Previously, if X allocated all 6 TTYs (for multi-session for example) no
getty would be available anymore to guarantee console-based logins.
With the new ReserveVT= switch in logind.conf we can now choose one VT
(6 by default) that will always be subject to autovt-style activation,
i.e. we'll always have a getty on TTY6, and X will never take possession
of it.
This takes handling of chassis power and sleep keys as well as the lid
switch over from acpid.
This logic is enabled by default for power and sleep keys, but not for
the lid switch.
If a graphical session is in the foreground no action is taken under the
assumption that the graphical session does this.
Lennart Poettering