On Mar 9, 2006, at 7:30 AM, Christopher Nelson wrote:
>>
>>> As I understand Xen, it must run on linux. VMWare ESX server is a
>>> microkernel that's very close to the hardware. It does not require
>>> windows or linux to run on top of.
>>>
>> Xen runs on NetBSD, Linux and can run on FreeBSD with patches
>> that I think will be in FreeBSD 6.1.
>
>
> Actually, it's the other way around. NetBSD, Linux, and FreeBSD
> run on
> XEN. Xen is a hypervisor, and it runs BELOW the OS. Otherwise the
> OS's
> wouldn't be able to be virtualised, would they? Even on VMX-enabled
> procs, the OS's have to run on top of Xen, not vice-versa.
>
> You may be thinking about the dom0 OS, that provides the services for
> other OS's.
>
Pedant alert! [just kidding, it's worth clarifying :)]
I am, in fact, talking about the fact that Xen "lives inside" (and
outside) the kernels of NetBSD, Linux and FreeBSD, and that these 3
run in ring 0 on Intel CPUs.
Any of those three can be used to manage guest OSes running in Ring1.
Of course with VMX extensions I think even ring0 is able to be
context switched via some assembly routines, which is why it's
possible to run things like Windows that haven't been ported (in a
released form) to use the Xen hypercalls as several guest OSes have.
Dave
> -={C}=-
