[virtio-comment] [RFC PATCH v7 0/2] virtio-vsock: introduce SOCK_SEQPACKET description

[virtio-comment] [RFC PATCH v7 0/2] virtio-vsock: introduce SOCK_SEQPACKET description

[Arseny Krasnov]

This adds description of SOCK_SEQPACKET type for virtio-vsock.

Here is merged Linux implementation:
https://lore.kernel.org/netdev/20210611110744.3650456-1-arseny.krasnov@kaspersky.com/

Here is extra patchset for record boundaries:
https://lkml.org/lkml/2021/8/10/482

Also this patchset has patch which replaces enums to defines in
virtio-vsock part of spec. SOCK_SEQPACKET patch is based on it.

 Arseny Krasnov(2):
  virtio-vsock: use C style defines for constants
  virtio-vsock: SOCK_SEQPACKET description

 virtio-vsock.tex | 83 ++++++++++++++++++++++++++++++----------------
 1 file changed, 55 insertions(+), 28 deletions(-)

 v6 -> v7:
 - Added record boundaries bit description.

-- 
2.25.1


This publicly archived list offers a means to provide input to the
OASIS Virtual I/O Device (VIRTIO) TC.

In order to verify user consent to the Feedback License terms and
to minimize spam in the list archive, subscription is required
before posting.

Subscribe: virtio-comment-subscribe@lists.oasis-open.org
Unsubscribe: virtio-comment-unsubscribe@lists.oasis-open.org
List help: virtio-comment-help@lists.oasis-open.org
List archive: https://lists.oasis-open.org/archives/virtio-comment/
Feedback License: https://www.oasis-open.org/who/ipr/feedback_license.pdf
List Guidelines: https://www.oasis-open.org/policies-guidelines/mailing-lists
Committee: https://www.oasis-open.org/committees/virtio/
Join OASIS: https://www.oasis-open.org/join/

[virtio-comment] [RFC PATCH v7 1/2] virtio-vsock: use C style defines for constants

[Arseny Krasnov]

This:
1) Replaces enums with C style "defines", because
   use of enums is not documented, while "defines"
   are widely used in spec.
2) Adds defines for some constants.

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Arseny Krasnov <arseny.krasnov@kaspersky.com>
---
 virtio-vsock.tex | 54 +++++++++++++++++++++++++-----------------------
 1 file changed, 28 insertions(+), 26 deletions(-)

diff --git a/virtio-vsock.tex b/virtio-vsock.tex
index da7e641..ad57f9d 100644
--- a/virtio-vsock.tex
+++ b/virtio-vsock.tex
@@ -86,23 +86,18 @@ \subsection{Device Operation}\label{sec:Device Types / Socket Device / Device Op
 operation constants:
 
 \begin{lstlisting}
-enum {
-	VIRTIO_VSOCK_OP_INVALID = 0,
-
-	/* Connect operations */
-	VIRTIO_VSOCK_OP_REQUEST = 1,
-	VIRTIO_VSOCK_OP_RESPONSE = 2,
-	VIRTIO_VSOCK_OP_RST = 3,
-	VIRTIO_VSOCK_OP_SHUTDOWN = 4,
-
-	/* To send payload */
-	VIRTIO_VSOCK_OP_RW = 5,
-
-	/* Tell the peer our credit info */
-	VIRTIO_VSOCK_OP_CREDIT_UPDATE = 6,
-	/* Request the peer to send the credit info to us */
-	VIRTIO_VSOCK_OP_CREDIT_REQUEST = 7,
-};
+#define VIRTIO_VSOCK_OP_INVALID        0
+/* Connect operations */
+#define VIRTIO_VSOCK_OP_REQUEST        1
+#define VIRTIO_VSOCK_OP_RESPONSE       2
+#define VIRTIO_VSOCK_OP_RST            3
+#define VIRTIO_VSOCK_OP_SHUTDOWN       4
+/* To send payload */
+#define VIRTIO_VSOCK_OP_RW             5
+/* Tell the peer our credit info */
+#define VIRTIO_VSOCK_OP_CREDIT_UPDATE  6
+/* Request the peer to send the credit info to us */
+#define VIRTIO_VSOCK_OP_CREDIT_REQUEST 7
 \end{lstlisting}
 
