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From: Terry Lambert <terry@lambert.org>
Message-Id: <199707220027.RAA12189@phaeton.artisoft.com>
Subject: Re: Cloned devices???
To: jpt@msc.edu (Joseph Thomas)
Date: Mon, 21 Jul 1997 17:27:25 -0700 (MST)
Cc: freebsd-hackers@FreeBSD.ORG
In-Reply-To: <199707212319.SAA06830@uh.msc.edu> from "Joseph Thomas" at Jul 21, 97 06:19:49 pm
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> 	I'm looking for a way to do what the 'clone' device in
> SunOS/streams allows the driver to do. Any pointers/ideas?

This should be easy under devfs.  A static (non-devfs) version
would be pretty easy as well, but much less general.

[ ... ]

> 	/dev has node clone, major M, minor 0.
> 
> 	application does:
> 
> 	for ( i = 0; i < 3; i++ )
> 		fd[i] = open ( "/dev/clone", O_RDWR );
> 
> where fd[0] would actually point to a device with major M, minor 1,
>       fd[1] would point to major M, minor 2,
>   and fd[2] would point to major M, minor 3.
>  
> 
> what I'd like to avoid is:
> 
> 	/dev/clone00	major M, minor 0
> 	/dev/clone01	major M, minor 1

Why?  There's really no good reason to not expose the device in the
name space; for pty's, you would *definititely* want to expose the
slave side in the namespace!  The devfs version would not expose the
slave until the master had been created via cloning, but the static
would want to always export the slave.


					Terry Lambert
					terry@lambert.org
---
Any opinions in this posting are my own and not those of my present
or previous employers.