[libvirt] [RFC PATCH v2 3/3] qemu: memory pre-pinning support for RDMA migration

[Eric Blake]

On 04/28/2014 03:38 AM, Paolo Bonzini wrote:
> Il 04/04/2014 22:46, Eric Blake ha scritto:
>>> >
>>> > I'm still not seeing what's wrong with depending on the version
>>> > number since other features are also depending on the version
>>> > number.
>> Every feature where we have to guess based on version number is due to a
>> bug in qemu for not providing enough information for libvirt to probe
>> for the feature's existence.  We hate those features, and I have been
>> lobbying hard on the qemu list that all NEW features should be
>> discoverable.  rdma is one such feature - I recall you making changes in
>> your series there so that it is discoverable in response to my early
>> review comments - so now please USE that methodology from libvirt.
>>
> 
> I think that relied on the QAPI introspection.  The MigrationCapability
> rdma-pin-all will be present only if QEMU supports RDMA migration.
> 
> But QAPI introspection is not there yet. :(

I know that qapi introspection is not there yet, but
'query-migrate-capabilities' IS there, and the presence or absence of
rdma-pin-all in the set of queried capabilities IS a reliable witness of
whether rdma support is available.


-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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