Cannot boot Linux from USB using Ctrl+L or Ctrl+U, RW_Legacy firmware missing? Running ARM-based processor

System Details

  • Device: Notebook, Samsung XE303C12 (ARM-based Exynos 5250)
  • OS: ChromeOS
  • Firmware Type: Stock
  • Firmware Version: Google_Snow.2695.117.0
  • Internal storage type: eMMC

Summary of the Issue

I recently came into an oldschool Chromebook (Model XE303C12) and wanted to install Kali Linux Purple on it to make it usable for my purposes. I successfully went through all the typical steps:

  • Powerwash

  • Disable OS Verification

  • Enable Developer Mode

  • Activate USB Boot Support with:

    • crossystem dev_boot_usb=1
    • crossystem dev_boot_legacy=1
  • Restart, insert USB w/ Linux installation media

It’s at this point that Ctrl+U doesn’t work-- the screen flickers briefly and two error beeps are returned-- and Ctrl+L does nothing at all. Having read through many forums at this point, I know that Ctrl+U is only useful for booting ChromeOS or ChromiumOS on an Intel processor, so this is what I assume the problem is. Based on MrChromium’s info in this post, it seems most likely that this model’s image doesn’t come packaged with RW_Legacy firmware.

I tried downloading this firmware using MrChromium’s Firmware Utility Script, but was unable to as, according to the error returned, “This script only supports 64-bit OS on x86_64-based devices. ARM devices are unsupported.”

So, I seem to be at a dead end. Am I missing something, or is there a technical limitation to this model that prevents me from installing any other OS?

Steps to Reproduce

  1. Flash Kali Linux Purple to a USB drive via Rufus

  2. Powerwash ChromeOS

  3. Launch Recovery Mode with ESC + REL + PWR

  4. Disable OS Verification and enable Developer Mode with Ctrl+D

  5. Activate USB Boot Support with:

    • crossystem dev_boot_usb=1
    • crossystem dev_boot_legacy=1
  6. Insert USB, restart, attempt Ctrl+U; then Ctrl+L

  7. Attempt to run MrChromium Firmware Utility Script in ChromeOS terminal

Expected Behavior

Using Ctrl+L opens SeaBIOS splash screen, then ESC to open boot menu

that is NOT the expected behavior on an ARM device. SeaBIOS does not exist. legacy boot mode does not exist. CTRL+U to boot Linux (via a ChromeOS signed kernel) is the only option for ARM devices. 2 beeps means your don’t have a bootable image on USB.

Tysm! I barely know what I’m doing, I’m mostly just inferring based on posts I’ve read. I’ll do some more research how kernels work (I have no clue what that is), but do you have any recommendations for what to try? I just downloaded the Linux iso and added it to the USB with Rufus.

Linux distros meant for ARM architecture devices will usually have instructions on how to prepare things for ChromeOS devices.