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Subject: [PATCH v10 3/3] virtio-vsock: SOCK_SEQPACKET description
From: Arseny Krasnov <arseny.krasnov@kaspersky.com> This adds description of SOCK_SEQPACKET socket type support for virtio-vsock. Signed-off-by: Arseny Krasnov <arseny.krasnov@kaspersky.com> Signed-off-by: Stefano Garzarella <sgarzare@redhat.com> --- virtio-vsock.tex | 39 +++++++++++++++++++++++++++++++++++---- 1 file changed, 35 insertions(+), 4 deletions(-) diff --git a/virtio-vsock.tex b/virtio-vsock.tex index bf015ac..9fa93f2 100644 --- a/virtio-vsock.tex +++ b/virtio-vsock.tex @@ -20,6 +20,7 @@ \subsection{Feature bits}\label{sec:Device Types / Socket Device / Feature bits} \begin{description} \item VIRTIO_VSOCK_F_STREAM (0) stream socket type is supported. +\item VIRTIO_VSOCK_F_SEQPACKET (1) seqpacket socket type is supported. \end{description} \subsection{Device configuration layout}\label{sec:Device Types / Socket Device / Device configuration layout} @@ -139,15 +140,17 @@ \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 @@ -248,6 +251,34 @@ \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 and record boundaries}\label{sec:Device Types / Socket Device / Device Operation / Seqpacket Sockets / Boundaries} +Two types of boundaries supported: message and record boundaries. + +A message contains data sent by a single system call. Message boundary means +that data of single send system call is guaranteed to be read wholly by single +receive system call. If receive buffer is not enough, then out of size data +will be dropped. + +Record is any number of subsequent messages, where last message is sent with POSIX +MSG_EOR flag set. Record boundary means that receiver gets MSG_EOR flag set +in the corresponding message where sender set it. + +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 << 0) +\end{lstlisting} + +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 (1 << 1) +\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 -- 2.31.1
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