Preparations

To modify the hardware, you initially switch the device to root or developer mode. To do this, press Esc+F3, and at the same time switch on the device. Chromebooks have a slightly modified keyboard without dedicated F-keys, you need to take into account that the Refresh button on the Google device is the F3 key (Figure 1).

Figure 1: The slightly modified keyboard layout of the Chromebook requires a little getting used to.

After a warning message telling you that Chrome OS is supposedly missing, which you can skip by pressing Ctrl+D, the operating system displays a mask for logging on. You need to register with Google here and then sign up with the access data of your new Google account.

If you are already registered with Google, you can log in with the existing data to authenticate. The device is now in developer mode, and you can switch it off again.

The next step is to remove the read-only protection for the firmware, which requires opening the unit. Hewlett-Packard provides for all its devices, including the Chromebook, detailed documentation in the form of service guide PDF file [9]. Because both devices have BIOS modules that allow writing and both are protected by a screw, you need to remove the screw to modify the firmware (Figure 2).

Figure 2: The read-only screw for the firmware is clearly marked in the HP Chromebook.

You should strictly follow the instructions to avoid accidentally damaging other components. The screws are marked by a large triangle printed on the circuit board next to them and have a flat, oversized head. After removing the write-protect screw, reassemble the device; no further hardware intervention is needed. Then reboot and skip the messages again by pressing Ctrl+D.

After signing on and enabling the Internet connection by entering the data for the purpose of authentication, press Ctrl+Alt+T to pop up a terminal. Enter the shell command at the Crosh Developer prompt to launch bash. Subsequently, enter the command sequence from Listing 1.

This loads the alternative firmware from the specified website and installs it. When replacing the firmware, follow the messages on the screen precisely, because incorrect input will destroy the firmware and lead to an unusable system.

The routine installs the free Coreboot code, to start the mainboard and all its components. Then, the script loads the SeaBIOS as payload for Coreboot. Because these operations are transparent, no more manual settings are necessary. After successfully replacing the firmware on the device, turn the machine off.

Preparing a USB Stick

Then, download the ISO image from GalliumOS from the project site and install it on a USB stick. This needs to be a device with at least 4GB capacity; you should delete all partitions before installing the ISO image. First, type the lsblk command to discover the USB flash drive's name.

Remove any existing partitions on the drive by typing the fdisk/dev/<device file> or cfdisk/dev/<device file>, taking care to replace the placeholder with the correct name in each case. You need to enter both commands with administrator rights.

After following the steps to delete all partitions, unmount the stick. Now copy the ISO image from GalliumOS to the storage medium by typing the command dd if=<Image-Datei> of=/dev/ bs=1M. The process can take up to several minutes depending on the throughput of the system.

When done, type the sync command to write all the data from memory to the device. Then, remove the stick from your computer and plug it into the USB port on the Chromebook.

First Start

When you first start the Chromebook with the USB stick plugged, the host calls the SeaBIOS and branches to the GRUB boot manager on the Flash stick, in which you can launch GalliumOS Live. The second option in the Boot Manager GalliumOS CLI boots the live version of the operating system up to a login prompt but does not enable the desktop.

The option GalliumOS Live Image and Installer booted on the modified HP Chromebook without any trouble and very quickly showed us a live system with a visually customized Xfce desktop (Figure 3).

Figure 3: Virtually indistinguishable from a conventional Xubuntu: GalliumOS on the Chromebook.