Re: [Xen-users] Why HVM?

Pasi Kärkkäinen
Sun, 29 Aug 2010 18:32:40 -0000

On Fri, Aug 27, 2010 at 08:43:01PM +1000, James Harper
wrote:
> > Hi Jonathan,
> >
> > The only big advantage is that customers can install operating systems
> that do
> > not support pv operation (e.g. Windows). Some small advantages like
> using own
> > GRUB or kernels can be achieved in pv environment, too (pvgrub,
> pygrub), but
> > those hosters probably don''t enable that for pv VPS.
> > Another little point is that not all HVM features are available for pv
> guests,
> > especially with pv_ops guest and host kernels (for example: USB
> passthrough,
> > PCI / VGA passthrough; the first two not yet with pv_ops kernels, VGA
> > passthrough is always only available for HVMs). But as long as you
> don''t want
> > to offer physical hardware to your clients, this doesn''t
matter for
> VPS
> > hosting.
> >
> > Probably I missed an important point, but AFAIK there is no advantage
> of
> > having a Linux server system in a HVM instead of a PV VM.
> >
>
> How good is VNC access under PV these days? With HVM you get a virtual
> keyboard, video, and mouse which can get you out of trouble if you do
> something dumb and lose network access.
>

PVFB (paravirtual framebuffer) has been available for years for Linux PV
guests..
so each guest using pvfb will have a separate qemu-dm providing the VNC access.

-- Pasi