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From: sdyer@bbncca.ARPA (Steve Dyer)
Newsgroups: net.unix-wizards
Subject: Re: Minor device numbers: too small!
Message-ID: <649@bbncca.ARPA>
Date: Sat, 31-Mar-84 12:57:42 EST
Article-I.D.: bbncca.649
Posted: Sat Mar 31 12:57:42 1984
Date-Received: Sun, 1-Apr-84 08:15:38 EST
References: <1096@proper.UUCP>
Organization: Bolt, Beranek and Newman, Cambridge, Ma.
Lines: 18
Keywords: minor device number,terminals,future Unix releases

Though I cannot yet conceive of needing more than 256 minor device
numbers, it should be relatively easy for anyone with source code
or the ability to link a new kernel with customized new device drivers
to have more than 256 devices of a particular class (e.g. ttys.)

Rather than using a single major device number to specify a device class,
simply use *several*, and you'll get 256 for each major device you claim.
That is, duplicate the cdevsw[] entries for each major device number.  Now,
the only issue is how to resolve an individual device data structure (such
as a particular "struct tty") given both a major and minor device number.
Most drivers merely used the minor device number as an index into an array.
Here, you'll have to be a bit more careful, but it shouldn't be hard.

How long will it be before we hear: "User ID numbers: too small!"
-- 
/Steve Dyer
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