Hi Ferruh, Dan, Sure, I remember last year discussion but now I see the problem in current implementation.
Ferruh, here is an example: We have a thread in the application that processes KNI commands from the kernel. It receives config_network_if command to set interface up, calls rte_eth_dev_start, and here is the problem. We cannot call current rte_kni_update_link from here as the interface is not yet up in the kernel, as we didn't send a response for config_network_if yet. So we need to send a response first and only after that, we can use rte_kni_update_link. Actually, we don't even know the exact time between we send a response and the moment when the kernel receives it and the interface becomes up. We always have a dependency on the interface state in the kernel. With ioctl approach, we don't have such dependency - we can call rte_kni_update_link whenever we want, even when the interface is down in the kernel. As I explained, it's common when processing config_network_if to set interface up. Igor On Mon, Oct 14, 2019 at 11:56 PM Dan Gora <d...@adax.com> wrote: > 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 <d...@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...@adax.com> > > > > If you search for KNI and d...@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.yi...@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" >
