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] Does XEN use TUN/TAP interface?

To: Daniel Stodden <stodden@xxxxxxxxxx>
Subject: Re: [Xen-devel] Does XEN use TUN/TAP interface?
From: "Daniel P. Berrange" <berrange@xxxxxxxxxx>
Date: Sun, 16 Mar 2008 17:12:10 +0000
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx, Pavel Muller <pav.muller@xxxxxxxxx>
Delivery-date: Sun, 16 Mar 2008 10:12:49 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxx
In-reply-to: <1205686219.17474.7.camel@xxxxxxxxxxxxxxxxxxxx>
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>
References: <73804daf0803160752h3d798739oa8ccffcbb1aa9cc2@xxxxxxxxxxxxxx> <1205686219.17474.7.camel@xxxxxxxxxxxxxxxxxxxx>
Reply-to: "Daniel P. Berrange" <berrange@xxxxxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
User-agent: Mutt/1.4.1i
On Sun, Mar 16, 2008 at 05:50:19PM +0100, Daniel Stodden wrote:
> On Sun, 2008-03-16 at 15:52 +0100, Pavel Muller wrote:
> > Hello,
> > I want to ask if XEN use TUP/TAP interfaces or use other interface?
> 
> No. TUN/TAP is typically used for hosted VMs. Broadly speaking, it's
> only useful if a significant part of the VMM is running in user mode on
> top of a native Linux, as is the case with VMware Workstation,
> VirtualBox, UserModeLinux etc.
> 
> Xen is a hypervisor, running below all OSes on bare hardware. The
> network virtualization is based on a Linux OS (dom0), but the guests
> aren't running on top of that, but rather as siblings on a common
> virtualization layer.

Whether it is a separate hypervisor / Dom0, or a combined HV+Dom0 is not
really relevant to this question. In both cases the driver backends are 
in the Linux host OS and not the hypervisor itself.

> 
> There's a dedicated interface class (vifN.M) in dom0. The purpose is
> similar, but the interplay with guests is quite a different one.

This is correct for paravirt guest or PV drivers, but is wrong for fullvirt. 
The QEMU device model used for fullvirt guests *does* use TUN/TAP devices 
as the backend for its emulated ne2k/rtl8139 NICs.

Dan.
-- 
|: Red Hat, Engineering, Boston   -o-   http://people.redhat.com/berrange/ :|
|: http://libvirt.org  -o-  http://virt-manager.org  -o-  http://ovirt.org :|
|: http://autobuild.org       -o-         http://search.cpan.org/~danberr/ :|
|: GnuPG: 7D3B9505  -o-  F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 :|

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