Samsung Chromebook Plus

These instructions are written for installing to a USB drive with the sda device, assuming no other USB drives are plugged in. For an SD card, click here to magically adjust the instructions for the mmcblk1 device that an SD card will register as.

1. Get a root shell as described in the previous section.
2. Since ChromeOS will automatically mount any partitions it finds, unmount everything now:

   umount /dev/sda*

3. Start fdisk to create a GPT partition table:

   fdisk /dev/sda

4. At the fdisk prompt:
   1. Type g. This will create a new empty GPT partition table.
   2. Write the partition table and exit by typing w.
5. Partition the micro SD card:

   cgpt create /dev/sda
   cgpt add -i 1 -t kernel -b 8192 -s 65536 -l Kernel -S 1 -T 5 -P 10 /dev/sda

6. To create the rootfs partition, we first need to calculate how big to make the partition using information from cgpt show. Look for the number under the start column for Sec GPT table which is 15633375 in this example:

   localhost / # cgpt show /dev/sda
          start        size    part  contents
              0           1          PMBR
              1           1          Pri GPT header
           8192       65536      1   Label: "Kernel"
                                     Type: ChromeOS kernel
                                     UUID: E3DA8325-83E1-2C43-BA9D-8B29EFFA5BC4
                                     Attr: priority=10 tries=5 successful=1
   
       15633375          32          Sec GPT table
       15633407           1          Sec GPT header

7. Replace the xxxxx string in the following command with that number to create the root partition:

   cgpt add -i 2 -t data -b 73728 -s `expr xxxxx - 73728` -l Root /dev/sda

8. Tell the system to refresh what it knows about the disk partitions:

   partx -a /dev/sda

9. Format the root partition:

   mkfs.ext4 /dev/sda2

10. Download and extract rootfs tarball:

    cd /tmp
    curl -LO http://os.archlinuxarm.org/os/ArchLinuxARM-aarch64-chromebook-latest.tar.gz
    mkdir root
    mount /dev/sda2 root
    tar -xf ArchLinuxARM-aarch64-chromebook-latest.tar.gz -C root

11. Flash the kernel to the kernel partition:

    dd if=root/boot/vmlinux.kpart of=/dev/sda1

12. Unmount the root partition:

    umount root
    sync

13. Reboot the computer.
14. At the splash screen, instead of pressing Ctrl-D to go to ChromeOS, press Ctrl-U to boot to the external drive.
15. After logging in as root (password is "root"), you can connect to a wireless network by running:

    wifi-menu

16. Initialize the pacman keyring and populate the Arch Linux ARM package signing keys:

    pacman-key --init
    pacman-key --populate archlinuxarm

Xorg

• The Mali T860MP4 GPU is not supported at this time. Therefore, no particular Xorg drivers are needed. The built in modesetting driver will correctly detect the display.
• xf86-input-libinput is preferred over evdev and synaptics for the best experience with the touchpad and touchscreen.

Audio

Use alsaucm (part of the alsa-utils package) to set up the sound card:

ALSA_CONFIG_UCM=/opt/alsa/ucm alsaucm -c rk3399-gru-sound set _verb HiFi

Note that the port will display as "Headphones" despite using the speakers. When paired with pulseaudio and pulseaudio-alsa, be aware that the full volume range is addressed through levels 0-9 of the Master volume control. Levels 10-100 provide no additional gain.

If using pulseaudio, the following can be placed in your ~/.config/pulse/default.pa file to create a loopback device that fixes the volume levels, so that 0-100% in a desktop environment's volume bar will correspond to the audio level heard in the spaker.

.include /etc/pulse/default.pa
  
load-module module-null-sink sink_name=corrected_speakers sink_properties=device.description=corrected_speakers

load-module module-loopback source=corrected_speakers.monitor sink=alsa_output.platform-sound.stereo-fallback remix=false

set-sink-volume alsa_output.platform-sound.stereo-fallback 6553

set-default-sink corrected_speakers