Sample virtual machine XML configuration

The XML configuration of a virtual machine (VM), also referred to as a domain XML, determines the VM’s settings and components. The following table shows a sample XML configuration of a VM and explains the contents.

To obtain the XML configuration of a VM, you can use the virsh dumpxml command followed by the VM’s name.

# virsh dumpxml testguest1
Table 1. Sample XML configuration
Domain XML Section Description
<domain type='kvm'> <name>Testguest1</name> <uuid>ec6fbaa1-3eb4-49da-bf61-bb02fbec4967</uuid> <memory unit='KiB'>1048576</memory> <currentMemory unit='KiB'>1048576</currentMemory>

This is a KVM virtual machine called Testguest1, with 1024 MiB allocated RAM.
<vcpu placement='static'>1</vcpu>

The VM is allocated with a single virtual CPU (vCPU).

For information about configuring vCPUs, see Optimizing virtual machine CPU performance.
<os> <type arch='x86_64' machine='pc-q35-rhel10.0.0'>hvm</type> <boot dev='hd'/> </os>

The machine architecture is set to the AMD64 and Intel 64 architecture, and uses the Intel Q35 machine type to determine feature compatibility. The OS is set to be booted from the hard disk drive.
<features> <acpi/> <apic/> </features>

The acpi and apic hypervisor features are enabled.
<cpu mode='host-model' check='partial'/>

The host CPU definitions from capabilities XML (obtainable with virsh domcapabilities) are automatically copied into the VM’s XML configuration. Therefore, when the VM is booted, libvirt picks a CPU model that is similar to the host CPU, and then adds extra features to approximate the host model as closely as possible.
<clock offset='utc'> <timer name='rtc' tickpolicy='catchup'/> <timer name='pit' tickpolicy='delay'/> <timer name='hpet' present='no'/> </clock>

The VM’s virtual hardware clock uses the UTC time zone. In addition, three different timers are configured for synchronization with the QEMU hypervisor.
<on_poweroff>destroy</on_poweroff> <on_reboot>restart</on_reboot> <on_crash>destroy</on_crash>

When the VM powers off, or its OS terminates unexpectedly, libvirt terminates the VM and releases all its allocated resources. When the VM is rebooted, libvirt restarts it with the same configuration.
<pm> <suspend-to-mem enabled='no'/> <suspend-to-disk enabled='no'/> </pm>

The S3 and S4 ACPI sleep states are disabled for this VM.
<devices> <emulator>/usr/libexec/qemu-kvm</emulator> <disk type='file' device='disk'> <driver name='qemu' type='qcow2'/> <source file='/var/lib/libvirt/images/Testguest.qcow2'/> <target dev='vda' bus='virtio'/> </disk> <disk type='file' device='cdrom'> <driver name='qemu' type='raw'/> <target dev='sdb' bus='sata'/> <readonly/> </disk>

The VM uses the /usr/libexec/qemu-kvm binary file for emulation and it has two disk devices attached.

The first disk is a virtualized hard-drive based on the /var/lib/libvirt/images/Testguest.qcow2 stored on the host, and its logical device name is set to vda.

The second disk is a virtualized CD-ROM and its logical device name is set to sdb.
<controller type='usb' index='0' model='qemu-xhci' ports='15'/> <controller type='sata' index='0'/> <controller type='pci' index='0' model='pcie-root'/> <controller type='pci' index='1' model='pcie-root-port'> <model name='pcie-root-port'/> <target chassis='1' port='0x10'/> </controller> <controller type='pci' index='2' model='pcie-root-port'> <model name='pcie-root-port'/> <target chassis='2' port='0x11'/> </controller> <controller type='pci' index='3' model='pcie-root-port'> <model name='pcie-root-port'/> <target chassis='3' port='0x12'/> </controller> <controller type='pci' index='4' model='pcie-root-port'> <model name='pcie-root-port'/> <target chassis='4' port='0x13'/> </controller> <controller type='pci' index='5' model='pcie-root-port'> <model name='pcie-root-port'/> <target chassis='5' port='0x14'/> </controller> <controller type='pci' index='6' model='pcie-root-port'> <model name='pcie-root-port'/> <target chassis='6' port='0x15'/> </controller> <controller type='pci' index='7' model='pcie-root-port'> <model name='pcie-root-port'/> <target chassis='7' port='0x16'/> </controller> <controller type='virtio-serial' index='0'/>

The VM uses a single controller for attaching USB devices, and a root controller for PCI-Express (PCIe) devices. In addition, a virtio-serial controller is available, which enables the VM to interact with the host in a variety of ways, such as the serial console.

For more information about virtual devices, see Types of virtual devices.
<interface type='network'> <mac address='52:54:00:65:29:21'/> <source network='default'/> <model type='virtio'/> </interface>

A network interface is configured in the VM that uses the default virtual network and the virtio network device model.

For information about configuring the network interface, see Optimizing virtual machine network //performance.
<serial type='pty'> <target type='isa-serial' port='0'> <model name='isa-serial'/> </target> </serial> <console type='pty'> <target type='serial' port='0'/> </console> <channel type='unix'> <target type='virtio' name='org.qemu.guest_agent.0'/> <address type='virtio-serial' controller='0' bus='0' port='1'/> </channel>

A pty serial console is configured on the VM, which enables rudimentary VM communication with the host. The console uses the UNIX channel on port 1. This is configured automatically and changing these settings is not recommended.

For more information about interacting with VMs, see Interacting with virtual machines by using the web console.
<input type='tablet' bus='usb'> <address type='usb' bus='0' port='1'/> </input> <input type='mouse' bus='ps2'/> <input type='keyboard' bus='ps2'/>

The VM uses a virtual usb port, which is configured to receive tablet input, and a virtual ps2 port configured to receive mouse and keyboard input. This is configured automatically and changing these settings is not recommended.
<graphics type='vnc' port='-1' autoport='yes' listen='127.0.0.1'> <listen type='address' address='127.0.0.1'/> </graphics>

The VM uses the vnc protocol for rendering its graphical output.
<redirdev bus='usb' type='tcp'> <source mode='connect' host='localhost' service='4000'/> <protocol type='raw'/> </redirdev> <memballoon model='virtio'> <address type='pci' domain='0x0000' bus='0x00' slot='0x07' function='0x0'/> </memballoon> </devices> </domain>

The VM uses tcp re-director for attaching USB devices remotely, and memory ballooning is turned on. This is configured automatically and changing these settings is not recommended.