Can't get grub2 boot menu via COM2 port












1















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)






centos7 grub serial







share|improve this question



























    1















    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)






    centos7 grub serial







    share|improve this question

























      1












      1








      1








      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)






      centos7 grub serial







      share|improve this question














      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)






      centos7 grub serial




      centos7 grub serial






      share|improve this question













      share|improve this question











      share|improve this question




      share|improve this question










      asked 49 mins ago









      mrcomrco

      1094




      1094






















          2 Answers
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          2














          Your GRUB_SERIAL_COMMAND is specifying to use serial port 0, but you specifically said you wanted to use serial port 1.



          You specified --unit=0, which means serial port 0.



          You should instead use --unit=1, to use serial port 1.




          Also, your serial command begins with 115200n8 which is not valid and should not be present. It should instead start with serial.






          share|improve this answer
























          • I truly appreciate your timely help.

            – mrco
            20 mins ago



















          1














          If you only need the second one, simply change the --unit=0 into --unit=1.




          The serial unit 0 is usually called ‘COM1’, so, if you want to use COM2, you must specify ‘--unit=1’ instead. -- grub manual







          share|improve this answer
























          • I'm too young too simple,,,it works!!

            – mrco
            21 mins ago











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          2 Answers
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          active

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          2 Answers
          2






          active

          oldest

          votes









          active

          oldest

          votes






          active

          oldest

          votes









          2














          Your GRUB_SERIAL_COMMAND is specifying to use serial port 0, but you specifically said you wanted to use serial port 1.



          You specified --unit=0, which means serial port 0.



          You should instead use --unit=1, to use serial port 1.




          Also, your serial command begins with 115200n8 which is not valid and should not be present. It should instead start with serial.






          share|improve this answer
























          • I truly appreciate your timely help.

            – mrco
            20 mins ago
















          2














          Your GRUB_SERIAL_COMMAND is specifying to use serial port 0, but you specifically said you wanted to use serial port 1.



          You specified --unit=0, which means serial port 0.



          You should instead use --unit=1, to use serial port 1.




          Also, your serial command begins with 115200n8 which is not valid and should not be present. It should instead start with serial.






          share|improve this answer
























          • I truly appreciate your timely help.

            – mrco
            20 mins ago














          2












          2








          2







          Your GRUB_SERIAL_COMMAND is specifying to use serial port 0, but you specifically said you wanted to use serial port 1.



          You specified --unit=0, which means serial port 0.



          You should instead use --unit=1, to use serial port 1.




          Also, your serial command begins with 115200n8 which is not valid and should not be present. It should instead start with serial.






          share|improve this answer













          Your GRUB_SERIAL_COMMAND is specifying to use serial port 0, but you specifically said you wanted to use serial port 1.



          You specified --unit=0, which means serial port 0.



          You should instead use --unit=1, to use serial port 1.




          Also, your serial command begins with 115200n8 which is not valid and should not be present. It should instead start with serial.







          share|improve this answer












          share|improve this answer



          share|improve this answer










          answered 26 mins ago









          Michael Hampton♦Michael Hampton

          166k26305625




          166k26305625













          • I truly appreciate your timely help.

            – mrco
            20 mins ago



















          • I truly appreciate your timely help.

            – mrco
            20 mins ago

















          I truly appreciate your timely help.

          – mrco
          20 mins ago





          I truly appreciate your timely help.

          – mrco
          20 mins ago













          1














          If you only need the second one, simply change the --unit=0 into --unit=1.




          The serial unit 0 is usually called ‘COM1’, so, if you want to use COM2, you must specify ‘--unit=1’ instead. -- grub manual







          share|improve this answer
























          • I'm too young too simple,,,it works!!

            – mrco
            21 mins ago
















          1














          If you only need the second one, simply change the --unit=0 into --unit=1.




          The serial unit 0 is usually called ‘COM1’, so, if you want to use COM2, you must specify ‘--unit=1’ instead. -- grub manual







          share|improve this answer
























          • I'm too young too simple,,,it works!!

            – mrco
            21 mins ago














          1












          1








          1







          If you only need the second one, simply change the --unit=0 into --unit=1.




          The serial unit 0 is usually called ‘COM1’, so, if you want to use COM2, you must specify ‘--unit=1’ instead. -- grub manual







          share|improve this answer













          If you only need the second one, simply change the --unit=0 into --unit=1.




          The serial unit 0 is usually called ‘COM1’, so, if you want to use COM2, you must specify ‘--unit=1’ instead. -- grub manual








          share|improve this answer












          share|improve this answer



          share|improve this answer










          answered 23 mins ago









          anxanx

          1,4541719




          1,4541719













          • I'm too young too simple,,,it works!!

            – mrco
            21 mins ago



















          • I'm too young too simple,,,it works!!

            – mrco
            21 mins ago

















          I'm too young too simple,,,it works!!

          – mrco
          21 mins ago





          I'm too young too simple,,,it works!!

          – mrco
          21 mins ago


















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