Xen 3.x Configuration File Options

From Xen
Revision as of 11:52, 4 December 2011 by Lars (talk | contribs)

Icon todo.png To Do:

This page can probably be removed as the same content is available in Xen Man Pages; on the other hand it may make sense to just archive this under Xen 3.x

Icon todo.png Needs Formatting

Some character formatting issues that need fixing

Xen Configuration File Options

Originial Document at http://www.xen.org/files/Support/XenConfigurationDetails.pdf


This file contains a complete summary of all the configuration options available in open source Xen. I am using the Xen 3.4 source tree so some of these options may not be available in previous versions. The complete list of options is viewable in the python source file create.py in xen/tools/python/xen/xm/.

The file contains two types of configuration settings: options and variables. The options are listed below with a ** before them and variables are listed below in bold/italics.


To assist the reader of the document, here are some sample configurations that are commonly used. A complete list of examples can be found at /xen-3.4.0/tools/examples.

Example 1 (Comments in Italics) (from http://www.linuxdevcenter.com/pub/a/linux/2006/01/26/xen.html)

Kernel image file

kernel = /boot/vmlinuz-2.6.11-1.1366_FC4xenU

Initial memory allocation (MB) for new domain

memory = 128

Name of domain (must be unique)

name = "dokeos.x-tend.be"

Additional configuration settings

extra = "selinux=0 3"

Network Interfaces

vif = ['ip = "", bridge=xen-br0']

Disk devices domain has access to

disk = ['phy:vm_volumes/root.dokeos,sda1,w' ,'phy:vm_volumes/var.dokeos,sda3,w' ,'phy:vm_volumes/www.dokeos,sda4,w' ,'phy:vm_volumes/swap.dokeos,sda2,w' ]

Set root device

root = "/dev/sda1 ro"

Example 2 (Comments in Italics) (Source xmexample1 from Xen source code)

Kernel image file

kernel = "/boot/vmlinuz-2.6.10-xenU"

Optional ramdisk

ramdisk = “/boot/initrd.gz”

Domain build function; default is linux

builder = "linux"

Initial memory allocation (MB) for new domain

memory = 64

Name of domain (must be unique)

name = "ExampleDomain"

128-bit UUID for the domain

uuid = “06ed00fe-1162-4fc4-b5d8-11993ee4a8b9”

List of which CPUs this domain is allowed to use; VCPU0 runs on CPU2 & VCPU1 runs on CPU3

cpus = [“2”, “3”]

Number of virtual CPUs to use (default is 1)

vcpus = 2

Network interface created with defaults

vif = [ ]

Frame buffer device; default is no frame buffer; example below creates one using the SDL backend

vfb = [ 'sdl=1' ]

TPM instance the user domain should communicate

vtpm = [ 'instance=1,backend=0' ]

Root device for NFS

root = “/dev/nfs”

NFS server

nfs_server = ''

Root directory on NFS server

nfs_root = '/full/path/to/root/directory'

Sets runlevel 4

extra = “4”

Domain exit behavior settings

on_poweroff = 'destroy'

on_reboot = 'restart'

on_crash = 'restart'

Configure PVSCSI devices

vscsi = [ '/dev/sdx, 0:0:0:0' ]



  • help: Print this help.

help or h (default = 0)

  • help_config: Print the available configuration variables (vars) for the "configuration script

help_config (default = 0)


  • quiet:Quiet.

quiet or q (default =0)

  • path: Search path for configuration scripts

path (default='.:/etc/xen')

  • defconfig: Use the given Python configuration script

defconfig or f (default='xmdefconfig')

  • config: Domain configuration to use (SXP)

config or F (default=None)

  • dryrun: Dry run – prints the configuration in SXP but does not create the domain
dryrun or n (defaut = 0)
  • xmldryrun: Dry run – prints the configuration in XML but does not create the domain

xmldryrun or x (defaut = 0)

  • skipdtd: Skip DTD checking - skips checks on XML before creating.

skipdtd or s (default = 0)

  • paused: Leave the domain paused after it is created
paused or p (default=0)
  • vncviewer: Connect to the VNC display after the domain is created
vncviewer (default = 0)
  • vncviewer-autopass: Pass VNC password to viewer via stdin and -autopass

vncviewer-autopass (default = 0)

  • console_autoconnect:Connect to the console after the domain is created.

console_autoconnect or c (domain=0)


Kernel + Memory Size

  • kernel: Path to the kernel image

kernel (Default=' '; Value='FILE')

  • loader: Path to HVM firmware

loader (Default=' ' ;Value='FILE')

