[dpdk-dev] rte_kni.ko with lo_mode=lo_mode_ring

[Ferruh Yigit]

On 9/2/2016 3:16 PM, Wiles, Keith wrote:
> HI Gary,
> 
> Regards,
> Keith
> 
>> On Sep 2, 2016, at 8:39 AM, Mussar, Gary <gmussar at ciena.com> wrote:
>>
>> The pktgen docs state that the rte_kni.ko should be loaded with lo_mode=lo_mode_ring however the source in dpdk master does not appear to understand this value. This wasn't an issue in the past since the kni code would simply disable lo_mode if you passed in an unknown value.
>>
>> The Ubuntu 4.4.0-36-generic kernel no longer loads the module if the passed value is not in the table of known values (the 4.4.0-34-generic kernel would still load the module).
>>
>> I have 2 questions:
>> 1)
>> Why does pktgen specify using a value for lo_mode that the source does not support? Is lo_mode_ring something that is coming but not yet submitted?
> 
> The KNI support and kernel module is more of a DPDK issue then Pktgen, which is the application on top of DPDK. I do not know the reason lo_mode_ring is not working correctly. Look in the Maintainers file and see who maintains the KNI code.

"lo_mode_ring" is not supported loopback mode, supported ones are:
lo_mode_none
lo_mode_fifo
lo_mode_fifo_skb

Please point the document with incorrect usage.

> 
>>
>> 2)
>> Is the Ubuntu kernel being over aggressive in parameter checking or is this a "good" thing? If it is good, then should the pktgen docs be indicating that an unsupported value be used for lo_mode?
> 
> I assume the Ubuntu Kernel is attempting to protect itself. Each time the kernel is updated it is a good think to recompile DPDK and the KNI kernel module or the module may not load because of a version mis-match.

Yes this looks like the issue,
instead of kernel version or parameter protection, kernel-module version
mismatch. Please re-compile kni module.

> 
>>
>> Gary
>