Re: [Xen-users] how does hypervisor isolates DomU from Dom0

["Nick Couchman" <Nick.Couchman@xxxxxxxxx>]

>>> On 2010/08/15 at 14:19, Tapas Mishra <mightydreams@xxxxxxxxx> wrote: 
> I am not clear with the working of hypervisor xen.
> How does an instruction executed by kernel in Ring0 of DomU gets
> mapped or executed by hypervisor and then is excuted in Dom0.
> Is this thing some where on the wiki page?

I'm not all that familiar with the internals of Xen, but I think the high-level 
answer to your question is, it depends.  It depends on what type of domU you're 
running.  Paravirtualized domUs are aware that they are virtualized and that 
they do not have ring 0 access, so I'm guessing they do not attempt to execute 
instructions in ring 0 without passing it through to the hypervisor, which 
brokers those requests.  HVM domUs, on the other hand, are full machines (more 
along the lines of how VMware does virtualization) that can run an unmodified 
kernel.  So, kernels in HVM domUs attempt to access ring 0 resources, which 
must then be translated by the HVM and passed on to the hypervisor.

That's my understanding of how it works...

-Nick



--------
This e-mail may contain confidential and privileged material for the sole use 
of the intended recipient.  If this email is not intended for you, or you are 
not responsible for the delivery of this message to the intended recipient, 
please note that this message may contain SEAKR Engineering (SEAKR) 
Privileged/Proprietary Information.  In such a case, you are strictly 
prohibited from downloading, photocopying, distributing or otherwise using this 
message, its contents or attachments in any way.  If you have received this 
message in error, please notify us immediately by replying to this e-mail and 
delete the message from your mailbox.  Information contained in this message 
that does not relate to the business of SEAKR is neither endorsed by nor 
attributable to SEAKR.

_______________________________________________
Xen-users mailing list
Xen-users@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-users