Debian 9: GRUB2 and Linux with serial console


Table of Contents

1 /etc/default/grub

Change /etc/default/grub as below.

  • Change GRUB terminal to console and ttyS0. This will provide one GRUB to a monitor display and serial console.
  • Change linux kernel console to tty1 and ttyS0. This setting will be taken over to userland, and there will be two login prompt for tty1 and ttyS0.

$ cat /etc/default/grubGRUB_DEFAULT=0GRUB_TIMEOUT=1GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`GRUB_CMDLINE_LINUX_DEFAULT=””GRUB_CMDLINE_LINUX=”console=tty1 console=ttyS0,115200″GRUB_TERMINAL=”console serial”GRUB_SERIAL_COMMAND=”serial –speed=115200 –unit=0 –word=8 –parity=no –stop=1″

2 grub-mkconfig

Update /boot/grub/grub.cfg with grub-mkconfig.

$ sudo grub-mkconfig -o /boot/grub/grub.cfgGenerating grub configuration file …Found linux image: /boot/vmlinuz-3.16.0-4-amd64Found initrd image: /boot/initrd.img-3.16.0-4-amd64done

Reboot Debian 9.

$ sudo reboot

3 Execution result

GRUB to monitor display is as below.

0001_GRUB-to-Display.png

GRUB to serial console is as below. This article used “sudo virsh console <vmname>” for connecting serial console.

0002_GRUB-to-SerialConsole.png

Login prompt to monitor display is as below. tty1 is displayed with press Ctrl + Alt + F1.

0003_Linux-to-Display.png

Login prompt to serial console is as below.

0004_Linux-to-SerialConsole.png

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