From mboxrd@z Thu Jan  1 00:00:00 1970
From: Dan Carpenter <dan.carpenter@oracle.com>
Subject: Re: [PATCH] drivers: staging: lustre: lustre: include: add
 "__attribute__((packed))" for the related union
Date: Mon, 20 Jan 2014 15:30:46 +0300
Message-ID: <20140120123045.GV7444@mwanda>
References: <52DA4E6A.1000308@gmail.com> <20140118100547.GS7444@mwanda>
 <52DA56C2.5010802@gmail.com> <20140118142404.GT7444@mwanda>
 <52DBA3D4.3090308@gmail.com> <52DD0EFF.2010305@imgtec.com>
Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
Return-path: <driverdev-devel-bounces@linuxdriverproject.org>
Content-Disposition: inline
In-Reply-To: <52DD0EFF.2010305@imgtec.com>
List-Id: <linux-metag.vger.kernel.org>
List-Unsubscribe: <http://driverdev.linuxdriverproject.org/mailman/options/driverdev-devel>, 
 <mailto:driverdev-devel-request@linuxdriverproject.org?subject=unsubscribe>
List-Archive: <http://driverdev.linuxdriverproject.org/pipermail/driverdev-devel>
List-Post: <mailto:driverdev-devel@linuxdriverproject.org>
List-Help: <mailto:driverdev-devel-request@linuxdriverproject.org?subject=help>
List-Subscribe: <http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel>, 
 <mailto:driverdev-devel-request@linuxdriverproject.org?subject=subscribe>
Errors-To: driverdev-devel-bounces@linuxdriverproject.org
Sender: driverdev-devel-bounces@linuxdriverproject.org
To: James Hogan <james.hogan@imgtec.com>
Cc: devel@driverdev.osuosl.org, andreas.dilger@intel.com, Chen Gang <gang.chen.5i5j@gmail.com>, Greg KH <gregkh@linuxfoundation.org>, bergwolf@gmail.com, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, oleg.drokin@intel.com, jacques-charles.lafoucriere@cea.fr, jinshan.xiong@intel.com, linux-metag@vger.kernel.org

Ah.  From so metag is a new arch and not a compiler like the changelog
says.

On Mon, Jan 20, 2014 at 11:56:47AM +0000, James Hogan wrote:
> struct a {
> 	struct b {
> 		unsigned int x;
> 		unsigned short y;
> 	} x;
> 	unsigned short y;
> } __packed;

This is not the code we are discussing.  It should look like:

struct a {
	union {
		short x;
		short y;
	}
	short z;
};

Any normal person would assume that sizeof(struct a) would be 4 but
apparently on metag it is 8.  That totally defeats the point of using
a union in the first place.  It's easy enough to add a __packed to the
lustre declaration but I expect this to cause an endless stream of bugs.

It it is really stupid.

regards,
dan carpenter