Hello.
I noticed that "some" versions of linux guests shows quite
bad behavour of mouse cursor: it freezes after some idle
time, and when you move mouse, it jumps after some delay
to rather distant position. So, mouse becomes "freezy/jumpy",
so to say.
Quite some painful debugging pointed to the following
udev rule:
---- /lib/udev/rules.d/42-qemu-usb.rules ----
#
# Enable autosuspend for qemu emulated usb hid devices.
#
# Note that there are buggy qemu versions which advertise remote
# wakeup support but don't actually implement it correctly. This
# is the reason why we need a match for the serial number here.
# The serial number "42" is used to tag the implementations where
# remote wakeup is working.
#
ACTION=="add", SUBSYSTEM=="usb", ATTR{product}=="QEMU USB Tablet",
ATTR{serial}=="42", TEST=="power/control", ATTR{power/control}="auto"
---- end ----
(And a few other similar rules, for other QEMU USB devices).
Removing this rule restores correct mouse behavour.
As far as I can see, this rule is to reduce polling interrupt
frequency, but apparently it does not help: any usb device
connected to guest, and the host CPU usage rises anyway, with
or without this rule.
Now the question: should we remove this rule? Why it is needed
to start with?
(qemu version 1.1, but the same bad behavour happens with other
versions too).
Thanks,
/mjt
