Howto: Boot your GoFlex/Dockstar rootfs into QEMU (sort of)

Vlad — Sun, 02 Oct 2011 15:44:39 -0500

Sometimes, it might be useful to be able to boot you GoFlex/Dockstar rootfs in a virtual machine.
Unfortunately, as of now qemu doesn't support emulating Marvell Kirkwood CPU's. Nevertheless you can
still boot your rootfs in a virtual environment, using a versatile arm kernel. The emulated hardware will, however, be different. Also, there's no uboot emulation.

I'm assuming that you're using a Ubuntu system, but probably every Debian based distro should be fine.
Connect your flash drive containing the rootfs to your Ubuntu box and mount it under /media/rootfs.

Open a terminal and run

sudo -s
wget http://people.debian.org/~aurel32/qemu/armel/initrd.img-2.6.32-5-versatile
wget http://people.debian.org/~aurel32/qemu/armel/vmlinuz-2.6.32-5-versatile
wget http://security.debian.org/debian-security/pool/updates/main/l/linux-2.6/linux-image-2.6.32-5-versatile_2.6.32-35squeeze2_armel.deb
apt-get install qemu-system libcap2-bin bridge-utils
setcap cap_net_admin=ei /usr/bin/qemu
nano /etc/network/interfaces

add this to the end of the file

auto eth0
iface eth0 inet dhcp

auto br0
iface br0 inet dhcp
        bridge_ports eth0
        bridge_stp off
        bridge_fd 0
        bridge_maxwait 0

now run

ifdown eth0
ifup br0
modprobe tun
nano /etc/qemu-ifup

replace the content of the file with this

#!/bin/sh
echo "Executing /etc/qemu-ifup"
echo "Bringing up $1 for bridged mode..."
/sbin/ifconfig $1 0.0.0.0 promisc up
echo "Adding $1 to br0..."
/usr/sbin/brctl addif br0 $1
sleep 2

now run

dd if=/dev/zero of=kirkwood_rootfs.img bs=1MB count=2000
mkfs.ext3 -F kirkwood_rootfs.img
mount -o loop kirkwood_rootfs.img /mnt
cp -a /media/rootfs/* /mnt
nano /mnt/sbin/autologin.sh

paste this

#!/bin/sh
exec /bin/login -f root

now run

chmod +x /mnt/sbin/autologin.sh
echo 'c1:2345:respawn:/sbin/agetty -l /sbin/autologin.sh -n 38400 tty1 linux' >> /mnt/etc/inittab
cp linux-image-2.6.32-5-versatile_2.6.32-35squeeze2_armel.deb /mnt/root
rm /mnt/etc/udev/rules.d/70-persistent-net.rules
umount /mnt

Finally, start QEMU

qemu-system-arm -M versatilepb -m 128M -kernel vmlinuz-2.6.32-5-versatile -initrd initrd.img-2.6.32-5-versatile -hda kirkwood_rootfs.img -append "root=/dev/sda" -net nic,macaddr=00:16:3e:00:00:01 -net tap

You will be automatically logged in as root, but network will not work. In QEMU do this

dpkg -i linux-image-2.6.32-5-versatile_2.6.32-35squeeze2_armel.deb
reboot

After the reboot your virtual machine should also have internet access.

Sources:
http://www.linuxquestions.org/questions/linux-software-2/autologin-without-gui-374338/
http://people.debian.org/~aurel32/qemu/armel/
http://www.aurel32.net/info/debian_arm_qemu.php
https://help.ubuntu.com/community/KVM/Networking