From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:54836) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Wjpu7-0002C3-7q for qemu-devel@nongnu.org; Mon, 12 May 2014 09:04:33 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Wjptz-0003Pk-K2 for qemu-devel@nongnu.org; Mon, 12 May 2014 09:04:27 -0400 Received: from mx1.redhat.com ([209.132.183.28]:3574) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Wjptz-0003Pc-Be for qemu-devel@nongnu.org; Mon, 12 May 2014 09:04:19 -0400 Received: from int-mx14.intmail.prod.int.phx2.redhat.com (int-mx14.intmail.prod.int.phx2.redhat.com [10.5.11.27]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id s4CD4Ijf022917 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK) for ; Mon, 12 May 2014 09:04:18 -0400 From: Kevin Wolf Date: Mon, 12 May 2014 15:04:07 +0200 Message-Id: <1399899851-5641-2-git-send-email-kwolf@redhat.com> In-Reply-To: <1399899851-5641-1-git-send-email-kwolf@redhat.com> References: <1399899851-5641-1-git-send-email-kwolf@redhat.com> Subject: [Qemu-devel] [PATCH 1/5] qcow1: Make padding in the header explicit List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: kwolf@redhat.com, stefanha@redhat.com, ppandit@redhat.com We were relying on all compilers inserting the same padding in the header struct that is used for the on-disk format. Let's not do that. Mark the struct as packed and insert an explicit padding field for compatibility. Signed-off-by: Kevin Wolf --- block/qcow.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/block/qcow.c b/block/qcow.c index 937dd6d..3684794 100644 --- a/block/qcow.c +++ b/block/qcow.c @@ -48,9 +48,10 @@ typedef struct QCowHeader { uint64_t size; /* in bytes */ uint8_t cluster_bits; uint8_t l2_bits; + uint16_t padding; uint32_t crypt_method; uint64_t l1_table_offset; -} QCowHeader; +} QEMU_PACKED QCowHeader; #define L2_CACHE_SIZE 16 -- 1.8.3.1