Serial console output for virtualized guests doesn't work.

Solution Verified - Updated -

Issue

  • Although Red Hat's Virtualization Guide says that serial console output for fully virtualized guests works, it doesn't really work at all.
  • Please see "Chapter 36.3. Troubleshooting with serial consoles" in that document.

http://www.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6-Beta/html/Virtualization/sect-Virtualization-Troubleshooting_-Troubleshooting_with_serial_consoles.html

 To output kernel information from a fully virtualized Linux guest into the domain modify
 the /boot/grub/grub.conf file by inserting the line console=tty0 console=ttys0,115200.

 title Red Hat Enterprise Linux Server (2.6.32-36.x86-64)
   root (hd0,0)
   kernel /vmlinuz-2.6.32-36.x86-64 ro root=/dev/volgroup00/logvol00 console=tty0 console=ttys0,115200
   initrd /initrd-2.6.32-36.x86-64.img
  • As you see, the above description says that the following boot parameters are required in /boot/grub/grub.conf.

        console=tty0 console=ttys0,115200
    
  • However, even if those boot parameters are inserted, serial console doesn't work at all.

  • We suspect "ttys0" in the above description is incorrect.  We believe "ttyS0" is correct because serial console output for virtualized guests works well by specifying "ttyS0" instead of "ttys0".  We believe this issue is just a bug of the document.

Environment

  • Red Hat Enterprise Linux 6

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