  • features: Features to enable in guest kernel

features (Default=' ';Value='FEAUTRES')

  • ramdisk: Path to ramdisk image (optional)


  • builder: Function to use to build the domain

builder (Default='linux'; Value='FUNCTION')

  • memory: Domain memory in MB

memory (Default=128; Value='MEMORY')

  • maxmem: Maximum domain memory in MB

maxmem (Default=None; Value='MEMORY')

  • boot: Default Boot Device

boot (Default='c';Value='a|b|c|d')

  • shadow_memory: Domain shadow memory in MB

shadow_memory (Default=0; Value='MEMORY)

  • bootloader: Path to bootloader

bootloader (default=None; Value='File')

  • bootargs: Arguments to pass to boot loader

bootargs (default=None; Value='Name')

  • bootentry: DEPRECATED. Entry to boot via boot loader. Use bootargs.

bootentry (default=None; Value='Name')

  • s3integrity: Should domain memory integrity be verified during S3? (0=protection is disabled;

1=protection is enabled. s3integrity (Default=1; Value='TBOOT_MEMORY_PROTECT')

  • machine_address_size: Maximum machine address size

machine_address_size (Default=None;Value='BITS')

  • suppress_spurious_page_faults: Do not inject spurious page faults into this guest

suppress_spurious_page_faults (Default=None;Value='yes|no')


  • cpu: CPU to run the VCPU0 on

cpu (default=None; Value='CPU')

  • cpus: CPUS to run the domain on

cpus (default=None; Value='CPUS')

  • cpu_cap: Set the maximum amount of cpu. CAP is a percentage that fixes the maximum

amount of cpu cpu_cap (default=None; Value='CAP')

  • cpu_weight: Set the cpu time ratio to be allocated to the domain

cpu_weight (default=None; Value='WEIGHT')

  • vcpus: # of Virtual CPUS in domain

vcpus (default=1; Value='VCPUS')

  • vcpus_avail: Bitmask for virtual CPUs to make available immediately

vcpus_avail (default=None; Value='VCPUS')

  • cpuid: Cpuid Description

cpuid (Default=[];Value=”IN[,SIN]:eax=EAX,ebx=EBX,ecx=EXC,edx=EDX”)

  • cpuid_check: Cpuid check Description

cpuid_check (Default=[];Value=”IN[,SIN]:eax=EAX,ebx=EBX,ecx=EXC,edx=EDX”)


  • hostname: Set the kernel IP hostname

hostname (Default=;Value=”NAME”)

  • ip: Set the kernel IP interface address.

ip (Default=' ' ; Value='IPADDR' )

  • interface: Set the kernel IP interface name.

interface (Default='”eth0”;Value=”INTF”)

  • dhcp: Set the kernel dhcp option

dhcp (Default='off'; Values=”off|dhcp”)

  • vif: Add a network interface with the given MAC address and bridge. The vif is configured by

calling the given configuration script. If type is not specified, default is netfront. If mac is not specified a random MAC address is used. If not specified then the network backend chooses it's own MAC address. If bridge is not specified the first bridge found is used. If script is not specified the default script is used. If backend is not specified the default backend driver domain is used. If vifname is not specified the backend virtual interface will have name vifD.N where D is the domain id and N is the interface id. If rate is not specified the default rate is used. If model is not specified the default model is used. If accel is not specified an accelerator plugin module is not used. This option may be repeated to add more than one vif. Specifying vifs will increase the number of interfaces as needed. vif (Default=[]; Value="type= TYPE, mac=MAC, bridge=BRIDGE, ip=IPADDR, script= SCRIPT," + \ "backend=DOM, vifname=NAME, rate=RATE, model=MODEL, accel=ACCEL" )

  • vtpm: Add a TPM interface. On the backend side use the given instance as virtual TPM

instance. The given number is merely the preferred instance number. The hotplug script will determine which instance number will actually be assigned to the domain. The associtation between virtual machine and the TPM instance number can be found in /etc/xen/vtpm.db. Use the backend in the given domain. The type parameter can be used to select a specific driver type that the VM can use. To prevent a fully virtualized domain (HVM) from being able to access an emulated device model, you may specify 'paravirtualized' here. vtpm (Default= [] ; Value= "instance=INSTANCE,backend=DOM,type=TYPE")

  • netmask: Set the kernel IP netmask

netmask (Default=' ' ; Value='MASK' )

  • gateway: Set the kernel IP gateway.

gateway (Default=' ' ; Value=”IPADDR” )

