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

[Michael R. Hines]

On 04/05/2014 04:46 AM, Eric Blake wrote:
> On 04/04/2014 12:29 AM, Michael R. Hines wrote:
>> Yes, it's present, but it still does not guarantee that QEMU supports
>> it if RDMA was compiled out - only the version number is a
>> (minimal) guarantee, and even then the hardware can still throw
>> an error if RDMA itself is not supported.
> Which sounds like you want a feature test (is it supported in the build
> you are talking to, answer is always correct) and not a version test (is
> the build you are talking to new enough to possibly have the feature,
> but if you guess wrong you may get an error from the hardware)
>
>> 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.

Acknowledged =)

- Michael