Subject: Re: console code overhaul
To: Paul Kranenburg <pk@cs.few.eur.nl>
From: Eduardo E. Horvath <eeh@one-o.com>
List: port-sparc64
Date: 02/29/2000 10:59:01
> I will shortly commit a fairly extensive set of changes to the console
> code. This change will partly restore the way the console was handled
> before the zs driver went MI. The reasons for this:
> 
> 	- the console should (and can) work if only PROM primitives
> 	  are available for I/O. The current code is tied to the
> 	  `zs' driver so hard that the kernel panics or the console 
> 	  is simply dead whenever it's attached to slightly different
> 	  hardware (c.f. Javastation 1).
> 
> 	- theoretically, the (Sun) keyboard driver (and the mouse too,
> 	  for that matter) can be configured to attach to some other
> 	  serial hardware.
> 
> 	- console configuration depends on device unit numbers that
> 	  are hard-coded in the kernel configuration file.
> 
> 
> The new code simply runs the console through PROM primitives only until
> a device driver detects that it is attaching the console input or output
> device, in which case it can redirect console I/O through one or more
> of its own entry points. There's now also some support to route
> console input and output through different channels; however, attaching
> different channels to /dev/console is still a challenge..
> 
> Since the console configuration stuff is firmly tied to information
> provided by the machine's PROM, I cannot possibly test these changes
> on every possible sparc (or sun3) model.  If you find anything amiss,
> please send me mail (or post in this forum) about it.

Neat!  How does the new scheme work?  What needs to happen to have the
console (kbd,mouse) attach to a `com' (16550) device?  (I've also
started work on an SAB 82532 driver which will need to be integrated.)

=========================================================================
Eduardo Horvath				eeh@netbsd.org
	"I need to find a pithy new quote." -- me