20.16.15. Guest Virtual Machine Interfaces
A character device presents itself to the guest virtual machine as one of the following types.
To set the parallel port, use a management tool to make the following change to the domain XML
...
<devices>
<parallel type='pty'>
<source path='/dev/pts/2'/>
<target port='0'/>
</parallel>
</devices>
...Figure 20.60. Guest virtual machine interface Parallel Port
<target> can have a port attribute, which specifies the port number. Ports are numbered starting from 0. There are usually 0, 1 or 2 parallel ports.
To set the serial port use a management tool to make the following change to the domain XML:
...
<devices>
<serial type='pty'>
<source path='/dev/pts/3'/>
<target port='0'/>
</serial>
</devices>
...Figure 20.61. Guest virtual machine interface serial port
<target> can have a port attribute, which specifies the port number. Ports are numbered starting from 0. There are usually 0, 1 or 2 serial ports. There is also an optional type attribute, which has two choices for its value, one is isa-serial, the other is usb-serial. If type is missing, isa-serial will be used by default. For usb-serial an optional sub-element <address> with type='usb' can tie the device to a particular controller, documented above.
The
<console> element is used to represent interactive consoles. Depending on the type of guest virtual machine in use, the consoles might be paravirtualized devices, or they might be a clone of a serial device, according to the following rules:
- If no
targetTypeattribute is set, then the default devicetypeis according to the hypervisor's rules. The defaulttypewill be added when re-querying the XML fed into libvirt. For fully virtualized guest virtual machines, the default device type will usually be a serial port. - If the
targetTypeattribute isserial, and if no<serial>element exists, the console element will be copied to the<serial>element. If a<serial>element does already exist, the console element will be ignored. - If the
targetTypeattribute is notserial, it will be treated normally. - Only the first
<console>element may use atargetTypeofserial. Secondary consoles must all be paravirtualized. - On s390, the console element may use a targetType of sclp or sclplm (line mode). SCLP is the native console type for s390. There's no controller associated to SCLP consoles.
In the example below, a virtio console device is exposed in the guest virtual machine as /dev/hvc[0-7] (for more information, see http://fedoraproject.org/wiki/Features/VirtioSerial):
...
<devices>
<console type='pty'>
<source path='/dev/pts/4'/>
<target port='0'/>
</console>
<!-- KVM virtio console -->
<console type='pty'>
<source path='/dev/pts/5'/>
<target type='virtio' port='0'/>
</console>
</devices>
...
...
<devices>
<!-- KVM s390 sclp console -->
<console type='pty'>
<source path='/dev/pts/1'/>
<target type='sclp' port='0'/>
</console>
</devices>
...Figure 20.62. Guest virtual machine interface - virtio console device
If the console is presented as a serial port, the
<target> element has the same attributes as for a serial port. There is usually only one console.
