Please note: I no longer maintain, provide, or support custom Chromebook firmware; this page is left here for archive purposes only.
This page contains a command to download and run a script, which will flash custom firmware with a SeaBIOS payload on approaching 40 models of Intel based Chromebook – allowing you to run an alternative OS such as Linux. The script will work with ChromeOS or pretty much any Linux distro (at least no one has told me otherwise).
There are 3 types of firmware mod – RW_LEGACY, BOOT_STUB, and Full ROM – not all Chromebooks work with each one:
RW_LEGACY modifies a 2MB section of the ROM leaving the stock functionality intact, including the scary developer screen, and will not brick your device. Some Chromebooks already come with a working RW_LEGACY slot, although many of them do not (non-functional keyboard on Panther, non-functional display on Auron_Yuna, or just plain missing, etc.). As well as fixing aforementioned bugs, updating the RW_LEGACY slot can enable further functionality such as booting from SD card/eMMC. So, even in the case of a functioning stock RW_LEGACY, it may be fortuitous to update.
BOOT_STUB modifies the last 1MB of the ROM, removing the scary developer screen, but also removes the ability to run ChromeOS natively, carrying a chance of bricking your device. This also leaves the “REFRESH + POWER” functionality of the stock ROM intact, meaning, when you press these keys, the device will immediately reboot and attempt to run ChromeOS Recovery (which isn’t there any more), and give you a blank screen. The only way to then stop it from attempting to run ChromeOS Recovery on every boot, is to take the device apart and disconnect the battery.
Full ROM, as the name suggests, is a complete ROM containing a coreboot build with a slice of SeaBIOS on top, and is the most risky. Again, this will remove the ability to run ChromeOS natively. Flashing one of these will wipe out your product data. In the case of Sandy/Ivybridge Chromebooks a full ROM enables hardware virtualisation extensions and suspend. Other models full ROM’s also probably contain idiosyncrasies that the stock firmware does not.
You need to be in dev mode and to have disabled write-protect by enabling a jumper/removing a screw (usually the latter, located somewhere on the main board). Disabling write-protect is not necessary when flashing RW_LEGACY unless you want to make the legacy slot default. See each respective supported Chromebook’s developer information page (if available) for info on opening your Chromebook up and disabling write-protect.
Jenkins is now being used along with some scripts, to automate building, and to reduce chances of a brick from human error. Run the script like so, making sure you are only in Crosh shell *not* the *root* Crosh shell if running from ChromeOS:
cd;bash <(curl https://johnlewis.ie/flash_cb_fw.sh)