CentOS 5 Virtualization Guide - Chapter 24. Configuration files

Chapter 24. Configuration files

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Red Hat Virtualization configuration files contain the following standard variables. Configuration items within these files must be enclosed in single quotes('). These configuration files reside in the /etc/xen directory.

Item	Description
`pae`	Specifies the physical address extension configuration data.
`apic`	Specifies the advanced programmable interrupt controller configuration data.
`memory`	Specifies the memory size in megabytes.
`vcpus`	Specifies the numbers of virtual CPUs.
`console`	Specifies the port numbers to export the domain consoles to.
`nic`	Specifies the number of virtual network interfaces.
`vif`	Lists the randomly-assigned MAC addresses and bridges assigned to use for the domain's network addresses.
`disk`	Lists the block devices to export to the domain and exports physical devices to domain with read only access.
`dhcp`	Enables networking using DHCP.
`netmask`	Specifies the configured IP netmasks.
`gateway`	Specifies the configured IP gateways.
`acpi`	Specifies the advanced configuration power interface configuration data.

Table 24.1. Red Hat Virtualization configuration files

The table below, Table 24.2, “Red Hat Virtualization configuration files reference”, is formatted output from xm create --help_config.

Parameter	Description
`vncpasswd` = `NAME`	Password for VNC console on HVM domain.
vncviewer=`no` \| `yes`	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. Only valid when vnc=1.
`vncconsole` =`no` \| `yes`	Spawn a vncviewer process for the domain's graphical console. Only valid when vnc=1.
`name` = `NAME`	Domain name. Must be unique.
`bootloader` = `FILE`	Path to boot loader.
`bootargs` = `NAME`	Arguments to pass to boot loader.
`bootentry` = `NAME`	DEPRECATED. Entry to boot via boot loader. Use `bootargs` .
`kernel` = `FILE`	Path to kernel image.
`ramdisk` = `FILE`	Path to ramdisk.
`features` = `FEATURES`	Features to enable in guest kernel
`builder` = `FUNCTION`	Function to use to build the domain.
`memory` = `MEMORY`	Domain memory in MB.
`maxmem` = `MEMORY`	Maximum domain memory in MB.
`shadow_memory` = `MEMORY`	Domain shadow memory in MB.
`cpu` = `CPU`	CPU to run the VCPU0 on.
`cpus` = `CPUS`	CPUS to run the domain on.
`pae` = `PAE`	Disable or enable PAE of HVM domain.
`acpi` = `ACPI`	Disable or enable ACPI of HVM domain.
`apic` = `APIC`	Disable or enable APIC of HVM domain.
`vcpus` = `VCPUS`	# of Virtual CPUS in domain.
`cpu_weight` = `WEIGHT`	Set the new domain's cpu weight. `WEIGHT` is a float that controls the domain's share of the cpu.
`restart` = `onreboot` \| `always` \| `never`	Deprecated. Use `on_poweroff,` `on_reboot` , and `on_crash` instead. Whether the domain should be restarted on exit. - `onreboot` : restart on exit with shutdown code reboot - always: always restart on exit, ignore exit code - never: never restart on exit, ignore exit code
`on_poweroff` = `destroy` \| `restart` \| `preserve` \| `destroy`	Behavior when a domain exits with reason 'poweroff'. - destroy: the domain is cleaned up as normal; - restart: a new domain is started in place of the old one; - preserve: no clean-up is done until the domain is manually destroyed (using xm destroy, for example); - rename-restart: the old domain is not cleaned up, but is renamed and a new domain started in its place.
`on_reboot` = `destroy` \| `restart` \| `preserve` \| `destroy`	Behavior when a domain exits with reason 'reboot'. - destroy: the domain is cleaned up as normal; - restart: a new domain is started in place of the old one; - preserve: no clean-up is done until the domain is manually destroyed (using xm destroy, for example); - rename-restart: the old domain is not cleaned up, but is renamed and a new domain started in its place.
`on_crash` = `destroy` \| `restart` \| `preserve` \| `destroy`	Behavior when a domain exits with reason 'crash'. - destroy: the domain is cleaned up as normal; - restart: a new domain is started in place of the old one; - preserve: no clean-up is done until the domain is manually destroyed (using xm destroy, for example); - rename-restart: the old domain is not cleaned up, but is renamed and a new domain started in its place.
