Overview

There are 2 ways to do a fresh installation of GalliumOS on Chromebook:

Traditional Mode - replace ChromeOS entirely. Need a USD drive.
chrx Mode - install from ChromeOS command line.

The master guide is on wiki.galliumos.org, or there’s another simpler guide for beginners.

一、Traditional installtion

Go to chrome://system, and look for hardware_class. For my case it says “Akali” and “C5B-A4B-xxxxxxxx”
Go to https://wiki.galliumos.org/Hardware_Compatibility and check against your hardware class. I got “Intel Kaby Lake”.
Go to https://galliumos.org/download and download ISO of your version.
Enabling Developer Mode (Esc+F3(refresh)+Power), and reboot.
Enable Legacy Mode booting.
1. With your ChromeOS booted, press [Ctrl+Alt+T] and get a terminal (“crosh”) window
2. Run: ‘shell’
3. Then:
  
  sudo crossystem dev_boot_legacy=1
4. If you have seen an error, simply skip and continue. (Reference: https://www.reddit.com/r/chrultrabook/comments/o9538s/trying_to_boot_from_usb_what_is_dev_boot_altfw_as/)
Disable WP (write protection). Check your device on this MrChromebox page to decide how you going to do it. In my case I use the CR50 method
- If you still not sure, check out this video: https://www.youtube.com/watch?v=EGZ6KfjEPP0
Check WP status, At crosh>
```
 sudo sh
 flashrom --wp-status
```
Update Firmware. Press [Ctrl+Alt+T] to get a terminal (“crosh”) window, then type in “shell“
- Decide if you wish to update RW_LEGACY or install Full Firmware/UEFI
- Run:
```
  cd; curl -LO https://mrchromebox.tech/firmware-util.sh && sudo bash firmware-util.sh
```
  In case Github not accissible, try this link:
```
  cd; curl -LO https://mar2ndx.github.io/files/mrchromebox/firmware-util.sh && sudo bash firmware-util.sh
```
At promp, first you need to set GBB Flags (here is an explanation of why).

Important: If you choose an ISO install of GalliumOS (thus removing ChromeOS), and choose to use the Legacy Boot Mode of the stock firmware (ie, with the stock or updated RW_LEGACY firmware), and you allow your battery to drain completely, you might have a problem booting GalliumOS. This is due to the Developer Mode boot flag enabling Legacy Boot mode being reset when power is lost - see crossystem flags.

Google Binary Block (GBB) flags are firmware level settings stored directly in the firmware flash chip itself in a read-only (RO) area

I’ve made this mistake before. Had to do an entire factory restore of ChromeOS.

To set GBB, under ChromeOS at chronos@localhost / $ prompt, run this:

 cd; curl -LO mrchromebox.tech/firmware-util.sh
 sudo install -Dt /usr/local/bin -m 755 firmware-util.sh
 sudo firmware-util.sh

Or under Linux:

 cd; curl -LO https://mrchromebox.tech/firmware-util.sh && sudo bash firmware-util.sh

Very important: you MUST execute this command as a normal/non-root user.

Next, continue to use the same firmware-util.sh script to install firmware. Should be simple enough.

Then, plugin the GalliumOS installation disk into USD, and reboot.
Now start the actual installation process of GalliumOS!
Burn the ISO using BalenaEtcher. I used my old Mac to do the job.
Keep your USB drive plugged-in before rebooting. On the “OS verification is OFF“ screen, press Ctrl + L
Install GalliumOS (I recommend using the English mode + Wiki connected to install).
You may or may not need to press Ctrl + L every time you boot the system, depending on which fireware script you chose to install.

[Important] Power Drain

如果电脑突然没电了，你的 Chromebook 无法启动，而是哔哔很大的两声，这说明你的 dev_boot_legacy flag 被 GBB 给 unset 成 0 了。

Sorry to tell you, 你只能恢复原 ChromeOS，然后重来一次了。你的数据都没了。

没别的办法，你猜我怎么知道的？

Reference：

Important: If you choose an ISO install of GalliumOS (thus removing ChromeOS), and choose to use the Legacy Boot Mode of the stock firmware (ie, with the stock or updated RW_LEGACY firmware), and you allow your battery to drain completely, you might have a problem booting GalliumOS. This is due to the Developer Mode boot flag enabling Legacy Boot mode being reset when power is lost - see crossystem flags.

https://wiki.galliumos.org/Firmware#crossystem

How to fix: 必须改 GBB，但是不建议直接改 c++ 代码，因为是只读的。最便捷的方法是使用 MrChromebox’s ChromeOS firmware utility script.

二、chrx installation

这种模式很好，因为 ChromeOS 被原本保留了。恢复起来也很方便。

主要问题就是硬盘太小。低端Chromebook 普遍采用 32G 的 flash drive。装 ChromeOS 使用一大半，GalliumOS 占用 7-8G，空间就没了。

Troubleshooting

开机画面（dev mode）键盘选项

[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