Single Application ROOTFS Creation

This document outlines the steps to customize a ROOTFS based on Bianbu Minimal for running a single application using the labwc display server.

Environmental requirements and basic ROOTFS creation

To prepare the host environment and generate a basic ROOTFS, refer to Bianbu 2.1/2.2 ROOTFS Creation. Once the essential and common configurations are complete, proceed with the Labwc-specific setup below.

Labwc Configuration

When a desktop login manager is not required, you can directly launch Labwc to provide a Wayland display environment. The process is as follows:

1. Install labwc
2. Configure getty@tty1.service to automatically log in to the specified user when the system starts
3. Configure .bashrc or .zshrc in the user directory to start start Labwc upon login
4. Configure the autostart file in the Labwc configuration directory to start the application automatically

Install labwc

Run the following commands to update and install labwc in the chroot environment:

chroot $TARGET_ROOTFS /bin/bash -c "apt-get update"
chroot $TARGET_ROOTFS /bin/bash -c "DEBIAN_FRONTEND=noninteractive apt-get -y --allow-downgrades upgrade"
chroot $TARGET_ROOTFS /bin/bash -c "DEBIAN_FRONTEND=noninteractive apt-get -y --allow-downgrades install labwc"

Configure getty@tty1.service

By modifying the configuration of getty@tty1.service, you can enable automatic login for the specified user at system startup. First, update the ExecStart setting of the service:

chroot $TARGET_ROOTFS /bin/bash -c "mkdir -p /usr/lib/systemd/system/getty@tty1.service.d"
chroot $TARGET_ROOTFS /bin/bash -c "cat > /usr/lib/systemd/system/getty@tty1.service.d/override.conf <<'EOF'
[Service]
ExecStart=
ExecStart=-/sbin/agetty --noclear --autologin root %I \$TERM
EOF"

Configure .bashrc to automatically start Labwc

Modify the shell configuration file of the root user (the default shell is bash) to start Labwc automatically after login.

Append the Labwc startup command at the end of /root/.bashrc, and specify the configuration directory as /root/.config/labwc:

chroot "$TARGET_ROOTFS" /bin/bash -c "echo 'labwc -C /root/.config/labwc' >> /root/.bashrc"

Configure autostart

Take glmark2-es2-wayland as an example of an application to start automatically.

First, install glmark2-es2-wayland:

chroot $TARGET_ROOTFS /bin/bash -c "DEBIAN_FRONTEND=noninteractive apt-get -y --allow-downgrades install glmark2-es2-wayland"

Then create or modify the /root/.config/labwc/autostart file:

chroot "$TARGET_ROOTFS" /bin/bash -c "mkdir -p /root/.config/labwc"
chroot "$TARGET_ROOTFS" /bin/bash -c "touch /root/.config/labwc/autostart"
chroot "$TARGET_ROOTFS" /bin/bash -c "printf 'glmark2-es2-wayland >/dev/null 2>&1 &\n' > /root/.config/labwc/autostart"

To set a wallpaper when Labwc starts, place the wallpaper file under the system directory in rootfs (e.g., /usr/share/wallpapers/wallpaper.png), and then modify the autostart file. The example below uses a wallpaper from the bianbu-wallpapers deb package:

chroot "$TARGET_ROOTFS" /bin/bash -c "DEBIAN_FRONTEND=noninteractive apt-get -y --allow-downgrades install bianbu-wallpapers swaybg"
chroot "$TARGET_ROOTFS" /bin/bash -c "printf 'swaybg -m fill -i /usr/share/backgrounds/SolidIsland-2.png >/dev/null 2>&1 &\n' >> /root/.config/labwc/autostart"

Tip: After all packages are installed, run the following command to clean the cache and reduce the final firmware size:

chroot $TARGET_ROOTFS /bin/bash -c "DEBIAN_FRONTEND=noninteractive apt-get clean"

Configure rc.xml

rc.xml is the core configuration file for Labwc. It is used to define behaviors, keyboard shortcuts, themes, window rules, and more. For details, refer to the official documentation: https://github.com/labwc/labwc/blob/master/docs/rc.xml.all.

Below is a basic example of /root/.config/labwc/rc.xml that maximizes the glmark2-es2-wayland window upon launch:

chroot "$TARGET_ROOTFS" /bin/bash -c "mkdir -p /root/.config/labwc"
chroot "$TARGET_ROOTFS" /bin/bash -c "cat > /root/.config/labwc/rc.xml <<'EOF'
<?xml version=\"1.0\"?>
<labwc_config>
  <windowRules>
    <windowRule identifier=\"glmark2-es2-wayland\" matchOnce=\"true\">
      <skipTaskbar>yes</skipTaskbar>
      <action name=\"ToggleMaximize\" />
      <action name=\"ToggleAlwaysOnTop\" />
    </windowRule>
  </windowRules>
</labwc_config>
EOF"

After completing the above configuration, the system can automatically log in to the root user and start glmark2-es2-wayland when it starts.

Generate Partition Images

See the corresponding section in bianbu 2.1/2.2 ROOTFS creation.

Create Firmware

See Firmware Creation Guide.