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From: Peter da Silva <peter@bonkers.taronga.com>
Message-Id: <199504191240.HAA14829@bonkers.taronga.com>
Subject: Re: [DEVFS] your opinions sought!
To: julian@freefall.cdrom.com (Julian Elischer)
Date: Wed, 19 Apr 1995 07:40:06 -0500 (CDT)
Cc: fs@freefall.cdrom.com, hackers@freefall.cdrom.com,
        hardware@freefall.cdrom.com
In-Reply-To: <199504190519.WAA06359@freefall.cdrom.com> from "Julian Elischer" at Apr 18, 95 10:19:33 pm
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> I personally favour something hierachical,
> such as:

> /devices/disks/sd0/all
> /devices/disks/sd0/FAT/all	/* I suppose it could be called C: */
> /devices/disks/sd0/BSD/all
> /devices/disks/sd0/BSD/a
> /devices/disks/sd0/BSD/b
> /devices/disks/sd0/BSD/c
> /devices/disks/sd0/99/all	/* MACH but not recognised */
> /devices/disks/sd0/DOSX/all
> /devices/disks/sd0/DOSX/A
> /devices/disks/sd0/DOSX/B
> /devices/disks/sd1/all
> /devices/disks/sd1/BSD/all
> /devices/disks/sd1/BSD/b
> /devices/disks/sd1/BSD/c
> /devices/disks/sd1/BSD/d
> /devices/disks/wd0/all
> /devices/disks/wd0/BSD/all
> /devices/disks/wd0/BSD/a

First of all... you need two views of the same devices:

	sd0 is the first scsi disk

	c0t0l0 is the disk at scsi bus 0 target 0 lun 0

I don't see any reason in devfs to make these symlinks, since it's all
virtual anyway... just have them both have the same major/minor. 

Secondly, is there a technical reason for separating wdn from sdn in the
disk-only view?

Finally, since you only show things that actually exist, there's not much
point to a deep hierarchy. Sun's devfs uses a hierarchy and it's a pain...

A little hierarchy to avoid /dev chaos with everything in one place, yes,
but how about just two levels?

(warning, this gets pretty blue sky towards the end...)

Cooked:
	/devices/disk/d0		# whole first disk
	/devices/disk/d0s0		# first slice (dos, no parts)
	/devices/disk/d0s1		# second slice
	/devices/disk/d0s1p0		# second slice first partition
	/devices/disk/d0s1p1		# second slice second partition

Raw:
	/devices/rdisk/d0		# whole first disk
	/devices/rdisk/d0s0		# first slice (dos, no parts)
	/devices/rdisk/d0s1		# second slice
	/devices/rdisk/d0s1p0		# second slice first partition
	/devices/rdisk/d0s1p1		# second slice second partition

Tapes:
	/devices/tape/t0		# first tape
	/devices/ntape/t0		# first tape, no rewind

Serial:
	/devices/tty/0
	/devices/tty/1
	/devices/tty/2
	/devices/tty/3
	/devices/tty/4

	/devices/cua/0			# non-modem-control of course

Pty:
	/devices/pty/0 .. nnnn		# created as needed?

Explicit:
	/devices/wd/c0d0		# first disk on first wd
	/devices/wd/c0d0s0		# ...
	/devices/scsi/c0t0l0		# first device on first SCSI...

Now we get a bit fuzzy... what's the logical naming?
	/devices/sio/t3p0		# single port IRQ 3
	/devices/sio/c3p0		# single port IRQ 3 non modem control
	/devices/sio/i10p0		# multiport card IRQ 10 ...