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Installing "real" linux on a Google Pixelbook

This repo documents the process of replacing ChromeOS on a stock Google Pixelbook with a "real" linux distribution. It also contains an automated configuration script that will fix things that are broken in a stock install, like sound, display and keyboard backlights, touchpad sensitivity, etc.

A very nice feature of the method described here is that it does not require taking the machine apart! Previous resources I've come across have instructed people to disassemble their Pixelbook and disconnect the battery cable to disable the firmware write protect. This method avoids the need for that, although you will need to spend ~$20 USD on a special USB cable. See the installation instructions for details.

The automated configuration targets Ubuntu 19.04 (Disco Dingo), although it's likely that the basic techniques used will work for any distribution. I initially tried using Fedora Workstation 29, but ran into an issue where the system would crash immediately after resuming from suspend. I assumed this was due to my tweaks, but decided to give another distro a shot and found Ubuntu worked without issue. As a nice bonus, bluetooth works out of the box on Ubuntu, whereas Fedora required some fiddling post-install.

Why

I absolutely love the Pixelbook hardware. The keyboard is better than any laptop keyboard I've ever used, including the sorely missed pre-butterfly MacBook Pro keyboards. I also really like the 3:2 screen aspect ratio, the beautiful chassis and design, etc.

I bought the machine in the first place because I was excited about Crostini, which is a quite clever means of running linux inside a container (which is itself inside a virtual machine) on ChromeOS.

While I immensely respect what the Chromium team is doing with Crostini, it's just not workable for me as a primary workstation in its current state. When I discovered that you could install a real UEFI firmware and install "real linux", I decided to give it a try, and the result was close enough to great that I decided to see if I could take it the rest of the way there.

Current Status

Here's what's working at the moment:

Feature Stock Ubuntu After modifications
WiFi Working Working
Bluetooth Working Working
Touchscreen Working Working
Suspend Working Working
Touchpad Working, but awkward Working (tweaked to feel nice)
Display backlight Always on at 100% Adjustable using standard controls
Sound Broken Working, see details
Keyboard backlight Broken Working (using helper script to adjust)
Swap Working zram swap only see details
Hibernate Untested Unsupported, see details

Known limitations:

  • It seems like dual-boot setups (and possibly other installs that don't use full UEFI firmware) fail to extract files from the recovery image.
  • Running the install script while booting from an external USB has not been verified to work, and might suffer from a similar issue. Please update this issue if you're able to test it out.

Please open an issue if you find other problems.

Installation

There are three main phases involved in getting from a stock Pixelbook to a really nice Ubuntu install:

  1. Flash UEFI firmware
  2. Install stock Ubuntu
  3. Run the automatic configuration script

Once the install is complete, you'll probably want to read the post-install notes to learn about the quirks that were added.

Requirements

Before you start, you'll need to have the following things to complete the process:

  • A SuzyQable CCD Debugging cable, ~$15 USD + shipping
  • A USB-A to USB-C adapter
  • 2 USB flash drives with USB-C connectors or adapters. Anything over 2GB should be fine
  • A willingness to accept that this is a potentially destructive process that may render your expensive Pixelbook inoperable or otherwise busted. See the scary disclaimer below.

Disclaimer

The process described in this document could cause irreversible damage to your expensive laptop, and you should prepare yourself mentally and emotionally for that outcome before you begin.

I accept absolutely no responsibility for the consequences of anyone choosing to follow or ignore any of the instructions in this document, and make no guarantees about the quality or effectiveness of the software in this repo.

That said, the chances of damage are quite low, and you're (presumably) all adults capable of weighing your own risk/reward thresholds. If you get into a jam, raise an issue in this repo and I'll try to help as time allows.

Flashing UEFI Firmware

To boot operating systems other than ChromeOS, we need to replace the Pixelbook firmware with a more standard UEFI firmare implementation.

Luckily, the indefatigable MrChromebox has developed a full replacement firmware for many ChromeOS devices, including the Pixelbook.

However, before we can flash the firmware, we need to disable a security feature called Firmware Write Protect.

Disabling Write Protect

The Pixelbook (like all ChromeOS devices), ships with the firmware Write Protect setting enabled, which prevents us from mucking about with the firmware.

The Write Protect setting is enforced by an embedded controller called cr50.

There are two ways to disable the Write Protect setting: disassemble the Pixelbook and remove the battery cable, or buy a special debugging cable for ~$15 USD.

I'm guessing that most people reading this would rather do the latter, so this guide assumes you've already bought the cable.

Prepare the Pixelbook for closed-case-debugging

Before we can connect our special debug cable, we need to enable Closed Case Debugging (ccd) mode on the Pixelbook.

