Introduce virtio-msg ERROR message

Signed-off-by: Bertrand Marquis <[email protected]>

transport-msg.tex

@@ -48,6 +48,8 @@ \subsection{Messages Definition}\label{sec:Virtio Transport Options / Virtio Ove
 Name & ID & Sender \\
 \hline
 \hline
+VIRTIO_MSG_ERROR               & 0x0  & Any    \\
+\hline
 VIRTIO_MSG_CONNECT             & 0x1  & Driver \\
 \hline
 VIRTIO_MSG_DISCONNECT          & 0x2  & Driver \\
@@ -87,6 +89,25 @@ \subsection{Messages Definition}\label{sec:Virtio Transport Options / Virtio Ove
 
 \newcommand{\msgdef}[1]{\subsubsection{VIRTIO_MSG_#1}\label{sec:Virtio Transport Options / Virtio Over Messages / Messages Definition / VIRTIO_MSG_#1}}
 
+\msgdef{ERROR}
+
+The Error message is used to signal to the driver or the device that a message
+it wanted to send could not be sent. The message contain an error code defined
+using the Standard Posix Error Codes (TODO: add a reference).
+
+This message can be received by the driver or the device and can be sent as an
+answer to an other message by the driver or the device or any element between
+them involved in the communication.
+
+\begin{tabular}{|l|l|l|l|}
+\hline
+Type & Offset & Size (bytes) & Content \\
+\hline \hline
+Any     & 0 & 4 & Posix Error Code \\
+        & 4 & 32 & Reserved (MBZ) \\
+\hline
+\end{tabular}
+
 \msgdef{CONNECT}
 
 The Connect message is used to signal to the device that the driver will start