docs/system/devices/vhost-user-input.rst

   1 .. _vhost_user_input:
   2
   3 QEMU vhost-user-input - Input emulation
   4 =======================================
   5
   6 This document describes the setup and usage of the Virtio input device.
   7 The Virtio input device is a paravirtualized device for input events.
   8
   9 Description
  10 -----------
  11
  12 The vhost-user-input device implementation was designed to work with a daemon
  13 polling on input devices and passes input events to the guest.
  14
  15 QEMU provides a backend implementation in contrib/vhost-user-input.
  16
  17 Linux kernel support
  18 --------------------
  19
  20 Virtio input requires a guest Linux kernel built with the
  21 ``CONFIG_VIRTIO_INPUT`` option.
  22
  23 Examples
  24 --------
  25
  26 The backend daemon should be started first:
  27
  28 ::
  29
  30   host# vhost-user-input --socket-path=input.sock       \
  31       --evdev-path=/dev/input/event17
  32
  33 The QEMU invocation needs to create a chardev socket to communicate with the
  34 backend daemon and access the VirtIO queues with the guest over the
  35 :ref:`shared memory <shared_memory_object>`.
  36
  37 ::
  38
  39   host# qemu-system                                                             \
  40       -chardev socket,path=/tmp/input.sock,id=mouse0                            \
  41       -device vhost-user-input-pci,chardev=mouse0                               \
  42       -m 4096                                                                   \
  43       -object memory-backend-file,id=mem,size=4G,mem-path=/dev/shm,share=on     \
  44       -numa node,memdev=mem                                                     \
  45       ...