In the absence of an HCDP, we used to assume there were legacy COM ports
at 0x3f8 and 0x2f8, but I recently removed that assumption.
 
"console=ttyS0" still works (assuming you have CONFIG_SERIAL_8250_ACPI
turned on so you can find the ttyS0 device), but the console doesn't
start working until the serial driver initializes.  If you need an
early console and you know where it lives, something like
"console=uart,io,0x3f8" will start working very early.
Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>