Double-tap Suppressed by Debounce in VM Guest on Host With Touchpad
Summary
Fast double-taps get treated as a single click in a VM Guest on a host with a Mac touchpad.
This is similar to https://bugs.freedesktop.org/show_bug.cgi?id=105974 with different hardware.
The issue occurs with VMware and VirtualBox VMs.
Suspected Root Cause: The host delivers a synthesized double-click to the guest, and the time between the clicks is very small, so the debounce logic suppresses the second click.
evemu-record shows two "VirtualPS/2 VMware Virtual Mouse" devices and a "VMware VMware Virtual USB Mouse". Capture of the first of these is attached. It looks to me like the second tap comes 8 ms after the first, and I'm betting that is treated as bounce.
Steps to reproduce
- Install Ubuntu 18.04 in a VMware Fusion 10.1.3 guest.
- Login
- Double-tap on any desktop icon. Close it. This first attempt works well.
- Double-tap on any desktop icon, minimizing the time between taps. This will be treated as a single-click. (You must double-TAP, not double-CLICK.)
Also occurs with:
- Issue also occurs with Ubuntu 18.10 and Fedora 28.
- Issue also occurs with VirtualBox 5.2.18.
- Issue does NOT occur if the host is a Dell Precision with a touchpad (using tap-to-click).
- Issue does NOT occur on the Macbook if a physical mouse is used.
- Issue does NOT occur on the Macbook if physical touchpad double-clicks are used -- only when double-TAPS.
Touchpad:
The MacBook host deals with the touchpad. I am using tap-to-click in the host, but the device presented to the guest is just a PS/2 mouse. There is no tap or clickfinger processing in the guest.
Configuration options:
I have set no configuration options. (Ubuntu out-of-the-box or Fedora out-of-the-box may have set libinput configuration, but I've not altered that.)
libinput version you encountered the bug on
Behavior is present in libinput 1.10.4-1 but not in 1.8.2-1ubuntu2. (I haven't tried the versions in between.) Still present in 1.12.0-1.
Hardware information:
- Host model is "MacBookPro11,3" (a mid-2014 15" MacBook Pro with Retina)
- Host has a trackpad which supports physical clicks as well as tap-to-click. Tap-to-click is enabled in the HOST.
- Guest virtual hardware is VirtualPS/2 VMware Virtual Mouse
Other log output:
-
libinput record
output: attached as trackpad-libinput-record.yml -
libinput debug-events --verbose
output: attached as debug-events.txt - evmu-record output: attached as fast-double-tap-evmu.txt
- content of /sys/class/dmi/id/modalias: attached as modalias.txt
- output from udevadm: attached as udevadm
debug-events.txt fast-double-tap-evmu.txt modalias.txt trackpad-libinput-record.yml udevadm.txt