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Re: [Xen-devel] Can VMWare modules run alongside in XEN kernel?

To: "Daniel P. Berrange" <berrange@xxxxxxxxxx>
Subject: Re: [Xen-devel] Can VMWare modules run alongside in XEN kernel?
From: Mark Williamson <mark.williamson@xxxxxxxxxxxx>
Date: Tue, 14 Aug 2007 02:20:43 +0100
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx, Peter Teoh <tthtlc@xxxxxxxxxxxxxx>
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> On Tue, Aug 14, 2007 at 02:04:43AM +0100, Mark Williamson wrote:
> > > I would like to have VMware modules running in the XEN kernel, NOT in
> > > DOM0 kernel but outside at the hypervisor level, is that possible?
> >
> > Nope, afraid that can't work.  Xen doesn't provide all the facilities
> > that a Linux kernel does, so it's not able to support Linux modules at
> > all.  As you noticed, it also doesn't allow loadable modules...
> Urm, sure it does - whether the xen kernel allows modules or not is just a
> KConfig setting. The XenSource kernel builds may not allow loadable modules
> but all Fedora Xen kernels are fully modular. You're right that VMware
> won't load/work, but that's a separate issue to the question of loadable
> module support in general.

That's true, but the OP was asking about running the modules in Xen itself "at 
the hypervisor level" and not in the dom0 Linux kernel.  Xen used to support 
Linuxy APIs for modules, but even those have mostly gone now, so it's 
definitely not doable.

> > The VMware modules really both need a) to run in ring0 (satisfied by your
> > suggestion) and to b) be supported by a full host Linux kernel.
> > Unfortunately, with Linux running in ring 1, whatever you do you are not
> > going to be able to satisfy both of these :-(
> Might be able to run VMware inside a HVM/fullyvirt guest.

Yes, that's true :-)  I can run Xen inside HVM already - regularly, in fact - 
but never tried VMware.


Dave: Just a question. What use is a unicyle with no seat?  And no pedals!
Mark: To answer a question with a question: What use is a skateboard?
Dave: Skateboards have wheels.
Mark: My wheel has a wheel!

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