Installing/Preparing

To install any new operating system onto your ChromeOS device, you must first enable Developer Mode. Many models also require updating firmware, depending on the install type.

To determine what preparation steps your device requires, you will need to know your device's Hardware ID. This is available from inside ChromeOS by navigating to chrome://system, where it's called hardware_class.

Next, check our Hardware Compatibility page to determine your device's CPU family. For example, the Acer C720's Hardware ID is PEPPY, and the CPU Family is Haswell.

Armed with this information, we can begin:

Step 1: Enable Developer Mode

WARNING: Enabling Developer Mode will erase all user data in ChromeOS. If you have locally-stored data, back it up first. Cloud data will not be lost.

1. With device shut down, press Esc+F3(refresh)+Power to boot into Recovery Mode
2. You will see the Recovery Mode boot screen, informing you that "ChromeOS is damaged or missing" (although it is not)
3. Press [Ctrl+D] to enable Developer Mode, then follow confirmation steps (usually just pressing enter)
4. Your machine will reboot to a white screen which says "OS verification is OFF". This is Developer Mode.
5. Enable Legacy Mode booting (you can skip this step if updating firmware, since it will be done automatically for you)
   1. Press [Ctrl+D] to boot ChromeOS in Developer Mode
   2. Configure WiFi if necessary, and log in to Chrome (Guest account is fine)
   3. Press [Ctrl+Alt+T] to get a ChromeOS terminal ("crosh") window
   4. At the prompt, enter shell
   5. At the chronos@localhost / $ prompt, run the following:
      • sudo crossystem dev_boot_legacy=1

Step 2: Flash Firmware (if required or desired)

Here's where you'll need to know your Hardware ID and CPU Family.

• Sandy Bridge models require custom firmware (exception: LINK)
• Bay Trail and Braswell models require custom firmware
• Haswell, Broadwell, and Skylake models can benefit from custom firmware; some models require it depending on install type. See: Hardware_Compatibility

Custom firmware (for many models) is available in multiple types and from multiple sources. See Firmware for more discussion.

Step 2a: Disable write-protection (if required)

Some types of firmware update (BOOT_STUB and Full ROM) require disabling firmware write-protection on your device. Be sure to read the Firmware page first! Write protection (WP) on ChromeOS devices is usually controlled by a screw on the motherboard, but some models also have conductive stickers, and a few older models have a jumper. The location and appearance of the WP screw/sticker/jumper vary between models, but in all cases you will need to open your device.

A web search for "<model or hardware id> chromebook disable write-protect" will often return detailed instructions, with photos, for your model. If not, feel free to ask for help in /r/GalliumOS or #galliumos.

Step 2b: Install/Update Firmware

You can install/update your firmware from the ChromeOS terminal, or from a running Linux system. These instructions describe the process from the ChromeOS terminal.

1. Boot into ChromeOS by pressing [Ctrl+D] at the "OS verification is OFF" Developer Mode boot screen
2. Configure WiFi if necessary, and log in to Chrome (Guest account is fine)
3. Press [Ctrl+Alt+T] to get a ChromeOS terminal ("crosh") window
4. At the prompt, enter shell
5. Decide which firmware you want to install. See Firmware.
6. At the chronos@localhost / $ prompt, run the command to flash your firmware. These commands are current as of this writing, but be sure to check the developer's site for any changes.
7. Run MrChromebox's Firmware Utility Script (developer's site)
   • cd; curl -LO https://mrchromebox.tech/firmware-util.sh && sudo bash firmware-util.sh
8. Then follow the on-screen instructions to install your chosen firmware type

Step 3. Install GalliumOS

You are now ready to install GalliumOS from ISO or via chrx.

Other options from the Developer Mode screen

The Developer Mode boot screen offers a few additional options. The most important one is Ctrl+L for Legacy Mode booting, which you will use to boot GalliumOS after installing (depending on your firmware choice). Here is the full list:

• [Ctrl+D] to boot ChromeOS in Developer Mode, or
• [Ctrl+L] to boot Legacy Mode (usually used for Linux, after installing)
• [Ctrl+U] to boot a ChromeOS (or ChromiumOS) image from USB (you'll never need to use this)
• [TAB] for some boot configuration information