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Date:      Wed, 19 Apr 1995 15:28:00 +0100
From:      Dougal <simonm@dcs.gla.ac.uk>
To:        hackers@freefall.cdrom.com
Subject:   Re: [DEVFS] your opinions sought! 
Message-ID:  <199504191528.IAA22087@freefall.cdrom.com>
In-Reply-To: Your message of "Wed, 19 Apr 1995 03:54:11 PDT."             <199504191054.DAA08184@ref.tfs.com> 

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You know, I thought the major advantage of having a /dev directory is
that the kernel doesn't have to know the names of all the various
devices, because this mapping is specified by the filesystem.  The
devfs is about to hardwire all this stuff in, at the expense of some
kernel bloat.

The dubious advantages of devfs:

[ Julian Elischer ]
> You might want to use it if it always had the right major and minor numbers
> for devices that were dynamically added in.. 
> one time it might be major 35 and the next time you boot, it could
> be major 37 because you loaded the new WIZBANG driver as well.

The device entry can be created by an auxilliary program at module
load time, and deleted afterwards.  Does FreeBSD have support for
this?  I can't remember offhand.

> it also means that disk slices can be shown only when they
> actually exist on the disk..

Well, it's perfectly feasible (and adds less kernel bloat) to query
the kernel at boot time for attached devices and build up the /dev
directory based on the information.  This IMHO is a better solution
than the devfs.

> (plus lots of other reasons to do with 'upcoming' stuff.)

I hope this doesn't mean that some future things will actually
*require* the devfs, please keep it optional.

Just my 2p,

Simon



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