This page contains information about the Chromebook Pixel (2015) that is interesting and/or useful to software developers. For general information about getting started with developing on Chromium OS (the open-source version of the software on the Chrome Notebook), see the Chromium OS Developer Guide.
Caution: Modifications you make to the system are not supported by Google, may cause hardware, software or security issues and may void warranty.
An unrelated note: Holding just Refresh and poking the Power button hard-resets the machine without entering Recovery. That‘s occasionally useful, but use it with care - it doesn’t sync the disk or shut down politely, so there's a nonzero chance of trashing the contents of your stateful partition.
Enabling Developer mode is the first step to tinkering with your Chromebook. With Developer mode enabled you can do things like poke around on a command shell (as root if you want), install Chromium OS, or try other OS's. Note that Developer mode turns off some security features like verified boot and disabling the shell access. If you want to browse in a safer, more secure way, leave Developer mode turned OFF. Note: Switching between Developer and Normal (non-developer) modes will remove user accounts and their associated information from your Chromebook.
On this device, both the recovery button and the dev-switch have been virtualized.
To invoke Recovery mode, you hold down the ESC and Refresh (F3) keys and press the Power button.
To enter Dev-mode, you first invoke Recovery, and at the Recovery screen press Ctrl-D (there's no prompt - you have to know to do it). It will ask you to confirm, then reboot into dev-mode.
Dev-mode works the same as always: It will show the scary boot screen and you need to press Ctrl-D or wait 30 seconds to continue booting.
By default, USB booting is disabled. Once you are in Dev-mode and have a root shell, you can run:
sudo crossystem dev_boot_usb=1
and reboot once to boot from USB drives with Ctrl-U.
To leave Dev-mode and go back to normal mode, just follow the instructions at the scary boot screen. It will prompt you to confirm.
Make sure you don't have your Pixel stacked on top of another Pixel (or possibly other laptop), as the sensor for detecting the screen closed will activate from the magnet in the device below, preventing booting.
The Pixel firmware saves an event log to read-write flash that can be useful for troubleshooting your device.
The event log is based on SMBIOS Type 15 Event Log format, but uses a number of OEM events to provide additional information. The mosys application that is part of Chromium OS can be used to read and decode the log by running mosys eventlog list as the root user in Chrome OS if the device is in developer mode or opening chrome://system and looking for the eventlog entry in normal/verified mode.
This device uses coreboot and Depthcharge as a payload to boot the system. See here for a detailed description of the Samus FMAP / firmware flash layout. You can find the source in the Chromium OS coreboot git tree and the Chromium OS depthcharge git tree in the firmware-samus-6300.B branches.
WARNING: Opening the case and fiddling with the stuff inside could easily brick your system and make it unrecoverable. DO NOT ATTEMPT if you are not familiar with this process. Really, just don't.
It's the screw (plus a golden washer) between the USB-A connector and the left speaker.