Comment 9 for bug 1853357

With Ubuntu 19.10:

I am not able to reproduce the issue with a single monitor of a
different brand plugged into the DisplayLink adapter. There are three
differences here and I don't have the equipment available where I am
right now to narrow down which of them is relevant:

* one monitor instead of two;
* different brand and dimensions of monitor; and
* I'm only using the HDMI plug on the DisplayLink adapter, not the DVI
  plug.

However, one thing I do observe with this configuration -- which
again, doesn't crash -- is that screen updates to the DisplayLink
monitor are Extremely Slow. Like I am typing in a terminal window and
it sometimes takes a second or two between when I type something and
when the results of the typing show up in the terminal. If I move the
same terminal window onto the built-in laptop display the lag goes
away.

The update lag does not occur when I use Xorg instead of Wayland.

Attempting to test Ubuntu 20.04 on same laptop booting from Thumb
drive:

Live CD user doesn't support Wayland.

Tried creating new user, Wayland wasn't available for that user
either.

Of course DisplayLink stuff isn't installed either, so the laptop
doesn't actually notice the DisplayLink display when I plug it in.

So to make this test work I would have to figure out how to install
Wayland in the running live image and install the DisplayLink stuff
too. The DisplayLink stuff I can figure out, but not sure about how to
enable Wayland sessions in the live image.

Attempting to test Ubuntu 20.04 on a slightly different laptop:

I upgraded a spare laptop to Ubuntu 20.04, managed to get DisplayLink
installed onto it (I had to tweak the installer package not to compile
and install the dkms modules and to use the ones that ship with Ubuntu
instead), and tested it. Again, keep in mind that in my current setup
I'm unable to reproduce the hanging issue, but I did reproduce the
display lag.

Next steps:

1. On the laptop where I encountered the hanging issue, I am using the
   evdi kernel module and library that are shipped with the
   DisplayLink reference implementation release from last July, rather
   than the newer module and library that are included in Ubuntu. I
   need to reinstall evdi on that laptop using the tweak I mentioned
   above for 20.04, so that I am using the Ubuntu version of the
   module and library with 19.10, to see if the problem persists.
   I.e., the crashing issue may resolve if I use the evdi kernel
   module and library that ship with Ubuntu.

2. If not, then test various configurations and try to identify which
   of the factors above triggers the issue (one monitor vs. two; brand
   and dimensions of monitor; HDMI vs. DVI plug in adapter).

3. Test whether I am able to reproduce the issue in 20.04 on the spare
   laptop with the monitor configuration with which I encountered the
   issue in 19.10.

4. Try to figure out how to install and enable both Wayland and the
   DisplayLink manager in a running Live CD session so that I can test
   with the laptop that I know has encountered this issue in the past.