From owner-cvs-all  Wed Dec  1 15:27:48 1999
Delivered-To: cvs-all@freebsd.org
Received: from bubba.whistle.com (bubba.whistle.com [207.76.205.7])
	by hub.freebsd.org (Postfix) with ESMTP
	id 89055150F0; Wed,  1 Dec 1999 15:27:45 -0800 (PST)
	(envelope-from archie@whistle.com)
Received: (from archie@localhost)
	by bubba.whistle.com (8.9.2/8.9.2) id PAA45003;
	Wed, 1 Dec 1999 15:27:45 -0800 (PST)
From: Archie Cobbs <archie@whistle.com>
Message-Id: <199912012327.PAA45003@bubba.whistle.com>
Subject: Re: cvs commit: src/sys/kern uipc_mbuf.c src/sys/sys mbuf.h
In-Reply-To: <199912012141.OAA00992@caspian.plutotech.com> from "Justin T. Gibbs" at "Dec 1, 1999 02:41:51 pm"
To: gibbs@FreeBSD.org (Justin T. Gibbs)
Date: Wed, 1 Dec 1999 15:27:45 -0800 (PST)
Cc: cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org
X-Mailer: ELM [version 2.4ME+ PL54 (25)]
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Sender: owner-cvs-all@FreeBSD.ORG
Precedence: bulk

Justin T. Gibbs writes:
> >  Modified files:
> >    sys/kern             uipc_mbuf.c 
> >    sys/sys              mbuf.h 
> >  Log:
> >  The functions m_copym() and m_copypacket() return read-only copies,
> >  because in the case of mbuf clusters they only increment the reference
> >  count rather than actually copying the data.
> >  
> >  Add comments to this effect, and add a new routine called m_dup() that
> >  returns a real, writable copy of an mbuf chain.
> 
> How does this work in a 0 copy system?

Not sure what a '0 copy system' is..

Basically all it does is create a completely new mbuf chain containing
the same data as the original.  Definitely at least 1 copy :-)

You rarely need this, but 'ipfw tee' is one of those cases.

-Archie

___________________________________________________________________________
Archie Cobbs   *   Whistle Communications, Inc.  *   http://www.whistle.com


To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe cvs-all" in the body of the message