Serial console not working

Hi there! I'm trying to find out why my setup is not booting on a real machine
(some Dell PowerEdge R210 node; ned says it cannot find rom/l4re), but I'm
unable to redirect output to the serial console.

I'm able to use the serial console for both grub and linux, so it's not a
hardware issue. An excerpt of my grub2 configuration:

  serial --unit=1 --speed=115200 --word=8 --parity=no --stop=1
  terminal_input serial
  terminal_output serial
  # ...
  # for the linux entry
  linux   /vmlinuz-3.16.0-4-amd64 root=UUID=7573ed62-a910-4b97-a577-dde47a16f87a ro console=ttyS1,115200n8 quiet

Now, here's the entry I'm using for L4, which never gets me any output on the
serial console:

  menuentry 'Test' {
    set root=(hd0,1)
    multiboot /l4/bootstrap -serial
    module /l4/fiasco -serial_esc -comspeed 115200 -comport 1
    module /l4/sigma0
    module /l4/moe rom/test.cfg
    module /l4/l4re
    module /l4/ned
    module /l4/test.cfg
    module /l4/bin/test
  }

Thanks,
  Lluis