[ovs-dev] [RFC] dpdk: Deprecate pdump support.

[Flavio Leitner]

Hi Ilya,

On Fri,  1 Nov 2019 13:06:33 +0100
Ilya Maximets <i.maximets at ovn.org> wrote:

> The conventional way for packet dumping in OVS is to use ovs-tcpdump
> that works via traffic mirroring.  DPDK pdump could probably be used
> for some lower level debugging, but it is not commonly used for
> various reasons.
> 
> There are lots of limitations for using this functionality in
> practice. Most of them connected with running secondary pdump process
> and memory layout issues like requirement to disable ASLR in kernel.
> More details are available in DPDK guide:
> https://doc.dpdk.org/guides/prog_guide/multi_proc_support.html#multi-process-limitations
> 
> Beside the functional limitations it's also hard to use this
> functionality correctly.  User must be sure that OVS and pdump utility
> are running on different CPU cores, which is hard because non-PMD
> threads could float over available CPU cores.  This or any other
> misconfiguration will likely lead to crash of the pdump utility
> or/and OVS.
> 
> Another problem is that the user must actually have this special pdump
> utility in a system and it might be not available in distributions.
> 
> This change disables pdump support by default introducing special
> configuration option '--enable-dpdk-pdump'.  Deprecation warnings will
> be shown to users on configuration and in runtime.

The deprecation idea sounds good to me, but I don't see a reason to
break the existing behavior if we are going to remove that later on.
Wouldn't just the deprecation notice for next release be sufficient
and then we remove in the after release?

fbl