Re: [dpdk-dev] [PATCH v3 0/2] slow data path communication between DPDK port and Linux

[Thomas Monjalon <thomas.monjalon@6wind.com>]

2016-03-16 10:26, Ferruh Yigit:
> On 3/16/2016 8:22 AM, Panu Matilainen wrote:
> > On 03/16/2016 10:19 AM, Ferruh Yigit wrote:
> >> On 3/16/2016 7:26 AM, Panu Matilainen wrote:
> >>> On 03/14/2016 05:32 PM, Ferruh Yigit wrote:
> >>>> On 3/9/2016 11:17 AM, Ferruh Yigit wrote:
> >>>>> This patch sent to keep record of latest status of the work.
> >>>>>
> >>>>>
> >>>>> This is slow data path communication implementation based on existing KNI.
> >>>>>
> >>>>> Difference is: librte_kni converted into a PMD, kdp kernel module is almost
> >>>>> same except all control path functionality removed and some simplification done.
> >>>>>
> >>>>> Motivation is to simplify slow path data communication.
> >>>>> Now any application can use this new PMD to send/get data to Linux kernel.
> >>>>>
> >>>>> PMD supports two communication methods:
> >>>>>
> >>>>> 1) KDP kernel module
> >>>>> PMD initialization functions handles creating virtual interfaces (with help of
> >>>>> kdp kernel module) and created FIFO. FIFO is used to share data between
> >>>>> userspace and kernelspace. This is default method.
> >>>>>
> >>>>> 2) tun/tap module
> >>>>> When KDP module is not inserted, PMD creates tap interface and transfers
> >>>>> packets using tap interface.
> >>>>>
> >>>>> In long term this patch intends to replace the KNI and KNI will be
> >>>>> depreciated.
> >>>>>
> >>>>
> >>>> Self-NACK: Will work on another option that does not introduce new
> >>>> kernel module.
> >>>>
> >>>
> >>> Hmm, care to elaborate a bit? The second mode of this PMD already was
> >>> free of external kernel modules. Do you mean you'll be just removing
> >>> mode 1) from the PMD or looking at something completely different?
> >>>
> >>> Just thinking that tun/tap PMD sounds like a useful thing to have, I
> >>> hope you're not abandoning that.
> >>>
> >>
> >> It will be KNI PMD.
> >> Plan is to have something like KDP, but with existing KNI kernel module.
> >> There will be tun/tap support as fallback.
> > 
> > Hum, now I'm confused. I was under the impression everybody hated KNI 
> > and wanted to get rid of it, and certainly not build future solutions on 
> > top of it?
> 
> We can't remove it.

Why?

> We can't replace/improve it -you were one of the major opposition to this.
> This doesn't leave more option other than using it.

Why cannot we replace it by something upstream?

> There won't be any update in KNI kernel module, library + sample app
> will be converted into PMD.