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Date: Thu, 1 Aug 2013 17:00:05 +0200
From: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20130801150005.GE2387@stefanha-thinkpad.redhat.com>
References: <cover.1375325971.git.jcody@redhat.com>
	<9e47d3ea77357b438ce2164f6e226d216553c58e.1375325971.git.jcody@redhat.com>
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In-Reply-To: <9e47d3ea77357b438ce2164f6e226d216553c58e.1375325971.git.jcody@redhat.com>
Subject: Re: [Qemu-devel] [PATCH v2 4/9] block: vhdx - log support struct
	and defines
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To: Jeff Cody <jcody@redhat.com>
Cc: kwolf@redhat.com, famz@redhat.com, qemu-devel@nongnu.org

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.