Xen devel - Oct 2011 - how hypervisor separates assembly instructions

As far as my understanding goes a CPU gets Assembly instructions to work and
upon those instructions it works. These assembly instructions come
from the OS running on top of bare metal.
I have some understanding of hypercalls.
So what does a hypercall implement that it is able to separate the
different Assembly instructions
coming from different Guest OSeS or in other words how does the
hypervisor separates the Assembly instructions which should be run for
different Guest OSeS running on top of hypervisor.I want to know it
technically not theoretically.

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------------------------------

Tapas

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On 14/10/11 16:43, Tapas Mishra wrote:
> As far as my understanding goes a CPU gets Assembly instructions to work
The CPU reads computer opcode from memory.  (Assembly instructions are
the name for the mnemonics, not the binary representation which the CPU
actually runs)
>  and
> upon those instructions it works. These assembly instructions come
> from the OS running on top of bare metal.
Not really.  All programs are just opcode which the CPU can run.  OS''s
are the same as regular programs in this regard.
> I have some understanding of hypercalls.
> So what does a hypercall implement that it is able to separate the
> different Assembly instructions
> coming from different Guest OSeS or in other words how does the
> hypervisor separates the Assembly instructions which should be run for
> different Guest OSeS running on top of hypervisor.I want to know it
> technically not theoretically.
The hypervisor "separates" different operating systems in the same way
that regular operating systems separate different processes.
> --
> ------------------------------
>
> Tapas
>
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-- 
Andrew Cooper - Dom0 Kernel Engineer, Citrix XenServer
T: +44 (0)1223 225 900, http://www.citrix.com


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On Fri, Oct 14, 2011 at 9:22 PM, Andrew Cooper
<andrew.cooper3@citrix.com> wrote:
> The hypervisor "separates" different operating systems in the
same way
> that regular operating systems separate different processes.
>
Hi,
thanks for your message I want to understand this last 2 lines in
detail.As how does the hypervisor separates different OS and things
"run."

-- 
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Tapas

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Tapas Mishra writes ("Re: [Xen-devel] how hypervisor separates assembly
instructions"):
> thanks for your message I want to understand this last 2 lines in
> detail.As how does the hypervisor separates different OS and things
> "run."
I think your questions would best be dealt with by you attending a
basic course in computer architecture.  If you aren''t already on one,
that is.

In any case xen-devel is not the appropriate please for this
conversation, I''m afraid.  Please would others not respond; it may
seem helpful, but actually it just attracts more inappropriate
questions, particularly at this time of year.

Ian.

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