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To: Bruce Evans <bde@zeta.org.au>
From: "Poul-Henning Kamp" <phk@phk.freebsd.dk>
In-Reply-To: Your message of "Fri, 27 Feb 2004 23:16:09 +1100."
             <20040227230124.D2469@gamplex.bde.org> 
Date: Fri, 27 Feb 2004 14:35:33 +0100
Message-ID: <11616.1077888933@critter.freebsd.dk>
cc: Dag-Erling =?iso-8859-1?q?Sm=F8rgrav?= <des@des.no>
cc: arch@freebsd.org
Subject: Re: per-device sysctls 
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In message <20040227230124.D2469@gamplex.bde.org>, Bruce Evans writes:
>On Thu, 26 Feb 2004, Dag-Erling [iso-8859-1] Smørgrav wrote:
>
>> "M. Warner Losh" <imp@bsdimp.com> writes:
>> > How is this different than the sysctl stuff that already exsists for
>> > this and is accessed by devinfo?
>>
>>  1) it is immensely easier to access
>>
>>  2) it gives drivers a well-defined place to put their per-device
>>     sysctl variables - devinfo doesn't address that issue at all
>
>Only broken drivers use sysctl variables.  ioctl(3) is a much better
>interface that sysctl(3) for accessing per-device info.  sysctl(8) is
>a better interface than ioctl(8) for handling the few device control
>things that can be done in a generic way, but this is only because
>there are so few such things that ioctl(8) doesn't exist.

sysctl is superior for properties that should not be vulnerable
to any user who happens to be able to open the device.

-- 
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.