Re: [PATCH] xen: core dom0 support
From: H. Peter Anvin
Date: Wed Mar 04 2009 - 14:20:57 EST
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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