Switching a XenServer VM from PVM back to HVM

(Disclaimer: I am by no means an expert with XenServer. So please don’t take anything you read here for granted. It’s my own experience and what I found in documentation and online.)

If switching a XenServer Linux VM to paravirtualization fails, you usually end up with a non booting VM which is quite annoying. Switching it back to hardware assisted virtualization isn’t difficult, if you know what to do:

  1. Open a console on the XenServer host (local or via ssh)
  2. Get the UUID of the VM you want to change:
    xe vm-list name-label="NameOfTheVM"
  3. change two parameters of the VM
    1. Set HVM-boot-policy to “BIOS order”
      xe vm-param-set uuid=UuidOfTheVM HVM-boot-policy="BIOS order"
    2. Set PV-bootloader to “”
      xe vm-param-set uuid=UuidOfTheVM PV-bootloader=""

If everything works, the virtualization mode of the VM in XenCenter should be switched back to “Hardware-assisted Virtualization (HVM)” and the VM will boot again.

Source: This Citrix Forum post

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