Xephyr Input is Broken- can't find driver for keyboard or mouse.
Copying details from the bug I just created in Ubuntu (https://bugs.launchpad.net/ubuntu/+source/xorg-server/+bug/1828671) - this could be user or packaging errors, but I suspect it's a real issue
I'm using Xephyr for a multiseat system (4 GPUs -> up to 12 screens; using VirtualGL for 3D acceleration.)
The eventual command line that LightDM ends up running is:
Xephyr -fullscreen :0 -seat seat5 -auth /var/run/lightdm/root/:0 -nolisten tcp
In 18.04 and earlier this works great.
Important note: There is a strong chance my system had the version of Xephyr from the Multiseat PPA with Evdev support patches (https://launchpad.net/~ubuntu-multiseat/+archive/ubuntu/xephyr/+packages).
In 19.04 I get:
root@redstone-server:~# DISPLAY=:200.1 Xephyr -fullscreen -seat seat6 :20
Pointer option key (_source) of value (server/udev) not assigned!
Pointer option key (major) of value (13) not assigned!
Pointer option key (minor) of value (80) not assigned!
Pointer option key (config_info) of value (udev:/sys/devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.5/2-1.5.5/2-1.5.5.3/2-1.5.5.3.1/2-1.5.5.3.1:1.0/0003:045E:0083.001D/input/input58/event16) not assigned!
Pointer option key (GrabDevice) of value (on) not assigned!
couldn't find driver for pointer device "Microsoft Basic Optical Mouse" (/dev/input/event16)
Pointer option key (_source) of value (server/udev) not assigned!
Pointer option key (major) of value (13) not assigned!
Pointer option key (minor) of value (32) not assigned!
Pointer option key (config_info) of value (udev:/sys/devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.5/2-1.5.5/2-1.5.5.3/2-1.5.5.3.1/2-1.5.5.3.1:1.0/0003:045E:0083.001D/input/input58/mouse0) not assigned!
Pointer option key (GrabDevice) of value (on) not assigned!
couldn't find driver for pointer device "Microsoft Basic Optical Mouse" (/dev/input/mouse0)
Kbd option key (_source) of value (server/udev) not assigned!
Kbd option key (major) of value (13) not assigned!
Kbd option key (minor) of value (93) not assigned!
Kbd option key (config_info) of value (udev:/sys/devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.5/2-1.5.5/2-1.5.5.3/2-1.5.5.3.2/2-1.5.5.3.2:1.0/0003:045E:0752.001E/input/input59/event29) not assigned!
Kbd option key (GrabDevice) of value (on) not assigned!
couldn't find driver for keyboard device "Microsoft Wired Keyboard 400" (/dev/input/event29)The display is correct, but no user input (mouse or keyboard) works.
It looks like Xephyr can't find any input drivers. I also tried specifying drivers (eg Evdev, libinput, keyboard, mouse, ...) Nothing worked.
Extracting the version of Xephyr from https://launchpad.net/~ubuntu-multiseat/+archive/ubuntu/xephyr/+packages runs correctly.
Required details:
lsb_release -rd Description: Ubuntu 19.04 Release: 19.04
apt-cache policy xserver-xephyr xserver-xephyr: Installed: 2:1.20.4-1ubuntu3 Candidate: 2:1.20.4-1ubuntu3 Version table: *** 2:1.20.4-1ubuntu3 500 500 http://ca.archive.ubuntu.com/ubuntu disco/main amd64 Packages 100 /var/lib/dpkg/status