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To: Ed Schouten <ed@fxq.nl>
From: "Poul-Henning Kamp" <phk@phk.freebsd.dk>
In-Reply-To: Your message of "Sun, 17 Feb 2008 22:24:57 +0100."
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Date: Sun, 17 Feb 2008 21:33:41 +0000
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Cc: freebsd-arch@freebsd.org
Subject: Re: Device minor number uniqueness 
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In message <20080217212457.GX1340@hoeg.nl>, Ed Schouten writes:

>After digging into some more source code, it turns out a lot of drivers
>use minor number to store device numbers and such, but there is no real
>reason why we should enforce drivers to use unique minor numbers.

the major & minor together combine to the userland concept of a
"dev_t" which conforms to POSIX.

While I don't think POSIX demands that dev_t has to be unique per
device, the amount of software that assumes them to be is not to
be sneezed at.

If you just need a minor number to fill out the field, use the
unit number allocation functions.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk@FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.