[RFC PATCH] introduction.tex: introduce a glossary of terms

[Alex BennÃe <alex.bennee@linaro.org>]

It is useful to have a glossary of common terms at the front of the
document to define common terms we are going to use throughout the
specification. Whilst writing this list I notice we refer to a device
in host terms - perhaps we need slightly tighter definitions of what a
device is? For discussion I've defined a Device Interface in terms of
the guest visible side and a Device Backend in terms of what runs on
the host.

Cc: Nikos Dragazis <ndragazis@arrikto.com>
Cc: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Alex BennÃe <alex.bennee@linaro.org>
---
 introduction.tex | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/introduction.tex b/introduction.tex
index 33da3ec..c84a112 100644
--- a/introduction.tex
+++ b/introduction.tex
@@ -81,6 +81,36 @@ \section{Terminology}\label{Terminology}
 
 The key words ``MUST'', ``MUST NOT'', ``REQUIRED'', ``SHALL'', ``SHALL NOT'', ``SHOULD'', ``SHOULD NOT'', ``RECOMMENDED'', ``MAY'', and ``OPTIONAL'' in this document are to be interpreted as described in \hyperref[intro:rfc2119]{[RFC2119]}.
 
+\subsection{Glossary}\label{intro:Glossary}
+
+The following are definitions of common terms used throughout the specification.
+
+\begin{description}
+\item[Guest]
+  A virtual machine hosted by a hypervisor.
+\item[Host]
+  The system hosting a virtual machine. It may consist of multiple
+  components including a hypervisor, primary OS and it's user-space.
+\item[Device Interface]
+  The series of configuration, control and operation mechanisms
+  visible to the guest that make a Virtio device.
+\item[Device Driver]
+  The software (usually part of a kernel) running on the guest which
+  accesses the device interface.
+\item[Device Backend]
+  The software running on the host that services requests made of the
+  device interface. The implementation details of the backend should
+  be transparent to the guest.
+\item[Notification]
+  An asynchronous signal sent to either the device backend or the
+  device driver to indicate a virtqueue has been updated. For guests
+  this is typically a device interrupt.
+\item[Doorbell Register]
+  A guest visible register that when accessed will trigger a
+  notification to the backend via some implementation defined
+  mechanism.
+\end{description}
+
 \subsection{Legacy Interface: Terminology}\label{intro:Legacy
 Interface: Terminology}
 
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