linux-kernel - Re: what's the purpose of MAXHOSTNAMELEN?

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Date:	Tue, 29 Dec 2009 15:13:14 -0500 (EST)
From:	"Robert P. J. Day" <rpjday@...shcourse.ca>
To:	Jeff Garzik <jeff@...zik.org>
cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: what's the purpose of MAXHOSTNAMELEN?

On Tue, 29 Dec 2009, Jeff Garzik wrote:
... snip ..

> >    so lots of people define it but no one uses it.  it *is*
> > exported to user space in /usr/include/asm/param.h, but i still
> > have no idea what it's for in user space.  obsolete?
>
> According to RFC 1034, "Each node has a label, which is zero to 63
> octets in length"
>
> What is it used for in userspace, and why is it export from the
> kernel?  Good question...

  it's not clear what value that macro has in user space since (as
i've always understood it) the point of exporting a macro like that to
user space is so that user space apps can *agree* with kernel code
that employs the same macro.

  but if absolutely *nothing* in the kernel uses that macro, then
there's nothing for user space to "agree" with.  in other words, that
macro cannot *possibly* have any meaningful value in user space. does
that make sense?

  my reaction at this point is to simply remove that macro definition
from include/asm-generic/param.h.  anything in user space that's using
that macro is simply using a macro with a completely arbitrary value.

rday
--

========================================================================
Robert P. J. Day                               Waterloo, Ontario, CANADA

            Linux Consulting, Training and Kernel Pedantry.

Web page:                                          http://crashcourse.ca
Twitter:                                       http://twitter.com/rpjday
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