System

Q1: The system is stuck at the logo screen and does not enter the desktop?¶

Have you flashed the standard image from the cloud storage? Try a complete power‑off and reboot a few times. Do not place the antenna on top of the board, as it may cause interference or short circuits and lead to boot issues. Ubuntu systems take longer to boot on the first start — please wait a few minutes. If the issue persists, connect the debug serial port to capture logs.
On the first boot, Ubuntu systems need to automatically expand the root filesystem partition (resize2fs) and initialise services. For RK platform boards like K8/K7, the first Ubuntu boot may take 3–5 minutes; Android is relatively faster. You can check whether the system is still running by observing changes in the HDMI display (e.g., the Android boot animation running).
WiFi/Bluetooth antennas contain metal conductive parts. If placed flat on top of the board, they may short‑circuit resistors or capacitors, or generate electromagnetic interference with the DDR memory, causing data transmission errors. Secure the antenna away from the board (e.g., on the enclosure).
Connect the debug serial port (baud rate: RK 1500000 / AW 115200) and provide the full serial boot logs.

Try rebooting the device. The login screen may appear on the first boot. Log in via serial console and run df -h to check if any partition is full. Clean up unnecessary files or logs and reboot. If the login issue appears after modifying system configuration files, you can log in via serial and restore the changes.
Run df -h to check the usage of each partition. If the / or /home partition is 100% full, the desktop manager cannot create temporary files or user sessions, causing the system to get stuck at the login screen.
Ubuntu uses LightDM as the desktop manager by default. Run sudo systemctl status lightdm to check its status, and sudo systemctl restart lightdm to restart the service.
If the login issue is caused by modifications to configuration files such as /etc/environment, ~/.profile, ~/.bashrc, or ~/.xinitrc, you can log in via serial console and restore the modified files.

Check the status of the display manager (LightDM / SLiM). Stop the SLiM service (if installed): sudo systemctl stop slim. Clear SLiM cache. Verify whether the desktop environment has been accidentally uninstalled. Try reinstalling LightDM: sudo apt install --reinstall lightdm.
Check the LightDM log: cat /var/log/lightdm/lightdm.log and look for key lines such as starting and stop. Check the Xorg log: cat /var/log/Xorg.0.log to see if there are graphics driver loading failures (e.g., failed to load modedrivers).

The default startup scripts in the Linux system are: /etc/init.d/kickpi.sh and /usr/bin/hardware-optimization. hardware-optimization is started via etc/systemd/system/hardware-optimize.service.
systemd service method (recommended): create a .service file in /etc/systemd/system/, define [Service] ExecStart=<your script path> and [Install] WantedBy=multi-user.target, then run systemctl enable <your service> to enable auto‑start at boot.
On RK3576, the default behaviour of the Power button is: short press to suspend, long press to power off (system shutdown, PMU power‑off).

The chipid is burned at the factory and cannot be changed. It can be used as a unique device identifier. Allwinner platform: cat /sys/class/sunxi_info/sys_info; Rockchip platform: cat /sys/devices/platform/*-serial/rockchip_serial.
The chipid can be used for device license binding, license management, device identification, etc. Because it is factory‑programmed and cannot be altered, it is more reliable than a MAC address (which can be modified).
On RK3588 systems, you can also check the CPU serial number with cat /proc/cpuinfo | grep Serial.
On Allwinner platforms, you can also extract the chipid with cat /sys/class/sunxi_info/sys_info | grep chipid, or read the sunxi information in /proc/cpuinfo.

cat /sys/devices/system/cpu/cpufreq/policy0/cpuinfo_cur_freq
cat /sys/devices/system/cpu/cpufreq/policy4/cpuinfo_cur_freq
cat /sys/devices/system/cpu/cpufreq/policy6/cpuinfo_cur_freq
Use watch -n 1 "cat /sys/devices/system/cpu/cpufreq/policy*/cpuinfo_cur_freq" to monitor frequency changes across all cores in real time.

After modifying the logo, it is recommended to do a full compilation and flash. If you are using the multi‑screen compatible image from the cloud storage, flashing only the boot partition may cause boot issues due to conflicts.
Prepare the logo image (BMP format, 24‑bit depth, resolution matching the screen) → replace kernel/logo.bmp or kernel/logo_kernel.bmp in the SDK → run ./build.sh for a full compilation → flash the img image.
If you are using the multi‑screen compatible image from the cloud storage (which supports automatic detection of multiple screens), the logo in that image is specially handled. Replacing the logo and flashing only the boot partition may break the multi‑screen detection. It is recommended to perform a full compilation in the SDK and generate a complete update.img for flashing.

On Ubuntu, you can create symlinks using udev rules. On Android, you can configure fixed nodes in ueventd.rc.
Ubuntu udev rule example: create /etc/udev/rules.d/99-usb-serial.rules with content such as:
```
SUBSYSTEM=="tty", ATTRS{idVendor}=="1a86", ATTRS{idProduct}=="7523", SYMLINK+="ttyCH340"
```
After writing the file, run udevadm control --reload-rules && udevadm trigger to apply immediately.
Android ueventd.rc: add the following in the corresponding ueventd.rc file:
```
/dev/ttyUSB0              0660   root     shell
/dev/ttyACM0              0660   system   shell
```
To fix a device based on VID/PID, you may need to operate via init.rc using commands such as write /sys/class/tty/ttyUSB0/device/driver/unbind and similar approaches.