WARNING - OLD ARCHIVES

This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
   
 
 
Xen 
 
Home Products Support Community News
 
   
 

xen-devel

RE: [Xen-devel] Full virtualization and I/O

To: "Petersson, Mats" <Mats.Petersson@xxxxxxx>, "Thomas Heinz" <thomasheinz@xxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: RE: [Xen-devel] Full virtualization and I/O
From: "Puthiyaparambil, Aravindh" <aravindh.puthiyaparambil@xxxxxxxxxx>
Date: Wed, 22 Nov 2006 13:33:51 -0500
Delivery-date: Wed, 22 Nov 2006 10:34:13 -0800
Envelope-to: www-data@xxxxxxxxxxxxxxxxxx
In-reply-to: <907625E08839C4409CE5768403633E0B018E1752@xxxxxxxxxxxxxxxxx>
List-help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-id: Xen developer discussion <xen-devel.lists.xensource.com>
List-post: <mailto:xen-devel@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
Thread-index: AccOTMMXyfLU2o7TR++6i3jTVYJk4QAANWJgAAUM3DA=
Thread-topic: [Xen-devel] Full virtualization and I/O
Mats,

> For fully virtualized mode (hardware supported virtual machine, such
as
> Finally, while I'm on the subject of fully virtualized mode: It is
> currently not possible to give a DMA-based device to a
fully-virtualized
> domain. The reason for this is that the guest OS will have been told
> that memory is from 0..256MB (say), and it's actual machine physical
> address is at 256MB..512MB. The OS is completely unaware of this
> "mismatch". So the OS will perform some operation to take a virtual
> address of some buffer (say a network packet) and make it into a
> "physical address", which will be an address in the range of 0..256MB.
> This will of course (at least) lead to the wrong data being
transmitted,
> as the address of the actual data is somewhere in the range
> 256MB..512MB. The only solution to this is to have an IOMMU, which can
> translate the guest's understanding of a physical address (0..256MB)
to
> a machine physical address (256..512MB).

I know that individual domains can be given direct access to individual
PCI devices.

http://www.cl.cam.ac.uk/research/srg/netos/xen/readmes/user/user.html#SE
CTION03230000000000000000

Is this not possible with HVM domains? Is it possible for HVM domains to
be a PCI frontend and receive a PCI device which is "hidden" from Dom0?
Or is this what paravirtualized drivers for HVM domains are doing?

Thanks,
Aravindh

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