  • nfs_server: Set the address of the NFS server for NFS root.

nfs_server (Default=None;Value=”IPADDR”)

  • nfs_root: Set the path of the root NFS directory.

nfs_root (Default=None;Value=”PATH”)

  • device_model: Path to device model program.

device_model (Default=None;Value='FILE')

  • uuid: xenstore UUID (universally unique identifier) to use. One will be randomly generated if

this option is not set, just like MAC addresses for virtual network interfaces. This must be a unique value across the entire cluster. uuid (Default=None;Value=)

  • ioports: Add a legacy I/O range to a domain, using given params (in hex). For example

'ioports=02f8-02ff'. The option may be repeated to add more than one i/o range ioports (Default= [] ; Value= 'FROM[-TO]')


  • pci:Add a PCI device to a domain, using given params (in hex). For example 'pci=c0:02.1'.

If VSLOT is supplied the device will be inserted into that virtual slot in the guest, else a free slot is selected. If msitranslate is set, MSI-INTx translation is enabled if possible. Guest that doesn't support MSI will get IO-APIC type IRQs translated from physical MSI, HVM only. Default is 1. The option may be repeated to add more than one pci device. If power_mgmt is set, the guest OS will be able to program the power states D0-D3hot of the device, HVM only. Default=0. pci (Default=[]; Value=BUS:DEV.FUNC[@VSLOT][,msitranslate=0|1][,power_mgmt=0| 1]

  • vscsi: Add a SCSI device to a domain. The physical device is PDEV, which is exported to the

domain as VDEV(X:X:X:X) vscsi (Default= [];Value= 'PDEV,VDEV[,DOM]')

  • pci_msitranslate: Global PCI MSI-INTx translation flag (0=disable;1=enable)

pci_msitranslate (Default=1; Value='TRANSLATE')

  • pci_power_mgmt: Global PCI Power Management flag (0=disable; 1=enable)

pci_power_mgmt (Default=0; Value='POWERMGT')

  • xen_platform_pci: Is xen_platform_used?

xen_platform_pci (Default=1; Value='0|1')

  • serial:Path to serial or pty or vc

serial (Default=' ';Value='FILE')

  • keymap: Set keyboard layout used

keymap (Default=' '; Value='FILE')

  • usb: Emulate USB devices

usb (Default=0; Value='no|yes')

  • usbdevice: Name of USB device

usbdevice (Default=' '; Value='NAME')


  • viridian:Expose Viridian interface to x86 HVM guest?

viridian (default=0; Value='VIRIDIAN')

  • pae: Disable or enable PAE of HVM domain

pae (default=1; Value='PAE')

  • hap: Hardware Assisted Paging (HAP) status (0=hap is disabled;1=hap is enabled.)

hap (Default=1; Value='HAP')

  • acpi: Disable or enable ACPI of HVM domain.

acpi (default=1; Value='ACPI')

  • apic: Disable or enable APIC mode

apic (default=1; Value='APIC')


  • rtc_timeoffset: Set RTC offset

rtc_timeoffset (default=0; Value='RTC_TIMEOFFSET')

  • timer_mode: Timer mode (0=delay virtual time when ticks are missed; 1=virtual time is

always wallclock time timer_mode (default=1; Value='TIMER_MODE')

  • localtime: Is RTC set to localtime?

Localtime (Default=0; Value='no|yes')

  • vpt_align: Enable aligning all periodic vpt to reduce timer interrupts

vpt_align (default=1; Value='VPT_ALIGN')

  • vhpt: Log2 of domain VHPT size for IA64

vhpt (default=0; Value='VHPT')

  • hpet: Enable virtual high-precision event timer

hpet (default=0; Value='HPET')


  • irq: Add an IRQ (interrupt line) to a domain. For example 'irq=7'. This option may be repeated

to add more than one IRQ irq (Default = []; Value = 'IRQ')

  • blkif: Make the domain a block device backend.

blkif (Default=0; Value='no|yes')

  • netif: Make the domain a network interface backend

netif (Default=0; Value='no|yes')

  • tmpif: Make the domain a TPM interface backend

tmpif (Default=0; Value='no|yes')

  • vfb:Make the domain a framebuffer backend. Both sdl=1 and vnc=1 can be enabled at the same

time.For vnc=1, connect an external vncviewer. The server will listen on ADDR (default on port N+5900. N defaults to the domain id. If vncunused=1, the server will try to find an arbitrary unused port above 5900. vncpasswd overrides the XenD configured default password. For sdl=1, a viewer will be started automatically using the given DISPLAY and XAUTHORITY, which default to the current user's ones. OpenGL will be used by default unless opengl is set to 0. keymap overrides the XendD configured default layout file vfb (Default=[];Value= "vnc=1,sdl=1, vncunused=1, vncdisplay=N, vnclisten=ADDR, display=DISPLAY, xauthority=XAUTHORITY,vncpasswd=PASSWORD, opengl=1, keymap=FILE")

Disk Devices

  • root: Set the root= parameter on the kernel command line.

