ui: add a D-Bus display backend

The "dbus" display backend exports the QEMU consoles and other
UI-related interfaces over D-Bus.

By default, the connection is established on the session bus, but you
can specify a different bus with the "addr" option.

The backend takes the "org.qemu" service name, while still allowing
further instances to queue on the same name (so you can lookup all the
available instances too). It accepts any number of clients at this
point, although this is expected to evolve with options to restrict
clients, or only accept p2p via fd passing.

The interface is intentionally very close to the internal QEMU API,
and can be introspected or interacted with busctl/dfeet etc:

$ ./qemu-system-x86_64 -name MyVM -display dbus
$ busctl --user introspect org.qemu /org/qemu/Display1/Console_0

org.qemu.Display1.Console           interface -         -               -
.RegisterListener                   method    h         -               -
.SetUIInfo                          method    qqiiuu    -               -
.DeviceAddress                      property  s         "pci/0000/01.0" emits-change
.Head                               property  u         0               emits-change
.Height                             property  u         480             emits-change
.Label                              property  s         "VGA"           emits-change
.Type                               property  s         "Graphic"       emits-change
.Width                              property  u         640             emits-change
[...]

See the interfaces XML source file and Sphinx docs for the generated API
documentations.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/scripts/meson-buildoptions.sh b/scripts/meson-buildoptions.sh
index ae8f18edc2..50bd7bed4d 100644
--- a/scripts/meson-buildoptions.sh
+++ b/scripts/meson-buildoptions.sh
@@ -33,6 +33,7 @@ meson_options_help() {
   printf "%s\n" '  coreaudio       CoreAudio sound support'
   printf "%s\n" '  curl            CURL block device driver'
   printf "%s\n" '  curses          curses UI'
+  printf "%s\n" '  dbus-display    -display dbus support'
   printf "%s\n" '  docs            Documentations build support'
   printf "%s\n" '  dsound          DirectSound sound support'
   printf "%s\n" '  fuse            FUSE block device export'
@@ -131,6 +132,8 @@ _meson_option_parse() {
     --disable-curl) printf "%s" -Dcurl=disabled ;;
     --enable-curses) printf "%s" -Dcurses=enabled ;;
     --disable-curses) printf "%s" -Dcurses=disabled ;;
+    --enable-dbus-display) printf "%s" -Ddbus_display=enabled ;;
+    --disable-dbus-display) printf "%s" -Ddbus_display=disabled ;;
     --enable-docs) printf "%s" -Ddocs=enabled ;;
     --disable-docs) printf "%s" -Ddocs=disabled ;;
     --enable-dsound) printf "%s" -Ddsound=enabled ;;