Re: [Xen-users] Xen as virtual KVM

[Mark Williamson <mark.williamson@xxxxxxxxxxxx>]

> Just so that you understand it: It's perfectly possible to use ALL
> versions of OS's as HVM domains, so you could just set up your Linux and
> Windows domains to use HVM all the way - the graphics may not be as
> snappy as you get on real hardware, but it's definitely usable for
> testing purposes. And the advantage here is that you don't need any
> "messing about", and you can even leave all of them running at once and
> just click on the task-bar for which one you want to run at any given
> time (or run several in parallel - you just can't see all of them if you
> don't have a HUGE display on Dom0).

In fact, you could try running a virtual machine display full screen on each 
virtual desktop, then switch between them using ctrl+alt+left/right - that 
way you can have a different OS on each side of a cube (and be able to zoom 
out and look at all of them at once).

Cheers,
Mark

> --
> Mats
>
> > On 6/26/07, Petersson, Mats <Mats.Petersson@xxxxxxx> wrote:
> >     > -----Original Message-----
> >     > From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx
> >     > [mailto: xen-users-bounces@xxxxxxxxxxxxxxxxxxx
> >
> > <mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx> ] On Behalf Of
> >
> >     > Brandon Reno
> >     > Sent: 26 June 2007 15:28
> >     > To: xen-users@xxxxxxxxxxxxxxxxxxx
> >     > Subject: [Xen-users] Xen as virtual KVM
> >     >
> >     > I'm looking at doing something that may seem a little bit
> >     > odd, I would like to use xen to virtualize several desktop
> >     > environments, with a specific keystroke configured to switch
> >     > to that environment.
> >     > I will have either gentoo or debian as a dom0.  this will be
> >     > used only for management of the virtual machines.
> >     > I will have several full desktop environments for
> >
> > different users.
> >
> >     > For example, I will be using Gentoo with KDE/Beryl (soon to
> >     > be Fusion or whatever they are changing their name to)
> >     > I'd like to have a test environment for various trials of
> >     > different other flavours and for development
> >     > Additionally, I will be buying a new computer, supporting
> >     > AMD-V, will want to have 3 additional environments, Windows
> >     > XP and Vista, for application testing, and one
> >
> > Windows DE for my Wife.
> >
> >     > To accellerate as much as possible the different
> >     > environments,  I would need to setup the PCI video card to
> >     > passthrough to whichever domU is active.  It is not necessary
> >     > for more than one environment to be active and running at any
> >     > given time.
> >     > My theory is to simply configure each environment to pass
> >     > through the video card, and drop one environment (suspend?),
> >     > and switch to the next.  Do you see any problems with this
> >     > configuration, or have any advice?
> >
> >     You can do it with VNC/SDL in fully-virtual domains
> > with a virtual
> >     graphics card. That's a (nearly) no-brainer.
> >
> >     But unless you have at least two graphics cards in the
> > machine, Dom0
> >     will need to own the graphics card - it uses the VGA as
> > console during
> >     startup at the very least. So you need a second
> > graphics card to start
> >     with. I've seen complaints that pass-through of
> > graphics doesn't work,
> >     but don't take my word for it.
> >
> >     Using PCI passthrough, you would definitely have to
> > suspend ("xm save")
> >     the domain and resume another ("xm resstore") when
> > switching from one
> >     domain to another. Note that this takes several seconds
> > per save/restore
> >     cycle for any reasonable size domain - just writing
> > 128MB to the disk at
> >     50MB/s takes 2.5s or so, and there is more work than
> > this involved in
> >     the save-process.
> >
> >     HVM domains (Windows for example) can't use PCI
> > passthrough, at all, at
> >     this time (there's work to allow ONE instance of
> > Windows to do that -
> >     but that's still some way off, and I wouldn't rely on
> > this for the next
> >     3-6 months at least, although I'm not sure how far off
> > it really is).
> >
> >     > Additionally, I would need to write a program or series of
> >     > scripts to manage the switching of DEs, which doesn't seem to
> >     > be too much of a problem, except that it would need to
> >     > capture a few specific keystrokes (i.e. win+f1 thru win+f5)
> >     > to actually call the switch.
> >
> >     Why? What's wrong with clicking buttons/menus or typing
> > into a window
> >     someplace?
> >
> >     > I'm not sure where I would need to start to do this should
> >     > this program monitor /dev/input for the keypress, or would
> >     > this need to go into the hypervisor?
> >
> >     That's a good question - Dom0 doesn't (strictly) own
> > the keyboard, but
> >     you'd certainly have an easier task intercepting this
> > in Dom0 than you'd
> >     have in the Hypervisor, since the hypervisor won't
> > actually be able to
> >     make the switch happen anyways, so you NEED to get to
> > Dom0 someway
> >     anywyas to achieve this.
> >
> >     --
> >     Mats
> >
> >     > I currently have a few VMs on my server computer running
> >     > things like a webserver, samba share, Kerberos
> >     > Authentication, etc. and have been very happy with xen.  I'd
> >     > like to take the chance to document my findings on this
> >     > unique setup in case someone else would be interested.
> >     >
> >     > Any advice would be appreciated, or better yet, if someone
> >     > has done something like this, I'd like to hear about their
> >     > successes/failures.
> >     > Thanks,
> >     > Brandon Reno
>
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-- 
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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