[GEDI] [PATCH-for-9.1 v2 2/3] migration: Remove RDMA protocol handling

[Thomas Huth]

On 28/03/2024 16.01, Peter Xu wrote:
> On Thu, Mar 28, 2024 at 11:18:04AM -0300, Fabiano Rosas wrote:
>> Philippe Mathieu-Daudé <philmd at linaro.org> writes:
>>
>>> The whole RDMA subsystem was deprecated in commit e9a54265f5
>>> ("hw/rdma: Deprecate the pvrdma device and the rdma subsystem")
>>> released in v8.2.
>>>
>>> Remove:
>>>   - RDMA handling from migration
>>>   - dependencies on libibumad, libibverbs and librdmacm
>>>
>>> Keep the RAM_SAVE_FLAG_HOOK definition since it might appears
>>> in old migration streams.
>>>
>>> Cc: Peter Xu <peterx at redhat.com>
>>> Cc: Li Zhijian <lizhijian at fujitsu.com>
>>> Acked-by: Fabiano Rosas <farosas at suse.de>
>>> Signed-off-by: Philippe Mathieu-Daudé <philmd at linaro.org>
>>
>> Just to be clear, because people raised the point in the last version,
>> the first link in the deprecation commit links to a thread comprising
>> entirely of rdma migration patches. I don't see any ambiguity on whether
>> the deprecation was intended to include migration. There's even an ack
>> from Juan.
> 
> Yes I remember that's the plan.
> 
>>
>> So on the basis of not reverting the previous maintainer's decision, my
>> Ack stands here.
>>
>> We also had pretty obvious bugs ([1], [2]) in the past that would have
>> been caught if we had any kind of testing for the feature, so I can't
>> even say this thing works currently.
>>
>> @Peter Xu, @Li Zhijian, what are your thoughts on this?
> 
> Generally I definitely agree with such a removal sooner or later, as that's
> how deprecation works, and even after Juan's left I'm not aware of any
> other new RDMA users.  Personally, I'd slightly prefer postponing it one
> more release which might help a bit of our downstream maintenance, however
> I assume that's not a blocker either, as I think we can also manage it.
> 
> IMHO it's more important to know whether there are still users and whether
> they would still like to see it around.

Since e9a54265f5 was not very clear about rdma migration code, should we 
maybe rather add a separate deprecation note for the migration part, and add 
a proper warning message to the migration code in case someone tries to use 
it there, and then only remove the rdma migration code after two more releases?

  Thomas