From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([2001:4830:134:3::10]:50875)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <jcody@redhat.com>) id 1V4v9u-0004fh-2z
	for qemu-devel@nongnu.org; Thu, 01 Aug 2013 11:51:30 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <jcody@redhat.com>) id 1V4v9k-0001VQ-UX
	for qemu-devel@nongnu.org; Thu, 01 Aug 2013 11:51:21 -0400
Received: from mx1.redhat.com ([209.132.183.28]:39056)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <jcody@redhat.com>) id 1V4v9k-0001VD-NN
	for qemu-devel@nongnu.org; Thu, 01 Aug 2013 11:51:12 -0400
Received: from int-mx09.intmail.prod.int.phx2.redhat.com
	(int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22])
	by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id r71FpBK2011479
	(version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK)
	for <qemu-devel@nongnu.org>; Thu, 1 Aug 2013 11:51:11 -0400
Date: Thu, 1 Aug 2013 11:51:08 -0400
From: Jeff Cody <jcody@redhat.com>
Message-ID: <20130801155108.GK19714@localhost.localdomain>
References: <cover.1375325971.git.jcody@redhat.com>
	<9e47d3ea77357b438ce2164f6e226d216553c58e.1375325971.git.jcody@redhat.com>
	<20130801150005.GE2387@stefanha-thinkpad.redhat.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20130801150005.GE2387@stefanha-thinkpad.redhat.com>
Subject: Re: [Qemu-devel] [PATCH v2 4/9] block: vhdx - log support struct
	and defines
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Stefan Hajnoczi <stefanha@redhat.com>
Cc: kwolf@redhat.com, famz@redhat.com, qemu-devel@nongnu.org

On Thu, Aug 01, 2013 at 05:00:05PM +0200, Stefan Hajnoczi wrote:
> On Wed, Jul 31, 2013 at 11:23:49PM -0400, Jeff Cody wrote:
> > @@ -318,6 +323,18 @@ typedef struct VHDXMetadataEntries {
> >      uint16_t present;
> >  } VHDXMetadataEntries;
> >  
> > +typedef struct VHDXLogEntries {
> > +    uint64_t offset;
> > +    uint64_t length;
> > +    uint32_t head;
> > +    uint32_t tail;
> > +} VHDXLogEntries;
> > +
> > +typedef struct VHDXLogEntryInfo {
> > +    uint64_t sector_start;
> > +    uint32_t desc_count;
> > +} VHDXLogEntryInfo;
> 
> An array of VHDXLogEntryInfo structs would be affected by alignment on
> x86_64.  &a[1] != (void*)a + sizeof(VHDXLogEntryInfo).
> 
> IMO all on-disk structs should be QEMU_PACKED for safety.

Neither of the two structs above reflect on-disk structs (actually
VHDXLogEntryInfo is currently unused, so I should drop it from this
patch).

I should mention this in the commit message, since the patch context
isn't enough to show it, but the structs introduced in this patch are
below a comment demarcation line that calls out an end to the on-disk
structs:

/* ----- END VHDX SPECIFICATION STRUCTURES ---- */