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Date:      Thu, 7 Sep 2000 09:28:48 +0200 (CEST)
From:      Luigi Rizzo <luigi@info.iet.unipi.it>
To:        Ruslan Ermilov <ru@sunbay.com>
Cc:        Garrett Wollman <wollman@khavrinen.lcs.mit.edu>, cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org
Subject:   Re: cvs commit: src/sys/netinet ip_divert.c ip_icmp.c ip_input.c ip_mroute.c ip_output.c raw_ip.c udp_usrreq.c
Message-ID:  <200009070728.JAA27581@info.iet.unipi.it>
In-Reply-To: <20000907092610.A46475@sunbay.com> from Ruslan Ermilov at "Sep 7, 2000 09:26:10 am"

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> > According to Mike Karels (in a message to me dated 2 June 1997),
> > BSD/OS leaves the ip_id field in network order all the time, but swaps
> > in the raw IP code to preserve the old interface.  There is never any
> > arithmetic performed on the IP ID, only comparisons for equality, so
> > leaving out the swap should save a cycle or three.
> > 
> The same does NetBSD, but I feel more logical is to have all these fields
> in host byte order right after ip_input() processing.

The problem with swapping is that such fields can be part of an mbuf cluster,
which is potentially shared by other flows of control and thus not
expected to be modified.

	cheers
	luigi
-----------------------------------+-------------------------------------
  Luigi RIZZO, luigi@iet.unipi.it  . Dip. di Ing. dell'Informazione
  http://www.iet.unipi.it/~luigi/  . Universita` di Pisa
  TEL/FAX: +39-050-568.533/522     . via Diotisalvi 2, 56126 PISA (Italy)
  Mobile   +39-347-0373137
-----------------------------------+-------------------------------------


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