http://fedoraproject.org/wiki/Architectures/ARM/Samsung_Chromebook_2012

The Samsung Chromebook differs from previous units by having a virtual developer switch, as opposed to a physical one. Entering developer mode can be summarized as pressing ESC and Refresh while pressing power (Recovery Mode), then pressing Ctrl-D to enter Recovery mode. A warning message will be presented. After that, the unit will reset to erase all persistent data, and will then be able to boot custom Operating Systems. 


Performed on a machine reporting itself as
 "Linux 3.4.0 #1 SMP Wed Feb 27 13:26:59 PST 2013 armv7l ARMv7 Processor rev 4 (v7l) SAMSUNG EXYOS5 (Flattened..

Get into developer mode

1. Hold down keys: esc + 'Refresh' (the 3rd key from the right of the 'Esc'), then press the power on button
2. At the recovery screen, press ctrl+d
3. A red warning icon will be displayed and the system will emit a couple of beeps.
   The system will then reset after a short while and begin transitioning into developer mode.

   It will take ten or more minutes to complete the preparations.  A progress bar is visible at 
   the very top of the screen.

   Once the preparations are complete, the system will reboot and present a warning that
   OS verficiation is disabled.  The system will also emit a couple of beeps before booting
   into the initial setup screen where you can select the keyboard type and so on.

4. Select and login to a WiFi network.

   On the initial "Welcome!" setup screen, select your WiFi network and login with its
   password.  You'll need a working network connection in order to back up the kernel
   modules and firmare.

5. On the initial setup screen, you can drop into a virtual console.
   - Press ctrl+alt+forward arrow (top of keyboard - what would be labeled 'F2' on any other keyboard)

   Login and get a shell:

     login: root

   No password is required.


6. Ensure that you have a working network connection:

   # ifconfig -a

   Interface mlan0 should show an IP address with which you're familiar (assuming that you
   know about your WiFi!)

6. Back up the files that we'll need later to another host.

   # cd /
   # tar -cf - /{boot,opt,etc/X11,usr/{lib/xorg/modules,share/{alsa,vboot}},/lib/{firmware,modules}} | ssh user@anotherhost 'xz -z9 > chromeos-backup.tar.xz'

On your machine

 unpack the miniroot
  # chroot .
  # cd /var/log/packages
  # removepkg kernel*

  # cat << 'EOF' >> etc/fstab
LABEL=rootfs / ext4 defaults 1 1
EOF

cat << 'EOF' > /tmp/details

cd /tmp
echo "lsm.module_locking=0 console=tty1 debug verbose root=/dev/mmcblk1p3 rootwait ro " > /tmp/config
vbutil_kernel --pack /tmp/newkern --keyblock /usr/share/vboot/devkeys/kernel.keyblock\
 --version 1 --signprivate /usr/share/vboot/devkeys/kernel_data_key.vbprivk \
 --config /tmp/config --vmlinuz /boot/vmlinuz-3.4.0 --arch arm

dd if=/tmp/newkern of=/dev/mmcblk1p1
dd if=/tmp/newkern of=/dev/mmcblk1p2


crossystem dev_boot_usb=1
cgpt add -i 1 -S 1 -T 5 -P 10 -l KERN-A /dev/mmcblk1
cgpt add -i 2 -S 1 -T 5 -P 5 -l KERN-B /dev/mmcblk1
EOF


  # chromeos-firmwareupdate --mode=todev

  # exit 

mount /dev/sdb1 /mnt/hd
cd /mnt/hd
tar xf /mnt/prisroot/devel/armedslack/slackwarearm-devtools/minirootfs/roots/slack-current*z
tar xf /mnt/prisroot/devel/armedslack/slackwarearm-devtools/chromebook/EXCLUDE/chromeos-backup.tar.xz -C.
depmod -b. -va
sed  -i '/^s0:/d' etc/inittab

cat << 'EOF' >> etc/fstab
LABEL=rootfs / ext4 defaults 1 1
EOF

cp -fav /mnt/prisroot/devel/armedslack/slackwarearm-devtools/chromebook/EXCLUDE/rc.inet1.conf etc/rc.d
cp -fav /mnt/prisroot/devel/armedslack/slackwarearm-devtools/chromebook/EXCLUDE/wpa_supplicant.conf etc/

# Unpack the Xorg config files
# (taken from http://craigerrington.com/blog/installing-arch-linux-with-xfce-on-the-samsung-arm-chromebook/)
mkdir -vpm755 etc/X11/xorg.conf.d
tar xvvf /mnt/prisroot/devel/armedslack/slackwarearm-devtools/chromebook/chromebook_xorgconfs.tar.xz -C.

echo "lsm.module_locking=0 console=tty1 debug verbose root=/dev/mmcblk1p3 rootwait ro " > /tmp/config
vbutil_kernel --pack /tmp/newkern --keyblock /tmp/CI/usr/share/vboot/devkeys/kernel.keyblock\
 --version 1 --signprivate /tmp/CI/usr/share/vboot/devkeys/kernel_data_key.vbprivk \
 --config /tmp/config --vmlinuz /tmp/CI/boot/vmlinuz-3.4.0 --arch arm

dd if=/tmp/newkern of=/dev/sdb1
dd if=/tmp/newkern of=/dev/sdb2
cgpt add -i 1 -S 1 -T 5 -P 10 -l KERN-A /dev/sdb
cgpt add -i 2 -S 1 -T 5 -P 5 -l KERN-B /dev/sdb