[ovs-discuss] question regarding utilities/nlmon.c tool

Mohammad Heib mheib at redhat.com
Tue Nov 9 16:05:05 UTC 2021


hi folks,
i was looking for a way to monitor OVS TC Netlink messages that OVS sends
to TC when HW offloads are on (mostly for testing HWOL over non-supported
HW offload system ).

as i understood, those Netlink's messages will be sent back from the kernel
to TC Netlink multicast group after the TC subsystem is finished processing
those requests, and the userspace process can capture them by listing to
the appropriate group.

unfortunately, i didn't find any tool that give me the ability to capture
and parse (print) those TC Netlink messages.
so I started to implement my own tool but after a few more investigations I
found that nlmon already implement similar behavior for capturing Netlink
Link changes messages.

so I was wondering if:
1. I can convert nlmon code to be more generic and easier to add and
monitor new Netlink groups?
2. can I add Netlink TC messages monitoring implementation to nlmon?

if the answer to 2 was yes :) ,
I have some dependencies that need to be included from linux/pkt_cls.h
which is a kernel header file and not sure if I can include it in nlmon ?
is that possible to include this file in nlmon.c? or is it ok to copy those
dependencies to a local file (maybe nlmon.h) especially that most of those
dependencies are enums and defines (e.g TCA_*/TCA_FLOWER_*)?.

Thanks,
Mohammad
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