I want to connect my "CentOS Linux release 7.6.1810 (Core)" device via COM2 port,then I modify '/etc/default/grub':
GRUB_TIMEOUT=5
GRUB_DISTRIBUTOR="$(sed 's, release .*$,,g' /etc/system-release)"
GRUB_DEFAULT=saved
GRUB_DISABLE_SUBMENU=true
GRUB_TERMINAL_OUTPUT="serial"
GRUB_CMDLINE_LINUX="console=tty0 console=ttyS1,115200n8"
GRUB_DISABLE_RECOVERY="true"
GRUB_TERMINAL="serial console"
GRUB_SERIAL_COMMAND="115200n8 serial --speed=115200 --unit=0 --word=8 --parity=no --stop=1"
then run:
grub2-mkconfig -o /boot/grub2/grub.cfg
as the result I could only get the output after "boot menu", not including the grub2.
PS: I'm using COM2(ttyS1) not COM1(ttyS0)