--- name: "vmctl" section: "8" platform: "openbsd" package: "man" version: "8.0-current-20261101" release: "OpenBSD 8.0-current (2026-11-01)" platforms: ["openbsd"] url: "https://new.carta.tech/vmctl" --- # vmctl(8) control the virtual machine daemon ## NAME **vmctl** – control the virtual machine daemon ## SYNOPSIS **vmctl** \[**-v**\] *command* \[*arg* *...*\] ## DESCRIPTION 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. The **-v** option enables verbose mode. 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 *name* argument can only consist of alphanumeric characters, as well as '.', '-', and '\_', and must start with a letter. The *disk* argument is used by commands that take a path to a disk image file. It may be prefixed with a format prefix (raw:*disk* or qcow2:*disk*) in order to specify the disk image format. If left unspecified, the format defaults to ‘raw’ if it cannot be derived automatically. The commands are as follows: - **console** *id* Using [cu(1)](/cu/1.md) connect to the console of the VM with the specified *id*. - **create** \[**-b** *base* \| **-i** *disk*\] \[**-s** *size*\] *disk* Create a VM disk image file with the specified *disk* path. - **-b** *base* For ‘qcow2’, a *base* image may be specified. The base image is not modified and the derived image contains only the changes written by the VM. - **-i** *disk* Copy and convert the input *disk* to the newly created disk. This option conflicts with **-b** *base*. - **-s** *size* Specify the *size* of the new disk image, rounded to megabytes. If the **-b** option is specified, the size must match the size of the *base* image. For the **-i** option, the size cannot be smaller than the input disk size. The size can be omitted with the **-b** and **-i** options and will be obtained from the base or input image respectively. - **load** *filename* Load additional configuration from the specified file. - **log** **brief** \| **verbose** Disable or enable verbose debug logging. - **pause** *id* Pause a VM with the specified *id*. - **reload** Remove all stopped VMs and reload the configuration from the default configuration file. VMs that are currently running will not have their configuration reloaded. To reload configurations for currently running VMs, stop those VMs before issuing the reload command. - **reset** \[**all** \| **switches** \| **vms**\] Reset the running state, reset **switches**, or reset and terminate all **vms**. - **show** \[**-r**\] \[*id*\] An alias for the **status** command. - **start** \[**-cL**\] \[**-B** *device*\] \[**-b** *path*\] \[**-d** *disk*\] \[**-i** *count*\] \[**-m** *size*\] \[**-n** *switch*\] \[**-p** *count*\] \[**-r** *path*\] \[**-t** *name*\] *id* \| *name* Start a new VM *name* with the specified parameters. An existing VM may be started by referencing its *id*. - **-B** *device* Force system to boot from the specified device for this boot. *device* can be set to: - *cdrom* Boot the CD-ROM image. - *disk* Boot from disk. - *net* Perform a PXE boot using the first network interface. Currently *net* is only supported when booting a kernel using the **-b** flag while *disk* and *cdrom* only work with VMs booted using BIOS. - **-b** *path* Boot the VM with the specified OpenBSD kernel or custom BIOS image. If not specified, the default is to boot using the BIOS image in */etc/firmware/vmm-bios*. If the VM is an existing VM, use the provided image for only the next boot. - **-c** Automatically connect to the VM console. - **-d** *disk* Use a disk image at the specified *disk* path (may be specified multiple times to add multiple disk images). - **-i** *count* Number of network interfaces to add to the VM. - **-L** Add a local network interface. [vmd(8)](/vmd/8.md) 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. The maximum amount of memory assignable to a VM is governed by the datasize parameter for the vmd user in */etc/login.conf*. - **-n** *switch* Add a network interface that is attached to the specified virtual *switch*. See the SWITCH CONFIGURATION section in [vm.conf(5)](/vm.conf/5.md) for more information. - **-p** *count* Number of virtual CPUs to provide to a newly created VM or VM instance, or override the configured count for the next boot of an existing VM. The default is 1 and the maximum is 64. - **-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)](/vioscsi/4.md)). - **-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, and interface names. - **status** \[**-r**\] \[*id*\] List VMs running on the host, optionally listing just the selected VM *id*. If the **-r** flag is present, the output will only contain running VMs. - **stop** \[**-fw**\] \[**-a** \| *id*\] Stop (terminate) a VM defined by the specified VM *id* or all running VMs (**-a**). By default, a graceful shutdown will be attempted if the VM supports the [vmmci(4)](/vmmci/4.md) device. 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. - **unpause** *id* Unpause (resume from a paused state) a VM with the specified *id*. - **wait** *id* Wait until the specified VM has stopped. If the **-i**, **-L**, or **-n** options are specified during VM startup, a corresponding number of host-side [tap(4)](/tap/4.md) interfaces will be allocated and mapped to the [vio(4)](/vio/4.md) 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 [veb(4)](/veb/4.md)), or using [pf(4)](/pf/4.md) nat-to rules to create private or host-side NATed networks, as desired. For each [tap(4)](/tap/4.md) network interface on the host, [vmd(8)](/vmd/8.md) will set the interface's description to allow easy identification of the corresponding VM by ID, interface number, and name: ``` # ifconfig tap0 tap0: flags=8842 mtu 1500 lladdr fe:e1:ba:d8:50:d1 description: vm1-if0-myvm index 15 priority 0 llprio 3 groups: tap status: active ``` ## 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)](/vio/4.md) interface inside the VM and a corresponding [tap(4)](/tap/4.md) interface on the host. When using local interfaces, [vmd(8)](/vmd/8.md) 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)](/vmd/8.md) allocates a pair of addresses for the guest-side [vio(4)](/vio/4.md) and host-side [tap(4)](/tap/4.md) 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). If NAT is desired, the *net.inet.ip.forwarding* [sysctl(8)](/sysctl/8.md) must also be set to 1. When using local interfaces, the DHCP configuration offered to the guest VM specifies the address of the corresponding host [tap(4)](/tap/4.md) 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 egress from 100.64.0.0/10 to any nat-to (egress) ``` 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 tcp } 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)](/vmd/8.md). ## 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 -s 4.5G disk.img ``` Convert a disk image from the ‘raw’ format to ‘qcow2’: ``` $ vmctl create -i disk.img disk.qcow2 ``` Create a new VM with 1GB memory, one network interface, one disk image ('disk.img') and boot from kernel '/bsd': ``` # vmctl start -m 1G -i 1 -b /bsd -d disk.img "myvm" ``` Start a new VM instance with the name 'myvm' from a pre-configured VM 'openbsd.4G': ``` # vmctl start -t "openbsd.4G" -d mydisk.img "myvm" ``` Terminate VM number 1: ``` # vmctl stop 1 ``` ## SEE ALSO [pf(4)](/pf/4.md), [tap(4)](/tap/4.md), [veb(4)](/veb/4.md), [vio(4)](/vio/4.md), [vmm(4)](/vmm/4.md), [vm.conf(5)](/vm.conf/5.md), [rc.conf(8)](/rc.conf/8.md), [sysctl(8)](/sysctl/8.md), [vmd(8)](/vmd/8.md) ## HISTORY The **vmctl** command first appeared in OpenBSD 5.9. ## AUTHORS Mike Larkin ⟨*mlarkin@openbsd.org*⟩ and Reyk Floeter ⟨*reyk@openbsd.org*⟩.