Re: [PATCH v9 5/8] docs / tools: specific migration v4 to include DOMAIN_CONTEXT

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 24/09/2020 14:10, Paul Durrant wrote:
> From: Paul Durrant <pdurrant@xxxxxxxxxx>
>
> A new 'domain context' framework was recently introduced to facilitate
> transfer of state for both PV and HVM guests. Hence this patch mandates the
> presence of a new DOMAIN_CONTEXT record in version 4 of the libxc migration
> stream.
> This record will incorprate the content of the domain's 'shared_info' page
> and the TSC informaiton so the SHARED_INFO and TSC_INFO records are 
> deprecated.
> It is intended that, in future, this record will contain state currently
> present in the HVM_CONTEXT record. However, for compatibility with earlier
> migration streams, the version 4 stream format continues to specify an
> HVM_CONTEXT record and XEN_DOMCTL_sethvmcontext will continue to accept all
> content of that record that may be present in a version 3 stream.
>
> Signed-off-by: Paul Durrant <pdurrant@xxxxxxxxxx>

What's the plan for the remainder of the work?  We don't want to burn
multiple version numbers for each bit of incremental work.

One option might be to specify the full extent of the work, and use an
environment variable to alter the behaviour of the sending side, while
it is still work-in-progress.

~Andrew