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Date:      Tue, 15 Oct 2002 18:46:36 -0400 (EDT)
From:      Garrett Wollman <wollman@lcs.mit.edu>
To:        Poul-Henning Kamp <phk@FreeBSD.ORG>
Cc:        net@FreeBSD.ORG, arch@FreeBSD.ORG
Subject:   RFC: eliminating the _IP_VHL hack.
Message-ID:  <200210152246.g9FMka0o007721@khavrinen.lcs.mit.edu>
In-Reply-To: <60637.1034720233@critter.freebsd.dk>
References:  <60637.1034720233@critter.freebsd.dk>

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<<On Wed, 16 Oct 2002 00:17:13 +0200, Poul-Henning Kamp <phk@FreeBSD.ORG> said:

> In the meantime absolutely no code has picked up on this idea,

It was copied in spirit from OSF/1.

> The side effect of having some source-files using the _IP_VHL hack and
> some not is that sizeof(struct ip) varies from file to file,

Not so.  Any compiler which allocates different amounts of storage to
one eight-bit member versus two four-bit bitfield members is seriously
broken (and would defeat the whole purpose).

> I would therefore propose to eliminate the _IP_VHL hack from the kernel
> to end this state of (potential) confusion, and invite comments to the
> following patch:

Much better to delete the bogus BYTE_ORDER kluge from ip.h.  (Note
that the definition of the bitfields in question has nothing
whatsoever to do with the actual byte order in use; it simply relies
on the historical behavior of compilers which allocated space for
bitfields in BYTE_ORDER order.)

-GAWollman


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