I added console=ttyS0,57600n8 to my kernel command line. I get the normal boot messages until this
[ 5.123106] EXT4-fs (sda1): mounted filesystem with ordered data mode. Opts: (null)
Begin: Running /scripts/local-bottom ... done.
Begin: Running /scripts/init-bottom ... done.
Then no more output. I am trying to debug a kernel panic using kdump, but can't quite get kdump to work. I want the serial console to get kdump working.
 I worked around the problem using a virtual machine.