20.16.17. Host Physical Machine Interface

A character device presents itself to the host physical machine as one of the following types:

Table 20.23. Character device elements

ParameterDescriptionXML snippet
Domain logfileDisables all input on the character device, and sends output into the virtual machine's logfile 
      			   	   <devices>
      			   	      <console type='stdio'>
      			   	         <target port='1'/>
                           </console>
                        </devices>
Device logfileA file is opened and all data sent to the character device is written to the file. 
      			   	   <devices>
      			   	      <serial type="file">
      			   	         <source path="/var/log/vm/vm-serial.log"/>
      			   	         <target port="1"/>
      			   	      </serial>
      			   	   </devices>
Virtual consoleConnects the character device to the graphical framebuffer in a virtual console. This is typically accessed via a special hotkey sequence such as "ctrl+alt+3" 
      			   	   <devices>
      			   	      <serial type='vc'>
                              <target port="1"/>
                           </serial>
                        </devices>
Null deviceConnects the character device to the void. No data is ever provided to the input. All data written is discarded. 
                        <devices>
                           <serial type='null'>
                              <target port="1"/>
                           </serial>
                        </devices>
Pseudo TTYA Pseudo TTY is allocated using /dev/ptmx. A suitable client such as virsh console can connect to interact with the serial port locally. 
                        <devices>
                           <serial type="pty">
                              <source path="/dev/pts/3"/>
                              <target port="1"/>
                           </serial>
                        </devices>
NB Special caseNB special case if <console type='pty'>, then the TTY path is also duplicated as an attribute tty='/dev/pts/3' on the top level <console> tag. This provides compat with existing syntax for <console> tags. 
Host physical machine device proxyThe character device is passed through to the underlying physical character device. The device types must match, eg the emulated serial port should only be connected to a host physical machine serial port - do not connect a serial port to a parallel port. 
                        <devices>
                           <serial type="dev">
                              <source path="/dev/ttyS0"/>
                              <target port="1"/>
                           </serial>
                        </devices>
Named pipeThe character device writes output to a named pipe. See pipe(7) man page for more info. 
                        <devices>
                           <serial type="pipe">
                              <source path="/tmp/mypipe"/>
                              <target port="1"/>
                           </serial>
                        </devices>
TCP client/serverThe character device acts as a TCP client connecting to a remote server. 
                        <devices>
                           <serial type="tcp">
                              <source mode="connect" host="0.0.0.0" service="2445"/>
                              <protocol type="raw"/>
                              <target port="1"/>
                           </serial>
                        </devices>
Or as a TCP server waiting for a client connection. 
                        <devices>
                           <serial type="tcp">
                              <source mode="bind" host="127.0.0.1" service="2445"/>
                              <protocol type="raw"/>
                              <target port="1"/>
                           </serial>
                        </devices>
Alternatively you can use telnet instead of raw TCP. In addition, you can also use telnets (secure telnet) and tls. 
                        <devices>
                           <serial type="tcp">
                              <source mode="connect" host="0.0.0.0" service="2445"/>
                              <protocol type="telnet"/>
                              <target port="1"/>
                           </serial>
                           <serial type="tcp">
                              <source mode="bind" host="127.0.0.1" service="2445"/>
                              <protocol type="telnet"/>
                              <target port="1"/>
                           </serial>
                        </devices>
UDP network consoleThe character device acts as a UDP netconsole service, sending and receiving packets. This is a lossy service. 
                        <devices>
                           <serial type="udp">
                              <source mode="bind" host="0.0.0.0" service="2445"/>
                              <source mode="connect" host="0.0.0.0" service="2445"/>
                              <target port="1"/>
                           </serial>
                        </devices>
UNIX domain socket client/serverThe character device acts as a UNIX domain socket server, accepting connections from local clients. 
                        <devices>
                           <serial type="unix">
                              <source mode="bind" path="/tmp/foo"/>
                              <target port="1"/>
                           </serial>
                           </devices>