[coreboot] Adding information about the console(s) to lbtable

[Patrick Georgi]

Hi,

I work on adding information about the console to the lbtable, so that 
the payload can parse it to figure out where it might find a user.

Right now, I only store TTYS0_BASE (that config variable) in a special 
lbtable record (LB_TAG_SERIAL) and let the payload assume it should use 
the serial port.

Before I go on, I have a couple of questions:
 - Do we want to store more information than coreboot itself uses?
   (eg. serial ports that aren't used, but known to exist)
   - if so, what kind of information: io ports, irqs, memory areas, ...
 - how should this information be mapped to devices?
   - our own naming scheme (serial0, ...)
   - adopting an existing one (com1, ttyS0, cua0, ..)
 - How flexible should the console routing be?
   - multiple target consoles
   - multiple targets of the same type (eg. both COM1 and COM2)

I don't want to design a too flexible system (that no-one uses and is 
only partially implemented by payloads), but I don't want to force 
payloads to adapt to an ever-changing interface either. I also don't want 
to work on this and scrap everything on pre-commit time, because the 
consensus is that the design sucks, which is why I ask for opinions. :-)

Once this is settled, I'll implement it for lbv2 and lbv3 and add support 
to the various utilities (lxbios and whoever else dumps the table).


Regards,
Patrick