Re: [Xen-devel] Xen Interfaces

[Mark Williamson <mark.williamson@xxxxxxxxxxxx>]

> I am interested in using Xen.  I need clarification on how the VMs
> and/or Domains talk to one another??  Securely?? What are the Interfaces
> and security policies for Xen??  I have read massive documentation but I
> just need some extra clarity this.  Thank You.

The domains use a limited control-plane signalling mechanism (e.g. control 
messages in Xen 2.0, xenstore in Xen 3.0) to set up communications.  The two 
mechanisms for bulk data comms are:

* shared memory: domUs pass IO requests to the backend in dom0 using shared 
memory.  The backend then maps their IO buffers to put the data there.
* interdomain event channels: these are like interrupt lines, allowing a 
communicating pair of domains to notify each other that there is new data in 
the shared memory.  i.e. they indicate "hey, I queued more requests, go 
look!", "hey, I completed some requests, you can retire them now" but not 
what data was actually transferred

Does that help?

Cheers,
Mark

>
>
>
> Kashif J. Brown SR
>
> Research Programmer Analyst
>
> Information Technology & Systems Division
>
>
>
> Institute for Defense Analyses
>
> 4850 Mark Center Drive
>
> Alexandria, VA 22311-1882
>
> Tel. (703) 933-6532  Fax (703) 845-6848
>
> em. kabrown@xxxxxxx

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