The Linux kernel itself will use the serial console by default if there's no VGA device: If no console device is specified, the first device found capable

The Linux kernel itself will use the serial console by default if there's no VGA device: If no console device is specified, the first device found capable of acting as a system console will be used. At this time, the system first looks for a VGA card and then for a serial port. So if you don't have a VGA card in your system the first serial port will automatically become the console. https://www.kernel.org/doc/Documentation/admin-guide/serial-console.rst https://www.kernel.org/doc/Documentation/admin-guide/serial-...