Re: [PATCH net-next 0/2] DSA trace events

[Steven Rostedt <rostedt@goodmis.org>]

On Fri, 21 Apr 2023 15:47:08 +0300
Vladimir Oltean <vladimir.oltean@nxp.com> wrote:

> On Fri, Apr 21, 2023 at 09:38:50PM +0900, Masami Hiramatsu wrote:
> > If the subsystem maintainers are OK for including this, it is OK.
> > But basically, since the event is exposed to userland and you may keep
> > these events maintained, you should carefully add the events.
> > If those are only for debugging (after debug, it will not be used
> > frequently), can you consider to use kprobe events?
> > 'perf probe' command will also help you to trace local variables and
> > structure members as like gdb does.  
> 
> Thanks for taking a look. I haven't looked at kprobe events. I also
> wasn't planning on maintaining these assuming stable UABI terms, just
> for debugging. What are some user space consumers that expect the UABI
> to be stable, and what is it about the trace events that can/can't change?

Ideally, tooling will use the libtraceevent library[1] to parse the
events. In that case, if an event is used by tooling, you'll need to
keep around the fields that are used by the tooling.

-- Steve

[1] https://git.kernel.org/pub/scm/libs/libtrace/libtraceevent.git/