[libvirt] [PATCH] libxl: advertise support for migration V3

Joao Martins joao.m.martins at oracle.com
Tue Aug 30 17:38:13 UTC 2016

On 08/30/2016 06:21 PM, Jim Fehlig wrote:
> On 08/30/2016 08:45 AM, Joao Martins wrote:
>> On 08/29/2016 06:20 PM, Jim Fehlig wrote:
>>> The libxl driver has long supported migration V3 but has never
>>> indicated so in the connectSupportsFeature API. 
>> Hmm, but IIRC it was only since "recent" commit 8db77b3 right?
> The libxl driver has supported the VIR_DRV_FEATURE_MIGRATION_PARAMS V3 family of
> migration functions since commit 9b8d6e1e in May 2014.

>>  Or rather Nikolay's
>> reworking top-level migration code, which effectively would convert to the params
>> versions accordingly. Before that rework I think one had to implement both params and
>> non-params variants. Would it be worth adding a comment mainly to help the reader?
> I think you are right, but support for V3 is independent of the params vs
> non-params variants. virt-manager uses the generic virDomainMigrate() function
> in src/libvirt-domain.c, and at least as far back as libvirt 1.2.5 that function
> tests whether both source and destination support 
> VIR_DRV_FEATURE_MIGRATION_V{1,2,3}. If the driver doesn't advertise support for
> any of the versions, virDomainMigrate() returns VIR_ERR_NO_SUPPORT.
Hmm, OK. IIRC the problems I once observed where more around virDomainMigrateToURI -
which got addressed in the series containing the commit above. Anyhow sorry for the

>> (I vaguely remember this as I dropped my v3 patch as being no longer necessary)
>>> As a result, apps
>>> such as virt-manager that use the more generic virDomainMigrate API
>>> fail with
>>> libvirtError: this function is not supported by the connection driver:
>>> virDomainMigrate
>>> Add VIR_DRV_FEATURE_MIGRATION_V3 to the list of features marked as
>>> supported in the connectSupportsFeature API.
>> FWIW and irrespective of the comment above:
>> Reviewed-by: Joao Martins <joao.m.martins at oracle.com>
> Thanks. Along with Cedric's ACK, and considering it is a trivial bug fix, I plan
> to push this for RC2.



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