OracleVM Serial Console Not Working - serial_console (serial_console) main process ended, respawning

 

After upgrading to the latest OracleVM 3.3.3 and updating all Oracle Linux 6 guests to the latest versions I started to see problems with OL6 serial console interface. First of all, the serial console didn’t seem to work at all, I could not connect to the console via OracleVM Manager serial console. Secondly there started to be continuous error messages in the OL6 /var/log/messages file:

Dec  4 06:30:34 atlassian init: serial_console (serial_console) main process (4704) terminated with status 1
Dec  4 06:30:34 atlassian init: serial_console (serial_console) main process ended, respawning

At the same time all Oracle Linux 5 servers worked fine and also few OL6 servers as well, but most of the OL6 servers suffered from this.

Those OL6 servers that worked fine had symbolic link in /dev/ where “serial_console” pointed to hvc0 device. Those OL6 servers that had problems this symbolic link points to ttyS0.

Don’t know exactly what is the root cause of this problem, but looks like there are two symlink definitions in kernel device udev rules and in some servers they point to hvc0 and some servers to ttyS0.

My fix to this problem was to edit the udev rules

vi /etc/udev/rules.d/50-udev.rules

Original content:

KERNEL=="ttyS0",                SYMLINK+="serial_console"
KERNEL=="hvc0",                 SYMLINK+="serial_console"

Remove the ttyS0 line so that the content looks like:

KERNEL=="hvc0",                 SYMLINK+="serial_console"

Save the file and reboot the server. After this serial console should work ok and no extra error messages should be appearing in the messages log file.