For cross-VM S5 notify via vUART, life_mngr service is running on UOS.
It is listening on COM2 to get SOS's commands.
The protocol is: SOS send "shutdown", UOS feedback "acked".
When SOS triggle shutdown, SOS can 1) check VM's status until UOS
stopped, 2) retry shutdown UOS normally with timeout.
So, no matter life_mngr server is running, SOS's shutdown procedure will
properly finish.
Tracked-On: #3564
Signed-off-by: Yuan Liu <yuan1.liu@intel.com>
Yuan Liu