D-Bus display — QEMU documentation

# D-Bus display

QEMU can export the VM display through D-Bus (when started with `-display dbus`), to allow out-of-process UIs, remote protocol servers or other interactive display usages.

Various specialized D-Bus interfaces are available on different object paths under `/org/qemu/Display1/`, depending on the VM configuration.

QEMU also implements the standard interfaces, such as org.freedesktop.DBus.Introspectable.

## org.qemu.Display1.VM interface

interface org.qemu.Display1.VM

  This interface is implemented on `/org/qemu/Display1/VM`.

  property Name: s
    Access:

      read-only

    Emits Changed:

      yes

    The name of the VM.

  property UUID: s
    Access:

      read-only

    Emits Changed:

      yes

    The UUID of the VM.

  property ConsoleIDs: au
    Access:

      read-only

    Emits Changed:

      yes

    The list of consoles available on `/org/qemu/Display1/Console_$id`.

  property Interfaces: as
    Access:

      read-only

    Emits Changed:

      yes

    This property lists extra interfaces provided by the /org/qemu/Display1/VM object, and can be used to detect the capabilities with which they are communicating.

    Unlike the standard D-Bus Introspectable interface, querying this property does not require parsing XML.

    (earlier version of the display interface do not provide this property)

## org.qemu.Display1.Console interface

interface org.qemu.Display1.Console

  This interface is implemented on `/org/qemu/Display1/Console_$id`. You may discover available consoles through introspection or with the `org.qemu.Display1.VM.ConsoleIDs` property.

  A console is attached to a video device head. It may be “Graphic” or “Text” (see `Type` and other properties).

  Interactions with a console may be done with `org.qemu.Display1.Keyboard`, `org.qemu.Display1.Mouse` and `org.qemu.Display1.MultiTouch` interfaces when available.

  method RegisterListener(ay listener, h listener) → ()
    Arguments:

      - listener (h) – a Unix socket FD, for peer-to-peer D-Bus communication.

      - listener – a Unix socket FD, for peer-to-peer D-Bus communication.

    Register a console listener, which will receive display updates, until it is disconnected.

    Multiple listeners may be registered simultaneously.

    The listener is expected to implement the `org.qemu.Display1.Listener` interface.

  method SetUIInfo(q width_mm, q height_mm, i xoff, i yoff, u width, u height) → ()
    Arguments:

      - width_mm (q) – the physical display width in millimeters.

      - height_mm (q) – the physical display height in millimeters.

      - xoff (i) – horizontal offset, in pixels.

      - yoff (i) – vertical offset, in pixels.

      - width (u) – console width, in pixels.

      - height (u) – console height, in pixels.

    Modify the dimensions and display settings.

  property Label: s
    Access:

      read-only

    Emits Changed:

      yes

    A user-friendly name for the console (for ex: “VGA”).

  property Head: u
    Access:

      read-only

    Emits Changed:

      yes

    Graphical device head number.

  property Type: s
    Access:

      read-only

    Emits Changed:

      yes

    Console type (“Graphic” or “Text”).

  property Width: u
    Access:

      read-only

    Emits Changed:

      yes

    Console width, in pixels.

  property Height: u
    Access:

      read-only

    Emits Changed:

      yes

    Console height, in pixels.

  property DeviceAddress: s
    Access:

      read-only

    Emits Changed:

      yes

    The device address (ex: “pci/0000/02.0”).

  property Interfaces: as
    Access:

      read-only

    Emits Changed:

      yes

    This property lists extra interfaces provided by the `/org/qemu/Display1/Console_$id` object, and can be used to detect the capabilities with which they are communicating.

    Unlike the standard D-Bus Introspectable interface, querying this property does not require parsing XML.

