# Playing with XEN



## BlueCoder (Apr 25, 2013)

OK so I now have NetBSD running as well on my P4 firewall. I get to play with XEN. I have the DOM0 up and running now so I can now play with XEN. Only issue I had getting DOM0 up was that it requires the NetBSD kernel to be PAE compiled. Also it seems XEN doesn't support kernel modules so you have to compile everything you need into the kernel.

I just about have a Freebsd DOMU installed. Taking a break at the moment.

But I just learned that OpenBSD doesn't support para-virtualized DOMU! I totally can't believe it. There was even a patch a few years ago but it wasn't imported into the mainline I believe. It seems Theo doesn't like virtualization. I'm normally a big fan of his but I have to cry foul. PV for many workloads runs faster than HVM and his boycott doesn't stop HVM. It just rubs me the wrong way.

The ideal is a PV/HVM hybrid kernel. Where only things that are faster like memory paging is actually HVM. All other things would be PV which means no context switches for the most part. Not sure how far along XEN is with that although I think most of the work is adapting code in the client DOMU's.

Well at least I have FreeBSD DOMU that I can use to do some benchmark testing. I don't actually need any of this for any reason. Just trying it out. Better to know how to do something before you need it.


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## oed (Apr 26, 2013)

Just one comment with regards to virtualization support in OpenBSD. OpenBSD 5.3 and later has virtio drivers. I've been running those as a guest on a KVM server. AFAIK you can also use virtio drivers on BHyVe. I've never tried Xen, though, so I can't comment on that.


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