docs/multiseat.txt - qemu - Git at Google


 multiseat howto (with some multihead coverage)
 ==============================================

 host side
 ---------

 First you must compile qemu with a user interface supporting
 multihead/multiseat and input event routing.  Right now this
 list includes sdl2, gtk (both 2+3) and vnc:

   ./configure --enable-sdl --with-sdlabi=2.0

 or

   ./configure --enable-gtk


 Next put together the qemu command line (sdk/gtk):

 qemu	-enable-kvm -usb $memory $disk $whatever \
 	-display [ sdl | gtk ] \
 	-vga std \
 	-device usb-tablet

 That is it for the first seat, which will use the standard vga, the
 standard ps/2 keyboard (implicitly there) and the usb-tablet.  Now the
 additional switches for the second seat:

 	-device pci-bridge,addr=12.0,chassis_nr=2,id=head.2 \
 	-device secondary-vga,bus=head.2,addr=02.0,id=video.2 \
 	-device nec-usb-xhci,bus=head.2,addr=0f.0,id=usb.2 \
 	-device usb-kbd,bus=usb.2.0,port=1,display=video.2 \
 	-device usb-tablet,bus=usb.2.0,port=2,display=video.2

 This places a pci bridge in slot 12, connects a display adapter and
 xhci (usb) controller to the bridge.  Then it adds a usb keyboard and
 usb mouse, both connected to the xhci and linked to the display.

 The "display=video2" sets up the input routing.  Any input coming from
 the window which belongs to the video.2 display adapter will be routed
 to these input devices.

 The sdl2 ui will start up with two windows, one for each display
 device.  The gtk ui will start with a single window and each display
 in a separate tab.  You can either simply switch tabs to switch heads,
 or use the "View / Detach tab" menu item to move one of the displays
 to its own window so you can see both display devices side-by-side.

 For vnc some additional configuration on the command line is needed.
 We'll create two vnc server instances, and bind the second one to the
 second seat, simliar to input devices:

 	-display vnc=:1,id=primary \
 	-display vnc=:2,id=secondary,display=video.2

 Connecting to vnc display :1 gives you access to the first seat, and
 likewise connecting to vnc display :2 shows the second seat.

 Note on spice: Spice handles multihead just fine.  But it can't do
 multiseat.  For tablet events the event source is sent to the spice
 agent.  But qemu can't figure it, so it can't do input routing.
 Fixing this needs a new or extended input interface between
 libspice-server and qemu.  For keyboard events it is even worse:  The
 event source isn't included in the spice protocol, so the wire
 protocol must be extended to support this.


 guest side
 ----------

 You need a pretty recent linux guest.  systemd with loginctl.  kernel
 3.14+ with CONFIG_DRM_BOCHS enabled.  Fedora 20 will do.  Must be
 fully updated for the new kernel though, i.e. the live iso doesn't cut
 it.

 Now we'll have to configure the guest.  Boot and login.  "lspci -vt"
 should list the pci bridge with the display adapter and usb controller:

     [root@fedora ~]# lspci -vt
     -[0000:00]-+-00.0  Intel Corporation 440FX - 82441FX PMC [Natoma]
                [ ... ]
                \-12.0-[01]--+-02.0  Device 1234:1111
                             \-0f.0  NEC Corporation USB 3.0 Host Controller

 Good.  Now lets tell the system that the pci bridge and all devices
 below it belong to a separate seat by dropping a file into
 /etc/udev/rules.d:

     [root@fedora ~]# cat /etc/udev/rules.d/70-qemu-autoseat.rules
     SUBSYSTEMS=="pci", DEVPATH=="*/0000:00:12.0", TAG+="seat", ENV{ID_AUTOSEAT}="1"

 Reboot.  System should come up with two seats.  With loginctl you can
 check the configuration:

     [root@fedora ~]# loginctl list-seats
     SEAT
     seat0
     seat-pci-pci-0000_00_12_0

     2 seats listed.

 You can use "loginctl seat-status seat-pci-pci-0000_00_12_0" to list
 the devices attached to the seat.

 Background info is here:
   http://www.freedesktop.org/wiki/Software/systemd/multiseat/


 guest side with pci-bridge-seat
 -------------------------------

 Qemu version FIXME and newer has a new pci-bridge-seat device which
 can be used instead of pci-bridge.  Just swap the device name in the
 qemu command line above.  The only difference between the two devices
 is the pci id.  We can match the pci id instead of the device path
 with a nice generic rule now, which simplifies the guest
 configuration:

     [root@fedora ~]# cat /etc/udev/rules.d/70-qemu-pci-bridge-seat.rules
     SUBSYSTEM=="pci", ATTR{vendor}=="0x1b36", ATTR{device}=="0x000a", \
             TAG+="seat", ENV{ID_AUTOSEAT}="1"

 Patch with this rule will be submitted to upstream udev/systemd, so
 long-term, when systemd with this lands in distros, things will work
 just fine without any manual guest configuration.

 Enjoy!

