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14.6. Editing a Guest Virtual Machine's configuration file
Instead of using the
dumpxml
option (refer to Section 14.5.23, “Creating a Virtual Machine XML Dump (Configuration File)”), guest virtual machines can be edited either while they are running or while they are offline. The virsh edit
command provides this functionality. For example, to edit the guest virtual machine named rhel6
:
# virsh edit rhel6
This opens a text editor. The default text editor is the
$EDITOR
shell parameter (set to vi
by default).
14.6.1. Adding Multifunction PCI Devices to KVM Guest Virtual Machines
This section will demonstrate how to add multi-function PCI devices to KVM guest virtual machines.
- Run the
virsh edit [guestname]
command to edit the XML configuration file for the guest virtual machine. - In the address type tag, add a
multifunction='on'
entry forfunction='0x0'
.This enables the guest virtual machine to use the multifunction PCI devices.<disk type='file' device='disk'> <driver name='qemu' type='raw' cache='none'/> <source file='/var/lib/libvirt/images/rhel62-1.img'/> <target dev='vda' bus='virtio'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0' multifunction='on'/ </disk>
For a PCI device with two functions, amend the XML configuration file to include a second device with the same slot number as the first device and a different function number, such asfunction='0x1'
.For Example:<disk type='file' device='disk'> <driver name='qemu' type='raw' cache='none'/> <source file='/var/lib/libvirt/images/rhel62-1.img'/> <target dev='vda' bus='virtio'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0' multifunction='on'/> </disk> <disk type='file' device='disk'> <driver name='qemu' type='raw' cache='none'/> <source file='/var/lib/libvirt/images/rhel62-2.img'/> <target dev='vdb' bus='virtio'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x1'/> </disk>
lspci
output from the KVM guest virtual machine shows:$ lspci 00:05.0 SCSI storage controller: Red Hat, Inc Virtio block device 00:05.1 SCSI storage controller: Red Hat, Inc Virtio block device