John’s custom SeaBIOS is able to modify a Chromebook’s BIOS so that it can boot from a USB drive in order to install Linux. Some of you may be wondering, what’s the difference between the RW_LEGACY and BOOT_SLOT BIOS mods?
Although John has explained the differences I thought it would be helpful to reiterate them since I’ve noticed that this question is a reoccurring one amongst commenters.
Using the RW_LEGACY modified BIOS allows you to dual boot Chrome OS and Linux. You can also wipe Chrome OS completely and run Linux on its own if you prefer. Every time you turn on the Chromebook you will need to do the following:
- To get to Chrome OS you have to press CTRL+D at the initial Chrome screen.
- To boot Linux you have to press CTRL+L at the initial Chrome screen and then press ESC at the SeaBIOS screen and choose the drive to boot from.
RW_LEGACY is the best option if you’re not comfortable with opening up the Chromebook to disable write protect and are worried about bricking the device. With RW_LEGACY you can’t brick the device and don’t need to disable write protect.
Some people prefer not to press key combinations at boot, so using the BOOT_STUB mod is the better option.
If you choose the BOOT_STUB option the boot process is modified so that you only get the SeaBIOS screen and after a sec or two Linux boots up directly without the need to press any keys. This is the option if you want to wipe Chrome OS entirely and just boot Linux.
For this option you’ll need to roll up your sleeves and disable write protect by removing the Chromebook’s back cover. This carries the risk of bricking your device or damaging the Chromebook’s motherboard when you open it up.
In my opinion the risk of damage is minimal as long as you are careful and follow the instructions provided. After having opened my Chromebook several times to make how to videos I can report that no damage has occurred (I hope I’m not tempting fate!).
For those readers that are not confident with doing this, stick to the RW_LEGACY option, you’ll still be able to run Linux and pressing a few key combinations on startup is only a minor nuisance.