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Subject: Re: DEVFS vs "regular /dev"
To: davidg@Root.COM
Date: Thu, 21 Mar 1996 12:16:31 -0800 (PST)
From: "JULIAN Elischer" <julian@ref.tfs.com>
Cc: phk@critter.tfs.com, terry@lambert.org, scrappy@ki.net,
        current@freebsd.org
In-Reply-To: <199603211313.FAA05246@Root.COM> from "David Greenman" at Mar 21, 96 05:13:54 am
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> 
> 
> 
> >> >> > This assumes that the file system abstractions currently in place
> >> >> > change as well, since the /dev FS can't be mounted *after* the / FS
> >> >> > has been mounted as an inferior FS --
> >> >> why not?
> >> >> you don't need a mounted /dev to mount root.
> >> >> that's done specially.
> >> >
> >> >So you don't need a mounted root to have a mounted /dev, of course!
> >> 
> >>    That's silly. The root filesystem is mounted long before /dev would be, 
> >
> >Not that long before.  /sbin/init will have to mount it to get in touch
> >with /dev/console, /dev/null and ...
> 
>    No, it will be mounted in the kernel.
>From within the kernel's point of view, the devfs is always available
I could easily add a function that would 'open' a device by name
even if the devfs is not mounted..
e.g.
 error = deviceopen("console",O_RDONLY,0,&vnpointer);
 if (error) 
 {
	printf(" failed to open /dev/console, errno = %d",error);
 }

 maybe even a version that given a proc struct, will open it on behalf
 of that process..
> 
> -DG
> 
> David Greenman
> Core-team/Principal Architect, The FreeBSD Project
>