Re: [Xen-devel] [RFC PATCH v2] Data integrity extension(DIX) support for xen-block

[Bob Liu <bob.liu@xxxxxxxxxx>]

On 04/20/2016 04:59 PM, David Vrabel wrote:
> On 20/04/16 08:26, Bob Liu wrote:
>>
>>  /*
>> + * Recognized only if "feature-data-integrity" is present in backend xenbus 
>> info.
>> + * A request with BLKIF_OP_DIX_FLAG indicates the following request is a 
>> special
>> + * request which only contains integrity-metadata segments of current 
>> request.
>> + *
>> + * If a backend does not recognize BLKIF_OP_DIX_FLAG, it should *not* 
>> create the
>> + * "feature-data-integrity" node!
>> + */
>> +#define BLKIF_OP_DIX_FLAG (0x80)
> 
> This looks fine as a mechanism for actually transferring the data but
> you do need to specify:
> 
> 1. The format of this DIX data.  You may reference external
> specifications for this.
> 

Sure!

> 2. A mechanism for reporting which DIX formats the backend supports and
> a way for the frontend to select one (if multiple are selected).
> 

The "feature-data-integrity" could be extended to "unsigned int" instead of 
"bool",
so as to report all DIX formats backend supports.

> 3. The behaviour the frontend can expect from the backend.  (e.g., if
> the frontend writes sector S with DIX data D, a read of sector S with
> complete with DIX data D).
> 

Sorry, I didn't get the point of this example.

Thank you for your review!

-- 
Regards,
-Bob

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