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Date: Wed, 09 Nov 2011 10:46:20 +0100
From: Kevin Wolf <kwolf@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH] block: Fix vpc initialization of the
 Dynamic Disk Header
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To: Charles Arnold <carnold@suse.com>
Cc: qemu-devel@nongnu.org

Am 08.11.2011 20:25, schrieb Charles Arnold:
> The Data Offset field in the Dynamic Disk Header is an 8 byte field.
> Although the specification (2006-10-11) gives an example of initializing
> only the first 4 bytes, images generated by Microsoft on Windows initialize 
> all 8 bytes.
> 
> Failure to initialize all 8 bytes results in errors from utilities
> that check specifically for the complete Data Offset field initialization.
> 
> Signed-off-by: Charles Arnold <carnold@suse.com>
> 
> diff --git a/block/vpc.c b/block/vpc.c
> index 416f489..35ac3fd 100644
> --- a/block/vpc.c
> +++ b/block/vpc.c
> @@ -585,7 +585,7 @@ static int vpc_create(const char *filename, QEMUOptionParameter *options)
> 
>      memcpy(dyndisk_header->magic, "cxsparse", 8);
> 
> -    dyndisk_header->data_offset = be64_to_cpu(0xFFFFFFFF);
> +    dyndisk_header->data_offset = be64_to_cpu(0xFFFFFFFFFFFFFFFFULL);
>      dyndisk_header->table_offset = be64_to_cpu(3 * 512);
>      dyndisk_header->version = be32_to_cpu(0x00010000);
>      dyndisk_header->block_size = be32_to_cpu(block_size);

Can you please add a short comment explaining why we deviate from the
specification in this point? If someone notices the discrepancy later,
he shouldn't have to dig up the git commit message.

Kevin