Disable the VyOS serial port on vm installation ( delete system console device ttyS0 )

I wanted to post this into the How-To section , but I was unable to add/create a new topic.
Disable the VyOS serial port on vm installation ( delete system console device ttyS0 )

VyOS-delete-system-console-device-ttyS0.txt
delete system console device ttyS0

When running a virtual VyOS , there is no Serial port.
VyOS by default ( on a virtual VyOS ) will generate constant logs about problems trying to configure the non-existant RS-232 serial port.

Example:
show log all
Aug 14 10:40:32 VyOS-Router agetty[615582]: /dev/ttyS0: not a tty
Aug 14 10:40:42 VyOS-Router systemd[1]: serial-getty@ttyS0.service: Deactivated successfully.
Aug 14 10:40:43 VyOS-Router systemd[1]: serial-getty@ttyS0.service: Scheduled restart job, restart counter is at 123872.
– or –
show log all | grep serial
– or –
show log all | grep getty
– or –
show log all | grep getty | tail -9
show log all | grep serial | tail -9

To disable the serial port in VyOS ( ttyS0 ) , type in this configuration command ( below ) in the config mode:
delete system console device ttyS0

  • commit
  • save
  • exit
    now the serial port messages in VyOS will stop.

you can verify this has stopped by using this $ command below:
show log all | grep serial | tail -9

Aug 14 10:40:43 VyOS-Router systemd[1]: Stopped serial-getty@ttyS0.service - Serial Getty on ttyS0.
Aug 14 10:40:43 VyOS-Router systemd[1]: Started serial-getty@ttyS0.service - Serial Getty on ttyS0.

  • note:
    If you are running a remote syslog server , it might of been filling up with VyOS syslogs about the VyOS serial device ( depending on how you configured your syslogging ).
    If is , this should of cleaned it up.

North Idaho Tom Jones

EDIT - note: If you use the serial port , then you probably do not want to do this. Read the posts below …

Hi TJ,

may I ask which hypervisor you are using?

We prefer the (virtual) serial console over the graphical kvm console. Here with PVE8.2 the serial ports are not spamming our logs. Of course they trigger a message for console connect/disconnect events but that’s completely fine for us. Last getty message seen hours ago.

Best regards,
vyozzy

vyozzy - Re: … hypervisor you are using …

Proxmox

I myself prefer the graphical console when working with a vm.

  • note ; in general , on all my Vms , On my hypervisor , I normally delete/remove any devices not used or needed. I do this to keep my VM interrupt lookups tables small , so that the virtual VM CPU does not need to check every possible device when different CPU interrupts occur. I found this helps almost any computer system run a tad bit faster that by default had shared interrupts to multiple devices. Example , a shared IRQ that services the CD-ROM controller card and a network card. The driver servicing the IRQ has fewer devices to check.

EDIT - add additional note; Some OSes can also poll devices , by removing un-used devices , there are fewer devices to poll - thus there is less OS polling - which helps the OS run a tad-bit faster.

North Idaho Tom Jones

For that same reason I generally remove the graphic card from any VM that doesn’t need one (especially network equipment ;-)).
Note: Serial console supports copy and paste out-of-the-box (although I prefer ssh for management, in emergency situations c&p is a welcome feature).

vyozzy - Re: … I in generally remove the graphic card from any VM …

Good idea - however - IMO , as much as I like CLI ( and ability to paste ), I mostly need/use the graphics console.
I wonder which one uses the most CPU - prob the graphics card I would suppose, ( KVM console display , KVM keyboard & KVM mouse ) - just thinking …

North Idaho Tom Jones

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