On Fri, Apr 15, 2016 at 07:01:26AM +0300, Leon Romanovsky wrote: > On Thu, Apr 14, 2016 at 01:48:31PM -0400, Ira Weiny wrote: > > On Thu, Apr 14, 2016 at 10:45:50AM -0600, Jason Gunthorpe wrote: > > > On Thu, Apr 14, 2016 at 08:41:35AM -0700, Dennis Dalessandro wrote: > > > > This patch series removes the write() interface for user access in favor of an > > > > ioctl() based approach. This is in response to the complaint that we had > > > > different handlers for write() and writev() doing different things and expecting > > > > different types of data. See: > > > > > > I think we should wait on applying these patches until we globally sort out > > > what to do with the rdma uapi. > > > > > > It just doesn't make alot of sense for drivers to have their own personal > > > char devices. :( > > > > I'm afraid I have to disagree at this time. Someday we may have "1 char device > > to rule them all" but right now we don't have any line of sight to that > > solution. It may be _years_ before we can agree to the semantics which will > > work for all high speed, kernel bypass, rdma, low latency, network devices. > > You didn't ever try to come and work on the solution. We talked about > finite time frame (_months_) which is doable based on knowledge that user > space parts are developed by the same companies and all our future changes > will be in one subsystem. How can you say that I am not working on a solution? We spent most of last week discussing possible solutions and I am in support of a more common core. But ask yourself this. If hfi1 did not support verbs at all would this even be an issue? > > You were supposed to prepare "wish list" from this new API as an initial > phase. If you do it, you will find that it is very short and in the > initial meeting you will see that it similar to other participants in > linux-rdma community. The list of operations may be short. But the way in which you do those in a performant way for each hardware device is _very_ different. This is a problem which has been debated for years and no one has come up with an elegant solution. Every solution ends up being, to quote a presenter at last weeks conference, "shoving a square peg into a round hole". Until we all admit 2 things. 1) That there are devices which don't operate on QPs 2) That the High Speed interconnect core should present something more abstract than a QP interface we are not really creating a common layer. I do admit Jasons idea has some merit but I'm just not sure it provides so much benefit that it is worth the effort at this time. Ira -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
