How to make a customize ubuntu rootfs image

Install required packages

  sudo apt-get install qemu-user-static binfmt-support

Generate the image

  dd if=/dev/zero of=rootfs.img bs=1M count=1024
  mkfs.ext4 -F -L linuxroot rootfs.img #kernel use the label linuxroot to mount the rootfs as /
  sudo mount -o loop rootfs.img /mnt

The fast way is to make a ubuntu image is downloading a recent pre-built ubuntu rootfs from linaro

  wget http://releases.linaro.org/14.10/ubuntu/trusty-images/alip/linaro-trusty-alip-20141024-684.tar.gz
  sudo tar zxvf linaro-*.tar.gz -C /mnt
  cd /mnt
  sudo mv binary/* .
  sudo rmdir binary

Copy the kernel modules you built from Building the kernel

  sudo mkdir -p /mnt/lib/modules
  sudo cp -r /path/to/marsboard-linux-rockchip/modules/lib/modules/3.0.36+ /mnt/lib/modules

Prepare chroot

  sudo cp /usr/bin/qemu-arm-static /mnt/usr/bin
  sudo modprobe binfmt_misc
  sudo mount -t devpts devpts /mnt/dev/pts
  sudo mount -t proc proc /mnt/proc

Chroot and post configuration

  sudo chroot /mnt

Now we are in the target rootfs, let's continue to configure the system.

Change the default shell to bash.

  root@target:# rm /bin/sh && ln -s /bin/bash /bin/sh

Install the pre-installed packages

  root@target:# apt-get update
  root@target:# apt-get install ssh vim usbutils wpasupplicant wireless-tools

Now we are done! :D

  root@target:# exit
  sync
  sudo umount /mnt

Now you have rootfs.img as the rootfs image for marsboard. Trouble shooting bluez package configure error

Setting up bluez (4.101-0ubuntu8b1) ... reload: Unknown instance: invoke-rc.d: initscript dbus, action "force-reload" failed. start: Job failed to start invoke-rc.d: initscript bluetooth, action "start" failed. dpkg: error processing bluez (--configure): subprocess installed post-installation script returned error exit status 1 dpkg: dependency problems prevent configuration of blueman: blueman depends on bluez (>= 4.25); however: Package bluez is not configured yet. ...

It turns out the bluez package needs the dbus service running in order to configure properly. The following works:

  service dbus start
  dbus start/running, process 24551
  dpkg --configure bluez

Non root user can not use the network

Edit /etc/group and add

  inet:x:3003:root
  net_raw:x:3004:root

and then run

  gpasswd -a username inet