Changes between Version 8 and Version 9 of Paravirtualization

Timestamp:

Nov 22, 2008, 2:19:07 AM (15 years ago)

Author:

price

Comment:

more context

Paravirtualization

@@ -1 +1 @@
 Xen supports two different types of virtualization: Hardware-supported virtualization (HVM) and paravirtualization (ParaVM).
 
-Most XVM VMs are initially created as HVMs. HVMs virtualize a full machine, down to the metal. They use special processor capabilities to do this. This allows you to run an unmodified operating system. For example, this is the only way to run Windows under Xen. However, I/O performance suffers as a result of this virtualization approach.
+XVM VMs installed from a boot CD are HVMs. HVMs virtualize a full machine, down to the metal. They use special processor capabilities to do this. This allows you to run an unmodified operating system. For example, this is the only way to run Windows under Xen. However, I/O performance suffers as a result of this virtualization approach.
 
 ParaVMs on the other hand, modify the guest operating system to remove privileged operations, replacing them with calls to the Xen hypervisor. ParaVMs have significantly better performance, but require a modified kernel. Only a few operating systems have support for running as a paravirtualized Xen guest: Linux, NetBSD, OpenBSD, FreeBSD, and !OpenSolaris being the most well known.
 
-Because of the performance benefits, you should consider using a ParaVM if possible.
+Because of the performance benefits, you should consider using a ParaVM if possible.  The easy way to do this is to use the autoinstaller.  If you have an HVM that you want to keep, you can convert it into a ParaVM with the steps below.
 
 == Converting a Linux Guest to ParaVM ==
+
+These steps presume you have a working HVM machine and want to make it boot as a ParaVM.  If you use the autoinstaller you can get a ParaVM from the beginning.
 
 === Installing the Necessary Packages ===