vmctl(8) - OpenBSD manual pages

NAME

vmctl — control the virtual machine daemon

The vmctl utility is used to control the virtual machine monitor (VMM) subsystem. A VMM manages virtual machines (VMs) on a host. The VMM subsystem is responsible for creating, destroying, and executing VMs.

Within the commands, the size argument can be specified with a human-readable scale, using the format described in scan_scaled(3). The id argument can be either a numeric, non-zero identifier or alternatively the name of a virtual machine.

The commands are as follows:

console id

Using cu(1) connect to the console of the VM with the specified id.

create path -s [size [-b base]]

Creates a VM disk image file with the specified path and size, rounded to megabytes. The disk path may be prefixed with a format prefix (raw: or qcow2:) in order to specify the disk format. If left unspecified, the format defaults to raw if it cannot be derived automatically. For qcow2, a base image may be specified. The base image is not modified. The derived image contains only the changes written by the VM. When creating a derived image, the size may be omitted, and probed from the base image. If it is provided, it must match the base image size.

load filename

Load additional configuration from the specified file.

log brief

Disable verbose debug logging.

log verbose

Enable verbose debug logging.

pause id

Pause a VM with the specified id.

receive name

Receive a VM from standard input and start it with the specified name.

reload

Remove all stopped VMs and reload the configuration from the default configuration file.

reset [all]

Reset the running state.

reset switches

Reset the configured switches.

reset vms

Reset and terminate all VMs.

send id

Send a VM with the specified id to standard output and terminate it. The VM is paused during send processing. Data sent to standard output contains the VM parameters and its memory, not the disk image.

In order to move a VM from one host to another, disk files must be synced between the send and the receive processes and must be located under the same path.

show [id]

An alias for the status command.

start name [-cL] [-b path] [-d path] [-i count] [-m size] [-n switch] [-r path] [-t name]

Starts a VM defined by the specified name and parameters:

-b path: Boot the VM with the specified kernel or BIOS image. If not specified, the default is to boot using the BIOS image in /etc/firmware/vmm-bios.
-c: Automatically connect to the VM console.
-d path: Disk image file (may be specified multiple times to add multiple disk images). The disk path may be prefixed with a format prefix (raw: or qcow2:) in order to specify the disk format. If left unspecified, the format defaults to raw if it cannot be derived automatically.
-i count: Number of network interfaces to add to the VM.
-L: Add a local network interface. vmd(8) will auto-generate an IPv4 subnet for the interface, configure a gateway address on the VM host side, and run a simple DHCP/BOOTP server for the VM. See LOCAL INTERFACES below for more information on how addresses are calculated and assigned when using the -L option.
-m size: Memory size of the VM, rounded to megabytes. The default is 512M.
-n switch: Add a network interface that is attached to the specified virtual switch. See SWITCH CONFIGURATION in vm.conf(5) for more information.
-r path: ISO image file for virtual CD-ROM. This image file will be available in the selected VM as a SCSI CD-ROM device attached to a virtio SCSI adapter (e.g. vioscsi(4)).
-t name: Use an existing VM with the specified name as a template to create a new VM instance. The instance will inherit settings from the parent VM, except for exclusive options such as disk, interface lladdr, or interface names.

Note that the VM name supplied to the 'start' command can only consist of alphanumeric characters, including '.', '-', and '_'. The name cannot start with '.', '-' or '_'.

status [id]

Lists VMs running on the host, optionally listing just the selected VM id.

stop id [-fw]

Stops (terminates) a VM defined by the specified VM id. By default, a graceful shutdown will be attempted if the VM supports the vmmci(4) device. Once stopped, if the VM was not defined in a configuration file, then it is removed.

The following options can be specified when stopping a VM:

-f: Forcefully stop the VM without attempting a graceful shutdown.
-w: Wait until the VM has been terminated.

stop -a [-fw]

Stop all running VMs.

unpause id

Unpause (resume from a paused state) a VM with the specified id.

If the -i option is specified during VM startup, a corresponding number of host-side tap(4) interfaces will be allocated and mapped to the vio(4) interfaces inside the guest VM. This tap/vio interface mapping allows guest network traffic to be manipulated by the host. Any valid host-side interface configuration may be performed on these tap interfaces, such as bridging (via bridge(4)), or using pf(4) nat-to rules to create private or host-side NATed networks, as desired.

LOCAL INTERFACES

Local interfaces can be used to easily configure VM networking without needing to manually assign network addresses. A local interface is added to a VM using the -L option to the 'vmctl start' command and results in the addition of a vio(4) interface inside the VM and a corresponding tap(4) interface on the host. When using local interfaces, vmd(8) will provide DHCP services to the guest VM and offer addresses selected from the 100.64.0.0/10 IPv4 range. From within the 100.64.0.0/10 range, vmd(8) allocates a pair of addresses for the guest-side vio(4) and host-side tap(4) interfaces as follows:

For the first local interface:

The host (tapX) address is assigned 100.64.n.2, where 'n' is the numeric VM ID visible in the 'vmctl status' command
The guest (vio0) address is assigned 100.64.n.3

For the second and subsequent local interface(s):

The second local interface uses 100.64.n.4 and 100.64.n.5 for the host (tapX) and guest (vio1) interfaces, respectively.
Subsequent local interfaces are numbered similarly, continuing with 100.64.n.6 and 100.64.n.7, etc

Multiple -L options can be provided to the 'vmctl start' command, if more than one interface is desired. Local interfaces are assigned to the VM before any other interfaces specified with the -i option (thus, local interfaces, if requested, are numbered starting at vio0 inside the guest VM).

When using local interfaces, the DHCP configuration offered to the guest VM specifies the address of the corresponding host tap(4) interface as both the default route and the (sole) nameserver. Guest VM traffic can optionally be NATed through the host with an entry in the host machine's /etc/pf.conf similar to the following:

pass out on $ext_if from 100.64.0.0/10 to any nat-to $ext_if

If NAT is desired, the net.inet.ip.forwarding sysctl(8) must also be set to 1.

If desired, DNS queries originating from guest VMs can be redirected to a different DNS server with an entry in the host machine's /etc/pf.conf similar to the following:

pass in proto udp from 100.64.0.0/10 to any port domain \
      rdr-to $dns_server port domain

FILES

/etc/vm.conf: Default configuration file.
/var/run/vmd.sock: UNIX-domain socket used for communication with vmd(8).

EXIT STATUS

The vmctl utility exits 0 on success, and >0 if an error occurs. vmctl may fail due to one of the following reasons:

The VMM subsystem could not be enabled or disabled as requested.
A requested VM-based operation could not be completed.

EXAMPLES

Create a 4.5 Gigabyte disk image, disk.img:

$ vmctl create disk.img -s 4.5G

Create a new VM with 1GB memory, one network interface, one disk image ('disk.img') and boot from kernel '/bsd':

# vmctl start "myvm" -m 1G -i 1 -b /bsd -d disk.img

Start a new VM instance with the name 'myvm' from a pre-configured VM 'openbsd.4G':

# vmctl start "myvm" -t "openbsd.4G" -d mydisk.img

vmd(8) will create a new tap(4) network interface on the host side and set the description to indicate the VM by ID, interface number, and name:

# ifconfig tap0
tap0: flags=8842<BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
	lladdr fe:e1:ba:d8:50:d1
	description: vm1-if0-myvm
	index 15 priority 0 llprio 3
	groups: tap
	status: active

Terminate VM number 1: