Proxmox Host Console over Serial Port

[M_D]

I have a Proxmox server with a single discrete GPU, and the CPU does not have an iGPU - the only video output from the box is via the discrete GPU.

And I want to pass it through to a VM. Which leaves me in the precarious position that if, for example, I misconfigured Proxmox in the Web UI, and lost network access - I cannot access the PVE console, because the only system video output is passed through to a VM, and am therefore stuck - which is a situation I would rather avoid.

However, my server does have a DB9 serial port - since the PVE console is text-based, is there a way to configure Proxmox to run it's console on the serial port? I have found various guides about adding a serial port to a VM (not what I want), and one other guide referencing grub on the host - but I think I am using systemd-boot, not grub for PVE host.

Is this possible?

 

[raiskate32]

Yes, it is definitely possible to configure the Proxmox console to run on a serial port. Since you're using systemd-boot, the process is slightly different than when using GRUB, but it can still be configured. You'll need to modify the kernel parameters to enable serial console output. Here's a step-by-step guide:
Edit systemd-boot configuration:
Locate your Proxmox host's EFI system partition (usually /boot/efi) and open the relevant loader configuration file. This is typically found in /boot/efi/loader/entries.
Adjust the kernel options:
Add the following parameters at the end of the kernel command line:
console=tty0 console=ttyS0,9600n8
Replace ttyS0 with the appropriate serial device for your setup (e.g., ttyS1), and update the baud rate (9600 in this case) to match your serial connection settings.
Update serial settings in Proxmox:
To ensure the Proxmox console is accessible via the serial port, you'll also need to adjust the /etc/issue configuration to output the login prompt to the serial console. Append something like this to your getty service for the specific port.
Reboot and test:
After saving the changes, reboot your Proxmox host. You should now see console output on your serial port. Use a tool like screen or minicom on a connected computer to monitor it.
This approach should get the Proxmox console fully functional on the serial port. If you encounter any issues or need adjustments, double-check hardware compatibility and the baud rate settings. Feel free to reach out if anything's unclear!

 

[M_D]

Thank you for the instructions! I will certainly give this a try when I have some time.

Just a couple of questions to clarify:

- I assume this configuration won't remove the standard video output to the GPU - E.G if I mess up the serial console, I still have video output (and of course network access)?

- When you say "Append something like this to your getty service for the specific port", what are you saying I should append to the getty service exactly?

- Finally, I am using dual SSD's for the Proxmox OS, in a ZFS RAID1 mirror. I believe the EFI partition is sync'd between the disks, so if one fails, it will still boot (although I have yet to test this on this host). If I edit the /boot/efi/loader/entries file, will the changes automatically propagate to the mirror EFI partition on the other disk, or must this be done manually?