Re: [dpdk-dev] [PATCH v3] kni: rework rte_kni_update_link using ioctl

[Dan Gora <dg@adax.com>]

Here's another link to the thread where this was discussed last year..
Igor was actually on this thread as well...

https://mails.dpdk.org/archives/dev/2018-August/110383.html

On Mon, Oct 14, 2019 at 4:01 PM Dan Gora <dg@adax.com> wrote:
>
> My original patch to add this feature was basically the same thing as
> this: setting the link status via a KNI ioctl. That method was
> rejected after _much_ discussion and we eventually settled on the
> currently implementation.
>
> My original patch was here: Message-Id: <20180628225548.21885-1-dg@adax.com>
>
> If you search for KNI and dg@adax.com in the DPDK devel list you
> should be able to suss out the whole discussion that lead to the
> current implementation.
>
> thanks
> dan
>
> On Mon, Oct 14, 2019 at 1:17 PM Ferruh Yigit <ferruh.yigit@intel.com> wrote:
> >
> > On 10/14/2019 5:10 PM, Ferruh Yigit wrote:
> > > On 9/25/2019 10:36 AM, Igor Ryzhov wrote:
> > >> Current implementation doesn't allow us to update KNI carrier if the
> > >> interface is not yet UP in kernel. It means that we can't use it in the
> > >> same thread which is processing rte_kni_ops.config_network_if, which is
> > >> very convenient, because it allows us to have correct carrier status
> > >> of the interface right after we enabled it and we don't have to use any
> > >> additional thread to track link status.
> > >
> > > Hi Igor,
> > >
> > > The existing thread tracks the link status of the physical device and reflects
> > > the changes to the kni netdev, but the "struct rte_kni_ops"
> > > (rte_kni_ops.config_network_if) works other way around, it captures (some)
> > > requests to kni netdev and reflects them to the underlying physical device.
> > > Even 'rte_kni_update_link()' updated to use ioctl, the thread still looks
> > > required and this patch doesn't really changes that part.
> > >
> > > Also I am reluctant to extend the KNI ioctl interface when there is a generic
> > > way to do that work.
> > >
> > > What is the use case of updating kni netdev carrier status when the interface is
> > > down?
> >
> > btw, if the problem is status of the interface being 'no-carrier' by default,
> > this can be changed by "carrier=on" parameter of the kni kernel module:
> > "insmod ./build/kmod/rte_kni.ko carrier=on"