From: Arnd Bergmann <arnd@arndb.de>
Subject: Re: [PATCH] net: define __packed for the userspace code
Date: Sun, 22 Aug 2010 15:07:41 +0200
Message-ID: <201008221507.42023.arnd@arndb.de>
References: <1282475544-24708-1-git-send-email-xiaosuo@gmail.com> <AANLkTin1BOgHBc4sTwFAmQhKFNvZ+90herc4Dsh9P8y2@mail.gmail.com>
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Cc: "David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <eric.dumazet@gmail.com>,
	linux-kernel@vger.kernel.org, netdev@vger.kernel.org
To: Changli Gao <xiaosuo@gmail.com>
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On Sunday 22 August 2010 13:23:42 Changli Gao wrote:
> On Sun, Aug 22, 2010 at 7:12 PM, Changli Gao <xiaosuo@gmail.com> wrote:
> > This commit
> >
> >  commit bc10502dba37d3b210efd9f3867212298f13b78e
> >  Author: Eric Dumazet <eric.dumazet@gmail.com>
> >  Date:   Thu Jun 3 03:21:52 2010 -0700
> >
> >    net: use __packed annotation
> >
> > makes use of __packed in the userspace code. So we'd better define __packed
> > for the userspace code too.
> >
> 
> Oh, sorry. This patch can't work as include/linux/compiler.h isn't
> exported to the userspace. But where should we define __packed for the
> userspace code? include/linux/types.h?

I would try to avoid making those structures packed to start with.
>From what I can see, they structures annotated in the above commit
mostly don't even require explicit packing because they are already
packed. Not marking them packed makes the code portable to non-gcc
compilers.

	Arnd