Re: [Xen-devel] [PATCH v3 COLOPre 23/26] docs/libxl: Introduce COLO_CONTEXT to support migration v2 colo streams

[Yang Hongyang <yanghy@xxxxxxxxxxxxxx>]

On 06/30/2015 06:42 PM, Ian Campbell wrote:
> On Thu, 2015-06-25 at 14:25 +0800, Yang Hongyang wrote:
> > From: Wen Congyang <wency@xxxxxxxxxxxxxx>
> This seems to mix up forward and backward facing information in a single
> record?
Yes, it is the negotiation record for COLO.

> > Signed-off-by: Wen Congyang <wency@xxxxxxxxxxxxxx>
> > ---
> >   docs/specs/libxl-migration-stream.pandoc | 21 ++++++++++++++++++++-
> >   tools/libxl/libxl_sr_stream_format.h     | 11 +++++++++++
> >   tools/python/xen/migration/libxl.py      |  9 +++++++++
> >   3 files changed, 40 insertions(+), 1 deletion(-)
> >
> > diff --git a/docs/specs/libxl-migration-stream.pandoc 
> > b/docs/specs/libxl-migration-stream.pandoc
> > index d41932a..7e1edaa 100644
> > --- a/docs/specs/libxl-migration-stream.pandoc
> > +++ b/docs/specs/libxl-migration-stream.pandoc
> > @@ -121,7 +121,9 @@ type         0x00000000: END
> >
> >                0x00000004: CHECKPOINT_END
> >
> > -             0x00000005 - 0x7FFFFFFF: Reserved for future _mandatory_
> > +             0x00000005: COLO_CONTEXT
> > +
> > +             0x00000006 - 0x7FFFFFFF: Reserved for future _mandatory_
> >                records.
> >
> >                0x80000000 - 0xFFFFFFFF: Reserved for future _optional_
> > @@ -216,3 +218,20 @@ A checkpoint end record marks the end of a checkpoint in 
> > the image.
> >
> >   The end record contains no fields; its body_length is 0.
> >
> > +COLO\_CONTEXT
> > +--------------
> > +
> > +A COLO context record contains the control information for COLO.
> I don't know what Andy thinks, but this seems like a rather generic
> catch-all record type to me. It would seem better to have one or more
> more concrete records for different aspects (e.g. status of the
> secondary VM, although that seems like a backchannel thing too and as I
> mentioned before I'm not sure those should be interleaved in the spec in
> this way).
I will leave this to Andy.

> > +
> > +     0     1     2     3     4     5     6     7 octet
> > +    +------------------------+------------------------+
> > +    | control_id             | padding                |
> > +    +------------------------+------------------------+
> > +
> > +--------------------------------------------------------------------
> > +Field            Description
> > +------------     ---------------------------------------------------
> > +control_id       0x00000000: New checkpoint
> I think we already have a checkpoint record type, don't we?
Yes, but the meaning is diffrent, the checkpoint record means the
end of a checkpoint, this means a new checkpoint is needed.

> > +                 0x00000001: Secondary VM is suspended
> > +                 0x00000002: Secondary VM is ready
> > +                 0x00000003: Secondary VM is resumed
>
> .
--
Thanks,
Yang.

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