Install Fuchsia on a Chromebook

Supported Chromebooks

These Chromebooks are used regularly by developers and should be stable.

  • Google Pixelbook Go (atlas)

Formerly supported Chromebooks

These Chromebooks are supported on a best-effort basis, and are not regularly tested.

  • Google Pixelbook (eve)

Other ChromeOS devices

Other x86-based ChromeOS devices may or may not work. ARM-based ChromeOS devices will not work out of the box.

Prerequisites

Ensure that you have a chromebook-x64 build for Fuchsia.

  1. Complete the Download the Fuchsia source code guide.

  2. As part of Configure and Build Fuchsia, set your build configuration to use the following Chromebook product:

    fx set workstation_eng.chromebook-x64 --release

Update ChromeOS

If your Chromebook has never been booted, it is best to boot it normally to check for any critical updates, as follows:

  1. Boot the Chromebook normally. Opening the lid usually powers on the device. If this doesn't work, the power button is on the left side of the device, near the front of the wrist rest.
  2. Tap the "Let's go" button.
  3. Connect to a wired or wireless network.
  4. Accept the terms to proceed to the update check step.
  5. The device should check for updates, install any found.
  6. After rebooting from any updates, tap 'Browse as Guest' in the lower left corner.
  7. From the browser UI, go into "Settings->About Chrome OS" or "Help->About Chrome OS" and confirm the newly installed version.

Put your device into developer mode

  1. Power off the Chromebook.
  2. Go into Recovery Mode. Hold down Esc+Refresh (first and third buttons on the top row of the keyboard). Then press the Power button (bottom left side of the device).
  3. Start by disabling OS verification by pressing Ctrl+D. You should see "To turn OS verification OFF, press ENTER". Press Enter to confirm.
  4. When your device reboots, you'll get confirmation that OS verification is OFF. Press Ctrl+D again to enter Developer Mode.
  5. Wait for the device to re-configure itself, which will take several minutes. Initially it may not appear to be doing anything. Let the device sit for a minute or two. You will hear two loud <BEEP>s early in the process. The process is complete when you hear two more loud <BEEP>s.
  6. The device should reboot itself when the Developer Mode transition is complete. You can now jump to Step #2 in the "Boot from USB" section.

Boot from USB

  1. Boot into ChromeOS.
  2. You should see a screen that says "OS verification is OFF" and approximately 30 seconds later the boot will continue. Wait for the Welcome or Login screen to load. Ignore any link for "Enable debugging features".
  3. Press Ctrl+Alt+Refresh/F3 to enter a command shell. If pressing this key combination has no effect, try rebooting the Chromebook once more.
  4. Enter 'chronos' as the user with a blank password
  5. Enable USB booting by running sudo crossystem dev_boot_usb=1
  6. (optional) Default to USB booting by running sudo crossystem dev_default_boot=usb.
  7. Plug the USB drive into the Chromebook.
  8. Reboot by typing sudo reboot
  9. On the "OS verification is OFF" screen press Ctrl+U to bypass the timeout and boot from USB immediately. (See Tips and Tricks for other short circuit options)

The USB drive is only needed for booting when you want to re-pave or otherwise netboot the device.

If you didn't make USB booting the default (Step #6), you will need to press Ctrl+U at the grey 'warning OS-not verified' screen to boot from USB when you power on your device.

If the device tries to boot from USB, either because that is the default or you pressed Ctrl+U, and the device fails to boot from USB you'll hear a fairly loud <BEEP>.

Note that ChromeOS bootloader USB enumeration during boot has been observed to be slow. If you're having trouble booting from USB, it may be helpful to remove other USB devices until the device is through the bootloader and also avoid using a USB hub.

Tips and Tricks

By default the ChromeOS bootloader has a long timeout to allow you to press buttons. To shortcut this you can press Ctrl+D or Ctrl+U when on the grey screen that warns that the OS will not be verified. Ctrl+D will cause the device to skip the timeout and boot from its default source. Ctrl+U will skip the timeout and boot the device from USB.

Configuring boot source from Fuchsia

Fuchsia has an equivalent to crossystem called cros_nvtool. You can run cros_nvtool set dev_boot_default <usb|disk> to modify the default boot source of the system to USB or disk, respectively.

Going back to ChromeOS

To go back to ChromeOS you must modify the priority of the Fuchsia kernel partition to be lower than that of at least one of the two ChromeOS kernel partitions.

  1. Press Alt+Esc to get to a virtual console if not already on one
  2. Press Alt+Fullscreen to get to a terminal emulator on Fuchsia

  3. Find the disk that contains the KERN-A, KERN-B, and KERN-C partitions with the lsblk command. Below this is device 000, note how the device path of the kernel partitions is an extension of that device.

