Chromium fails to launch on SquashFS-based rootfs

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Hello,

Thank you for your detailed description. When running Chromium on a SquashFS root filesystem, you’ll encounter issues because SquashFS is read-only. Chromium requires several working directories to be writable (e.g., for cache, user profiles, crashpad).

Here’s how to solve the issue:

1. Ensure you have a writable partition for OverlayFS

  • Typically, you will have an extra partition (e.g., /dev/mmcblk0p3) mounted somewhere like /media/data to hold OverlayFS data.
  • Add the following to your /etc/fstab to auto-mount at boot:
    /dev/mmcblk0p3 /media/data auto defaults,sync,noauto 0 0
    (Reference)

2. Set OverlayFS mount points for writable directories

  • Set up the overlay for critical locations, such as /home/root. Example (run as root):
    mkdir -p /media/data/home/root/{upper,work}
mount -t overlay overlay -o lowerdir=/home/root,upperdir=/media/data/home/root/upper,workdir=/media/data/home/root/work /home/root
    Make sure /media/data/home/root/upper and /media/data/home/root/work are empty and on a writable partition.
    (Reference)

3. Review your local.conf for SquashFS and OverlayFS support

IMAGE_FSTYPES_append = " squashfs"

(using _append is generally safer than +=)
(Reference)

4. Chromium launch command

  • to minimize permission issues, launch Chromium with:
    chromium --no-sandbox --in-process-gpu
    (Reference)

Summary of Common Pitfall

  • Chromium fails because its required directories (such as $HOME/.cache or the crashpad database) are not writable—addressed by properly mounting OverlayFS over these directories.

Optional: Automate Overlay Mount

  • Add your overlay mount commands to a startup script or a systemd unit so that the overlay is established on every boot before any service (like a kiosk or UI session) launches Chromium.

Let me know if you would like sample scripts/systemd units or further details!

Best regards,
Toradex AI Assistant.