How to: Enable Serial Console for guest virtual machine (VM) on Proxmox VE (PVE)

This article explains how to redirect messages to a serial console in on Debian and use Serial Console on Proxmox VE.

We need to add serial0 to the virtual machine. Use following command to add the serial0 port

qm set [vmid] -serial0 socket

Now we need to configure the Debian:

nano /etc/default/grub
GRUB_CMDLINE_LINUX_DEFAULT="console=ttyS0,115200n8 console=tty1"
GRUB_TERMINAL="serial console"
GRUB_SERIAL_COMMAND="serial --speed=115200 --unit=0 --word=8 --parity=no --stop=1"

Now we need to update the grub by using following command

# Debian/Ubuntu etc.
# RHEL/CentOS/Fedora
grub2-mkconfig --output=/boot/grub2/grub.cfg

Set to autostart the serial consol service.

mkdir -p /etc/systemd/system/serial-getty@ttyS0.service.d/
nano /etc/systemd/system/serial-getty@ttyS0.service.d/override.conf
ExecStart=-/sbin/agetty -o '-p -- \\u' 115200 %I $TERM

systemctl daemon-reload
systemctl restart serial-getty@ttyS0.service
systemctl enable serial-getty@ttyS0.service

Reboot and test the autostart of the Serial Console

init 6
ps -ef | grep ttyS0
systemctl status serial-getty@ttyS0.service