Ubuntu Server USB installation with installer's output on ttyS0 (serial port)

Question

I need to install Ubuntu Server 16.04 on computer that has no CD/DVD input, nor VGA output. I want to perform installation using USB drive with the installer output sent by serial port (ttyS0).

I've prepared usb-drive installer using Unetbootin, I've also modified some files to be able to perform installation using serial connection:

isolinux/isolinux.cfg

include menu.cfg
default menu.c32
prompt 0
timeout 0

isolinux/txt.cfg

default install
label install
  menu label ^Install Ubuntu Server
  kernel /install/vmlinuz
  append vga=normal initrd=/install/initrd.gz -- console=tty0 console=ttyS0,56700n8r nosplash debug -

syslinux.cfg

CONSOLE 0
SERIAL 0 56700 0
default menu.c32
prompt 0
menu title UNetbootin
timeout 100

label unetbootindefault
kernel /ubnkern
append vga=normal initrd=/ubninit nomodeset askmethod console=tty0 console=ttyS0,56700n8r

My problem: the installer doesn't start, there is no output on ttyS0. Is there any other method to perform installation without vga? I will be glad with any sugestions.

Answer 1

I need to install Ubuntu Server 16.04 on computer that has no CD/DVD input, nor VGA output. I want to perform installation using USB drive with the installer output sent by serial port (ttyS0).

An alternative answer, which does not require modifying the installation media.

At the GNU Grub screen, you will see a short list of options. In 19.04, *Install Ubuntu Server is highlighted.

Press the 'e' key to edit the kernel command line.

Add the text console=ttyS0,115200n8 (or whatever is appropriate for your serial line) to the end of the line beginning linux, but before the three dashes ---. In my case, after editing, the text in the green box becomes

setparams 'Install Ubuntu Server'                                           

        set gfxpayload=keep                                                 
        linux        /casper/vmlinuz   boot=casper quiet console=ttyS0,1152\
00n8 ---                                                                    
        initrd        /casper/initrd                                        

(Notice the line break after console=... is escaped with a \.)

Press Ctrl-X to boot.

You will still get the message

error: no suitable video mode found.                                                      
Booting in blind mode

But output from the kernel boot immediately follows.

[    0.205167] Spectre V2 : Spectre mitigation: LFENCE not serializing, switching to generic retpoline                                                                              
[    1.399013] ACPI Error: Could not enable RealTimeClock event (20181213/evxfevnt-184)   

and the console is later usable.

Answer 2

56700 speed is an invalid console speed. Try adjusting your config files to use either 115200 speed or 38400.

sh-3.2# cu -l /dev/cu.usbserial -s 56700
cu: Unsupported baud rate 56700