Re: Xen

[Julio Merino <jmmv%NetBSD.org@localhost>]

On 8/2/11 3:16 PM, Daniel Carrera wrote:
> Hello,
> 
> In an earlier post I asked about why people like NetBSD and one person
> mentioned Xen. Since then I've been browsing the mail archives and I've
> seen Xen come up a few times. I'm going to ask a question that might be
> tremendously stupid, but if I don't ask I'll never learn:
> 
> Isn't Xen just a virtual machine like QEMU, VirtualBox, etc? What makes
> Xen special that people here talk about it while they don't talk about
> QEMU and VirtualBox?

Xen is a paravirtualization system: it requires changes to the guest
operating systems, unlike QEMU or VirtualBox which run unmodified
systems.  NetBSD has built-in support for Xen, while the support for
Linux has always been distributed as a set of patches (for reasons
unknown to me).

This scheme allows for higher performance of the virtual machines.

I recommend you to read the "Xen and the Art of Virtualization" paper:

www.cl.cam.ac.uk/research/srg/netos/papers/2003-xensosp.pdf

Kind regards,

-- 
Julio Merino / @jmmv