Bug 24712

Summary:

Input device hotplugging is incompatible with multiseat mode

Product:

xorg

Reporter:

Ilia K. <mail4ilia>

Component:

Server/Input/Core

Assignee:

Xorg Project Team <xorg-team>

Status:

RESOLVED FIXED

QA Contact:

Xorg Project Team <xorg-team>

Severity:

normal

Priority:

medium

CC:

peter.hutterer

Version:

git

Hardware:

All

OS:

Linux (All)

Whiteboard:

i915 platform:

i915 features:

Attachments:

Description	Flags
proposed fix	none
proposed fix	none
proposed fix	none

Description Ilia K. 2009-10-24 08:00:15 UTC

The usual deployment of multiseat environment involves running several instances of X server simultaneously. If hotplugging is enabled, all keyboards/mice are detected and used by all X servers, which makes multiseat environment practically unusable. A traditional workaround for this issue was disabling hotplugging with
 Option  "AutoAddDevices" "false"
However, this workaround misses all the advantages of hotplugging. Particularly, changing a physical keyboard/mouse requires X server restart. This is especially annoying when some low-end keyboards/mice/usb hubs "blink" (go off, then immediately on) due to EMI or something like that.

A possible solution is to allow hotplugging but "filter out" new input device notifications for unnecessary devices.

Comment 1 Ilia K. 2009-10-24 08:45:26 UTC

Created attachment 30657 [details] [review]
proposed fix

Attached patch implements the fix.
A user is able to attach x11_layout option to the device which is matched 
against current server layout id. If x11_layout option is missing, is "*" 
or equals to server layout id, the device is added. Otherwise it's ignored.

Assume that in xorg.conf AutoAddDevices option is set to true (which is a
default) and two ServerLayout sections are present:
Section "ServerLayout"
        Identifier     "Seat0"
        Screen      0  "Screen0" 0 0
EndSection
Section "ServerLayout"
        Identifier     "Seat1"
        Screen      0  "Screen1" 0 0
EndSection

Than the following file can be added as
/etc/hal/fdi/policy/30-multiseat_input.fdi :

<?xml version="1.0" encoding="UTF-8"?>
<!-- define which keyboard/mouse should be used by which instance of X server -->

<deviceinfo version="0.2">
  <device>
    <!-- Seat 0 uses usb hub 1-7 only -->
    <match key="info.category" string="input">
      <match key="linux.sysfs_path" contains="/sys/devices/pci0000:00/0000:00:02.1/usb1/1-7/">
        <merge key="input.x11_options.x11_layout" type="string">Seat0</merge>
      </match>
    </match>

    <!-- Seat 1 uses usb hub 1-8 only -->
    <match key="info.category" string="input">
      <match key="linux.sysfs_path" contains="/sys/devices/pci0000:00/0000:00:02.1/usb1/1-8/">
        <merge key="input.x11_options.x11_layout" type="string">Seat1</merge>
      </match>
    </match>

    <!-- input devices which don't match above rules will be added to all X instances -->
  </device>
</deviceinfo>

Comment 2 Ilia K. 2009-10-24 08:45:30 UTC

Created attachment 30658 [details] [review]
proposed fix

Attached patch implements the fix.
A user is able to attach x11_layout option to the device which is matched 
against current server layout id. If x11_layout option is missing, is "*" 
or equals to server layout id, the device is added. Otherwise it's ignored.

Assume that in xorg.conf AutoAddDevices option is set to true (which is a
default) and two ServerLayout sections are present:
Section "ServerLayout"
        Identifier     "Seat0"
        Screen      0  "Screen0" 0 0
EndSection
Section "ServerLayout"
        Identifier     "Seat1"
        Screen      0  "Screen1" 0 0
EndSection

Than the following file can be added as
/etc/hal/fdi/policy/30-multiseat_input.fdi :

<?xml version="1.0" encoding="UTF-8"?>
<!-- define which keyboard/mouse should be used by which instance of X server -->

<deviceinfo version="0.2">
  <device>
    <!-- Seat 0 uses usb hub 1-7 only -->
    <match key="info.category" string="input">
      <match key="linux.sysfs_path" contains="/sys/devices/pci0000:00/0000:00:02.1/usb1/1-7/">
        <merge key="input.x11_options.x11_layout" type="string">Seat0</merge>
      </match>
    </match>

    <!-- Seat 1 uses usb hub 1-8 only -->
    <match key="info.category" string="input">
      <match key="linux.sysfs_path" contains="/sys/devices/pci0000:00/0000:00:02.1/usb1/1-8/">
        <merge key="input.x11_options.x11_layout" type="string">Seat1</merge>
      </match>
    </match>

    <!-- input devices which don't match above rules will be added to all X instances -->
  </device>
</deviceinfo>

Comment 3 Peter Hutterer 2009-10-25 19:53:12 UTC

Wasn't this supposed to be addressed by ConsoleKit or something?

Comment 4 Peter Hutterer 2013-04-10 05:19:34 UTC

commit 159b03e13760920274b573a2bccdbf6a79f059e7
Author: Lennart Poettering <lennart@poettering.net>
Date:   Mon Jul 18 21:19:23 2011 +0200

    config: add udev/systemd multi-seat support

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