[ofiwg] fork support and MR cache

[Gal Pressman]

> On Thu, Oct 08, 2020 at 07:28:50PM +0000, Hefty, Sean wrote:
>> > Please don't recode the kernel interface outside rdma-core, that stuff
>> > is hard to do right.
>>
>> I'm was referring to calling:
>>
>> mr->context->ops.reg_mr(...)
>>
>> instead of indirectly through ibv_reg_mr().
> 
> I deleted those function pointers from the public header a long time
> ago. It was leaking internal ABI.
> 
>> I'm actually fine disabling the cache if fork is enabled.  But how can that be detected?
> 
> If you wan to propose an verbs API to show if the fork support MADV
> stuff has been enabled that seems reasonable to me.

When you say DONTFORK will be obsolete I assume you refer to:
https://lore.kernel.org/lkml/20200925222600.6832-1-peterx@redhat.com/

Right?

How will userspace rdma-core know whether DONTFORK is needed or not? Are there
any RDMA kernel changes I'm missing?