Apparently the ttyS0 console doesn't exist but ttyS1 does:
raccoon% sudo stty -F /dev/ttyS0
stty: /dev/ttyS0: Input/output error
raccoon% sudo stty -F /dev/ttyS1
speed 9600 baud; line = 0;
-brkint -imaxbel
The dmesg line agrees:
00:03: ttyS1 at I/O 0x2f8 (irq = 3, base_baud = 115200) is a 16550A
The console configuration is then moved from base to xeon to allow
changing it for the raccoon machine.
