I installed a new Ubuntu 14.04 as a Xen server and found out that on booting the following messages repeated itself many times,
[ 2.811553] init: plymouth-upstart-bridge main process (191) terminated with status 1
[ 2.812789] init: plymouth-upstart-bridge main process ended, respawning
[ 2.874117] init: plymouth-upstart-bridge main process (210) terminated with status 1
[ 2.875167] init: plymouth-upstart-bridge main process ended, respawning
[ 2.904155] init: plymouth-upstart-bridge main process (217) terminated with status 1
[ 2.905289] init: plymouth-upstart-bridge main process ended, respawning
[ 2.928618] init: plymouth-upstart-bridge main process (221) terminated with status 1
[ 2.929713] init: plymouth-upstart-bridge main process ended, respawning
[ 49.975826] Adding 2093052k swap on /dev/mapper/[...]
then the booting stopped to resume normally at least 10-15 sec later.
To make sure I eliminate those message I searched the net and found this site which is a very good and simple solution.
http://www.unrelatedshit.com/2014/07/30/kvm-too-fast-for-plymouth-upstart-bridge/
Solution:
The solution is quite simple: To fix it, simply add a sleep 2 to your /etc/init/plymouth-upstart-bridge.conf file.
Example:
[...]
stop on (stopping plymouth
or stopping plymouth-shutdown)
console output
exec plymouth-upstart-bridge
sleep 2
Reboot and watch the booting… no more silly error messages of plymouth-upstart-bridge.