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Manage your virtual machines
From the GUI
There are several methods from the GUI, but the easiest to set up is probably VirtManager. See the setup guide at the above link. Alternative management options include convirt (GUI) or convirt2 (WWW).
From the shell
You can manage your VMs from the shell using virsh. You can get a list of the available commands if you type "help". Type "help command" to get additional infos for a particular command.
Define your new VM
Before you can manage your new VM with virsh, you must define it:
$ virsh --connect qemu:///system
Connecting to uri: qemu:///system
Welcome to virsh, the virtualization interactive terminal.
Type: 'help' for help with commands
'quit' to quit
virsh # define /etc/libvirt/qemu/newvm.xml
Domain newvm defined from /etc/libvirt/qemu/newvm.xmlNote that to list newvm, you must use 'list --inactive' or 'list --all', since list without any options will only list currently running machines.
List your VMs
Virsh allows you to list the virtual machines available on the current host:
yhamon@paris:/etc/libvirt/qemu$ virsh --connect qemu:///system
Connecting to uri: qemu:///system
Welcome to virsh, the virtualization interactive terminal.
Type: 'help' for help with commands
'quit' to quit
virsh # help list
NAME
list - list domains
SYNOPSIS
list [--inactive | --all]
DESCRIPTION
Returns list of domains.
OPTIONS
--inactive list inactive domains
--all list inactive & active domains
virsh # list
Id Name State
----------------------------------
15 mirror running
16 vm2 running
virsh # list --all
Id Name State
----------------------------------
15 mirror running
16 vm2 running
- test5 shut off
Define, undefine, start, shutdown, destroy VMs
The VMs you see with list --all are VMs that have been "defined" from an XML file. Every VM is configured via a XML file in /etc/libvirt/qemu. If you want to remove a VM from the list of VMs, you need to undefine it:
virsh # undefine test5 # WARNING: undefine will delete your XML file! Domain test5 has been undefined virsh # list --all Id Name State ---------------------------------- 15 mirror running 16 vm2 running
To be able to undefine a virtual machine, it needs to be shutdown first:
virsh # shutdown mirror Domain mirror is being shutdown
This command asks for a nice shutdown (like running shutdown in command line).
Notice: Ubuntu 10.04 server doesn't have acpid installed by default. This package needs to be installed on the guest OS before it will listen to any requests from the host.
You can also use "destroy", the more brutal way of shutting down a VM, equivalent of taking the power cable off:
virsh # destroy mirror Domain mirror destroyed
If you have made a change to the XML configuration file, you need to tell KVM to reload it before restarting the VM:
virsh # define /etc/libvirt/qemu/mirror.xml Domain mirror defined from /etc/libvirt/qemu/mirror.xml
Then, to restart the VM:
virsh # start mirror Domain mirror started
Suspend and resume a Virtual Machine
Virsh allows you to easily suspend and resume a virtual machine.
virsh # suspend mirror Domain mirror suspended virsh # resume mirror Domain mirror resumed
Editing the attributes of a Virtual Machine
libvirt stores it's configuration as xml in '/etc/libvirt/qemu'. The xml is easy to understand, and is similar to VMware *.vmx files. While it is possible to edit these files in place and restart libvirt-bin for the changes to take effect, the recommended method for modifying the attributes of a virtual machine is via virsh (or virt-manager, if it supports changing the hardware you want to change). The concept is simple:
- export (aka 'dump') the xml of the virtual machine you want to edit
- edit the xml
- import (aka 'define') the xml
For example, to edit the machine named 'foo' (you can get a list of your machines with 'virsh list --all'), do:
$ virsh dumpxml foo > /tmp/foo.xml (edit /tmp/foo.xml as needed) $ virsh define /tmp/foo.xml
Adding CPUs
KVM allows you to create SMP guests. To allocate two CPUs to a VM, dump the xml as above, then edit your xml to have:
<domain type='kvm'> ... <vcpu>2</vcpu> ... </domain>
Now define the VM as above.
Adding Memory
To change the memory allocation in a VM, dump the xml as above, then edit your xml to have:
<domain type='kvm'> ... <memory>262144</memory> <currentMemory>262144</currentMemory> ... </domain>
Now define the VM as above. Keep in mind that the memory allocation is in kilobytes, so to allocate 512MB of memory, use 512 * 1024, or 524288.
Changing the Network Card Model
kvm and qemu currently default to using the rtl8139 NIC. Supported NICs in Ubuntu 8.04 LTS are i82551, i82557b, i82559er, ne2k_pci, pcnet, rtl8139, e1000, and virtio. To use an alternate NIC, dump the xml as above, then edit your xml to have:
<domain type='kvm'>
...
<interface type='network'>
...
<model type='e1000'/>
</interface>
...
</domain>Now define the VM as above.
Adding USB Device Pass-through
Limitations
USB protocol <=2.0
- Apparmor modifications needed
Apparmor Modification
In order for a software program to access the usb device correctly the apparmor abstraction for qemu must be changed. Edit /etc/apparmor.d/abstractions/libvirt-qemu add a line:
# this lets qemu read all USB device information and might be considered a security risk /run/udev/data/* r,
After making the changes the guest must be restarted to get its profile regenerated.
Adding USB devices
This can also be done via virt-manager.
First find the usb Vendor ID and Product ID.:
$ lsusb Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub Bus 005 Device 012: ID 0a5c:2110 Broadcom Corp. Bluetooth Controller Bus 005 Device 003: ID 0483:2016 SGS Thomson Microelectronics Fingerprint Reader Bus 005 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 004 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 003 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
In the event that the Broadcom Corp. Bluetooth Controller wants to be selected the vendor and product ids are 0a5c and 2110 respectively.
Hot Add
Create an xml snippet just representing the device like
<hostdev mode='subsystem' type='usb' managed='yes'>
<source>
<vendor id='0x0a5c'/>
<product id='0x2110'/>
</source>
</hostdev>You can then attach/detach that via:
$ virsh attach-device <guestname> <<our-device-xml-file> # work with it in the guest $ virsh detach-device <guestname> <<our-device-xml-file>
Static Add
The IDs can be entered into the xml profile. This can be done through virsh through the edit <domain> command.:
<domain type='kvm'>
<name>windowsxp</name>
…
<devices>
…
<hostdev mode='subsystem' type='usb'>
<source>
<vendor id='0x0a5c'/>
<product id='0x2110'/>
</source>
</hostdev>
</devices>
</domain>
Get new IDs
To get a new mac address to paste into your xml file, use this command:
MACADDR="52:54:$(dd if=/dev/urandom count=1 2>/dev/null | md5sum | sed 's/^\(..\)\(..\)\(..\)\(..\).*$/\1:\2:\3:\4/')"; echo $MACADDR
To get a new uuid for your xml file, use: uuidgen
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