Re: [Qemu-devel] -usbdevice tablet with Fedora-6 64bit guest

[Daniel P. Berrange]

On Tue, Sep 25, 2007 at 02:03:56PM +0200, Dan Kenigsberg wrote:
> On Thu, Sep 20, 2007 at 02:41:32PM +0100, Daniel P. Berrange wrote:
> > On Thu, Sep 20, 2007 at 03:36:26PM +0200, Dan Kenigsberg wrote:
> > > Hi,
> > > 
> > > I saw that using the tablet with Linux guest is possible
> > > http://thread.gmane.org/gmane.comp.emulators.qemu/11516
> > > yet I fail to do that.
> > > 
> > > I managed to compile, configure and load the evtouch X module, but still
> > > there is no movement of the mouse (after I disabled the default X
> > > pointer). I attach my Xorg.0.log for the joy of the readership.
> > 
> > Don't use the evtouch X module. Use the regular 'evdev' module.
> > 
> > Dan.
> 
> Dan, thanks for this info. However, my problem begins earlier than in X
> and using evdev instead of evtouch does not solve it.
> 
> It seems that some Linux guests have problems communicating with the
> tablet device. The most reproducible behavior that I noticed is when
> FC-6 starts: gpm senses the tablet, but only until haldaemon starts.
> After that, I cannot obtain any mouse event (even after stopping
> haldaemon).

By an unfortunate co-incidence I've just hit a similar problem myself. It
turns out QEMU mouse handling is more complex than I realized. QEMU can
export several different input devices to a guest OS, PS/2 mouse, VMWare
mouse, USB mouse, USB EvTouch tablet, USB Wacom tablet. Only one of these
devices will be fed mouse events from the host OS though at any time. The
default is that the most recently 'activated' mouse will get the events.
This starts off being the PS/2 mouse. Certain actions in the guest OS may
cause one or more of the other input devices to activate itself, and thus
claiming control of all input events from the host.

You can see what mice are configured at any time from the QEMU monitor by
typing 'info mice'. The active one has an * next to it.  What I suspect
is happening in your case is that you've configured the USB tablet, but
during initial boot only the PS/2 mouse is activated & GPM is actually
responding to events from the PS/2 mouse no the tablet. Then during boot 
something in HAL (or perhaps X itself) causes the USB tablet to become
active & thus the PS/2 mouse stops getting events. But then it sounds
like neither GPM or X are configured to use the USB tablet either, so
you end up with no movement at all.

So I guess it is probably a matter of suitably configuring Xorg to use
the USB tablet, though I can't remember exact syntax for Fedora Core 6,
in Fedora 7 I have successfully used:

Section "InputDevice"
  Name "Mouse0"
  Driver "evdev"
  Option "Name" "QEMU 0.8.2 QEMU USB Tablet"
  Option "Mode" "Absolute"
EndSection

NB, make sure 'Mouse0' is referenced as the CorePointer in the ServerLayout
section of the config. Also the 'Name' value varies acording to what QEMU
version you have[1] - check /proc/bus/input/devices for exact name seen
by the guest OS

Dan.

[1] Really rather unfortunate - if the QEMU version number were removed 
    from the printable USB device name exposed to guests the config for
    Xorg would be stable across QEMU version.
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