Hi Vlad,

On Sun, Feb 5, 2017 at 6:34 PM, Lazarenko, Vlad (WorldQuant)
<[email protected]> wrote:
> Gentlemen and gentleladies,
>
> I am trying to get the KNI working on my dev box. So I've loaded the 
> rte_kni.ko module and made sure /dev/kni has correct permissions. But when I 
> am trying to run the KNI example, it fails with "No supported Ethernet device 
> found" error:
>
> $ build/kni -n 4 -c 0xf0 -- -P -p 0x3 --config="(0,4,6),(1,5,7)"
> EAL: Detected 24 lcore(s)
> EAL: PCI device 0000:01:00.0 on NUMA socket -1
> EAL:   probe driver: 8086:10d3 net_e1000_em
> EAL: Error - exiting with code: 1
>   Cause: No supported Ethernet device found
>
> My dev box does not in fact have supported NICs. But my understanding about 
> KNI was that it allows to access Linux network stack trough the KNI kernel 
> module, where applications create a virtual Ethernet devices (i.e. 
> /sys/class/net/vEth*), thus there is no need for a real supported NIC or 
> taking over the entire NIC.
>
> On the other hand, the example application calls rte_eth_dev_count() first, 
> which in my case returns 0, and exits.
>
> Is my understanding about what KNI actually is wrong? Or am I missing 
> something else?
>

As far as I know the KNI sample app actually forwards traffic to/from
the kernel and a physical port therefore the check for physical
interfaces. If you want to use KNI for something else there's nothing
stopping you from starting a DPDK app and adding a KNI interface
without having a real NIC bound to DPDK.

I don't have a better example right now but, if you want, you can take
a look at how we do it in warp17 (using DPDK) when you start it
without any physical interfaces:

https://github.com/Juniper/warp17#using-kernel-network-interface-kni-interfaces

If you look at the HTTP example there we actually start the
application without any physical interfaces (only one KNI):

./build/warp17 -c FC3 -n 4  -m 32768 -- --kni-ifs 1


> Thanks,
> Vlad

Hope this helps..

Regards,
Dumitru

>
>
>
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-- 
Dumitru Ceara

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