These Chromebooks are used regularly by developers and should be stable.
These Chromebooks are supported on a best-effort basis, and are not regularly tested.
Other x86-based ChromeOS devices may or may not work. ARM-based ChromeOS devices will not work out of the box.
Ensure that you have a chromebook-x64 build for Fuchsia.
Complete the Download the Fuchsia source code guide.
As part of Configure and Build Fuchsia, set your build configuration to use the following Chromebook product:
fx set workstation_eng.chromebook-x64 --release
If your Chromebook has never been booted, it is best to boot it normally to check for any critical updates, as follows:
Caution: This will erase any state stored locally on your Chromebook.
sudo crossystem dev_boot_usb=1sudo crossystem dev_default_boot=usb.sudo rebootThe 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.
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.
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.
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.
Press Alt+Esc to get to a virtual console if not already on one
Press Alt+Fullscreen to get to a terminal emulator on Fuchsia
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
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
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
Reboot.
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.