# Set serial port unit and its baud rate
serial --unit=0 --speed=115200

# Set the terminal input/output to serial
# (If we don't do this then writing to the
# serial port doesn't work)
terminal_input serial ; terminal_output serial

# If timeout=-1 then grub waits forever.
timeout=1

# The default is 0
default=0

menuentry "test_ac_putchar" {
  multiboot2 /boot/test_ac_putchar test_ac_putchar
}

# Set serial port unit and its baud rate
serial --unit=0 --speed=115200

# Set the terminal input/output to serial
# (If we don't do this then writing to the
# serial port doesn't work)
terminal_input serial ; terminal_output serial

# Using timeout=1 so we can abort if desired,
# supposedly holding right shift can work while
# booting but it doesn't work for me with terminal
# input and output set to serial.
# FYI, timeout=-1 then grub waits forever.
timeout=1

# The default is 0
default=0

menuentry "test_ac_putchar" {
  multiboot2 /boot/test_ac_putchar test_ac_putchar
}

Update comment on why timeout=1
Update comment on why timeout=1