    $ lsblk
ID  SIZE TYPE             LABEL                FLAGS  DEVICE
000 232G                                              /dev/sys/platform/pci/00:1e.4/pci-sdhci/sdhci/sdmmc/block
001   5G data             STATE                       /dev/sys/platform/pci/00:1e.4/pci-sdhci/sdhci/sdmmc/block/part-000/block
002  16M cros kernel      KERN-A                      /dev/sys/platform/pci/00:1e.4/pci-sdhci/sdhci/sdmmc/block/part-001/block
003   4G cros rootfs      ROOT-A                      /dev/sys/platform/pci/00:1e.4/pci-sdhci/sdhci/sdmmc/block/part-002/block
004  16M cros kernel      KERN-B                      /dev/sys/platform/pci/00:1e.4/pci-sdhci/sdhci/sdmmc/block/part-003/block
005   4G cros rootfs      ROOT-B                      /dev/sys/platform/pci/00:1e.4/pci-sdhci/sdhci/sdmmc/block/part-004/block
006  64M cros kernel      KERN-C                      /dev/sys/platform/pci/00:1e.4/pci-sdhci/sdhci/sdmmc/block/part-005/block
007   4G cros rootfs      ROOT-C                      /dev/sys/platform/pci/00:1e.4/pci-sdhci/sdhci/sdmmc/block/part-006/block

  4. Use the gpt command to look at the device's (eg. 000) partition map.

    $ gpt dump /dev/class/block/000
blocksize=0x200 blocks=488554496
Partition table is valid
GPT contains usable blocks from 34 to 488554462 (inclusive)
Paritition 0: STATE
    Start: 478035968, End: 488521727 (10485760 blocks)
    id:   51E8D442-0419-2447-96E5-49CB60CF0B25
    type: EBD0A0A2-B9E5-4433-87C0-68B6B72699C7
    flags: 0x0000000000000000
Paritition 1: KERN-A
    Start: 20480, End: 53247 (32768 blocks)
    id:   054CD627-F23C-5C40-8035-C188FA57DE9C
    type: FE3A2A5D-4F32-41A7-B725-ACCC3285A309
    flags: priority=2 tries=0 successful=1
Paritition 2: ROOT-A
    Start: 8704000, End: 17092607 (8388608 blocks)
    id:   936E138F-1ACF-E242-9C5B-3667FAA3C10C
    type: 3CB8E202-3B7E-47DD-8A3C-7FF2A13CFCEC
    flags: 0x0000000000000000
Paritition 3: KERN-B
    Start: 53248, End: 86015 (32768 blocks)
    id:   A8667891-8209-8648-9D5E-63DC9B8D0CB3
    type: FE3A2A5D-4F32-41A7-B725-ACCC3285A309
    flags: priority=1 tries=0 successful=1
Paritition 4: ROOT-B
    Start: 315392, End: 8703999 (8388608 blocks)
    id:   8B5D7BB4-590B-E445-B596-1E7AA1BB501F
    type: 3CB8E202-3B7E-47DD-8A3C-7FF2A13CFCEC
    flags: 0x0000000000000000
Paritition 5: KERN-C
    Start: 17092608, End: 17223679 (131072 blocks)
    id:   C7D6B203-C18F-BC4D-9160-A09BA8970CE1
    type: FE3A2A5D-4F32-41A7-B725-ACCC3285A309
    flags: priority=3 tries=15 successful=1
Paritition 6: ROOT-C
    Start: 17223680, End: 25612287 (8388608 blocks)
    id:   769444A7-6E13-D74D-B583-C3A9CF0DE307
    type: 3CB8E202-3B7E-47DD-8A3C-7FF2A13CFCEC
    flags: 0x0000000000000000

  5. Note that KERN-A and KERN-B typically have ChromeOS kernels. The Zircon kernel appears as KERN-C as in the example above, or as ZIRCON-A instead in certain setups.

    To go to ChromeOS, lower the priority of KERN-C (or ZIRCON-A) by referencing the partition index on the disk that has that partition. E.g.:

    $ gpt edit_cros 5 -P 0 /dev/class/block/000

  6. Reboot.

  7. When the ChromeOS bootloader appears, press Space to re-enable OS Verification. Your device will reboot. This time, it will display a message with "Your system is repairing itself. Please wait". This operation will take around 5 minutes, after which the Chromebook will reboot one final time. The device will reboot to the initial setup screen.

To go back to the Fuchsia kernel, just re-pave the device.