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Android guest - Pointing Device possible bug (#17446)

Posted: 4. Jan 2018, 15:54
by Cyrrus30

[ModEdit; related ticket: #17446: Multiple pointing device reported when choosing USB Multi-Touch Tablet]
Hi!

I'm running Android x86 in VirtualBox (I know, it is not a supported guest), on a Windows host, running on a machine with a touch screen. I'm trying to have a proper touch behavior in the virtual machine, ideally without having to forward the USB device of the touch screen to the VM (this is causing issues where the USB driver would eventually detach itself and stop responding. But this is not the point of my post).

I've tried the differents "Pointing device" of the "System/Motherboard" settings tab. At first none of them seemed to give me the expected behavior in my host, but then I realized something:

If I enable USB Tablet, I can check from the Android command line (running the "dumpsys input" command) that this particular input device is present:
7: VirtualBox USB Tablet
    Classes: 0x800000004
    Path /dev/input/event3
    [...]

However, it doest not behave like a proper touch screen.

If I enable USB Multi-Touch Tablet, the touch seems broken too. But if I inspect the available input devices in Android, I can see that both devices are present:
7. VirtualBox USB Multi-Touch
    Classes: 0x80000014
    Path: /dev/input/event4
    [...]

8. VirtualBox USB Tablet
    Classes: 0x800000004
    Path /dev/input/event3
    [...]

After inspecting the touch events in the Android guest, I realized that the presence of both devices is the cause of my incorrect touch behavior. When I touch the screen, the Virtual Box Multi-Touch device reports the event, but as soon as I move my finger around, the touch is "intercepted" by the VirtualBox USB Tablet device.

To confirm that, I deleted the /dev/input/event3 file (the one mapped to the VirtualBox USB Tablet device). After that everything was correct. The touch screen was working properly and only the proper device was handling the touch.


So my question here is: is it an expected behavior that, when selecting VirtualBox USB Multi-Touch as the input device, my guest OS reports VirtualBox USB Multi-Touch AND VirtualBox USB Tablet as input devices? Or is it an issue in VirtualBox?


Thanks!

Re: Android guest - Pointing Device possible bug (#17446)

Posted: 10. Jan 2018, 23:16
by socratis
Added ticket related information.