First, enable Developer Mode on your Pixelbook.

Once you're running in Developer mode, open a crosh shell by pressing Ctrl+Alt+T and then type shell at the prompt.

We'll be using the gsctool command to "open" the CCD mode.

I made an asciinema cast to walk through opening CCD mode that might be helpful:

asciicast

If you'd rather not sit through that, the quick version is:

# at the crosh shell on the Pixelbook, in developer mode:
gsctool -a --ccd_open

This will take several minutes, and you have to sit by the Pixelbook the whole time, since it will periodically ask you to press the "PP" button, meaning the Pixelbook power button. Tap the button when asked, and eventually the Pixelbook will abruptly power down.

Important: when the Pixelbook reboots, it will take itself out of Developer Mode!

Once it's done resetting back to normal mode, turn off the machine and reboot while holding Esc and Refresh (the key with the circular arrow icon). At the recovery boot prompt, press Ctrl-D to re-enable Developer mode.

When you're back in Developer mode, open a crosh shell again and enter:

gsctool -a --ccd_info

In the status report that follows, you should see State: Open. This means the Pixelbook is ready to accept CCD commands using the special cable.

Use the CCD cable to connect to the cr50 console

Okay, it's special cable time!

We'll be using the Pixelbook to debug itself, so plug the USB-A end of the cable into the USB-A to USB-C adapter and plug the adapter into the right USB-C port on the Pixelbook. The USB-C end of the CCD cable must be plugged into the left USB-C port.

Now check to see if new ttyUSB devices show up in /dev:

ls /dev/tty*

Important Note: If you don't see any /dev/ttyUSB devices showing up when you plug in the cable, flip the USB-C end of the CCD cable over! Unlike most USB-C cables, the pins on the CCD cable are not bidirectional.

Now we can send commands to the cr50 console at /dev/ttyUSB0:

sudo su -
echo "wp false" > /dev/ttyUSB0
echo "wp false atboot" > /dev/ttyUSB0
echo "ccd set OverrideWP Always" > /dev/ttyUSB0
echo "ccd set FlashAP Always" > /dev/ttyUSB0

That will disable write protect, and also change the capabilities to allow overriding the write protect setting and flashing the firmware even if the CCD is locked. This makes it possible to recover if anything goes wrong during flashing and makes it easier to restore the original firmawre.

Once you've issued the commands above, check the status with gsctool -a -I - you should see that the OverrideWP and FlashAP capabilities have changed from the default of IfOpened to Always.

Now run crossystem wpsw_cur to verify the current write protect setting.

Alright, now that you've disabled Write Protect, you can flash the firmware!

You won't be needing the CCD cable anymore, so feel free to disconnect it and put it away.

Flashing the firmware

We'll be using MrChromebox's firmware utility script to flash the UEFI firmware.

I made an ascii-cast for this as well, if you want to follow along:

asciicast

On the Pixelbook, open a crosh shell and enter:

cd; curl -LO https://mrchromebox.tech/firmware-util.sh && sudo bash firmware-util.sh

At the prompt, enter the number for "Install / Update Full ROM Firmware" and follow the prompts.

Important: Make a backup when prompted! This is why the requirements section told you to get 2 USB flash drives. Seriously, USB drives are dirt cheap; don't skip this step.

After a couple minutes, you should be all set! Say goodbye to ChromeOS; by flashing this firmware you lose the ability to boot into ChromeOS, and you'll need to restore your firmware from the backup if you want to go back.

Installing stock Ubuntu

Now that you're running a standard UEFI firmware, installing Ubuntu works just like on a standard laptop.

Download an ISO image for Ubuntu Desktop 19.04 - other versions might work, but I make absolutely no guarantees, and I won't be able to help you out if things are broken. Note that I might not be able to help regardless, but if you run into issues and you're not running the same distro as me, chances are much higher I'll shrug my shoulders and ineffectually wish you good luck, rather than offering any useful help.

Write the image to disk using whatever method seems best - this is pretty Google-friendly & depends on your setup, so I'll let you figure this bit out.

Now attach the drive to your Pixelbook and boot.

You may need to press Esc when booting to bring up the UEFI menu. From there, select "Boot Manager" and choose the USB device as the boot target.

You should now boot into the Ubuntu installer.

Note: due to wonky touchpad support in the default Ubuntu kernel, the touchpad might not work unless you wiggle the cursor when the system is booting. If your mouse cursor isn't working in the installer (or in the stock Ubuntu install afterward), try rebooting and continuously moving your finger around on the trackpad while the system starts.