 \subsubsection{Virtqueue Flow Control}\label{sec:Device Types / Socket Device / Device Operation / Virtqueue Flow Control}
@@ -140,8 +135,12 @@ \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 for stream
-socket types.
+Currently only stream sockets are supported. \field{type} is 1 (VIRTIO_VSOCK_TYPE_STREAM)
+for stream socket types.
+
+\begin{lstlisting}
+#define VIRTIO_VSOCK_TYPE_STREAM 1
+\end{lstlisting}
 
 Stream sockets provide in-order, guaranteed, connection-oriented delivery
 without message boundaries.
@@ -222,10 +221,15 @@ \subsubsection{Stream Sockets}\label{sec:Device Types / Socket Device / Device O
 insufficient resources to establish the connection.
 
 When a connected socket receives VIRTIO_VSOCK_OP_SHUTDOWN the header
-\field{flags} field bit 0 indicates that the peer will not receive any more
-data and bit 1 indicates that the peer will not send any more data.  These
-hints are permanent once sent and successive packets with bits clear do not
-reset them.
+\field{flags} field bit VIRTIO_VSOCK_SHUTDOWN_F_RECEIVE (bit 0) set indicates
+that the peer will not receive any more data and bit VIRTIO_VSOCK_SHUTDOWN_F_SEND
+(bit 1) set indicates that the peer will not send any more data.  These hints are
+permanent once sent and successive packets with bits clear do not reset them.
+
+\begin{lstlisting}
+#define VIRTIO_VSOCK_SHUTDOWN_F_RECEIVE 0
+#define VIRTIO_VSOCK_SHUTDOWN_F_SEND    1
+\end{lstlisting}
 
 The VIRTIO_VSOCK_OP_RST packet aborts the connection process or forcibly
 disconnects a connected socket.
@@ -248,9 +252,7 @@ \subsubsection{Device Events}\label{sec:Device Types / Socket Device / Device Op
 The event buffer is as follows:
 
 \begin{lstlisting}
-enum virtio_vsock_event_id {
-        VIRTIO_VSOCK_EVENT_TRANSPORT_RESET = 0,
-};
+#define VIRTIO_VSOCK_EVENT_TRANSPORT_RESET 0
 
 struct virtio_vsock_event {
         le32 id;
-- 
2.25.1


This publicly archived list offers a means to provide input to the
OASIS Virtual I/O Device (VIRTIO) TC.

In order to verify user consent to the Feedback License terms and
to minimize spam in the list archive, subscription is required
before posting.

Subscribe: virtio-comment-subscribe@lists.oasis-open.org
Unsubscribe: virtio-comment-unsubscribe@lists.oasis-open.org
List help: virtio-comment-help@lists.oasis-open.org
List archive: https://lists.oasis-open.org/archives/virtio-comment/
Feedback License: https://www.oasis-open.org/who/ipr/feedback_license.pdf
List Guidelines: https://www.oasis-open.org/policies-guidelines/mailing-lists
Committee: https://www.oasis-open.org/committees/virtio/
Join OASIS: https://www.oasis-open.org/join/

[virtio-comment] [RFC PATCH v7 2/2] virtio-vsock: SOCK_SEQPACKET description

[Arseny Krasnov]

This adds description of SOCK_SEQPACKET socket type
support for virtio-vsock.

Signed-off-by: Arseny Krasnov <arseny.krasnov@kaspersky.com>
---
 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}
+
 \subsubsection{Device Events}\label{sec:Device Types / Socket Device / Device Operation / Device Events}
 
 Certain events are communicated by the device to the driver using the event
-- 
2.25.1


This publicly archived list offers a means to provide input to the
OASIS Virtual I/O Device (VIRTIO) TC.

In order to verify user consent to the Feedback License terms and
to minimize spam in the list archive, subscription is required
before posting.