    (earlier version of the display interface do not provide this property)

## org.qemu.Display1.Keyboard interface

interface org.qemu.Display1.Keyboard

  This interface is optionally implemented on `/org/qemu/Display1/Console_$id` (see `Console`).

  method Press(u keycode) → ()
    Arguments:

      - keycode (u) – QEMU key number (xtkbd + special re-encoding of high bit)

    Send a key press event.

  method Release(u keycode) → ()
    Arguments:

      - keycode (u) – QEMU key number (xtkbd + special re-encoding of high bit)

    Send a key release event.

  property Modifiers: u
    Access:

      read-only

    Emits Changed:

      yes

    The active keyboard modifiers:

        Scroll = 1 << 0
        Num    = 1 << 1
        Caps   = 1 << 2

## org.qemu.Display1.Mouse interface

interface org.qemu.Display1.Mouse

  This interface is optionally implemented on `/org/qemu/Display1/Console_$id` (see `Console` documentation).

  Button values:

      Left       = 0
      Middle     = 1
      Right      = 2
      Wheel-up   = 3
      Wheel-down = 4
      Side       = 5
      Extra      = 6

  method Press(u button) → ()
    Arguments:

      - button (u) – button value.

    Send a mouse button press event.

  method Release(u button) → ()
    Arguments:

      - button (u) – button value.

    Send a mouse button release event.

  method SetAbsPosition(u x, u y) → ()
    Arguments:

      - x (u) – X position, in pixels.

      - y (u) – Y position, in pixels.

    Set the mouse pointer position.

    Returns an error if not `IsAbsolute`.

  method RelMotion(i dx, i dy) → ()
    Arguments:

      - dx (i) – X-delta, in pixels.

      - dy (i) – Y-delta, in pixels.

    Move the mouse pointer position, relative to the current position.

    Returns an error if `IsAbsolute`.

  property IsAbsolute: b
    Access:

      read-only

    Emits Changed:

      yes

    Whether the mouse is using absolute movements.

## org.qemu.Display1.MultiTouch interface

interface org.qemu.Display1.MultiTouch

  This interface in implemented on `/org/qemu/Display1/Console_$id` (see `Console` documentation).

  Kind values:

      Begin       = 0
      Update      = 1
      End         = 2
      Cancel      = 3

  method SendEvent(u kind, t num_slot, d x, d y) → ()
    Arguments:

      - kind (u) – The touch event kind

      - num_slot (t) – The slot number.

      - x (d) – The x coordinates.

      - y (d) – The y coordinates.

    Send a touch gesture event.

  property MaxSlots: i
    Access:

      read-only

    Emits Changed:

      yes

    The maximum number of slots.

## org.qemu.Display1.Listener interface

interface org.qemu.Display1.Listener

  This client-side interface must be available on `/org/qemu/Display1/Listener` when registering the peer-to-peer connection with `Register`.

  method Scanout(u width, u height, u stride, u pixman_format, ay data) → ()
    Arguments:

      - width (u) – display width, in pixels.

      - height (u) – display height, in pixels.

      - stride (u) – data stride, in bytes.

      - pixman_format (u) – image format (ex: `PIXMAN_X8R8G8B8`).

      - data (ay) – image data.

    Resize and update the display content.

    The data to transfer for the display update may be large. The preferred scanout method is `ScanoutDMABUF`, used whenever possible.

  method Update(i x, i y, i width, i height, u stride, u pixman_format, ay data) → ()
    Arguments:

      - x (i) – X update position, in pixels.

      - y (i) – Y update position, in pixels.

      - width (i) – update width, in pixels.

      - height (i) – update height, in pixels.

      - stride (u) – data stride, in bytes.

      - pixman_format (u) – image format (ex: `PIXMAN_X8R8G8B8`).

      - data (ay) – display image data.

    Update the display content.

    This method is only called after a `Scanout` call.

  method ScanoutDMABUF(h dmabuf, u width, u height, u stride, u fourcc, t modifier, b y0_top) → ()
    Arguments:

      - dmabuf (h) – the DMABUF file descriptor.

      - width (u) – display width, in pixels.

      - height (u) – display height, in pixels.

      - stride (u) – stride, in bytes.

      - fourcc (u) – DMABUF fourcc.

      - modifier (t) – DMABUF modifier.

      - y0_top (b) – whether Y position 0 is the top or not.

