Path: utzoo!yunexus!geac!geaclib!daveb
From: daveb@geaclib.UUCP (David Collier-Brown)
Newsgroups: comp.unix.wizards
Subject: Re: Bigger process IDs and "dev_t"s
Message-ID: <3392@geaclib.UUCP>
Date: 9 Nov 88 01:23:28 GMT
Article-I.D.: geaclib.3392
References: <1988Nov7.190335.17023@utzoo.uucp>
Organization: GEAC Computers, Toronto, CANADA
Lines: 121

> In article <385@auspex.UUCP> guy@auspex.UUCP (Guy Harris) writes:
| You may end up having to Huffman-code them on some systems; SunOS 4.0
| currently has about 56 major devices in use ...

From article <1988Nov7.190335.17023@utzoo.uucp>, by henry@utzoo.uucp (Henry Spencer):
| How many machines do you know that
| actually have all 56 types of devices on them?  None, I bet.  Using
| the same major number for device XYZ across all machines is basically
| an administrative convenience, not a logical necessity.  

  Actually allowing one's supplier to preassign major numbers can
lead to some very non-nice situations:  I recently had a scanner
fail because it was installed as device number 43 (on SunOS 3.5),
instead of the usual 40 (as was used under 3.0..3.4).
  This tends to imply that some [expletive deleted] failed to use
the device name, and instead used a hard-coded magic number.  All it
takes is two errors of that type and we're back with OS/360 and "you
must use x'99.44/100' or it won't come clean.  No two devices may
use this number".

 --dave (why should I hand-craft a cdevsw, ANYWAY?) c-b























































































The number
| of major numbers *needed* on a given machine is the number of devices
| actually attached, plus a few for things like /dev/mem, minus a few
| for devices that always go together (e.g. most of the stuff on a Sun
| CPU board) and hence could share a common major number (as /dev/null
| and /dev/mem do).  Abandoning the standard devicetype->number mapping
| would obviously make system setup harder, but Sun really needs to get
| some competent people to put in some effort in that area anyway...
-- 
 David Collier-Brown.  | yunexus!lethe!dave
 Interleaf Canada Inc. |
 1550 Enterprise Rd.   | HE's so smart he's dumb.
 Mississauga, Ontario  |       --Joyce C-B