On Tue, Aug 10, 2021 at 02:47:06PM +0300, Arseny Krasnov wrote:
This adds description of SOCK_SEQPACKET socket type
support for virtio-vsock.
Signed-off-by: Arseny Krasnov <arseny.krasnov@xxxxxxxxxxxxx>
---
virtio-vsock.tex | 35 ++++++++++++++++++++++++++++++-----
1 file changed, 30 insertions(+), 5 deletions(-)
diff --git a/virtio-vsock.tex b/virtio-vsock.tex
index ad57f9d..ca76812 100644
--- a/virtio-vsock.tex
+++ b/virtio-vsock.tex
@@ -16,7 +16,10 @@ \subsection{Virtqueues}\label{sec:Device Types / Socket Device / Virtqueues}
\subsection{Feature bits}\label{sec:Device Types / Socket Device / Feature bits}
-There are currently no feature bits defined for this device.
+\begin{description}
+\item VIRTIO_VSOCK_F_SEQPACKET (1) SOCK_SEQPACKET socket type is
+ supported.
+\end{description}
\subsection{Device configuration layout}\label{sec:Device Types / Socket Device / Device configuration layout}
@@ -135,15 +138,17 @@ \subsubsection{Addressing}\label{sec:Device Types / Socket Device / Device Opera
consists of a (cid, port number) tuple. The header fields used for this are
\field{src_cid}, \field{src_port}, \field{dst_cid}, and \field{dst_port}.
-Currently only stream sockets are supported. \field{type} is 1 (VIRTIO_VSOCK_TYPE_STREAM)
-for stream socket types.
+Currently stream and seqpacket sockets are supported. \field{type} is 1 (VIRTIO_VSOCK_TYPE_STREAM)
+for stream socket types, and 2 (VIRTIO_VSOCK_TYPE_SEQPACKET) for seqpacket socket types.
\begin{lstlisting}
-#define VIRTIO_VSOCK_TYPE_STREAM 1
+#define VIRTIO_VSOCK_TYPE_STREAM 1
+#define VIRTIO_VSOCK_TYPE_SEQPACKET 2
\end{lstlisting}
Stream sockets provide in-order, guaranteed, connection-oriented delivery
-without message boundaries.
+without message boundaries. Seqpacket sockets provide in-order, guaranteed,
+connection-oriented delivery with message and record boundaries.
\subsubsection{Buffer Space Management}\label{sec:Device Types / Socket Device / Device Operation / Buffer Space Management}
\field{buf_alloc} and \field{fwd_cnt} are used for buffer space management of
@@ -244,6 +249,26 @@ \subsubsection{Stream Sockets}\label{sec:Device Types / Socket Device / Device O
destination) address tuple for a new connection while the other peer is still
processing the old connection.
+\subsubsection{Seqpacket Sockets}\label{sec:Device Types / Socket Device / Device Operation / Seqpacket Sockets}
+
+\paragraph{Message boundaries}\label{sec:Device Types / Socket Device / Device Operation / Seqpacket Sockets / Message boundaries}
+
+To provide message boundaries, last RW packet of each message has VIRTIO_VSOCK_SEQ_EOM
+bit (bit 0) set in the \field{flags} of packet's header.
+
+\begin{lstlisting}
+#define VIRTIO_VSOCK_SEQ_EOM 1
+\end{lstlisting}
+
+\paragraph{Record boundaries}\label{sec:Device Types / Socket Device / Device Operation / Seqpacket Sockets / Record boundaries}
+
+To provide record boundaries, last RW packet of each record has VIRTIO_VSOCK_SEQ_EOR
+bit (bit 1) set in the \field{flags} of packet's header.
+
+\begin{lstlisting}
+#define VIRTIO_VSOCK_SEQ_EOR 2
+\end{lstlisting}
+
Maybe we could have a single section where we talk about the boundaries
and list the two flags together.
We should also explain what we mean by message boundaries (payload sent
with a single system call) and record boundaries (payload with MSG_EOR
flag set).
Thanks,
Stefano
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