Now you can go ahead and install Ubuntu using the standard method. The installer defaults should all work fine, although I recommend encrypting your disk, or at least enabling LVM for volume management.

Note that you'll have to erase the entire Pixelbook disk; since we can't boot back to ChromeOS anyway, this is no big loss.

After a little while, you should get a message that your install is complete, and you can remove the USB drive and reboot. When the system comes back up, you can run my install script to finish the setup.

Running the install script

Boot into your new fresh Ubuntu install and log in.

Open a terminal and run the following to install some bare-minimum requirements:

sudo apt install -y git python ansible

# replace the values below with your info!
git config --global user.name "Your Name"
git config --global user.email "your@email.com"

Now clone this repository:

git clone https://github.com/yusefnapora/pixelbook-linux

Enter the pixelbook-linux directory and run the install script:

cd pixelbook-linux
./run-ansible.sh

The script will ask you a couple of questions, after which it will spend ~20 minutes downloading and installing stuff. If you don't know how to answer the questions, just accept the defaults.

If everything goes well, the script should complete successfully, and you can now reboot:

sudo reboot

When the system comes back up, you should boot into the ChromiumOS-flavored kernel. You'll be able to tell that you're using the correct kernel by the display backlight becoming very dim just after boot. Once the GUI is up, you can adjust the backlight using the Gnome slider in the upper-right corner.

After the install

Here's some info about the scripts and other customizations I added. If you're interested in the details or for more context, see the implementation details doc.

Switching audio outputs & inputs

Support for the audio hardware relies on a component called cras, short for the Chromium Audio Server. The install script will build cras for vanilla Linux and add configuration for ALSA and Pulseaudio to make things work, however, there's no way to switch between headphone and speaker outputs using the standard GUI controls.

To work around this, I wrote a little python script called eve-audio-ctl.py that wraps the cras_test_client program that gets built alongside cras.

Running the script with no arguments will show some status output:

$ eve-audio-ctl.py
Output Devices:
	hdmi2
	hdmi1
active:	headphone
	speaker

Input Devices:
	mic
active:	internal_mic
	post_dsp_loopback
	post_mix_pre_dsp_loopback

To switch outputs, use eve-audio-ctl.py -o <output-name>, e.g. eve-audio-ctl.py -o speaker.

Switching inputs works much the same, but with -i instead of -o: eve-audio-ctl.py -i internal_mic

Since it's nice to automatically switch to headphones when they're plugged in, there's also a -j flag that will listen for plug and unplug events. When headphones are plugged in, it will automatically switch the audio output to the headphones, and when they're removed it will switch to speakers. Likewise, if you plug in a headset with a microphone, it will switch the input to mic and switch back to internal_mic when removed.

The script needs to be running to detect the events, so I also added a systemd service that runs the script at boot. If you'd rather not have the script running, you can disable it with: sudo systemctl disable eve-headphone-jack-listener.

Unfortunately the script isn't smart enough to detect whether the headphones are plugged in when the system first starts - it can only detect changes, not the current state. So at boot the output will always default to speakers if you're running the systemd service.

Note that currently the volume won't be changed when you switch devices, so if you're playing audio through headphones and suddenly switch to speakers, it might be louder than you expect.

Keyboard backlight

You can control the brightness of the keyboard backlight by running the eve-keyboard-brightness.sh script.

The script can either set the brightness to an absolute value between 1 and 100, e.g.:

# set brightness to 50%
eve-keyboard-brightness.sh 50

# turn backlight off:
eve-keyboard-brightness.sh 0

Or, you can adjust the current brightness by prefixing a number with either + or -:

# increase brightness by 10:
eve-keyboard-brightness.sh +10

# decrease by 20:
eve-keyboard-brightness.sh -20

The latter form is especially handy when bound to a keyboard shortcut.

Remapping keyboard keys

If you decide after the install that you want to change the keyboard mapping, you can edit /lib/udev/hwdb.d/61-eve-keyboard.hwdb as root and change the keycodes on the right-hand of the equal signs for the keys you want to change.

A list of valid keycodes can be found in ansible/keycodes.txt.

After changing the file, you'll need to reload your hwdb config:

sudo udevadm hwdb --update
sudo udevadm trigger

Cleaning up installation files

The install process will dump some files into /opt/eve-linux-setup that can be safely removed afterward to reclaim ~1.5 GB of space. If you're not interested in fiddling around with the installer setup, it's a good idea to remove that directory:

sudo rm -rf /opt/eve-linux-setup

Do NOT remove /opt/google - it contains some files needed by the audio setup.

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