system/devices/vhost-user.rst

3 vhost-user back ends
4 --------------------
6 vhost-user back ends are way to service the request of VirtIO devices
10 vhost-user device
15 a ``chardev`` option which specifies the ID of the ``--chardev``
16 device that connects via a socket to the vhost-user *daemon*.
18 Each device will have an virtio-mmio and virtio-pci variant. See your
21 .. list-table:: vhost-user devices
23   :header-rows: 1
25   * - Device
26     - Type
27     - Notes
28   * - vhost-user-blk
29     - Block storage
30     - See contrib/vhost-user-blk
31   * - vhost-user-fs
32     - File based storage driver
33     - See https://gitlab.com/virtio-fs/virtiofsd
34   * - vhost-user-gpio
35     - Proxy gpio pins to host
36     - See https://github.com/rust-vmm/vhost-device
37   * - vhost-user-gpu
38     - GPU driver
39     - See contrib/vhost-user-gpu
40   * - vhost-user-i2c
41     - Proxy i2c devices to host
42     - See https://github.com/rust-vmm/vhost-device
43   * - vhost-user-input
44     - Generic input driver
45     - :ref:`vhost_user_input`
46   * - vhost-user-rng
47     - Entropy driver
48     - :ref:`vhost_user_rng`
49   * - vhost-user-scmi
50     - System Control and Management Interface
51     - See https://github.com/rust-vmm/vhost-device
52   * - vhost-user-snd
53     - Audio device
54     - See https://github.com/rust-vmm/vhost-device/staging
55   * - vhost-user-scsi
56     - SCSI based storage
57     - See contrib/vhost-user-scsi
58   * - vhost-user-vsock
59     - Socket based communication
60     - See https://github.com/rust-vmm/vhost-device
63 implementing the device and using the vhost-user protocol should work.
65 vhost-user-device
68 The vhost-user-device is a generic development device intended for
72   - Device ``virtio-id``
73   - The ``num_vqs`` it needs and their ``vq_size``
74   - The ``config_size`` if needed
78   vhost-user-device without first patching out::
81     dc->user_creatable = false;
83   in ``vhost-user-device.c`` and ``vhost-user-device-pci.c`` file and
86 vhost-user daemon
101 achieved via the ``memory-backend-file``, ``memory-backend-memfd``, or
102 ``memory-backend-shm`` objects.
103 A reference to a file-descriptor which can access this object
107 system memory as defined by the ``-m`` argument.
114 .. parsed-literal::
116   $ virtio-foo --socket-path=/var/run/foo.sock $OTHER_ARGS
121 .. parsed-literal::
124       -m 4096 \\
125       -chardev socket,id=ba1,path=/var/run/foo.sock \\
126       -device vhost-user-foo,chardev=ba1,$OTHER_ARGS \\
127       -object memory-backend-memfd,id=mem,size=4G,share=on \\
128       -numa node,memdev=mem \\