`blkif` =`no` \| `yes`	Make the domain a block device backend.
`netif` =`no` \| `yes`	Make the domain a network interface backend.
`tpmif` =`no` \| `yes`	Make the domain a TPM interface backend.
`disk` = `phy:DEV,VDEV,MODE[,DOM]`	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.
`pci` = `BUS:DEV.FUNC`	Add a PCI device to a domain, using given parameters (in hex). For example `pci=c0:02.1a` . The option may be repeated to add more than one pci device.
`ioports` = `FROM[-TO]`	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.
`irq` = `IRQ`	Add an IRQ (interrupt line) to a domain. For example `irq=7` . This option may be repeated to add more than one IRQ.
`usbport` = `PATH`	Add a physical USB port to a domain, as specified by the path to that port. This option may be repeated to add more than one port.
`vfb=type= {vnc,sdl} , vncunused= 1 , vncdisplay= N ,` `vnclisten= ADDR , display= DISPLAY ,` `xauthority= XAUTHORITY , vncpasswd= PASSWORD ,` `keymap` = `KEYMAP`	Make the domain a framebuffer backend. The backend type should be either `sdl` or `vnc` . For `type=vnc` , connect an external vncviewer. The server will listen on `ADDR` (default 127.0.0.1) 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. For `type=sdl` , a viewer will be started automatically using the given `DISPLAY` and `XAUTHORITY` , which default to the current user's ones.
`vif=type= TYPE , mac= MAC , bridge= BRIDGE , ip= IPADDR ,` `script= SCRIPT , backend= DOM , vifname` = `NAME`	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 not ioemu device. 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. This option may be repeated to add more than one vif. Specifying vifs will increase the number of interfaces as needed.
`vtpm=instance=` `INSTANCE` ,backend= `DOM`	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 association between virtual machine and the TPM instance number can be found in `/etc/xen/vtpm.db`. Use the backend in the given domain.
`access_control=policy=` `POLICY` ,label= `LABEL`	Add a security label and the security policy reference that defines it. The local ssid reference is calculated when starting or resuming the domain. At this time, the policy is checked against the active policy as well. This way, migrating through the save or restore functions are covered and local labels are automatically created correctly on the system where a domain is started or resumed.
`nics` = `NUM`	DEPRECATED. Use empty vif entries instead. Set the number of network interfaces. Use the vif option to define interface parameters, otherwise defaults are used. Specifying vifs will increase the number of interfaces as needed.
`root` = `DEVICE`	Set the `root` = parameter on the kernel command line. Use a device, e.g. `/dev/sda1`, or `/dev/nfs` for NFS root.
`extra` = `ARGS`	Set extra arguments to append to the kernel command line.
`ip` = `IPADDR`	Set the kernel IP interface address.
`gateway` = `IPADDR`	Set the kernel IP gateway.
`netmask` = `MASK`	Set the kernel IP netmask.
`hostname` = `NAME`	Set the kernel IP hostname.
`interface` = `INTF`	Set the kernel IP interface name.
`dhcp` = `off\|dhcp`	Set the kernel dhcp option.
`nfs_server` = `IPADDR`	Set the address of the NFS server for NFS root.
`nfs_root` = `PATH`	Set the path of the root NFS directory.
`device_model` = `FILE`	Path to device model program.
`fda` = `FILE`	Path to fda
`fdb` = `FILE`	Path to fdb
`serial` = `FILE`	Path to serial or pty or vc
`localtime` =`no` \| `yes`	Is RTC set to localtime
`keymap` = `FILE`	Set keyboard layout used
`usb` =`no` \| `yes`	Emulate USB devices
`usbdevice` = `NAME`	Name of a `USB` device to add
`stdvga` =`no` \| `yes`	Use `std vga` or Cirrus Logic graphics
`isa` =`no` \| `yes`	Simulate an `ISA` only system
`boot` = `a\|b\|c\|d`	Default boot device
`nographic` =`no` \| `yes`	Should device models use graphics?
`soundhw` = `audiodev`	Should device models enable audio device?
`vnc`	Should the device model use VNC?
`vncdisplay`	VNC display to use
`vnclisten`	Address for VNC server to listen on.
`vncunused`	Try to find an unused port for the VNC server. Only valid when vnc=1.
`sdl`	Should the device model use SDL?
`display` = `DISPLAY`	X11 display to use
`xauthority` = `XAUTHORITY`	X11 Authority to use
`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.