    Resize and update the display content with a DMABUF.

  method UpdateDMABUF(i x, i y, i width, i height) → ()
    Arguments:

      - x (i) – the X update position, in pixels.

      - y (i) – the Y update position, in pixels.

      - width (i) – the update width, in pixels.

      - height (i) – the update height, in pixels.

    Update the display content with the current DMABUF and the given region.

  method Disable() → ()

    Disable the display (turn it off).

  method MouseSet(i x, i y, i on) → ()
    Arguments:

      - x (i) – X mouse position, in pixels.

      - y (i) – Y mouse position, in pixels.

      - on (i) – whether the mouse is visible or not.

    Set the mouse position and visibility.

  method CursorDefine(i width, i height, i hot_x, i hot_y, ay data) → ()
    Arguments:

      - width (i) – cursor width, in pixels.

      - height (i) – cursor height, in pixels.

      - hot_x (i) – hot-spot X position, in pixels.

      - hot_y (i) – hot-spot Y position, in pixels.

      - data (ay) – the cursor data.

    Set the mouse cursor shape and hot-spot. The “data” must be ARGB, 32-bit per pixel.

  property Interfaces: as
    Access:

      read-only

    Emits Changed:

      yes

    This property lists extra interfaces provided by the /org/qemu/Display1/Listener object, and can be used to detect the capabilities with which they are communicating.

    Unlike the standard D-Bus Introspectable interface, querying this property does not require parsing XML.

    (earlier version of the display interface do not provide this property)

## org.qemu.Display1.Listener.Unix.Map interface

interface org.qemu.Display1.Listener.Unix.Map

  This optional client-side interface can complement org.qemu.Display1.Listener on `/org/qemu/Display1/Listener` for Unix-specific shared memory scanouts.

  method ScanoutMap(h handle, u offset, u width, u height, u stride, u pixman_format) → ()
    Arguments:

      - handle (h) – the shared map FD.

      - offset (u) – mapping offset, in bytes.

      - width (u) – display width, in pixels.

      - height (u) – display height, in pixels.

      - stride (u) – stride, in bytes.

      - pixman_format (u) – image format (ex: `PIXMAN_X8R8G8B8`).

    Resize and update the display content with a shared map.

  method UpdateMap(i x, i y, i width, i height) → ()
    Arguments:

      - x (i) – the X update position, in pixels.

      - y (i) – the Y update position, in pixels.

      - width (i) – the update width, in pixels.

      - height (i) – the update height, in pixels.

    Update the display content with the current shared map and the given region.

## org.qemu.Display1.Listener.Win32.Map interface

interface org.qemu.Display1.Listener.Win32.Map

  This optional client-side interface can complement org.qemu.Display1.Listener on `/org/qemu/Display1/Listener` for Windows specific shared memory scanouts.

  method ScanoutMap(t handle, u offset, u width, u height, u stride, u pixman_format) → ()
    Arguments:

      - handle (t) – the shared file mapping handle value (not a file handle)

      - offset (u) – mapping offset.

      - width (u) – display width, in pixels.

      - height (u) – display height, in pixels.

      - stride (u) – stride, in bytes.

      - pixman_format (u) – image format (ex: `PIXMAN_X8R8G8B8`).

    Resize and update the display content with a shared file mapping object.

  method UpdateMap(i x, i y, i width, i height) → ()
    Arguments:

      - x (i) – the X update position, in pixels.

      - y (i) – the Y update position, in pixels.

      - width (i) – the update width, in pixels.

      - height (i) – the update height, in pixels.

    Update the display content with the current shared map and the given region.

## org.qemu.Display1.Listener.Win32.D3d11 interface

interface org.qemu.Display1.Listener.Win32.D3d11

  This optional client-side interface can complement org.qemu.Display1.Listener on `/org/qemu/Display1/Listener` for Windows specific Direct3D texture sharing of the scanouts.

  method ScanoutTexture2d(t handle, u texture_width, u texture_height, b y0_top, u x, u y, u width, u height) → ()
    Arguments:

      - handle (t) – the NT handle for the shared texture (to be opened back with ID3D11Device1::OpenSharedResource1).

