Unleashed

Chromebooks have established themselves as a low-cost alternative to conventional entry-level laptops. Devices from many manufacturers and with many display sizes are available; however, all models are tightly tied to the Chrome OS operating system by Google.

Some potential buyers, toying with the idea of investing in such a device, are discouraged by the very limited capabilities of the operating system despite what is now quite powerful hardware. And, serious privacy concerns are another drawback to the system. Google is one of the largest collectors of data worldwide and makes things easy for itself by closely tying Chrome OS to its online services to extract personal data from users and thus generate profiles.

As a US corporate group, Google is forced to hand over the data to US authorities when ordered to do so. But the close bond between the operating system, Google's services, and the hardware is not hard-wired, so resourceful minds from the free developer community have broken these restraints and customized Linux for Chromebooks. The easiest approach is to create a dual-boot system using the ChrX tools [1]. Alternatively, you can use a separate Linux derivative in a window on Chrome OS in the form of Crouton [2].

Both of these options have serious drawbacks in that the parallel installation of two systems takes up unnecessary space on the relatively small Chromebook storage device. And, the use of Chrome OS rules out adequate data protection.

Therefore, the complete deletion of Chrome OS through an appropriately customized distribution is advisable. For cases in which users try to completely oust the system from their device, Google has taken numerous precautions to make it enormously difficult for less-skilled computer users to install alternative software.

Hurdles

Installing an alternative operating system instead of Chrome OS on a Chromebook involves not only replacing the device's firmware with a free alternative, but typically also includes some manipulation of the hardware. Most devices are equipped with a special jumper or a screw on the motherboard that switches the system software to read-only mode.

Write access is only allowed if you close the jumper or remove the screw; you can then modify the firmware. In many cases, both components are in place, and the manufacturer is likely to have glued a warranty seal over the corresponding screw so that the warranty is void in the case of removal. And, some companies do not disclose the position of the components on the motherboard of their devices, so you need to find these components by searching on the Internet.

Another problem is the lack of uniform hardware: Firmware modifications and thus replacement of the basic input/output system (BIOS) are by no means possible on all Chromebooks: Free solutions do not take into account certain Intel chipsets (yet) and will never work on Chromebooks with ARM architecture.

This rules out the exclusive installation of Linux on systems with Samsung's Exynos processors or Nvidia Tegra chips. Also CPUs by vendor Rockchip remain sidelined. Thus, it's advisable to check the lists with the basic technical specifications of the devices on the Internet before buying a Chromebook [3].

Software

For this test, my choice of distribution for the Chromebook was GalliumOS [4]. It is based on Xubuntu but is specifically optimized for the Intel hardware in some Chromebooks. Different versions of the system are available for different Intel processor generations; it currently supports the second generation (Sandy Bridge) architectures through the fifth generation (Broadwell).

Additionally, an ISO image for the Bay Trail architecture by Intel is also available, which groups the latest Atom processors. The ISO images each install a 64-bit operating system and are optimized in the form of special adaptations to the kernel especially for the less powerful hardware of the Bay Trail architecture. For example, two alternative schedulers for I/O operations (BFQ) and processes (BFS) are integrated into the kernel: They simplify process organization and minimize the latency when accessing memory.

The developers have also disabled unneeded modules in the kernel and removed unused system services. They have reduced the minimum GPU clock speed and improved the often unsatisfactory performance of the touchpad modules on standard systems by using the module from Chrome OS. Instead of the LightDM, LXDM – used regularly in Xubuntu – is on board as the display manager; again this conserves system resources.

GalliumOS is also very carefully documented; a compatible hardware list exists to help you choose the appropriate operating system components [5].

Hardware

To test the operating system as efficiently as possible, I used a brand-new Chromebook 14 G4 from Hewlett-Packard and a Chromebook 11 G4 EE by the same manufacturer (Table 1).

The current hardware let us check whether corresponding drivers are available on GalliumOS and what kind of resources the less powerful hardware offers. After all, the Chromebook 14 is equipped with a Celeron type N2940 processor and is thus a latest generation Bay Trail processor, offering quad-core performance without hyperthreading [6].

The Chromebook 11 G4's Celeron N2840, however, has only two cores, although its clock speed is slightly higher [7]. The processors which belong to the Atom CPU family are characterized by extremely low power consumption: Under load, they need a maximum of 7.5 watts; long battery life can thus be expected. The devices also work without fans and thus silently.

Both CPUs access 4GB memory on their respective devices. Additionally, the 14-inch device offers a conventional HD display with a resolution of 1366x768 pixels, although the manufacturer alternatively offers FHD-IPS display (1920x1080 pixels resolution).

The Chromebook 11 has an 11.6-inch HD display. The dual-band WiFi adapter installed in both devices, which supports the standard 802 11ac, is brand new. The devices also provide three or two USB ports, an HDMI port, and a headphone jack. There is also a slot for SD cards [8]. In terms of mass storage, the devices have eMMC Flash modules installed, each with a capacity of 16GB. Alternatively, there are models with 32GB eMMC cards as internal storage.