Restoring Legacy Boot (Linux Boot) on a Chromebook

press ctrl-alt-forward to jump to TTY2 and a standard login prompt
press ctrl-alt-forward to jump to TTY2 and a standard login prompt

I let the battery die completely on my Acer C720 Chromebook, and discovered that unfortunately if you do that, your Chromebook will no longer Legacy boot when you press Ctrl-L – it just beeps at you despondently, with no error message to indicate what’s going wrong.

Sadly, I found message after message on forums indicating that people encountering this issue just reinstalled ChrUbuntu from scratch. THIS IS NOT NECESSARY!

If you just get several beeps when you press Ctrl-L to boot into Linux on your Chromebook, don’t fret – press Ctrl-D to boot into ChromeOS, but DON’T LOG IN. Instead, change terminals to get a shell. The function keys at the top of the keyboard (the row with “Esc” at the far left) map to the F-keys on a normal keyboard, and ctrl-alt-[Fkey] works here just as it would in Linux. The [forward arrow] key two keys to the right of Esc maps to F2, so pressing ctrl-alt-[forward arrow on top row] will bring you to tty2, which presents you with a standard Linux login prompt.

Log in as chronos (no password, unless you’d previously set one). Now, one command will get you right:

sudo crossystem dev_boot_usb=1 dev_boot_legacy=1

That’s it. You’re now ready to reboot and SUCCESSFULLY Ctrl-L into your existing Linux install.

Published by

Jim Salter

Mercenary sysadmin, open source advocate, and frotzer of the jim-jam.

17 thoughts on “Restoring Legacy Boot (Linux Boot) on a Chromebook”

  1. I think I have exactly this issue. Battery drained out completely and now I get 2 short beep when pressing Ctrl-L. The problem however is that ChromeOS was completely wiped out and replaced by a Linux distro. Is there a way to boot into ChromeOS from an USB stick or SD card in order to enable legacy boot again ? Or any other trick to re-enable legacy boot ? I’d like to recover the data from the SSD, so reinstalling ChromeOS over it is not really an option.

    Thanks in advance for any suggestion,

  2. Sorry Xavier, I don’t have any suggestion for you other than to open up the Chromebook, pull the SSD and recover data on another piece of hardware, then replace and reinstall. You MIGHT be able to do some kind of alternate boot, but if so, I don’t have any idea how. =\

    Might I suggest leaving ChromeOS intact next time? 🙂

  3. THANK YOU FOR THIS. I fell asleep last night with my chromebook Pixel unplugged and when I woke up this morning to start work, it CTRL-L just beeped at me. I was going nuts trying to figure it out. Ferris Bueller, you’re my hero.

  4. THANK YOU! Although I read this too late to avoid having to copy my data back from other computers at least I can re-install Linux now

  5. Is there any way to protect the operating system when the computer loses all power? From what I’ve seen when the computer loses all power it doesn’t let you boot into anything and you have to do the process all over again.

  6. There is a hardware screw inside the case which can be turned? removed? something to permanently enable legacy boot. I haven’t ever personally messed with it, so beyond pointing you in the right direction to Google, that’s as far as I can help. =)

  7. Thanks for responding, because I’ve found that no matter what whenever it loses power, it can’t even boot into the Chrome OS even when you left it installed. It still says missing or damaged. This probably differs based on the individual chromebook then. What a shame.

  8. I know this is far past the date this was intended, but I got a cheap C720 for 40$ and wanted to install custom but it wouldn’t let me, thanks for keeping this post up!

  9. I installed the ChromeOS Firmware Utility Script and enabled RW_LEGACY firmware. I also went into the developer console and enabled USB and legacy boot. So the problem is that when I hit ctrl+l at the developer boot screen, it takes me to a white screen that says “Alternate Firmware Menu”

  10. I have an acer cb3532 and I cant not get ctrl L to work. I even did upgrade bios mrcrhomebox and still the funtion in devloper mode ctrl L I get nothing, Screw has been remvored WP. Any suggestions thank you in advanced..

  11. Thanks for this. Ran into a situation where I lost legacy boot and got the ‘beep’ at Ctrl-L. Was going to run the again but then thought a search might be beneficial — and it was.

    NOTE: At the time of this post, running the statement prompts with a response to “Please use ‘dev_boot_altfw’ instead of ‘dev_boot_legacy’.

  12. You’ll never know how I struggled to accomplish the same objective in other ways. You solved my problem in almost effortless fashion. I know a lot more now but you got me home – literally. Thank you.

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