Use a device, e.g. /dev/sda1, or /dev/nfs for NFS root root (Default =' '; Value='DEVICE')

  • disk: Add a disk device to a domain. The physical device is DEV, which is exported to the

domain as VDEV. The disk is read-only if MODE is 'r', read-write if MODE is 'w'. If DOM is specified it defines the backend driver domain to use for the disk. The option may be repeated to add more than one disk disk (default=[] ; Value='phy:DEV,VDEV,MODE[,DOM]')

  • access_control:Add a security label and the security policy reference that defines it.

The local ssid reference is calculated when starting/resuming the domain. At this time, the policy is checked against the active policy as well. This way, migrating through save/restore is covered and local labels are automatically created correctly on the system where a domain is started / resumed. access_control (Default= [] ; Value=”policy=POLICY,label=LABEL")


  • on_poweroff: Behavior when a domain exits with reason 'poweroff

on_poweroff (Default=None; Value='destroy|restart|preserve|rename-restart')

  • on_reboot: Behavior when a domain exits with reason 'reboot'

on_reboot (Default=None; Value='destroy|restart|preserve|rename-restart')

  • on_crash: Behavior when a domain exits with reason 'crash'

on_crash (Default=None; Value='destroy|restart|preserve|rename-restart|coredump-destroy| coredump-restart)

  • on_xend_start: Action to preform when xend starts

on_xend_start (Default='ignore'; Value='ignore|start')

  • on_xend_stop: Behaviour when Xend stops:

- ignore: Domain continues to run; - shutdown: Domain is shutdown; - suspend: Domain is suspended; on_xend_stop (Default='ignore'; Value='ignore|shutdown|suspend')

  • target: Set domain target

target (Default=0; Value='TARGET')

Graphics and Audio

  • console: Port to export the domain console on

console = /dev/console

  • nographic: Should device models use graphics

nographic (Default=0;Value='no|yes')

  • soundhw: Should device models enable audio device

soundhw (Default=' ';Value='audiodev')

  • sdl:Should the device model use SDL?

sdl (Default=None;Value=)

  • opengl: Enable\Disable OpenGL

opengl (Default=None; Value=' ')

  • vnc: Should the device model use VNC?

vnc (Default=None;Value=' ')

  • vncunused: Try to find an unused port for the VNC server. Only valid when vnc=1

vncdunused (Default=1;Value=' ')

  • videoram: Maximum amount of videoram a guest can allocate for frame buffer

videoram (Default=4; Value='MEMORY')

  • vncdisplay: VNC Display to use

vncdisplay (Default=None;Value=' ')

  • vnclisten: Address for VNC server to listen on

vnclisten (Default=None; Value=' ')

  • vncpasswd: Password for VNC console on HVM domain

vncpasswd='xxxxx' (default=None)

  • vncviewer: Spawn a vncviewer listening for a vnc server in the domain. The address of the

vncviewer is passed to the domain on the kernel command line using 'VNC_SERVER=<host>:<port>'. The port used by vnc is 5500 + DISPLAY. A display value with a free port is chosen if possible.\nOnly valid when vnc=1.\nDEPRECATED vncviewer (default = None; Value = 'no|yes')

  • vncconsole: Spawn a vncviewer process for the domain's graphical console. Only valid when

vnc=1 vncconsole (default=None; Value = 'no|yes')

  • stdvga: Use std vga or Cirrhus Logic Graphics

stdvga (Default=0; Value='no|yes')

  • isa: Simulate an ISA only system

isa (Default=0; Value='no|yes')

  • guest_os_type: Guest OS type running in HVM

guest_os_type (Default='default'; Value='NAME')

  • extra: Set extra arguments to append to the kernel command line

extra (Default=' ' ; Value = “ARGS” )

  • fda: Path to fda

fda (Default=' ';Value=FILE)

  • fdd: Path to fdb

fdb (Default=' ';Value=FILE)

  • display: X11 display to use

display (Default=None;Value='DISPLAY')

  • xauthority: X11 authority to use

display (Default=None;Value='XAUTHORITY')