Re: [Patch v4] tools/migrate: Fix regression when migrating from older version of Xen

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 30/07/13 10:42, Ian Campbell wrote:
> On Mon, 2013-07-29 at 18:07 +0100, Andrew Cooper wrote:
>> Changes since v3:
>>  * Plumb the xl "remus" flag down through libxl.  This is done by introducing
>>    libxl_domain_create_restore_remus()
> I don't think we want to expose the name of a particular HA strategy in
> the libxl API. If we were to add anything then it should be
> _checkpointed()

Sure.  That is rather better.

>  or something however my strong preference would be to
> add a flags parameter in a backwards compatible way now (perhaps using a
> similar scheme to Olaf's which I linked to before) rather than to start
> combinatorially exploding the API for each new variant.

That is impossible to backport; this is a fix for a regression affecting
all currently maintained version of Xen

>
> Image a new, hypothetical, "pre-migration" mode (contrasted to our
> current post-migration mode), now we have four API calls required (pre-
> vs. post-migration crossed with regular vs. checkpointed).

It isn't nice, but IanJ and I decided that this was the neatest way.

Unless we can agree on a different way of backporting this fix.

>
>> + * If this is defined, libxl_domain_create_restore() has had a _remus()
>> + * varient created to help fix a regression in the migration stream format.
> If you end up reusing any of this text then it should be "variant".
>
>

Ok

~Andrew