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 --with-sdlabi=2.0 13 14or 15 16 ./configure --enable-gtk 17 18 19Next put together the qemu command line (sdk/gtk): 20 21qemu -enable-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, simliar 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