      - texture_width (u) – texture width, in pixels.

      - texture_height (u) – texture height, in pixels.

      - y0_top (b) – whether Y position 0 is the top or not.

      - x (u) – the X scanout position, in pixels.

      - y (u) – the Y scanout position, in pixels.

      - width (u) – the scanout width, in pixels.

      - height (u) – the scanout height, in pixels.

    Resize and update the display content with a Direct3D 11 2D texture. You must acquire and release the associated KeyedMutex 0 during rendering.

  method UpdateTexture2d(i x, i y, i width, i height) → ()
    Arguments:

      - x (i) – the X update position, in pixels.

      - y (i) – the Y update position, in pixels.

      - width (i) – the update width, in pixels.

      - height (i) – the update height, in pixels.

    Update the display content with the current Direct3D 2D texture and the given region. You must acquire and release the associated KeyedMutex 0 during rendering.

## org.qemu.Display1.Listener.Unix.ScanoutDMABUF2 interface

interface org.qemu.Display1.Listener.Unix.ScanoutDMABUF2

  This optional client-side interface can complement org.qemu.Display1.Listener on `/org/qemu/Display1/Listener` for Unix-specific DMABUF scanout setup which support multi plane.

  method ScanoutDMABUF2(ah dmabuf, u x, u y, u width, u height, au offset, au stride, u num_planes, u fourcc, u backing_width, u backing_height, t modifier, b y0_top) → ()
    Arguments:

      - dmabuf (ah) – DMABUF file descriptor of each plane.

      - x (u) – display x offset, in pixels

      - y (u) – display y offset, in pixels

      - width (u) – display width, in pixels.

      - height (u) – display height, in pixels.

      - offset (au) – offset of each plane, in bytes.

      - stride (au) – stride of each plane, in bytes.

      - num_planes (u) – plane number.

      - fourcc (u) – DMABUF fourcc.

      - backing_width (u) – backing framebuffer width, in pixels

      - backing_height (u) – backing framebuffer height, in pixels

      - modifier (t) – DMABUF modifier.

      - y0_top (b) – whether Y position 0 is the top or not.

    Resize and update the display content with DMABUF.

## org.qemu.Display1.Clipboard interface

interface org.qemu.Display1.Clipboard

  This interface must be implemented by both the client and the server on `/org/qemu/Display1/Clipboard` to support clipboard sharing between the client and the guest.

  Once `Register`’ed, method calls may be sent and received in both directions. Unregistered callers will get error replies.

  Selection values:

      Clipboard   = 0
      Primary     = 1
      Secondary   = 2

  Serial counter

  To solve potential clipboard races, clipboard grabs have an associated serial counter. It is set to 0 on registration, and incremented by 1 for each grab. The peer with the highest serial is the clipboard grab owner.

  When a grab with a lower serial is received, it should be discarded.

  When a grab is attempted with the same serial number as the current grab, the one coming from the client should have higher priority, and the client should gain clipboard grab ownership.

  method Register() → ()

    Register a clipboard session and reinitialize the serial counter.

    The client must register itself, and is granted an exclusive access for handling the clipboard.

    The server can reinitialize the session as well (to reset the counter).

  method Unregister() → ()

    Unregister the clipboard session.

  method Grab(u selection, u serial, as mimes) → ()
    Arguments:

      - selection (u) – a selection value.

      - serial (u) – the current grab serial.

      - mimes (as) – the list of available content MIME types.

    Grab the clipboard, claiming current clipboard content.

  method Release(u selection) → ()
    Arguments:

      - selection (u) – a selection value.

    Release the clipboard (does nothing if not the current owner).

  method Request(u selection, as mimes) → (s reply_mime, ay data)
    Arguments:

      - selection (u) – a selection value

      - mimes (as) – requested MIME types (by order of preference).

    Returns:

      - reply_mime (s) – the returned data MIME type.

      - data (ay) – the clipboard data.

    Request the clipboard content.

