Problem loading/starting a KVM virtual machine on a CentOS 6.5 host that has SELINUX disabled

If you have recently built a KVM host for all your virtual machines and left SELINUX enabled, then all will be well, but what happens when you turn that setting off. Well you will end up with VM's that won't load with the error message

error: Failed to start domain Ubuntu1404
error: unsupported configuration: Unable to find security driver for label selinux

It is easy to fix , use the following command and just remove the seclabel section on the virtual machine domain XML - virsh edit Ubuntu1404

# virsh edit Ubuntu1404
...
  <;seclabel type='dynamic' model='selinux' relabel='yes'>;
    <label>system_u:system_r:svirt_t:s0:c95,c664</label>
    <imagelabel>system_u:object_r:svirt_image_t:s0:c95,c664</imagelabel>
  </seclabel>  

Once you have done that, the domains will load as normal.

Make sure if you have backup's of the domain XML, they are also changed, as I have found that they will over write the domain if your not careful

Check in /etc/libvirt/qemu to make sure the changes have happen, and the XML has been updated.

Getting a Jumpbox VM to work with Redhat EL 5 64 bit

If you use virtualization a lot , then I'm sure you will have come across a great company that offers a whole range of pre-built open source virtual images. That company is Jumpbox. I have used several of their images with great success, and the time to deploy is extremely quick, especially with VMware ESX or VMware server.

On this occasion though I wanted to get a moinmoin wiki going on a 64bit Redhat Xen server, and the default install script supplied with the images is for 32bit systems. It fails, telling you it can't find qemu, which is true as it won't given the default script. Also note that you must have hardware virtualization switched on in the BIOS to get these images to work on 32 or 64 bit systems.

You have to make a minor change to one part of the config file, JumpBox.xen , simply because this is where RH put the 64bit version of qemu.

Here is the section that needs changing.

devfiles = [
'/usr/lib/xen/bin/qemu-dm',
'/usr/lib/xen-ioemu-3.0/bin/qemu-dm'
]

I changed the line '/usr/lib/xen/bin/qemu-dm' to '/usr/lib64/xen/bin/qemu-dm'

You then use the start script "xm create -c JumpBox.xen", and the virtual machine is then visible in the virtual manager on the host server.