armhf is the gcc-arm-linux-gnueabihf. On Ubuntu server 12.04 LST (x86 o amd64), you can install this toolchain using the package manager (e.g. apt-get).

The toolchain files can be found in /usr/arm-linux-gnueabihf. This path should be used to configure the build tools (SDKs, Makefiles, ..) for cross-compilation.

Useful packages

The following is a list of useful packages which can be easily installed with apt-get:

• openssh-server
• wpasupplicant
• bluez
• bluez-tools
• obexpushd
• obexftp
• nano
• apt-utils
• python-software-properties
• ping
• rdate