    Return an error if the clipboard is empty, or the requested MIME types are unavailable.

  property Interfaces: as
    Access:

      read-only

    Emits Changed:

      yes

    This property lists extra interfaces provided by the /org/qemu/Display1/Clipboard object, and can be used to detect the capabilities with which they are communicating.

    Unlike the standard D-Bus Introspectable interface, querying this property does not require parsing XML.

    (earlier version of the display interface do not provide this property)

## org.qemu.Display1.Audio interface

interface org.qemu.Display1.Audio

  Audio backend may be available on `/org/qemu/Display1/Audio`.

  method RegisterOutListener(ay listener, h listener) → ()
    Arguments:

      - listener (h) – a Unix socket FD, for peer-to-peer D-Bus communication.

      - listener – a Unix socket FD, for peer-to-peer D-Bus communication.

    Register an audio backend playback handler.

    Multiple listeners may be registered simultaneously.

    The listener is expected to implement the `org.qemu.Display1.AudioOutListener` interface.

  method RegisterInListener(ay listener, h listener) → ()
    Arguments:

      - listener (h) – a Unix socket FD, for peer-to-peer D-Bus communication.

      - listener – a Unix socket FD, for peer-to-peer D-Bus communication.

    Register an audio backend record handler.

    Multiple listeners may be registered simultaneously.

    The listener is expected to implement the `org.qemu.Display1.AudioInListener` interface.

  property NSamples: u
    Access:

      read-only

    Emits Changed:

      yes

    The number of samples per read/write frames. (for example the default is 480, or 10ms at 48kHz)

    (earlier version of the display interface do not provide this property)

  property Interfaces: as
    Access:

      read-only

    Emits Changed:

      yes

    This property lists extra interfaces provided by the /org/qemu/Display1/Audio object, and can be used to detect the capabilities with which they are communicating.

    Unlike the standard D-Bus Introspectable interface, querying this property does not require parsing XML.

    (earlier version of the display interface do not provide this property)

## org.qemu.Display1.AudioOutListener interface

interface org.qemu.Display1.AudioOutListener

  This client-side interface must be available on `/org/qemu/Display1/AudioOutListener` when registering the peer-to-peer connection with `RegisterOutListener`.

  method Init(t id, y bits, b is_signed, b is_float, u freq, y nchannels, u bytes_per_frame, u bytes_per_second, b be) → ()
    Arguments:

      - id (t) – the stream ID.

      - bits (y) – PCM bits per sample.

      - is_signed (b) – whether the PCM data is signed.

      - is_float (b) – PCM floating point format.

      - freq (u) – the PCM frequency in Hz.

      - nchannels (y) – the number of channels.

      - bytes_per_frame (u) – the bytes per frame.

      - bytes_per_second (u) – the bytes per second.

      - be (b) – whether using big-endian format.

    Initializes a PCM playback stream.

  method Fini(t id) → ()
    Arguments:

      - id (t) – the stream ID.

    Finish & close a playback stream.

  method SetEnabled(t id, b enabled) → ()
    Arguments:

      - id (t) – the stream ID.

      - enabled (b)

    Resume or suspend the playback stream.

  method SetVolume(t id, b mute, ay volume) → ()
    Arguments:

      - id (t) – the stream ID.

      - mute (b) – whether the stream is muted.

      - volume (ay) – the volume per-channel.

    Set the stream volume and mute state (volume without unit, 0-255).

  method Write(t id, ay data) → ()
    Arguments:

      - id (t) – the stream ID.

      - data (ay) – the PCM data.

    PCM stream to play.

  property Interfaces: as
    Access:

      read-only

    Emits Changed:

      yes

    This property lists extra interfaces provided by the /org/qemu/Display1/AudioOutListener object, and can be used to detect the capabilities with which they are communicating.

    Unlike the standard D-Bus Introspectable interface, querying this property does not require parsing XML.

    (earlier version of the display interface do not provide this property)

## org.qemu.Display1.AudioInListener interface

interface org.qemu.Display1.AudioInListener

  This client-side interface must be available on `/org/qemu/Display1/AudioInListener` when registering the peer-to-peer connection with `RegisterInListener`.

  method Init(t id, y bits, b is_signed, b is_float, u freq, y nchannels, u bytes_per_frame, u bytes_per_second, b be) → ()
    Arguments:

      - id (t) – the stream ID.

