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.

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 and org.qemu.Display1.Mouse interfaces when available.

method RegisterListener(h listener) → ()
Arguments:

  • listener (h) – 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”).

org.qemu.Display1.Keyboard interface

interface org.qemu.Display1.Keyboard

This interface in 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 in 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:

Send a mouse button press event.

method Release(u button) → ()
Arguments:

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.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.

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:

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.

org.qemu.Display1.Audio interface

interface org.qemu.Display1.Audio

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

method RegisterOutListener(h listener) → ()
Arguments:

  • listener (h) – 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(h listener) → ()
Arguments:

  • listener (h) – 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.

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.

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.

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(h stream) → ()
Arguments:

  • 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.