For those of you not familiar with Chromebooks, check out Google's page on them. I encountered a Chromebook for the first time in the wild this past Saturday and was quite impressed with how snappy and functional for casual web browsing they were. A little bit of research later that afternoon I discovered several (the Intel ones) are capable of running Linux with minimal effort. After doing a fairly quick Google search I found that the Acer Chromebook CB3-131-C3SZ 11.6-Inch Laptop would allow support for dual booting Chrome OS and Linux if I flashed the rom with a custom one.

I decided to go with Gallium OS as my Linux distro as it is made, and optimized, for use on Chromebooks. Acer Chromebook CB3-131-C3SZ 11.6-Inch Laptop would allow support for dual booting Chrome OS and Linux if I flashed the ROM with a custom one. Flashing the ROM for this specific device was easy:

At the Chrome OS screen I logged into my WiFi network but NOT the OS.
Opened a crosh shell by pressing CTRL+ALT+F2(which is actually just a right arrow where the F2 key should be)
Logged in as 'chronos' with no password
Followed the instructions on https://johnlewis.ie/custom-chromebook-firmware/rom-download/ which download and install the firmware ROM for the chipset my model has. I went with 'RW_LEGACY' as it allows dual booting.

This flashed the rom and I then powered the machine off and turned it back on just to be safe before proceeding to the next step. I was now ready to install Gallium OS! This was equally as simple:

At the Chrome OS screen I logged into my WiFi network but NOT the OS again
Opened a crosh shell via Ctrl+ALT+F2 again
Logged in as 'chronos' with no password again
Then ran the chrx install script 'curl -Os https://chrx.org/go && sh go' which downloaded the install script and gave me a few options for the install, like setting the partition size (I gave 9 of the 12gb to it as recommended).

After about 15 minutes it had downloaded the distro and installed and bam there I was at the Gallium OS log in screen! It works great. Now when I turn on my Chromebook I have 30 seconds to select which OS I want by pressing either 'CTRL + D' for Chrome OS or by pressing 'CTRL + L' for Linux, if I do not select one within 30 seconds it automatically launches Chrome OS! I've read you can change the default as well as the time but it's not a big deal, within 1 second of pressing the power button you are at the screen then it's just a quick tap. Chrome OS takes about 9 seconds to load now from pressing 'CTRL+D' and Gallium OS takes roughly twice as long after pressing 'CTRL+L' to be at the log-in screen!

I have to say, this Acer Chromebook is a great little machine. Its housing is plastic but it makes a great little machine for browsing the web, chatting, using pushbullet to text etc while I sit on the couch watching TV or while sitting in a coffee shop people watching out the window!