      - bits (y) – PCM bits per sample.

      - is_signed (b) – whether the PCM data is signed.

      - is_float (b) – PCM floating point format.

      - freq (u) – the PCM frequency in Hz.

      - nchannels (y) – the number of channels.

      - bytes_per_frame (u) – the bytes per frame.

      - bytes_per_second (u) – the bytes per second.

      - be (b) – whether using big-endian format.

    Initializes a PCM record stream.

  method Fini(t id) → ()
    Arguments:

      - id (t) – the stream ID.

    Finish & close a record stream.

  method SetEnabled(t id, b enabled) → ()
    Arguments:

      - id (t) – the stream ID.

      - enabled (b)

    Resume or suspend the record stream.

  method SetVolume(t id, b mute, ay volume) → ()
    Arguments:

      - id (t) – the stream ID.

      - mute (b) – whether the stream is muted.

      - volume (ay) – the volume per-channel.

    Set the stream volume and mute state (volume without unit, 0-255).

  method Read(t id, t size) → (ay data)
    Arguments:

      - id (t) – the stream ID.

      - size (t) – the amount to read, in bytes.

    Returns:

      - data (ay) – the recorded data (which may be less than requested).

    Read “size” bytes from the record stream.

  property Interfaces: as
    Access:

      read-only

    Emits Changed:

      yes

    This property lists extra interfaces provided by the /org/qemu/Display1/AudioInListener object, and can be used to detect the capabilities with which they are communicating.

    Unlike the standard D-Bus Introspectable interface, querying this property does not require parsing XML.

    (earlier version of the display interface do not provide this property)

## org.qemu.Display1.Chardev interface

interface org.qemu.Display1.Chardev

  Character devices may be available on `/org/qemu/Display1/Chardev_$id`.

  They may be used for different kind of streams, which are identified via their FQDN `Name`.

  Here are some known reserved kind names (the `org.qemu` prefix is reserved by QEMU):

  org.qemu.console.serial.0

    A serial console stream.

  org.qemu.monitor.hmp.0

    A QEMU HMP human monitor.

  org.qemu.monitor.qmp.0

    A QEMU QMP monitor.

  org.qemu.usbredir

    A usbredir stream.

  method Register(ay listener, h stream) → ()
    Arguments:

      - listener (ay)

      - stream (h) – a Unix FD to redirect the stream to.

    Register a file-descriptor for the stream handling.

    The current handler, if any, will be replaced.

  method SendBreak() → ()

    Send a break event to the character device.

  property Name: s
    Access:

      read-only

    Emits Changed:

      yes

    The FQDN name to identify the kind of stream. See reserved names.

  property FEOpened: b
    Access:

      read-only

    Emits Changed:

      yes

    Whether the front-end side is opened.

  property Echo: b
    Access:

      read-only

    Emits Changed:

      yes

    Whether the input should be echo’ed (for serial streams).

  property Owner: s
    Access:

      read-only

    Emits Changed:

      yes

    The D-Bus unique name of the registered handler.

  property Interfaces: as
    Access:

      read-only

    Emits Changed:

      yes

    This property lists extra interfaces provided by the `/org/qemu/Display1/Chardev_$i` object, and can be used to detect the capabilities with which they are communicating.

    Unlike the standard D-Bus Introspectable interface, querying this property does not require parsing XML.

    (earlier version of the display interface do not provide this property)

## org.qemu.Display1.Chardev.VCEncoding interface

interface org.qemu.Display1.Chardev.VCEncoding

  Provides encoding information for virtual console chardevs.

  This interface is present on chardev objects that are virtual consoles, and exposes the character encoding used by the guest.

  property Encoding: s
    Access:

      read-only

    Emits Changed:

      yes

    The character encoding used by the virtual console (matching `ChardevVCEncoding`): `cp437` or `utf8`.