[Qemu-devel] [Bug 1834113] Re: QEMU touchpad input erratic after wakeup from sleep

[Bryce Harrington]

intel-microcode is closely related to kernel behavior, and so wouldn't
surprise me if it's involved - like I mentioned earlier invariably input
device + power management bugs are something kernel related.

However, looking at the diff for the intel-microcode upgrade the changes
are highly processor specific, and affects a small handful:

http://launchpadlibrarian.net/424908874/intel-
microcode_3.20190514.0ubuntu0.19.04.1_3.20190514.0ubuntu0.19.04.3.diff.gz

I'm guessing for a qemu environment these aren't even relevant, but if
one of the lines matches your host cpu then perhaps this would be worth
more investigation.  Otherwise, probably another red herring.


There is more you could try though.  I suggested some ideas in my previous 
comment.  You could also run xlsclients before and after reproducing the error, 
and see if there are any new X clients running that might have a grab on the 
cursor, and then kill them until the touchpad comes back.  (See 
http://who-t.blogspot.com/2010/11/high-level-overview-of-grabs.html)


I hate to mention this as a possibility, but like I mentioned earlier, 
sometimes these bugs can reproduce very non-reliably.  I've seen cases where, 
for instance, the root cause always existed but it was some change in usage or 
other random things, that caused the input behavior to suddenly start 
happening, only to disappear again - quite mysteriously - after some other 
system change.

The way input devices work, at least in context of this particular bug, is that 
each movement or click generates an "event", that gets communicated up through 
the system through various layers until an application consumes it.  You can 
read about this in more extensive detail at 
https://www.x.org/wiki/Development/Documentation/InputEventProcessing/
That leads us to two questions for this case:  A) Is the event getting 
generated at all?  and B) If it is, then is something unexpectedly consuming 
it?  So a good first step would be to eliminate one or the other of these.  
You've made some progress towards ruling out B.

For testing if the event is getting generated, the tool 'xev' is one of
the easiest and handiest places to start from.  Have you had a chance to
give that a test?  Run it from the command line when you've got the non-
responsive touchpad, and use the touchpad and see if anything prints in
the xev window.  You can do some googling to get some tips and tricks
for filtering xev output and to understand what its output means.

'xdotool' can also be useful; it's intended for automation but it lets
you manhandle mouse events, such as force a click or mouse up/down.
Longshot but at least is easy / low risk to try.

My guess though is the event isn't even getting generated.  In that case
i'd proceed with the standard troubleshooting techniques to see if
something's wrong with the device itself, and go from there.

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https://bugs.launchpad.net/bugs/1834113

Title:
  QEMU touchpad input erratic after wakeup from sleep

Status in QEMU:
  New
Status in libvirt package in Ubuntu:
  New
Status in qemu package in Ubuntu:
  Incomplete

Bug description:
  Using Ubuntu host and guest. Normally the touchpad works great. Within
  the last few days, suddenly, apparently after a wake from sleep, the
  touchpad will behave erratically. For example, it will take two clicks
  to select something, and when moving the cursor it will act as though
  it is dragging even with the button not clicked.

  A reboot fixes the issue temporarily.

  ProblemType: Bug
  DistroRelease: Ubuntu 19.04
  Package: qemu 1:3.1+dfsg-2ubuntu3.1
  Uname: Linux 5.1.14-050114-generic x86_64
  ApportVersion: 2.20.10-0ubuntu27
  Architecture: amd64
  CurrentDesktop: ubuntu:GNOME
  Date: Mon Jun 24 20:55:44 2019
  Dependencies:
   
  EcryptfsInUse: Yes
  InstallationDate: Installed on 2019-02-20 (124 days ago)
  InstallationMedia: Ubuntu 18.04 "Bionic" - Build amd64 LIVE Binary 
20180608-09:38
  Lsusb:
   Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
   Bus 001 Device 002: ID 8087:0025 Intel Corp. 
   Bus 001 Device 003: ID 0c45:671d Microdia 
   Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
  MachineType: Dell Inc. Precision 5530
  ProcEnviron:
   TERM=xterm-256color
   PATH=(custom, no user)
   XDG_RUNTIME_DIR=<set>
   LANG=en_US.UTF-8
   SHELL=/bin/bash
  ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-5.1.14-050114-generic 
root=UUID=18e8777c-1764-41e4-a19f-62476055de23 ro mem_sleep_default=deep 
mem_sleep_default=deep acpi_rev_override=1 scsi_mod.use_blk_mq=1 
nouveau.modeset=0 nouveau.runpm=0 nouveau.blacklist=1 acpi_backlight=none 
acpi_osi=Linux acpi_osi=!
  SourcePackage: qemu
  UpgradeStatus: No upgrade log present (probably fresh install)
  dmi.bios.date: 04/26/2019
  dmi.bios.vendor: Dell Inc.
  dmi.bios.version: 1.10.1
  dmi.board.name: 0FP2W2
  dmi.board.vendor: Dell Inc.
  dmi.board.version: A00
  dmi.chassis.type: 10
  dmi.chassis.vendor: Dell Inc.
  dmi.modalias: 
dmi:bvnDellInc.:bvr1.10.1:bd04/26/2019:svnDellInc.:pnPrecision5530:pvr:rvnDellInc.:rn0FP2W2:rvrA00:cvnDellInc.:ct10:cvr:
  dmi.product.family: Precision
  dmi.product.name: Precision 5530
  dmi.product.sku: 087D
  dmi.sys.vendor: Dell Inc.

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