Re: [Xen-devel] [PATCH v3 3/6] libxc/migration: Specification update for CHECKPOINT records

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 12/05/15 11:49, Yang Hongyang wrote:
> Hi Andrew, David,
>
>   Would you mind if I fix the comments, and combine this series with mine
> prepare patches for Remus, and then send it out together?

Go for it.  I am happy with Davids corrections.

~Andrew

>
> On 05/12/2015 05:54 PM, David Vrabel wrote:
>> On 12/05/15 10:35, Andrew Cooper wrote:
>>> Checkpointed streams need to signal the end of a consistent view of
>>> VM state,
>>> and the start of the libxl data.
>> [...]
>>> --- a/docs/specs/libxc-migration-stream.pandoc
>>> +++ b/docs/specs/libxc-migration-stream.pandoc
>> [...]
>>> @@ -578,6 +578,23 @@ The verify record contains no fields; its
>>> body_length is 0.
>>>
>>>   \clearpage
>>>
>>> +CHECKPOINT
>>> +----------
>>> +
>>> +A checkpoint record indicates that the records thusfar in the
>>> stream represent
>>
>> ...that all the preceding records in the stream represent...
>>
>>> +a consistent view of VM state.
>>
>>> +
>>> +     0     1     2     3     4     5     6     7 octet
>>> +    +-------------------------------------------------+
>>> +
>>> +The checkpoint record contains no fields; its body_length is 0
>>> +
>>> +A stream containing checkpoint records must have indicated itself as a
>>> +checkpointed stream in the Image Header.  Conversely, a stream not
>>> identified
>>> +as checkpointed must not contain checkpoint records.
>>
>> This paragraph is stale.
>>
>> I think you should expand a bit more on this record.  Perhaps:
>>
>>    If the stream is embedded in a higher level toolstack stream, the
>>    CHECKPOINT record marks the end of the libxc portion of the stream
>>    and the stream is handed back to the higher level for further
>>    processing.
>>
>>    The higher level stream may then hand the stream back to libxc to
>>    process another set of records for the next consistent VM state
>>    snapshot.  This next set of records may be terminated by another
>>    CHECKPOINT record or an END record.
>>
>> David
>> .
>>
>


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