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Date: Fri, 01 Oct 2010 17:11:20 +0300
From: Andriy Gapon <avg@freebsd.org>
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Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org,
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Subject: Re: svn commit: r213322 - head/sys/kern
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mdf@FreeBSD.org wrote:
> I thought CTLFLAG_TUN was only used to provide a more useful error
> message when writing to a read-only sysctl?  I think the CTLFLAG_TUN
> should not be here for a RW sysctl.

Yes, that's the only use for CTLFLAG_TUN _now_.
Perhaps in the future there could be other uses, such as a flag to sysctl to list
names which are also tunables.  Or some other creative use.

sysctl(9) says:

CTLFLAG_TUN      Also declare a system tunable with the same name to ini‐
                 tialize this variable.

While the above is not true or very ambiguous at the very least, I still don't see
any reason not to use the flag in this case.

-- 
Andriy Gapon