[arch-general] lxc: systemd-udev-trigger resets host kbd & mouse settings

[Carl Schaefer]

I've just started playing with lxc, and found that if I create a
container with:

# lxc-create -n arch -t archlinux

and then start it:

# lxc-start -n arch

it resets my X keyboard map and mouse acceleration settings (which are
set by setxkbmap/xset/xinput), though mouse button remapping done by
xmodmap is not affected.

I tracked it as far as the execution of:

  /usr/bin/udevadm trigger --type=devices --action=add

in /usr/lib/systemd/system/systemd-udev-trigger.service, which seems to
write "add" to most of the "uevent" files under /sys/devices.  I don't
know the reason for this, especially in a container, but disabling the
whole udev trigger service in the container keeps the host X input
settings intact without breaking anything obvious in the container (and
the container boots a lot faster now, too).

I'd appreciate any thoughts on what systemd-udev-trigger is doing,
whether it's appropriate in a container, and if there's a better way to
keep a container from changing X input settings on the host.
Carl