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Re: std location for system console


From: Niels Möller
Subject: Re: std location for system console
Date: 02 Sep 2002 19:08:13 +0200
User-agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.2

Marcus Brinkmann <address@hidden> writes:

> Maybe system console is not a good term to use.  What I meant is just the 10
> or so default virtual console you use for your 10 or so virtual terminals
> which have a getty started at boot time.

"console" is ambiguous. It can either mean some unit with a screen (or
typewriter ;-) and a keyboard (and in this meaning, it is a synonym to
"terminal"). Or it can mean the thing associated with /dev/console,
i.e. the place where random system messages are written to. And for
compatibility, /dev/console must have the latter meaning, I guess.

> The one grief I have with this name is that they are, in the current
> implementation, not terminals.  They are consoles.  I am not sure if
> there is a hard distinction here.

The word "tty" or "terminal" can also mean the screen+keyboard unit.
And it can mean a unix terminal device, i.e. something that has some
idiosyncratic properties like parity and speed (which really are
properties of the serial connection, not of the terminal attached to
it) as well as settings such as echoing which seems more related to
the terminal unit itself.

I think "virtual thing-with-screen-and-keyboard" is a correct
description of your server, and that is how I always have read the
word "terminal" in "virtual terminal". But perhaps that's just me.

> OTOH, maybe with Rolands terminal library, the console server will also
> provide tty nodes.

But for now, both the tty-node and your "console"-interface needs
names. These almost synonymous words are annoying. Say tty-code is
intergrated in the console server. Then you'd have both
/dev/vts/17/console and /dev/vts/17/tty. How confusing is that?

> The processes which look up these names are not Unix processes.  Unix
> process look up the tty node (but see above, it might become integrated some
> time).

So the "system configuration" is in the passive translator settings of
the tty nodes, right? It seems a little annoying and redundant to have
a bunch of almost identical tty nodes on disk. It would be nice if one
could just create the ttynodes on demand.

Hmm, one hack would be to have the console server provide nodes
/dev/vts/17/tty, which have only a passive translator setting, no
data. This will just tell libdiskfs to start corresponding term
servers when needed. If init has a dir_notify on /dev/vts you could
configure it to start getty on all new ttys that appear. I don't know
how one would handle ownership of the tty nodes, though, perhaps one
should look at /dev/pts and do something similar.

Regards,
/Niels




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