ArchLinux 2016.06.01: 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. ttyS0 will be managed by login prompt and tty1 will be managed by display manager like lxdm.

$ diff -uprN /etc/default/grub{.org,}— /etc/default/grub.org 2016-06-06 18:06:46.053333327 +0000+++ /etc/default/grub 2016-06-06 20:28:12.563333332 +0000@@ -1,7 +1,7 @@ GRUB_DEFAULT=0 GRUB_TIMEOUT=1 GRUB_DISTRIBUTOR=”Arch”-GRUB_CMDLINE_LINUX_DEFAULT=”quiet”+GRUB_CMDLINE_LINUX_DEFAULT=”console=tty1 console=ttyS0,115200″ GRUB_CMDLINE_LINUX=”” # Preload both GPT and MBR modules so that they are not missed@@ -11,8 +11,11 @@ GRUB_PRELOAD_MODULES=”part_gpt part_msdo #GRUB_HIDDEN_TIMEOUT=5 #GRUB_HIDDEN_TIMEOUT_QUIET=true+GRUB_TERMINAL=”console serial”+GRUB_SERIAL_COMMAND=”serial –speed=115200 –unit=0 –word=8 –parity=no –stop=1″+ # Uncomment to use basic console-GRUB_TERMINAL_INPUT=console+#GRUB_TERMINAL_INPUT=console # Uncomment to disable graphical terminal #GRUB_TERMINAL_OUTPUT=console

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-linuxFound initrd image: /boot/initramfs-linux.imgFound fallback initramfs image: /boot/initramfs-linux-fallback.imgdone

Reboot ArchLinux.

$ 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

tty1 is managed by display manager.

If pressing Ctrl + Alt + F2, tty2 will be managed by login prompt.

0003_Linux-to-Display.png

Login prompt to serial console is as below.

0004_Linux-to-SerialConsole.png

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