Re: [Qemu-devel] [PATCH v2 3/3] docs/qcow2: Limit refcount_order to [0, 6]

[Eric Blake <eblake@redhat.com>]

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On 09/02/2014 04:25 PM, Max Reitz wrote:
> Specify the upper limit of refcount_order to be 6 (that is,
> refcount_bits = 64). Any larger value does not make much sense when all
> offsets, sizes, cluster counts etc. "only" have a width of 64 bit as
> well, and very large values would be very difficult to support.
> Therefore, just cap it at the largest reasonable value.
> 
> Suggested-by: Eric Blake <eblake@redhat.com>
> Signed-off-by: Max Reitz <mreitz@redhat.com>
> ---
>  docs/specs/qcow2.txt | 1 +
>  1 file changed, 1 insertion(+)

Reviewed-by: Eric Blake <eblake@redhat.com>

> 
> diff --git a/docs/specs/qcow2.txt b/docs/specs/qcow2.txt
> index 0a878aa..121dfc8 100644
> --- a/docs/specs/qcow2.txt
> +++ b/docs/specs/qcow2.txt
> @@ -110,6 +110,7 @@ in the description of a field.
>                      in bits: refcount_bits = 1 << refcount_order). For version 2
>                      images, the order is always assumed to be 4
>                      (i.e. refcount_bits = 16).
> +                    This value may not exceed 6 (i.e. refcount_bits = 64).
>  
>          100 - 103:  header_length
>                      Length of the header structure in bytes. For version 2
> 

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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