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Use this file to discover all available pages before exploring further.

primemixxx supports two operating modes on the same hardware: MIXXX mode (SD card present, TKGL boot hook installed) and Engine OS mode (SD card removed, or Engine OS explicitly started). You can switch between them at runtime over SSH without rebooting, and switch at boot time simply by inserting or removing the SD card.

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Two Modes

ModeHow to ActivateWhat Runs
MIXXX modeSD card inserted at power-on (boot-time), or switch-to-mixxx (runtime)TKGL bootstrap → mixxx-app.service → MIXXX
Engine OS modeSD card removed at power-on (boot-time), or switch-to-engine (runtime)Stock engine.service → Engine DJ

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One-Time Install: The TKGL Boot Hook

Before the SD card can auto-launch MIXXX at boot, you need to install the TKGL boot hook to the device’s internal eMMC. This is a one-time step run from the SD card itself.
1

Insert SD card and SSH in

ssh root@192.168.42.1   # USB Ethernet (preferred)
# or
ssh root@primego.local  # WiFi
# Password: denonprime4
2

Run the install script

sh /media/TKGL_BOOTSTRAP/tkgl_bootstrap_DenonPrimeGO/install-device.sh
The installer performs these steps automatically:
  1. Remounts the rootfs read-write
  2. Copies tkgl-bootstrap-stub.sh to /data/tkgl-bootstrap-launcher
  3. Backs up /etc/systemd/system/engine.service → engine.service.orig
  4. Installs the TKGL stub as the new engine.service
  5. Runs systemctl daemon-reload && systemctl enable engine.service
After the core install, the script interactively offers optional services:
PromptServiceEffect
USB Ethernet gadgetusb-gadget-eth.serviceSSH via USB-C cable at 192.168.42.1
Power button monitorpowerbutton-monitor.serviceGraceful shutdown on power button press
mDNS fixfix-mdns.serviceAdvertises primego.local instead of buildroot.local
WiFi powersave off99-wifi-power-save.rulesPrevents SSH dropouts over WiFi
3

Reboot

reboot
After reboot, the device detects the SD card and automatically launches MIXXX — no SSH needed.

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Uninstalling the Boot Hook

To fully remove TKGL and return to stock Engine OS: 
sh /media/TKGL_BOOTSTRAP/tkgl_bootstrap_DenonPrimeGO/uninstall-device.sh
The uninstall script is the inverse of install-device.sh. It stops MIXXX, removes the TKGL stub, restores engine.service.orig, and interactively asks which optional services to keep or remove.

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Runtime Switching

Once the boot hook is installed, you can toggle between MIXXX and Engine OS over SSH at any time without rebooting.
Use USB Ethernet (192.168.42.1) for reliable SSH access. WiFi connections drop after ~30 seconds of silence — if you are switching modes or monitoring services over WiFi, keep a keepalive ping running: ping -i 25 <device-ip> > /dev/null &

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Switch to MIXXX

ssh root@192.168.42.1 switch-to-mixxx
What the script does internally: 
mount -o remount,rw / 2>/dev/null || true
systemctl stop engine.service
chmod +x /media/TKGL_BOOTSTRAP/tkgl_bootstrap_DenonPrimeGO/mixxx-bundle/mixxx_launcher.sh
systemctl start mixxx.service
systemctl start powerbutton-monitor.service

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Switch to Engine OS

ssh root@192.168.42.1 switch-to-engine
What the script does internally: 
systemctl stop mixxx.service
systemctl stop powerbutton-monitor.service
systemctl start engine.service

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Boot-Time Switching

You do not need SSH for boot-time switching:
ActionEffect
Insert SD card before power-onTKGL hook detects the card, auto-launches MIXXX
Remove SD card before power-onTKGL hook finds no card, falls back to original engine.service.orig
The fallback is unconditional — stock Engine OS boots without any SD card present, just as it did before TKGL was installed.

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Restarting MIXXX Correctly

MIXXX runs as a transient systemd unit (mixxx-app.service) created by the TKGL module via: 
systemd-run --unit=mixxx-app -- /data/mixxx/mixxx
The TKGL module (tkgl_mod_mixxx.sh) checks whether mixxx-app.service is already active before launching. If it is active — even with a dead PID — TKGL skips relaunch entirely. This means standard restart commands do not work correctly. The only correct restart sequence is: 
# 1. Stop the transient unit first (makes it inactive)
systemctl stop mixxx-app.service

# 2. Trigger TKGL to recreate it
systemctl restart engine.service
Do not use these methods to restart MIXXX — they silently fail:
systemctl restart mixxx-app.service   # TKGL sees the unit still "active", skips relaunch
pkill mixxx                            # PID dies but transient unit stays "active", TKGL skips
kill -9 <pid>                          # Same problem as pkill
In all three cases, TKGL’s idempotency guard sees an active mixxx-app.service and exits without relaunching MIXXX. The display goes black with no error.

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mixxx-app.service Masking

mixxx-app.service must not be masked. If it is masked (symlinked to /dev/null), systemd-run --unit=mixxx-app fails silently and MIXXX will not start at boot.To check and fix masking:
# Check if masked
systemctl status mixxx-app.service

# Unmask if needed
systemctl unmask mixxx-app.service

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Systemd Service Relationships

engine.service (TKGL stub)
  └─ TKGL bootstrap launcher (/data/tkgl-bootstrap-launcher)
       └─ mod_mixxx module (tkgl_mod_mixxx.sh)
            └─ systemd-run --unit=mixxx-app
                 └─ mixxx-app.service  ← transient unit
                      └─ /media/TKGL_BOOTSTRAP/tkgl_bootstrap_DenonPrimeGO/mixxx-bundle/mixxx_launcher.sh
                           └─ MIXXX binary
The key property of this chain: if anything in the TKGL layer fails — missing SD card, corrupt launcher, wrong permissions — you can always remove the SD card and reboot to drop back to stock Engine OS via engine.service.orig.

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