43 lines
2.1 KiB
Text
43 lines
2.1 KiB
Text
9 Using GRUB via a serial line
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This chapter describes how to use the serial terminal support in GRUB.
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If you have many computers or computers with no display/keyboard, it
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could be very useful to control the computers through serial
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communications. To connect one computer with another via a serial line,
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you need to prepare a null-modem (cross) serial cable, and you may need
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to have multiport serial boards, if your computer doesn't have extra
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serial ports. In addition, a terminal emulator is also required, such
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as minicom. Refer to a manual of your operating system, for more
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information.
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As for GRUB, the instruction to set up a serial terminal is quite
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simple. Here is an example:
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grub> serial --unit=0 --speed=9600
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grub> terminal_input serial; terminal_output serial
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The command 'serial' initializes the serial unit 0 with the speed
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9600bps. The serial unit 0 is usually called 'COM1', so, if you want to
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use COM2, you must specify '--unit=1' instead. This command accepts
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many other options, so please refer to *note serial::, for more details.
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The commands 'terminal_input' (*note terminal_input::) and
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'terminal_output' (*note terminal_output::) choose which type of
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terminal you want to use. In the case above, the terminal will be a
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serial terminal, but you can also pass 'console' to the command, as
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'terminal_input serial console'. In this case, a terminal in which you
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press any key will be selected as a GRUB terminal. In the example
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above, note that you need to put both commands on the same command line,
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as you will lose the ability to type commands on the console after the
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first command.
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However, note that GRUB assumes that your terminal emulator is
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compatible with VT100 by default. This is true for most terminal
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emulators nowadays, but you should pass the option '--dumb' to the
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command if your terminal emulator is not VT100-compatible or implements
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few VT100 escape sequences. If you specify this option then GRUB
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provides you with an alternative menu interface, because the normal menu
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requires several fancy features of your terminal.
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