Let's say you want to make the directory
/opt/test on your desktop machine
visible to a virtual machine you are running with libvirt.
All you have to do is:
virsh edit myvmname, edit the XML of the VM to have something like:
<domains ...> ... <devices ...> <filesystem type='mount' accessmode='passthrough'> <source dir='/opt/test'/> <target dir='testlabel'/> </filesystem> </devices> </domains>
/opt/test is the path you want to share with the VM, and
is just a mnemonic of your choice.
Make sure to set
accessmode to something reasonable for your use case.
According to the libvirt documentation, you can use:
More details are provided in the next section. For now, just ensure that the
<filesystem> blobs are under
<devices>, order does not
matter. Make also sure to save and exit.
Now start your virtual machine, with
virsh start myvmname, and get a console.
Append a few lines to
/etc/modules, to make sure the right modules are loaded:
$ sudo -s # cat >>/etc/modules <<EOF loop virtio 9p 9pnet 9pnet_virtio EOF
As a root user, load those modules:
# service kmod start
Now you should be ready to mount the file system:
# mount testlabel /opt/test -t 9p -o trans=virtio
et voila! If you
cd /opt/test you should be able to see the files in your host
if you want the file system to be automatically mounted at boot time, you can add something like:
testlabel /opt/test 9p trans=virtio 0 0
If you get access denied to your files in
/opt/test or can't write in the directory,
the problem is generally related to the
accessmode you picked, and the user your VM is
Don't forget that at the end of the day a Virtual Machine is just another process on your host operating system. This process is running with the privileges of a particular user, and only able to change and touch the files that the specific user is given access to.
If you run
ps aux |grep kvm or
ps aux |grep qemu on your host system, you will most likely see
system VM is running as user
libvirt-qemu on Debian, while it is
running as yourself if it is a
session VM. If you are confused about
VMs, you should read this article.
This means that kvm/qemu will be able to read or write files or directories either as you,
or as the
libvirt-qemu user. Make sure that file privileges and directories are set accordingly.
To change the uid under which
system VMs are run, you need to:
group to have the desired value.
service restart libvirt-bin and
service restart libvirt-guests.
Alternatively, you may want to change