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Re: xen considerations

On Tue, Oct 7, 2008 at 1:27 PM, Michael Kell Jensen <> 

> Hi im trying to get my laptop to also use the virtual hardware
> emulation.(T60p)
> I looked into how to do that.
> And the best fit i think was xen.
> I looked up xen on NetBSD (which i looked at before)
> My goal is to have Netbsd as Dom0 and on another partition(or two)
> i would install windows and linux, and use them via xen and HVM (i think it
> is). so i could use these operating systems with almost full performance. as
> guests - DomU.
> Im i on the right track for that.

You will need VT-x (Intel) or SVM (AMD) support in your cpu to use an HVM
with Xen.

> Then i could see that xen was a port fro netbsd, which i dont understand
> why. shouldnt it "just" be some extensions to the system / kernel.

The packages just install the Xen kernel and Xen cli tools for managing
domains.  Xen is support by NetBSD, but the Xen kernel is not part of the
NetBSD releases.

I'm using /boot from -current with a boot.cfg on my NetBSD 4.0 box with Xen
3.1.4.  I like this much better than using grub.

> Also will i have increased security risks when runnning xen enabled on my
> laptop. Worse Host performance other trouble ?
> Is there a better way to do this
Well running NetBSD+Xen means you're impacted by both NetBSD & Xen bugs.
Also you're possibly impacted by whatever you're running in an HVM, likes
Windows XP for example.  I think there are ways to mitigate the denial of
service impact of a misbehaving domU, but I'm not sure how necessary those
would be on a laptop setup where you're operating all the domains.

Various Xen docs quote rather small overhead for paravirtualization.  Just
booting dom0+Xen shouldn't really be noticable, but I would assume several
HVMs would have some impact.

Personally I would also like to see VirtualBox fully working under NetBSD
for less complicated / invasive VM work, but Xen is not really difficult to
setup for a few domains.


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