start -lDEBUG -o /tmp/112.log -F -n 112

# open  /etc/pve/qemu-server/101.conf and add the following parameter at the end of file
serial0: socket

qm set 101 -serial0 socket

dmesg | grep ttyS
[    0.457814] 00:0a: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A

# in /etc/default/grub change the GRUB_CMDLINE_LINUX parameter to
GRUB_CMDLINE_LINUX="quiet console=tty0 console=ttyS0" 

update-grub

/etc/init/ttyS0.conf 

# ttyS0 - getty
#
# This service maintains a getty on ttyS0 from the point the system is
# started until it is shut down again.

start on stopped rc or RUNLEVEL=[2345]
stop on runlevel [!2345]

respawn
exec /sbin/getty -L 9600 ttyS0 vt102

qm terminal <VMiD>