On Wed, Mar 18, 2015 at 07:21:22AM -0600, Eric Blake wrote:
On 03/18/2015 07:03 AM, Deepak Shetty wrote:
[please don't top-post on technical lists]
Hmm interesting, so without adding backing_fmt, if i enable the below in /etc/libvirt/qemu.conf, will it work ?
# If allow_disk_format_probing is enabled, libvirt will probe disk # images to attempt to identify their format, when not otherwise # specified in the XML. This is disabled by default. # # WARNING: Enabling probing is a security hole in almost all # deployments. It is strongly recommended that users update their # guest XML <disk> elements to include <driver type='XXXX'/> # elements instead of enabling this option. # #allow_disk_format_probing = 1
Along with what Eric says, here's some detailed description of issues (that are fixed) from Daniel Berrange: https://www.redhat.com/archives/libvir-list/2010-July/msg00221.html
It _might_ work in that libvirt will then probe the backing chain as qcow2, rather than treating it as raw; on the other hand, the upcoming qemu 2.3 is trying to deprecate probing altogether because of the security problems it represented, and so you may reach a point where even if you tell libvirt it is okay to probe, that qemu will refuse to open your image if you didn't specify backing format.
-- /kashyap