Re: [Xen-devel] [PATCH v2 4/6] libxc/save: Adjust stream-position callbacks for checkpointed streams

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

On Mon, 2015-05-11 at 12:56 +0100, Andrew Cooper wrote:
> On 11/05/15 12:36, Ian Campbell wrote:
> > On Fri, 2015-05-08 at 22:14 +0100, Andrew Cooper wrote:
> >> There are some records which should only be sent once in the stream, and 
> >> not
> >> repeated for each checkpoint.  {start,end}_of_stream() become 
> >> per-checkpoint,
> >> and a new start_of_stream() is introduced.
> >>
> >> There is no resulting change record order, but the X86_PV_INFO and
> >> X86_PV_P2M_FRAMES records are positively identified as once per stream, 
> >> rather
> >> than once per checkpoint.
> > In the case of the latter judging from the comments this is currently an
> > implementation detail and in principal we want to be able to resend the
> > p2m frames as well?
> 
> Correct, and the spec regarding X86_PV_P2M_FRAMES was explicitly
> intended to allow partial updates in the future.
> 
> It is currently an implementation bug (or many) that the P2M can't
> change during the live part of migration.

In which case I'd suggest avoiding saying "positively identified as once
per stream" since that gives the impression that this is per the spec
rather than just the current implementation.

Ian.


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