From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261309AbVFUMhq (ORCPT ); Tue, 21 Jun 2005 08:37:46 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261305AbVFUMgV (ORCPT ); Tue, 21 Jun 2005 08:36:21 -0400 Received: from clock-tower.bc.nu ([81.2.110.250]:2980 "EHLO lxorguk.ukuu.org.uk") by vger.kernel.org with ESMTP id S261299AbVFUMaa (ORCPT ); Tue, 21 Jun 2005 08:30:30 -0400 Subject: Re: struct iphdr in include/linux/ip.h (probably bug in headerfile) From: Alan Cox To: k8 s Cc: Linux Kernel Mailing List In-Reply-To: <699a19ea05062100157c17c09c@mail.gmail.com> References: <699a19ea05062100157c17c09c@mail.gmail.com> Content-Type: text/plain Content-Transfer-Encoding: 7bit Message-Id: <1119356872.3325.121.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.4.6 (1.4.6-2) Date: Tue, 21 Jun 2005 13:27:56 +0100 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Maw, 2005-06-21 at 08:15, k8 s wrote: > Hello, > > The following definition in linux/include/ip.h is creating problems. > > How does Endianness affect BIT ORDER > IT affetc only BYTE ORDER Bitfield order is a compiler property. Byte order is usually a processor property and the two are not exactly connected. A compiler given two bit fields can pack them from the high bit or from the low bit and may do different things depending on the platform. The defines tell the kernel whether the compiler packs bitfields into the low bits first or the high bits first.