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