doc: added some discussion to libvirt.

Signed-off-by: John Wilkins <john.wilkins@inktank.com>

diff --git a/doc/rbd/libvirt.rst b/doc/rbd/libvirt.rst
index 3f6fbb5bc3b76286e6452875509d55fa11a3be5f..e0228f0838872e28d88fce0fd1e4df61f7308f86 100644 (file)
--- a/doc/rbd/libvirt.rst
+++ b/doc/rbd/libvirt.rst
@@ -1,6 +1,25 @@
-========================
- Installing ``libvirt``
-========================
+=================================
+ Using ``libvirt`` with Ceph RBD
+=================================
+
+The ``libvirt`` library creates a virtual machine abstraction layer between 
+hypervisor interfaces and the software applications that use them. With 
+``libvirt``, developers and system administrators can focus on a common 
+management framework, common API, and common shell interface (i.e., ``virsh``)
+to many different hypervisors, including: 
+
+- QEMU/KVM
+- XEN
+- LXC
+- VirtualBox
+- etc.
+
+Ceph RADOS block devices support QEMU/KVM, which means you can use RADOS
+block devices with software that interfaces with ``libvirt``. For example, 
+OpenStack's integration to Ceph uses ``libvirt`` to interact with QEMU/KVM, 
+and QEMU/KVM interacts with RADOS block devices via ``librbd``.
+
+See `libvirt Virtualization API`_ for details.
 
 Installing ``libvirt`` on Ubuntu 12.04 Precise
 ----------------------------------------------
@@ -28,4 +47,5 @@ For Ubuntu distributions 11.10 oneiric and earlier, you must build
 See `libvirt Installation`_ for details.
 
 .. _AutoGen: http://www.gnu.org/software/autogen/
-.. _libvirt Installation: http://www.libvirt.org/compiling.html
\ No newline at end of file
+.. _libvirt Installation: http://www.libvirt.org/compiling.html
+.. _libvirt Virtualization API: http://www.libvirt.org
\ No newline at end of file