ports/131124: x11/xorg - New xorg 7.4 hangs until mouse is moved when AllowEmptyInput turned off

[Joe Marcus Clarke]

The following reply was made to PR ports/131124; it has been noted by GNATS.

From: Joe Marcus Clarke <marcus at freebsd.org>
To: Jung-uk Kim <jkim at freebsd.org>
Cc: freebsd-x11 at freebsd.org, Serge Shilov <serguei.shilov at gmail.com>,
        Peter Zehm <Peter.Zehm at crush-net.de>, rnoland at freebsd.org,
        freebsd-gnome at freebsd.org, bug-followup at freebsd.org
Subject: Re: ports/131124: x11/xorg - New xorg 7.4 hangs until mouse is	moved
 when AllowEmptyInput turned off
Date: Fri, 06 Feb 2009 16:27:34 -0500

 Jung-uk Kim wrote:
 > [Sorry for spamming y'all but I thought it is very important that 
 > everyone understands the situation clearly.]
 > 
 > On Thursday 05 February 2009 11:50 am, Serge Shilov wrote:
 >> The following reply was made to PR ports/131124; it has been noted
 >> by GNATS.
 >>
 >> From: Serge Shilov <serguei.shilov at gmail.com>
 >> To: bug-followup at freebsd.org,
 >>  xelah-freebsd-pr at xelah.com
 >> Cc:
 >> Subject: Re: ports/131124: x11/xorg - New xorg 7.4 hangs until
 >> mouse is moved when AllowEmptyInput turned off Date: Thu, 5 Feb
 >> 2009 19:40:29 +0300
 >>
 >>  I perform some experiments. Results is here.
 >>
 >>  I. Test other mice .
 >>  The 1st is
 >>  ums0: <A4Tech RF USB Mouse, class 0/0, rev 1.10/0.01, addr 2> on
 >> uhub0 ums0: 8 buttons and Z dir.
 >>
 >>  and the 2nd is
 >>  ums0: <Logitech Optical USB Mouse, class 0/0, rev 2.00/3.40, addr
 >> 2> on uhub0 ums0: 3 buttons and Z dir.
 >>
 >>  Bug still exist
 >>
 >>  II. Test direct connection mouse without hub.
 >>
 >>  Bug still exist.
 >>
 >>  Resume: It's not mice or hub or connection-via-hub problem. (But
 >> it may be some usb host problem)
 >>
 >>  III. Hot plug out and plug in mouse in X environment
 >>
 >>  After plug in mouse gehaviour BEGAN CONVENTIONAL. This can be
 >> recommended as workaround.
 >>
 >>  Notice:
 >>  1. After plug out mouse cursor may still disappeared. In this case
 >> you can switch to VT0-VT7 terminals, move mouse and switch back to
 >> X session. 2. This advice is provided 'as is' without any
 >> warranties of usefulness, capacity to work with your hardware or
 >> software and other sorts of warranties.
 >>
 >>  IV. After hot  X session restart (without OS and hardware restart)
 >> mouse still work.
 >>
 >>  V. Other cases:
 >>  Hot plug out and plug in mouse in text mode environment before
 >> start X session.
 >>  Start OS mouseless and plug in mouse before or after start X
 >> session. Hot OS restart after my workaround appliing.
 >>
 >>  In all this cases mouse behaviour was still buggy.
 >>
 >>  I'll be glad if my info help to resolve this problem.
 > 
 > 
 > A short answer:
 > 
 > Please remove "AllowEmptyInput" from your xorg.conf.
 > 
 > A longer answer:
 > 
 > http://docs.freebsd.org/cgi/mid.cgi?200902041908.50270.jkim
 > 
 > A technical answer:
 > 
 > Some devices are safe to be opened multiple times and shared by 
 > different input drivers (e.g., Linux evdev, I think) and some devices 
 > are not (e.g., our sysmouse).
 > 
 > Possible solutions (for ports maintainers):
 > 
 > - When hald probes mice, exclude all moused users 
 > (e.g., /dev/psm0, /dev/ums1, ...) from x11_driver and create a pseudo 
 > device UDI for /dev/sysmouse and set x11_driver property if moused(8) 
 > is running and /dev/sysmouse is not being used by Xserver.  If 
 > Xserver tries to open /dev/sysmouse, then the UDI has to be removed 
 > immediately.  When Xserver closes /dev/sysmouse, the fake UDI has to 
 > be restored immediately.
 > 
 > - Before Xserver starts auto-adding process, send a hint message to 
 > hald that the device is configured and enabled by static user 
 > configuration if CONFIG_HAL is defined and "AutoAddDevices" or 
 > "AutoEnableDevices" is on.  hald (i.e., FreeBSD mouse prober) 
 > excludes all sysmouse users from x11_driver and sends ACK/NACK 
 > message.  Then, Xserver continues/stops auto-adding process depending 
 > on it.
 > 
 > - Implement an ioctl command for sysmouse to report actual devices 
 > that it is controlling.  Let each input driver veto automagic 
 > configuration process if it is being used or unsafe.
 > 
 > - Some combinations of the above...
 > 
 > The first solution is the least intrusive but it is not bulletproof 
 > because of an unavoidable race condition.  The second solution is 
 > IMHO, a correct way but it requires Xserver change first.  The third 
 > solution is too platform-specific and it requires significant (and 
 > ugly) hacks for Xserver and input drivers, I think.
 > 
 > Any more ideas?
 
 What about modifying the sysmouse driver to more gracefully handle
 multiple open attempts (e.g. fail on subsequent attempts).  What effect
 would that have on X?
 
 Joe
 
 -- 
 Joe Marcus Clarke
 FreeBSD GNOME Team	::	gnome at FreeBSD.org
 FreeNode / #freebsd-gnome
 http://www.FreeBSD.org/gnome