Subscribe: virtio-comment-subscribe@lists.oasis-open.org
Unsubscribe: virtio-comment-unsubscribe@lists.oasis-open.org
List help: virtio-comment-help@lists.oasis-open.org
List archive: https://lists.oasis-open.org/archives/virtio-comment/
Feedback License: https://www.oasis-open.org/who/ipr/feedback_license.pdf
List Guidelines: https://www.oasis-open.org/policies-guidelines/mailing-lists
Committee: https://www.oasis-open.org/committees/virtio/
Join OASIS: https://www.oasis-open.org/join/

[virtio-comment] Re: [RFC PATCH v7 2/2] virtio-vsock: SOCK_SEQPACKET description

[Arseny Krasnov]

Hello, i'm a little bit confused about record boundaries description here:

is it neccessary to describe what is "message", what is "record" and MSG_EOR

bit from POSIX, because this is virtio spec and it is not related with Linux and POSIX

Thank You

On 10.08.2021 14:47, Arseny Krasnov wrote:
> This adds description of SOCK_SEQPACKET socket type
> support for virtio-vsock.
>
> Signed-off-by: Arseny Krasnov <arseny.krasnov@kaspersky.com>
> ---
>  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}
> +
>  \subsubsection{Device Events}\label{sec:Device Types / Socket Device / Device Operation / Device Events}
>  
>  Certain events are communicated by the device to the driver using the event

This publicly archived list offers a means to provide input to the
OASIS Virtual I/O Device (VIRTIO) TC.

In order to verify user consent to the Feedback License terms and
to minimize spam in the list archive, subscription is required
before posting.

Subscribe: virtio-comment-subscribe@lists.oasis-open.org
Unsubscribe: virtio-comment-unsubscribe@lists.oasis-open.org
List help: virtio-comment-help@lists.oasis-open.org
List archive: https://lists.oasis-open.org/archives/virtio-comment/
Feedback License: https://www.oasis-open.org/who/ipr/feedback_license.pdf
List Guidelines: https://www.oasis-open.org/policies-guidelines/mailing-lists
Committee: https://www.oasis-open.org/committees/virtio/
Join OASIS: https://www.oasis-open.org/join/

Re: [virtio-comment] [RFC PATCH v7 1/2] virtio-vsock: use C style defines for constants

[Stefano Garzarella]

On Tue, Aug 10, 2021 at 02:46:49PM +0300, Arseny Krasnov wrote:
>This:
>1) Replaces enums with C style "defines", because
>   use of enums is not documented, while "defines"
>   are widely used in spec.
>2) Adds defines for some constants.
>
>Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
>Signed-off-by: Arseny Krasnov <arseny.krasnov@kaspersky.com>
>---
> virtio-vsock.tex | 54 +++++++++++++++++++++++++-----------------------
> 1 file changed, 28 insertions(+), 26 deletions(-)


Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>

_______________________________________________
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization

Re: [virtio-comment] [RFC PATCH v7 1/2] virtio-vsock: use C style defines for constants

[Stefano Garzarella]

On Tue, Aug 10, 2021 at 02:46:49PM +0300, Arseny Krasnov wrote:
>This:
>1) Replaces enums with C style "defines", because
>   use of enums is not documented, while "defines"
>   are widely used in spec.
>2) Adds defines for some constants.
>
>Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
>Signed-off-by: Arseny Krasnov <arseny.krasnov@kaspersky.com>
>---
> virtio-vsock.tex | 54 +++++++++++++++++++++++++-----------------------
> 1 file changed, 28 insertions(+), 26 deletions(-)


Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>

Re: [virtio-comment] [RFC PATCH v7 2/2] virtio-vsock: SOCK_SEQPACKET description

[Stefano Garzarella]

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@kaspersky.com>
>---
> 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

_______________________________________________
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization

Re: [virtio-comment] [RFC PATCH v7 2/2] virtio-vsock: SOCK_SEQPACKET description

[Stefano Garzarella]

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@kaspersky.com>
>---
> 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