Table 24.2. Red Hat Virtualization configuration files reference

Table 24.4, “Configuration parameter default values” lists all configuration parameters available, the Python parser function used to set the value and each parameter's default value. The setter function gives an idea of what the parser does with the values you specify. It reads them as Python values, then feeds them to a setter function to store them. If the value is not valid Python, you get an obscure error message. If the setter rejects your value, you should get a reasonable error message, except it appears to get lost somehow, along with your bogus setting. If the setter accepts, but the value makes no sense, the program proceeds, and you can expect it to fall flat on its face somewhere down the road.

Parser function	Valid arguments
`set_bool`	Accepted values: `yes` `y` `no` `yes`
`set_float`	Accepts a floating point number with Python's float(). For example: `3.14` `10.` `.001` `1e100` `3.14e-10`
`set_int`	Accepts an integer with Python's int().
`set_value`	accepts any Python value.
`append_value`	accepts any Python value, and appends it to the previous value which is stored in an array.

Table 24.3. Python functions used to set parameter values

Parameter	Parser function	Default value
`name`	`setter`	`default value`
`vncpasswd`	`set_value`	`None`
`vncviewer`	`set_bool`	`None`
`vncconsole`	`set_bool`	`None`
`name`	`set_value`	`None`
`bootloader`	`set_value`	`None`
`bootargs`	`set_value`	`None`
`bootentry`	`set_value`	`None`
`kernel`	`set_value`	`None`
`ramdisk`	`set_value`	`''`
`features`	`set_value`	`''`
`builder`	`set_value`	`'linux'`
`memory`	`set_int`	`128`
`maxmem`	`set_int`	`None`
`shadow_memory`	`set_int`	`0`
`cpu`	`set_int`	`None`
`cpus`	`set_value`	`None`
`pae`	`set_int`	`0`
`acpi`	`set_int`	`0`
`apic`	`set_int`	`0`
`vcpus`	`set_int`	`1`
`cpu_weight`	`set_float`	`None`
`restart`	`set_value`	`None`
`on_poweroff`	`set_value`	`None`
`on_reboot`	`set_value`	`None`
`on_crash`	`set_value`	`None`
`blkif`	`set_bool`	`0`
`netif`	`set_bool`	`0`
`tpmif`	`append_value`	`0`
`disk`	`append_value`	`[]`
`pci`	`append_value`	`[]`
`ioports`	`append_value`	`[]`
`irq`	`append_value`	`[]`
`usbport`	`append_value`	`[]`
`vfb`	`append_value`	`[]`
`vif`	`append_value`	`[]`
`vtpm`	`append_value`	`[]`
`access_control`	`append_value`	`[]`
`nics`	`set_int`	`-1`
`root`	`set_value`	`''`
`extra`	`set_value`	`''`
`ip`	`set_value`	`''`
`gateway`	`set_value`	`''`
`netmask`	`set_value`	`''`
`hostname`	`set_value`	`''`
`interface`	`set_value`	`"eth0"`
`dhcp`	`set_value`	`'off'`
`nfs_server`	`set_value`	`None`
`nfs_root`	`set_value`	`None`
`device_model`	`set_value`	`''`
`fda`	`set_value`	`''`
`fdb`	`set_value`	`''`
`serial`	`set_value`	`''`
`localtime`	`set_bool`	`0`
`keymap`	`set_value`	`''`
`usb`	`set_bool`	`0`
`usbdevice`	`set_value`	`''`
`stdvga`	`set_bool`	`0`
`isa`	`set_bool`	`0`
`boot`	`set_value`	`'c'`
`nographic`	`set_bool`	`0`
`soundhw`	`set_value`	`''`
`vnc`	`set_value`	`None`
`vncdisplay`	`set_value`	`None`
`vnclisten`	`set_value`	`None`
`vncunused`	`set_bool`	`1`
`sdl`	`set_value`	`None`
`display`	`set_value`	`None`
`xauthority`	`set_value`	`None`
`uuid`	`set_value`	`None`

Chapter 24. Configuration files

Table 24.1. Red Hat Virtualization configuration files

Table 24.2. Red Hat Virtualization configuration files reference

Table 24.3. Python functions used to set parameter values

Table 24.4. Configuration parameter default values