Re: [Qemu-devel] [PATCH] hw/vmmouse.c: Disable vmmouse after reboot

["Andreas Färber" <afaerber@suse.de>]

Am 25.01.2012 21:04, schrieb Gerhard Wiesinger:
> Bugfix after reboot when vmmouse was enabled and another OS which uses
> e.g. PS/2
> mouse.
> 
> Details:
> When a guest activated the vmmouse followed by a reboot the vmmouse was
> still
> enabled and the PS/2 mouse was therefore unsusable. When another guest
> is then
> booted without vmmouse support (e.g. PS/2 mouse) the mouse is not working.
> 
> Reason is that VMMouse has priority and disables all other mouse entities
> and therefore must be disabled on reset.
> 
> Testscenario:
> 1.) Boot e.g. OS with VMMouse support (e.g. Windows with VMMouse tools)
> 2.) reboot
> 3.) Boot e.g. OS without VMMouse support (e.g. DOS) => PS/2 mouse
> doesn't work
>     any more. Fixes that issue.
> 
> Testscenario 2 by Jan Kiszka <jan.kiszka@siemens.com>:
> Confirm that this patch fixes a real issue. Setup: qemu.git,
> opensuse 11.4 guest, SDL graphic, system_reset while guest is using the
> vmmouse. Without the patch, the vmmouse become unusable after the
> reboot. Also, the mouse stays in absolute mode even before X starts again.
> 
> Fixed by:
> Disabling the vmmouse in its reset handler.
> 
> Signed-off-by: Gerhard Wiesinger <lists@wiesinger.com>

I've been able to reproduce this the day before yesterday, on my version
of qemu-kvm 0.15.1 with this patch apparently fixing the mouse after a
kdump.

Yesterday however the reporter applied the patch himself to qemu.git and
reported this patch not to fix it on their side.

We boot into the desktop, then do:
# echo 1 > /proc/sys/kernel/sysrq
# echo c > /proc/sysrq-trigger
System then reboots after a while and at login mouse does or does not work.

I had originally tried to kdump with just a virtio drive w/ default
settings; then I tried with the reporter's setting of -smp 4 (and
cache=unsafe) and was able to reproduce it. Afterwards I was able to
reproduce without -smp 4 as well; no recompilation occurred. Guest was
the same SLES11 SP2 RC2 all the time.

So, is there any indeterminism involved? I.e. is the mouse unusability
maybe not 100% reproducible? Anything else that may need to be fixed
beyond this patch?

Patch does not break anything, so for now:

Tested-by: Andreas Färber <afaerber@suse.de>

Thanks,
Andreas

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