Re: [PATCH rdma-next V1 00/13] [PATCH V1 for-next 00/13] IB/core: SG IOCTL based RDMA ABI

Matan Barak
2017-08-27T08:00:10Z

On 25/08/2017 21:27, Christopher Lameter wrote:
> On Fri, 25 Aug 2017, Hefty, Sean wrote:
>
>>> I think you should wait until after plumbers.
>>
>> I tried to review the code and gave up. I still find it overly complex for implementing what is conceptually a function dispatch table.
>

Every such an API could be defined as a way to trigger operations
(functions) from user-space to kernel....
It doesn't necessarily mean that when you take all requirements into
account it falls into a simple "function dispatch table" (i.e. netlink).

We all know the current uverbs design isn't flexible enough - hfi1 went
and implemented its own ABI and didn't use the RDMA subsystem default
one.... The goal of all of this is to have a suitable interface between
user-space and kernel that fits all the required RDMA consumers and
user-space drivers. This is mandatory giving the new fabrics and
features added lately to this subsystem.

Anyway, we established the concepts in the RDMA mailing list, linux
plumbers, OFVWG and OFA. There were a lot of RFC rounds. V0 of the
patches got comments, which are fixed here.

> Welll this fixes a long standing major issue in the ABI. No one else is
> working on it so its the only way to go. I think this ought to be merged
> ASAP. If it breaks something then at least everyone is affected and will
> be fixing this thing up so we can finally move beyond the rpc via file ops
> issue.
>
>

I totally agree. Most of the involved people attended at least some of
the conferences/meetings. The patches and RFCs exist in the ML for a
long time. It shouldn't break anything as currently it's just an
experimental interface along what we have now, but it'll allow people to
start test this infrastructure, port verbs and write new features.