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Jim Henderson wrote:
> On Sun, 04 Jan 2009 10:10:29 -0800, Darren New wrote:
>
>> Xen is an OS
>
> I don't know that I'd agree with that.
Is VM/CMS an OS? I bet IBM would say so. :-)
> A hypervisor is a hardware
> abstraction layer, messing about with the various memory rings in the
> system in order to make the OS running within the hypervisor believe it's
> running in Ring 0 when it's not in order to take advantage of memory
> protection features in the hardware without tripping the native hardware
> up when a child domain bombs out.
Sure. And Linux is a hardware abstraction layer, making your application
think it has a linear RAM address space to mess with and providing linear
sequences of bytes on disk to read and write (organized as a single tree of
names), when none of those are actually true. One of the jobs of an OS is
necessarily abstracting the hardware in *some* way, if you accept that
maintaining state and managing resources between independent applications is
part of the definition of an OS.
Of course you could argue either way. I was more contrasting Xen against a
BIOS than arguing that Xen must necessarily be considered an OS.
--
Darren New, San Diego CA, USA (PST)
Why is there a chainsaw in DOOM?
There aren't any trees on Mars.
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