Messages in this thread | | | Date | Wed, 04 Mar 2009 11:16:33 -0800 | From | "H. Peter Anvin" <> | Subject | Re: [PATCH] xen: core dom0 support |
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Anthony Liguori wrote: > > I think this is a bit misleading. I think you can understand the true > differences between Xen and KVM by s/hypervisor/Operating System/. > Fundamentally, a hypervisor is just an operating system that provides a > hardware-like interface to it's processes. > [...]
> > The real difference between KVM and Xen is that Xen is a separate > Operating System dedicated to virtualization. In many ways, it's a fork > of Linux since it uses quite a lot of Linux code. > > The argument for Xen as a separate OS is no different than the argument > for a dedicated Real Time Operating System, a dedicated OS for embedded > systems, or a dedicated OS for a very large system. >
In particular, Xen is a microkernel-type operating system. The dom0 model is a classic single-server, in the style of Mach. A lot of the "Xen could use a distributed dom0" arguments were also done with Mach ("the real goal is a multi-server") but such a system never materialized (Hurd was supposed to be one.) Building multiservers is *hard*, and building multiservers which don't suck is even harder.
-hpa
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