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    Is a serial console possible for an HVM VM?

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    • I
      ivanfetch
      last edited by

      Hello,

      I'd like to confirm whether a serial console (text console) is possible for HVM virtual machines?

      I am completely blind, and often use a serial console for OS installation and troubleshooting, including boot loaders and kernel output before an OS is booted. The XOA-provided web console is not accessible to screen-reading software.

      I've attempted to connect to a text console of an Ubuntu Linux VM using the xe console vm=ubuntu command, which reports: No text console available.

      Some googling suggests that a serial console is not possible with HVM virtual machines, but I'd like to confirm this before moving away from xc-png.

      Thank you for your help!

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      • A
        Andrew Top contributor @ivanfetch
        last edited by

        @ivanfetch Yes, but it may not be exactly what you want because it's not a true text console.

        From XCP Dom0 try xl console -t serial VMname (or ID number). This will connect you to /dev/ttyS0 serial port on the VM. You can also use xl console -t pv VMname to connect to /dev/hvc0 (that is not a serial port).

        Your VM needs to have a getty process or Console setup on that port.

        Use xl vm-list for a VM list.

        Control-] to exit the console (like telnet).

        I don't think this is 100% the solution you are looking for, but it's a place to start. You would need to boot a new VM and tell it to use the serial port as a console rather than the VGA that Xen provides. I was able to tell Debian 11 installer to use console=ttyS0 and then see/install it from the text console but I still had to use the VGA console to tell Debian to do that.

        Without providing instructions I would say there is a way to do everything from a command line but you would still need a boot ISO that ignores the VGA and uses the serial port. The best trick would be to create a VM without VGA support so the OS in the VM is forced to use the serial port (if supported). QEMU does have text-only serial console support as I have used it directly outside of Xen/XCP but I don't know if XCP will allow you to do that.

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        • I
          ivanfetch @Andrew
          last edited by

          @Andrew Thank you very much for your reply. This helped a lot, and I was able to get serial access to VMs configured to use the serial port.

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