Re: [Qemu-devel] [PATCH V18 1/6] docs: document for add-cow file format

[Stefan Hajnoczi]

On Wed, Apr 10, 2013 at 04:11:48PM +0800, Dong Xu Wang wrote:
> +The Header is included in the first bytes:
> +(HEADER_SIZE is defined in 40-43 bytes.)
> +    Byte    0  -  3:    magic
> +                        add-cow magic string ("ACOW").
> +
> +            4  -  7:    backing file name offset
> +                        Offset in the add-cow file at which the backing
> +                        file name is stored (NB: The string is not
> +                        lNUL-terminated).

s/lNUL/NUL/

> +            24 - 31:    features
> +                        Bitmask of features. If a feature bit is set
> +                        but not recognized, the add-cow file should be
> +                        dropped. They are not used in now.

"If a feature bit is set but not recognized, the opening the add-cow file must 
fail.  No features bits are currently defined."