xref: /openbmc/qemu/docs/multiseat.txt (revision 5135fe71)
1
2multiseat howto (with some multihead coverage)
3==============================================
4
5host devices
6------------
7
8First you must compile qemu with a user interface supporting
9multihead/multiseat and input event routing.  Right now this
10list includes sdl2, gtk (both 2+3) and vnc:
11
12  ./configure --enable-sdl
13
14or
15
16  ./configure --enable-gtk
17
18
19Next put together the qemu command line (sdk/gtk):
20
21qemu	-accel kvm -usb $memory $disk $whatever \
22	-display [ sdl | gtk ] \
23	-vga std \
24	-device usb-tablet
25
26That is it for the first seat, which will use the standard vga, the
27standard ps/2 keyboard (implicitly there) and the usb-tablet.  Now the
28additional switches for the second seat:
29
30	-device pci-bridge,addr=12.0,chassis_nr=2,id=head.2 \
31	-device secondary-vga,bus=head.2,addr=02.0,id=video.2 \
32	-device nec-usb-xhci,bus=head.2,addr=0f.0,id=usb.2 \
33	-device usb-kbd,bus=usb.2.0,port=1,display=video.2 \
34	-device usb-tablet,bus=usb.2.0,port=2,display=video.2
35
36This places a pci bridge in slot 12, connects a display adapter and
37xhci (usb) controller to the bridge.  Then it adds a usb keyboard and
38usb mouse, both connected to the xhci and linked to the display.
39
40The "display=video2" sets up the input routing.  Any input coming from
41the window which belongs to the video.2 display adapter will be routed
42to these input devices.
43
44Starting with qemu 2.4 and linux kernel 4.1 you can also use virtio
45for the input devices, using this ...
46
47	-device pci-bridge,addr=12.0,chassis_nr=2,id=head.2 \
48	-device secondary-vga,bus=head.2,addr=02.0,id=video.2 \
49	-device virtio-keyboard-pci,bus=head.2,addr=03.0,display=video.2 \
50	-device virtio-tablet-pci,bus=head.2,addr=03.0,display=video.2
51
52... instead of xhci and usb hid devices.
53
54host ui
55-------
56
57The sdl2 ui will start up with two windows, one for each display
58device.  The gtk ui will start with a single window and each display
59in a separate tab.  You can either simply switch tabs to switch heads,
60or use the "View / Detach tab" menu item to move one of the displays
61to its own window so you can see both display devices side-by-side.
62
63For vnc some additional configuration on the command line is needed.
64We'll create two vnc server instances, and bind the second one to the
65second seat, similar to input devices:
66
67	-display vnc=:1,id=primary \
68	-display vnc=:2,id=secondary,display=video.2
69
70Connecting to vnc display :1 gives you access to the first seat, and
71likewise connecting to vnc display :2 shows the second seat.
72
73Note on spice: Spice handles multihead just fine.  But it can't do
74multiseat.  For tablet events the event source is sent to the spice
75agent.  But qemu can't figure it, so it can't do input routing.
76Fixing this needs a new or extended input interface between
77libspice-server and qemu.  For keyboard events it is even worse:  The
78event source isn't included in the spice protocol, so the wire
79protocol must be extended to support this.
80
81
82guest side
83----------
84
85You need a pretty recent linux guest.  systemd with loginctl.  kernel
863.14+ with CONFIG_DRM_BOCHS enabled.  Fedora 20 will do.  Must be
87fully updated for the new kernel though, i.e. the live iso doesn't cut
88it.
89
90Now we'll have to configure the guest.  Boot and login.  "lspci -vt"
91should list the pci bridge with the display adapter and usb controller:
92
93    [root@fedora ~]# lspci -vt
94    -[0000:00]-+-00.0  Intel Corporation 440FX - 82441FX PMC [Natoma]
95               [ ... ]
96               \-12.0-[01]--+-02.0  Device 1234:1111
97                            \-0f.0  NEC Corporation USB 3.0 Host Controller
98
99Good.  Now lets tell the system that the pci bridge and all devices
100below it belong to a separate seat by dropping a file into
101/etc/udev/rules.d:
102
103    [root@fedora ~]# cat /etc/udev/rules.d/70-qemu-autoseat.rules
104    SUBSYSTEMS=="pci", DEVPATH=="*/0000:00:12.0", TAG+="seat", ENV{ID_AUTOSEAT}="1"
105
106Reboot.  System should come up with two seats.  With loginctl you can
107check the configuration:
108
109    [root@fedora ~]# loginctl list-seats
110    SEAT
111    seat0
112    seat-pci-pci-0000_00_12_0
113
114    2 seats listed.
115
116You can use "loginctl seat-status seat-pci-pci-0000_00_12_0" to list
117the devices attached to the seat.
118
119Background info is here:
120  http://www.freedesktop.org/wiki/Software/systemd/multiseat/
121
122
123guest side with pci-bridge-seat
124-------------------------------
125
126QEMU version 2.4 and newer has a new pci-bridge-seat device which
127can be used instead of pci-bridge.  Just swap the device name in the
128qemu command line above.  The only difference between the two devices
129is the pci id.  We can match the pci id instead of the device path
130with a nice generic rule now, which simplifies the guest
131configuration:
132
133    [root@fedora ~]# cat /etc/udev/rules.d/70-qemu-pci-bridge-seat.rules
134    SUBSYSTEM=="pci", ATTR{vendor}=="0x1b36", ATTR{device}=="0x000a", \
135            TAG+="seat", ENV{ID_AUTOSEAT}="1"
136
137Patch with this rule has been submitted to upstream udev/systemd, was
138accepted and should be included in the next systemd release (222).
139So, if your guest has this or a newer version, multiseat will work just
140fine without any manual guest configuration.
141
142Enjoy!
143
144--
145Gerd Hoffmann <kraxel@redhat.com>
146