 --
 Gerd Hoffmann <kraxel@redhat.com>

	multiseat howto (with some multihead coverage)
	==============================================

	host side
	---------

	First you must compile qemu with a user interface supporting
	multihead/multiseat and input event routing. Right now this
	list includes sdl2, gtk (both 2+3) and vnc:

	./configure --enable-sdl --with-sdlabi=2.0

	or

	./configure --enable-gtk


	Next put together the qemu command line (sdk/gtk):

	qemu -enable-kvm -usb $memory $disk $whatever \
	-display [ sdl \| gtk ] \
	-vga std \
	-device usb-tablet

	That is it for the first seat, which will use the standard vga, the
	standard ps/2 keyboard (implicitly there) and the usb-tablet. Now the
	additional switches for the second seat:

	-device pci-bridge,addr=12.0,chassis_nr=2,id=head.2 \
	-device secondary-vga,bus=head.2,addr=02.0,id=video.2 \
	-device nec-usb-xhci,bus=head.2,addr=0f.0,id=usb.2 \
	-device usb-kbd,bus=usb.2.0,port=1,display=video.2 \
	-device usb-tablet,bus=usb.2.0,port=2,display=video.2

	This places a pci bridge in slot 12, connects a display adapter and
	xhci (usb) controller to the bridge. Then it adds a usb keyboard and
	usb mouse, both connected to the xhci and linked to the display.

	The "display=video2" sets up the input routing. Any input coming from
	the window which belongs to the video.2 display adapter will be routed
	to these input devices.

	The sdl2 ui will start up with two windows, one for each display
	device. The gtk ui will start with a single window and each display
	in a separate tab. You can either simply switch tabs to switch heads,
	or use the "View / Detach tab" menu item to move one of the displays
	to its own window so you can see both display devices side-by-side.

	For vnc some additional configuration on the command line is needed.
	We'll create two vnc server instances, and bind the second one to the
	second seat, simliar to input devices:

	-display vnc=:1,id=primary \
	-display vnc=:2,id=secondary,display=video.2

	Connecting to vnc display :1 gives you access to the first seat, and
	likewise connecting to vnc display :2 shows the second seat.

	Note on spice: Spice handles multihead just fine. But it can't do
	multiseat. For tablet events the event source is sent to the spice
	agent. But qemu can't figure it, so it can't do input routing.
	Fixing this needs a new or extended input interface between
	libspice-server and qemu. For keyboard events it is even worse: The
	event source isn't included in the spice protocol, so the wire
	protocol must be extended to support this.


	guest side
	----------

	You need a pretty recent linux guest. systemd with loginctl. kernel
	3.14+ with CONFIG_DRM_BOCHS enabled. Fedora 20 will do. Must be
	fully updated for the new kernel though, i.e. the live iso doesn't cut
	it.

	Now we'll have to configure the guest. Boot and login. "lspci -vt"
	should list the pci bridge with the display adapter and usb controller:

	[root@fedora ~]# lspci -vt
	-[0000:00]-+-00.0 Intel Corporation 440FX - 82441FX PMC [Natoma]
	[ ... ]
	\-12.0-[01]--+-02.0 Device 1234:1111
	\-0f.0 NEC Corporation USB 3.0 Host Controller

	Good. Now lets tell the system that the pci bridge and all devices
	below it belong to a separate seat by dropping a file into
	/etc/udev/rules.d:

	[root@fedora ~]# cat /etc/udev/rules.d/70-qemu-autoseat.rules
	SUBSYSTEMS=="pci", DEVPATH=="*/0000:00:12.0", TAG+="seat", ENV{ID_AUTOSEAT}="1"

	Reboot. System should come up with two seats. With loginctl you can
	check the configuration:

	[root@fedora ~]# loginctl list-seats
	SEAT
	seat0
	seat-pci-pci-0000_00_12_0

	2 seats listed.

	You can use "loginctl seat-status seat-pci-pci-0000_00_12_0" to list
	the devices attached to the seat.

	Background info is here:
	http://www.freedesktop.org/wiki/Software/systemd/multiseat/


	guest side with pci-bridge-seat
	-------------------------------

	Qemu version FIXME and newer has a new pci-bridge-seat device which
	can be used instead of pci-bridge. Just swap the device name in the
	qemu command line above. The only difference between the two devices
	is the pci id. We can match the pci id instead of the device path
	with a nice generic rule now, which simplifies the guest
	configuration:

	[root@fedora ~]# cat /etc/udev/rules.d/70-qemu-pci-bridge-seat.rules
	SUBSYSTEM=="pci", ATTR{vendor}=="0x1b36", ATTR{device}=="0x000a", \
	TAG+="seat", ENV{ID_AUTOSEAT}="1"

	Patch with this rule will be submitted to upstream udev/systemd, so
	long-term, when systemd with this lands in distros, things will work
	just fine without any manual guest configuration.

	Enjoy!

	--
	Gerd Hoffmann <kraxel@redhat.com>