losing mouse location with vnc

losing mouse location with vnc

[Ross Boylan]

When I try to use a (Linux) VM via vnc there appear to be two mouse
locations at once.  One is the pointer displayed on the screen; the
other is the shown as a little box by krdc when I select "always show
local cursor" in the krdc menu.  It also appears when I use
xtightvncviewer.

The two locations are linked: moving the mouse moves both.  However, the
relation is sloppy, so that even if they two locations start the same
they quickly become different.

The pointer on the screen is the "real" location as far as the VM is
concerned; if I want to click on something inside my session, the
pointer has to be over it.

However, the alternate pointer controls whether my mouse is considered
inside or outside the VM.  So if I move the mouse so that the alternate
pointer is outside the screen, my real mouse jumps outside of the VM.

This is basically unworkable; since I see it with 2 different clients I
suspect the issue is with the VNC server, i.e., kvm.

Does this ring any bells?  Is there anything I can do to improve things?

I'm on debian lenny with a 2.6.30 kernel, kvm 72, amd64 architecture.
The VM is running the standard Lenny 2.6.26 kernel and KDE 3.5.10 (same
KDE as on the host machine).  Everything is happening on one physical
box.

I noticed some kvm only (not qemu) bugs about VNC display (e.g.,
https://bugzilla.redhat.com/show_bug.cgi?id=503156), but the seem to
describe different symptoms from mine (though I think I've seen some of
the tearing they describe as well).

I'd appreciate a cc, since I'm not on the list.

Thanks.

Ross Boylan

Re: losing mouse location with vnc

[Kenni Lund]

2009/9/12 Ross Boylan <ross@biostat.ucsf.edu>:
> When I try to use a (Linux) VM via vnc there appear to be two mouse
> locations at once.  One is the pointer displayed on the screen; the
> other is the shown as a little box by krdc when I select "always show
> local cursor" in the krdc menu.  It also appears when I use
> xtightvncviewer.

Try using "-usbdevice tablet" as an argument to the QEMU/KVM
executable, it will most likely fix your problem.

--
Kenni

Re: losing mouse location with vnc

[Ross Boylan]

On Sat, 2009-09-12 at 11:48 +0200, Kenni Lund wrote:
> 2009/9/12 Ross Boylan <ross@biostat.ucsf.edu>:
> > When I try to use a (Linux) VM via vnc there appear to be two mouse
> > locations at once.  One is the pointer displayed on the screen; the
> > other is the shown as a little box by krdc when I select "always show
> > local cursor" in the krdc menu.  It also appears when I use
> > xtightvncviewer.
> 
> Try using "-usbdevice tablet" as an argument to the QEMU/KVM
> executable, it will most likely fix your problem.
> 
Thank you for the suggestion.  Unfortunately, it doesn't seem to make a
difference.  Here's how I invoked it:

sudo vdeq kvm -net nic,vlan=1,macaddr=52:54:a0:14:01:01 \
    -name "Lenny BCU Server" \
    -serial file:kvm.log \
    -net vde,vlan=1,sock=/var/run/vde2/tap0.ctl \
    -boot c \
    -vnc :6 -usbdevice tablet \
    -hda /dev/turtle/Lenny06BCU \
    -soundhw es1370 -m 1G -smp 2

kvm 72+dfsg-5~lenny2 on a 2.6.26 kernel.

Ross