DomU

=Xen - [|DomU]=

A DomU is the counterpart to Dom0; it is an unprivileged [|domain] with (by default) no access to the hardware. It must run a [|FrontendDriver] for multiplexed hardware it wishes to share with other domains. A DomU is started by xend in Dom0, which the user accesses with the xm command-line tool. The kernel for a DomU comes from Dom0's filesystem, not from the filesystem exported to the DomU.

=[|XenDomUSupport]=

=DomU support in Linux distributions=

This page describes the current status of support in Linux distributions for running as Xen guests; if you are looking for dom0 support go [|here]. PV is the regular domU support that has been present in most Linux distributions for years and it is required to run on Amazon EC2 for example. PV on HVM is a new type of Xen guest support that exploits hardware nested paging while enabling PV interfaces for IO. Depending on the workload PV on HVM guests might be faster or slower than regular PV guests. See [[|3]] for more information.
 * **Distribution** || **run as PV guest** || **run as PV on HVM guest**[3] ||
 * Debian Lenny || yes || no ||
 * Debian Squeeze || yes || yes ||
 * Ubuntu 10.04 || yes[1] || no ||
 * Ubuntu 11.04 || yes[1] || yes[1] ||
 * Fedora 14 || yes || no ||
 * RHEL 5 || yes || yes ||
 * RHEL 6 || yes || yes[2] ||
 * SLES 10 || yes || yes ||
 * SLES 11 || yes || yes ||
 * OpenSUSE 11.4 || yes || yes ||
 * = **Planned or in beta as of October 2011** ||
 * Ubuntu 12.04 || yes[1] || yes[1] ||
 * Fedora 16 || yes || yes ||

[1] EC2 kernel only

[2] save/restore is known to have [|bugs]

[3] see [|XenLinuxPVonHVMdrivers] for resources about using optimized (paravirtualized) PV-on-HVM drivers =DomU support in BSDs and other Unix systems=

This list is currently incomplete. We are in the process of verifying support for Unixes.
 * **Distribution** || **run as PV guest** || **run as PV on HVM guest** ||
 * FreeBSD 8.2 || yes[3] || yes[3] ||
 * NetBSD 5.1 || yes[4] || yes[4] ||
 * [|OpenIndiana][5] || no[5] || yes ||

[3] See [|FreeBSD Xen page for more information]

[4] See [|NetBSD Xen HowTo for more information]

[5] There has not yet been a stable release of [|OpenIndiana] and there is some unclarity on whether it will work as PV guest

=DomU support for Windows=

Windows falls into the category of an unmodified operating system (in other words an operating system that has not been altered specifically to run on the Xen hypervisor). Thus, paravirtualization is not an option. The best way, therefore, to virtualize Windows is to use as a HVM) guest. The //Windows 7/XP/Vista/Server 2008// section of the [|HowTos] document points to instructions explaining how to do this. However, James Harper maintains a set of PV drivers that allow Windows to make use of the network and block backend drivers in Dom0. This gives Windows on Xen a substantial performance boost. The table below shows the drivers available. [6] GPLPV drivers can be downloaded from [|meadowcourt.org/downloads]; further information can be found on [|XenWindowsGplPv] [7] Signed GPLPV drivers are available for download from [|Uninvention]
 * **Distribution** || **run as PV guest** || **run as PV on HVM guest** ||
 * Windows Vista || no || yes[6][7] ||
 * Windows XP || no || yes[6][7] ||
 * Windows 2008 || no || yes[6][7] ||
 * Windows 2003 || no || yes[6][7] ||
 * Windows 2000 || no || yes[6][7] ||
 * Windows 7 || no || yes[6][7] ||