docs/interop/vhost-user.rst

4 Vhost-user Protocol
19 This protocol is aiming to complement the ``ioctl`` interface used to
26 The protocol defines 2 sides of the communication, *front-end* and
187 When the ``VHOST_USER_PROTOCOL_F_XEN_MMAP`` protocol feature has been
380 The protocol for vhost-user is based on the existing implementation of
398        The section on ``REPLY_ACK`` protocol extension.
421 Any protocol extensions are gated by protocol feature bits, which
423 older back-ends don't support negotiating protocol features, a feature
434 This reserved feature bit was reused by the vhost-user protocol to add
435 vhost-user protocol feature negotiation in a backwards compatible
437 work even though they are not aware of vhost-user protocol feature
500 queues.  This is treated as a protocol extension, hence the back-end has to
501 implement protocol features first. The multiple queues feature is supported
502 only when the protocol feature ``VHOST_USER_PROTOCOL_F_MQ`` (bit 0) is set.
514 Back-ends should always implement the ``VHOST_USER_PROTOCOL_F_MQ`` protocol
518 Front-ends must not rely on the ``VHOST_USER_PROTOCOL_F_MQ`` protocol feature for
520 require this protocol feature.
545 ``VHOST_USER_PROTOCOL_F_LOG_SHMFD`` protocol feature.
648 destination, following the usual protocol for establishing a connection
650 mappings and kick and call FDs as necessary, negotiating protocol
726 ``VHOST_USER_PROTOCOL_F_BACKEND_REQ`` protocol feature, to allow the
734 If ``VHOST_USER_PROTOCOL_F_BACKEND_SEND_FD`` protocol feature is
1015 protocol feature.
1031 Protocol features
1088   Get the protocol feature bitmask from the underlying vhost
1105   Enable protocol features in the underlying vhost implementation.
1170   When the back-end has ``VHOST_USER_PROTOCOL_F_LOG_SHMFD`` protocol feature,
1263   instead of waiting for the kick. Note that if the protocol feature
1282   instead of waiting for the call. Note that if the protocol features
1300   in the ancillary data. Note that if the protocol features
1316   is set in queried protocol features by
1340   present in ``VHOST_USER_GET_FEATURES`` and protocol feature bit
1356   is present in ``VHOST_USER_GET_FEATURES`` and protocol feature bit
1374   ``VHOST_USER_F_PROTOCOL_FEATURES`` has been negotiated, and protocol
1508   When ``VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD`` protocol feature has
1520   When ``VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD`` protocol feature has
1531   Sets the GPU protocol socket file descriptor, which is passed as
1532   ancillary data. The GPU protocol is used to inform the front-end of
1546   Only valid if the ``VHOST_USER_PROTOCOL_F_RESET_DEVICE`` protocol
1555   When the ``VHOST_USER_PROTOCOL_F_INBAND_NOTIFICATIONS`` protocol
1569   When the ``VHOST_USER_PROTOCOL_F_CONFIGURE_MEM_SLOTS`` protocol
1583   When the ``VHOST_USER_PROTOCOL_F_CONFIGURE_MEM_SLOTS`` protocol
1588   ``VHOST_USER_PROTOCOL_F_CONFIGURE_MEM_SLOTS`` protocol feature has
1607   When the ``VHOST_USER_PROTOCOL_F_CONFIGURE_MEM_SLOTS`` protocol
1612   ``VHOST_USER_PROTOCOL_F_CONFIGURE_MEM_SLOTS`` protocol feature has
1631   When the ``VHOST_USER_PROTOCOL_F_STATUS`` protocol feature has been
1642   When the ``VHOST_USER_PROTOCOL_F_STATUS`` protocol feature has been
1653   When the ``VHOST_USER_PROTOCOL_F_SHARED_OBJECT`` protocol
1786   ``VHOST_USER_PROTOCOL_F_HOST_NOTIFIER`` protocol feature has been
1795   When the ``VHOST_USER_PROTOCOL_F_INBAND_NOTIFICATIONS`` protocol
1809   When the ``VHOST_USER_PROTOCOL_F_INBAND_NOTIFICATIONS`` protocol
1823   When the ``VHOST_USER_PROTOCOL_F_SHARED_OBJECT`` protocol
1841   When the ``VHOST_USER_PROTOCOL_F_SHARED_OBJECT`` protocol
1857   When the ``VHOST_USER_PROTOCOL_F_SHARED_OBJECT`` protocol
1870 commands. This differs from the vhost protocol implementation where
1874 With this protocol extension negotiated, the sender (QEMU) can set the