Initialize a serial device. The serial port is not used for communication unless terminal is also specified. This command is available only if GRUB was compiled with serial support.
Specify the tty device to be used in the host operating system. This option can be used only in the grub shell.
Specify the parity. The possible values are no, odd, and even; the default is no.
Specify the I/O port. The value of port overrides any value specified for --unit.
Specify the transmission speed (default is 9600).
Specify the number of stop bits. The value of num is either 1 or 2 (default is 1).
Specify the serial port to use. The value of num is a number in the range 0–3; the default is 0, corresponding to COM1.
Specify the number of data bits. The value of num is a number in the range 5–8 (default is 8).