Re: [Xen-users] Paravirtualized Linux with graphics (X Window)?

[John Haxby <john.haxby@xxxxxxxxxx>]

Jeff Lane wrote:
> On Fri, Feb 27, 2009 at 12:33 AM, NAHieu <nahieu@xxxxxxxxx> wrote:
>   
> > On Fri, Feb 27, 2009 at 1:09 PM, Javier Guerra Giraldez
> > <javier@xxxxxxxxxxx> wrote:
> >     
> > > NAHieu wrote:
> > >       
> > > > I use "usbdevice='tablet'", but that doesnt help. My guest run Ubuntu 8.04.
> > > >         
> Try this...
>
> Log into your VM using your now working VNC and open a console.  Use
> xset like this:
>
> xset m 0 0
>
> Which should completely turn off mouse acceleration.  You may have to
> move your mouse outside the domU window and back to get it to take
> effect, but that should sync the black dot and the mouse pointer in
> the domU VNC window.
>
>   
That's part way towards a cure.

To get something that works completely you'll need a slightly different 
approach.  What I'm describing is what I've done on a Fedora 8 system, 
but the same will apply for Ubuntu 8.04 I think.
What you're aiming to do is replace the X mouse pointer with something 
that understands the absolute coordinates that the VNC pointer really 
wants ... let's cut to the chase.
On my system I look at /proc/bus/input/devices and in there there's a 
stanza like this:
   I: Bus=0001 Vendor=5853 Product=fffe Version=0000
   N: Name="Xen Virtual Pointer"
   P: Phys=xenbus/device/vkbd/0
   S: Sysfs=/class/input/input2
   H: Handlers=mouse1 event2 js0
   B: EV=f
   B: KEY=ff0000 0 0 0 0 0 0 0 0
   B: REL=3
   B: ABS=3

If you have a combined pointer and keyboard device you need something 
more complicated and probably a patch so I'll assume that you have this 
(you probably do).
Chances are that what you have is _exactly_ what I have, even down to 
the S: and H: lines.  These lines refer to "input2" and "event2" and 
both tell us that the Xen Virtual Pointer is attached to the file 
/dev/input/event2.
Armed with this you can now edit /etc/X11/xorg.conf.   I forget what 
Ubuntu has in there, but there's probably an InputDevice section that 
refers to a mouse, change it to look something like this:
   Section "InputDevice"
       Identifier      "Mouse0"
       Driver          "evdev"
       Option          "Device" "/dev/input/event2"
   EndSection

The identifier should be whatever you already have, the Driver and 
Option lines need to be changed to match mine (except that the 
/dev/input/event2 might need to be changed to match what shows up in 
/proc/bus/input/devices).
When you've done that, restart X and, with a little luck, it will all work.

If it doesn't, check /var/log/Xorg.0.log.   It will either tell you 
(eventually) that you've got some spelling mistake somewhere or that 
you're missing the evdev driver.   On Fedora that's in an rpm called 
xorg-x11-drv-evdev, but you'll have to go hunting with synaptic on Ubuntu.
Hope that helps.

jch



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