Just wanted to clarify certain aspects of Xen virtualization.

As I understood it, Xen was a paravirtualization platform, which usually required a modified Linux kernel in order to create virtual Linux systems.

At some point it gained the ability to run Windows and other unmodified operating systems in virtual machines.

Am I right in thinking that Xen has the ability to host unmodified guests in VM's if the processor has the hardware virtualization extensions built into it, and if it doesn't, Xen can only run Linux kernels modified to run in a paravirtualized environment?


That's right, Xen supports hardware assisted virtualization and allows running unmodified guests.

You can have a look at the list of HVM compatible processors and motherboards (although it seems that those lists haven't been updated recently)

  • But does it only run unmodified guests on particular processors, reverting to paravirtualization if you have a processor without hardware-assisted virtualization support? I.e., does it no longer work on older systems? XenServer doesn't work on older systems anymore (those that aren't 64 bit)...I was looking at a project with plain xen, though. – Bart Silverstrim Aug 4 '09 at 17:06
  • AFAIK, Xen can only run unmodified guests on processors that provide support for hardware virtualization. Anyway, you can run paravirtualized guests on any supported architecture. It would be helpful if you could tell us more about your environment and what do you want to run specifically, so we can offer a more conclusive answer. For example, what's the architecture of your host system and what OS you need to run as a Xen guest. – alemartini Aug 4 '09 at 17:27
  • It's an older dual-xeon processor system. I know that it's one that isn't on the HCL's for the current XenServer or VMWare hypervisors... – Bart Silverstrim Aug 4 '09 at 18:49
  • Oh, and for the OS, I'm planning most likely using Linux for the testing, but I didn't know if there's special modifications that have to be done. I've got some experience with virtualbox and VMWare, both of which install stock OS's, but paravirtualization would mean needing modified kernels, and I just wantet to know how much pain I'm asking for in maintaining and installing them. – Bart Silverstrim Aug 4 '09 at 18:51

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